Federico Zuckermann - Academia.edu (original) (raw)

Papers by Federico Zuckermann

American Journal of Reproductive Immunology and Microbiology, 1987

Recent technological advances have provided methods of detecting antigens encoded by the major hi... more Recent technological advances have provided methods of detecting antigens encoded by the major histocompatibility complex with greater precision, allowing the expression of such antigens on the components of the placenta to be clarified. Of specific interest is the expression of these antigens on trophoblast cells, the fetal-derived epithelial cells that confront maternal blood and tissues at the maternal-fetal interface. It is now clear that the different trophoblast subpopulations differentially express class I antigens, although none appear to express class II antigens. Class I antigens can be induced by exposure to interferons on some populations but apparently not others, suggesting that the regulation of their expression differs for subpopulations of trophoblast cells, depending on gestational stage and location. This restricted expression has important implications for maternal-fetal immune interactions during the different phases of pregnancy and perhaps also bears on physiological functions of the feto-placental unit, such as growth and differentiation.

Anaporc Revista De La Asociacion De Porcinocultura Cientifica, 2004

The Journal of Immunology

Veterinary Immunology and Immunopathology, 1994

The porcine T-cell population is unique in that there is a large percentage of CD+CD8+ dual expre... more The porcine T-cell population is unique in that there is a large percentage of CD+CD8+ dual expressing peripheral T-cells. This paper reviews the data available on these porcine T-cells and compares them to the much rarer dual expressing T-cells in humans. The percent of dual expressing cells increases with activation in in vitro culture with various antigens including pseudorabies virus. The percent of resting dual expressing cells also increases with the age of the pig. Flow-cytometric-sorted dual expressing cells responded in culture to the super antigen staphylococcal enterotoxin B. Selected CD4+CD8- cells cultured in vitro developed expression of CD8 and maintained the dual expressing phenotype for the 12 weeks of culture. Dual expressing cells freshly prepared from porcine blood did not express the IL-2 receptor as demonstrated by their failure to bind FITC-IL-2 and an anti-porcine IL-2 receptor monoclonal antibody. In response to activation with phorbol myristic acetate, CD4, but not CD8, was down regulated on the dual expressing T-cells. In summary, porcine dual expressing T-cells constitute a substantial percentage of the porcine peripheral T-cell pool. These cells appear to contain the majority of the memory T-cell with their frequency increasing with blood donor age and in vitro culture. Although the receptor specificity is not known, they have a functional receptor. Finally, the function of the two accessory molecules CD4 and CD8 in these cells is not known, but their regulation is distinct, thereby suggesting no equivalent roles in immune function.

Journal of the American Veterinary Medical Association, 1992

Immunosuppression suspected to be associated with retrovirus infection was diagnosed in an 18-mon... more Immunosuppression suspected to be associated with retrovirus infection was diagnosed in an 18-month-old female llama. The llama had a 6-month history of weight loss, intermittent lameness, and infections that were nonresponsive to treatment. Serial CBC indicated persistent nonregenerative anemia and leukopenia characterized by absolute neutropenia and lymphopenia. Functional hypoplasia of myeloid and erythroid cell lines was detected in serial bone marrow biopsy specimens. Notable pathologic findings included inadequate hematopoiesis, generalized lymphoid hypoplasia and plasma cell depletion, and pulmonary alveolar histiocytosis. Pneumocystis carinii cysts and viral particles of the size and morphologic features consistent with the retrovirus family were observed in lung sections examined by transmission electron microscopy. Antemortem macrophage and postmortem lymph node cultures were positive for reverse transcriptase activity.

Virus Research, 2012

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant swine pathogen which... more Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant swine pathogen which exhibits considerable sequence diversity. In an attempt to identify highly conserved T-cell epitopes contained in proteins of this virus, we examined heptadecamer peptides spanning the sequence of the PRRSV nonstructural proteins (NSPs) 9 and 10, both of which are highly conserved, for their ability to elicit a recall proliferative and interferon-gamma response in peripheral blood mononuclear cells obtained from pigs immunized against the type-II PRRSV strain FL-12. These studies led to the identification of four peptides, two from each NSP9 and NSP10 that appear to contain T-cell epitopes. Comparison of the amino acid sequence of these four peptide sequences to the analogous sequences from a diverse sample of type-II PRRSV strains indicated that these sequences are highly conserved and thus contain highly conserved T-cell epitopes. The identified epitopes may be important in the formulation of immunogens to provide broad cross-protection against diverse PRRSV strains.

Virus Research, 2010

Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on ... more Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre-including this research content-immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

Veterinary Research, 2000

Several studies were conducted to evaluate the characteristics of the immunity induced by infecti... more Several studies were conducted to evaluate the characteristics of the immunity induced by infection with wild type PRRS virus or vaccination with a PRRS modified live virus (MLV) vaccine. By monitoring the kinetics of the immune response to virus we made several remarkable observations. As a result of either infection with wild type PRRS virus or vaccination with a PRRS MLV vaccine, an antibody response was readily detectable by ELISA within 2 weeks after the administration of virus. A striking observation resulting from this research is that the generation of immunity able to mediate virus-inhibitory function, i.e., virus neutralizing antibodies and interferon gamma (IFN-$\gamma$)-producing T cells, becomes detectable only several weeks after exposure of pigs to either wild type virus or a MLV vaccine. The presence of virus-specific IFN-$\gamma$-producing cells was not frankly detectable until 8 to 10 weeks after virus administration. However, even then the frequency was fairly low as compared to the frequency of virus-specific cells induced by an Aujeszky's disease virus (ADV) MLV vaccine. In animals inoculated with the wild-type PRRS virus, the frequency of PRRS virus-specific IFN-$\gamma$-producing cells increased gradually over time so that by 9-10 months after infection it was comparable to the frequency induced by the administration of an ADV MLV vaccine within 2-3 weeks. By 12 months after infection with wild-type PRRS virus the titer of antibodies against this virus declines significantly, becoming even undetectable by ELISA in at least 30% of the pigs. In contrast, the intensity and quality of the virus-specific IFN-$\gamma$ response increases in both quality and quantity. Of note was the observation that the IFN-$\gamma$ ELISPOT remained at the same level in all animals infected with the wild-type virus from 300 to 690 days post infection (latest time tested). In contrast, during this time the presence of anti-PRRS virus antibodies in the serum of these animals decreased, so that at 690 days after infection 80% of the animals became negative by PRRSV IDEXX ELISA test. This is despite the fact that the frequency of IFN-$\gamma$-producing cells remained at the same level as that of the measurement at 300 days post infection. Although the reason for the delayed PRRS virus-inhibitory immune response is unclear at this time, we have evidence indicating that accessory cell-derived cytokines such as IL-12 and IL-10 are able to enhance and suppress, respectively, the intensity of the virus-specific cellular immune response at least in vitro. The complexity of the regulation of the immune response of pigs to PRRS virus is clearly indicated by the concomitant gradual decline of humoral immunity while the cell-mediated immunity increases. The rational development of effective PRRS virus vaccines requires an understanding of the mechanisms that regulate the kinetics, quality and intensity of the humoral and cellular immunity against this virus. Given the economic losses attributed to this disease this information is urgently needed. Based on these observations, it seems reasonable to postulate that an intrinsic property of PRRS virus is responsible for the inefficient stimulation of potentially protective immunity at least in the short term, namely, virus-neutralizing antibodies and IFN-$\gamma$-producing T cells. Although the reason(s) behind the poor immunogenicity of PRRS virus are unknown, we are currently examining several possibilities. We believe that clarification of this issue is essential for the development and formulation of a highly immunogenic and effective PRRS vaccine

Veterinary Research, 2000

An understanding of the role that different types of immune effector mechanisms have in mediating... more An understanding of the role that different types of immune effector mechanisms have in mediating protective immunity against virus diseases of swine is key to the development of effective vaccines for this species. The abundant literature available on the efficacy of vaccines against Aujeszky's disease virus (ADV) has provided evidence that inactivated ADV vaccines are not as effective as modified live virus (MLV) vaccines at stimulating protective immunity. The fact that similar titers of virus-neutralizing antibodies are present in pigs receiving either type of vaccine has fueled the speculation that cell-mediated immunity must therefore be responsible for mediating protection from disease. Certainly, the lesser ability of inactivated ADV vaccines to provide protective immunity must reflect the inability of this type of vaccine to induce sufficient levels of immune effector mechanism(s) important for protection. However, the exact nature of this deficit is unknown. We have examined this issue by measuring the serum titer of virus-neutralizing antibodies and the frequency of ADV-specific interferon-gamma (IFN-$\gamma$)-producing cells in the peripheral blood mononuclear cells of pigs after immunization with either inactivated or MLV ADV vaccines. We found that while both MLV and inactivated vaccines are able to induce similar levels of neutralizing antibodies, an inactivated vaccine is not as effective as a MLV vaccine at stimulating ADV-specific IFN-$\gamma$-producing cells. Indeed we found a correlation between the intensity of this response and the level of protective immunity. This correlation was further confirmed by the observation that pigs immunized with inactivated virus in combination with either human recombinant IL-12 or an oil-in-water adjuvant, develop an enhanced IFN-$\gamma$ response and level of protective immunity, as compared to pigs receiving the inactivated virus alone. In contrast, the titer of virus neutralizing antibodies produced in response to the inactivated vaccine was mildly affected by either of these adjuvants. The data obtained clearly show that there are differences in the quality and quantity of the immunity induced by a live versus an inactivated ADV vaccine. While inactivated commercial vaccines are equally efficient as a MLV vaccine at inducing humoral immunity, they only induce a weak and transient virus-specific IFN-$\gamma$ response. In contrast, a MLV vaccine induces a robust virus-specific IFN-$\gamma$ response. In all of the different ADV vaccine formulations tested in our experiments, a high level of protective immunity correlated with the presence of a strong IFN-$\gamma$ response, while the titer of virus-neutralizing antibodies did not. Although the results from this study do not rule out a role for humoral immunity in protection, they do suggest that cell-mediated immunity participate in providing a high degree of protective immunity. The data presented argue in favor of the notion that the level of cell-mediated immunity is a major factor in determining the level of protection from ADV-induced disease. At the very minimum, a strong IFN-$\gamma$ response in a pig is a good predictor that the animal has developed a strong protective immune response against this virus

Veterinary Microbiology, 2000

In¯uenza is a common respiratory disease in pigs, and since swine in¯uenza viruses are zoonotic p... more In¯uenza is a common respiratory disease in pigs, and since swine in¯uenza viruses are zoonotic pathogens, they also pose human health risks. Pigs infected with in¯uenza virus mount an effective immune response and are protected from subsequent challenge, whereas the currently available, inactivated-virus vaccine does not consistently confer complete protection to challenge. To develop and evaluate new vaccination strategies, it is imperative to fully understand the immune responses that are associated with protection following natural infection. Therefore, we have evaluated the phenotype and kinetics of immune responses to primary and re-challenge infection with H1N1 swine in¯uenza virus in the pig. Through the use of isotype-speci®c antibody secreting cell ELISPOT assays, interferon-g ELISPOT assays and isotype-speci®c ELISAs on serum, nasal wash and bronchoalveolar lavage samples, we de®ned the humoral and cellular immune responses, both locally in the respiratory tract and systemically, to this viral infection. Virus-speci®c serum IgG, IgA, and HI titers all peaked 2±3 weeks after primary infection and did not substantially increase after re-challenge. The predominant virus-speci®c isotype in serum was IgG. Pigs responded with virus-speci®c IgG and IgA in both the upper (nasal washes) and lower (bronchoalveolar lavages) airways; IgA was the predominant isotype in both sites. Despite the fact that the pigs were completely protected from re-challenge, the antibody titers in the nasal washes increased. Results of the antibody-secreting cell ELISPOT assays demonstrated that the numbers of both IgG and IgA secreting cells in the nasal mucosa were dramatically higher than in any other tissue examined. In contrast, IFN-g secreting cells were predominantly localized to the spleen and tracheobronchial lymph nodes. These data will be helpful in the future development and evaluation of novel vaccines.

Veterinary Immunology and Immunopathology, 1999

Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucohemorrhagic diarrhoea r... more Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucohemorrhagic diarrhoea resulting in significant economic losses to swine producers. The pathogenesis of this disease is poorly understood. Regardless, commercial vaccines have been developed and are in use. Thus, the present study was designed to examine cellular immune responses induced by parenteral S. hyodysenteriae vaccination. Significant antigen-specific interferon-gamma (IFN-gamma) and blastogenic responses were detected from peripheral blood lymphocytes isolated from vaccinated pigs. However, poor IFN-gamma responses were detected from colonic lymph node lymphocytes from these same pigs despite significant antigen-specific blastogenic responses. In addition, peripheral blood IFN-gamma responses were diminished by either in vitro depletion of CD4 expressing cells or by in vitro treatment with porcine IL-10. Colonic lymph node IFN-gamma responses were not inhibited by treatment with porcine IL-10. Vaccination also resulted in increased percentages of both mucosal and peripheral blood CD8 single positive cells with concurrent decreases in percentages of CD4 single positive cells as compared to percentages of these same populations from non-vaccinated pigs. In conclusion, these studies show that parenteral S. hyodysenteriae vaccination results in cellular immune responses detectable both peripherally (systemic immunity) as well as at the site of infection (mucosal immunity). However, it appears that regulatory mechanisms affecting IFN-gamma production in response to S. hyodysenteriae antigen differ between peripheral and colonic compartments.

Veterinary Immunology and Immunopathology, 1998

After initial evaluation of the 176 new and 19 control monoclonal antibodies (mAb) submitted to t... more After initial evaluation of the 176 new and 19 control monoclonal antibodies (mAb) submitted to the Second International Swine CD Workshop, 57 were assigned to the T-cell/activation marker subgroup. These 57 mAb were further analyzed using flow cytometry on whole blood lymphocytes, splenocytes, Peyer's patch lymphocytes, in vitro cell lines, broncho-alveolar lavage cells, Con A and PHA blasts, fetal cell populations, and by 2-color flow cytometry against mAb to porcine CD2, CD4, and CD8. Finally, the molecular weights of the target antigens were characterized when possible. As a result of these analyses, 23 mAb were distributed into 7 CD clusters. Newly confirmed mAb assignments included: two CD2; one CD4; two CD5; one wCD6; and one wCD25. Three new mAb were found that reacted with wCD8, one of which defined a new epitope, wCD8c. For the first time, mAb against porcine CD3 were identified, including 6 mAb that reacted with three different epitopes. Several new mAb reacted with antigens whose expression varied depending on the activation state of the test cell. These will require further characterization in order to assign a CD number.

Veterinary Immunology and Immunopathology, 1999

Mature T lymphocytes expressing the alphabeta T cell receptor are generally classified as either ... more Mature T lymphocytes expressing the alphabeta T cell receptor are generally classified as either CD4+ or CD8+, based on the mutually exclusive expression of these two lymphocyte coreceptors. Contrary to this conventional division, there is considerable evidence that significant numbers of CD4/CD8 double positive (DP) lymphocytes exist in the peripheral blood and secondary lymphoid tissues of swine, chickens and monkeys. Although CD4/CD8 DP T cells are rarely present in human peripheral blood the relative percentage of this lymphocyte population can increase spontaneously in healthy individuals and in persons suffering from certain disease conditions. DP can also be found among those T cells infiltrating arthritic joints, rejected kidney grafts and certain tumors. In humans, and rats, CD4/CD8 DP T cells appear transiently following activation of their progenitors. Murine DP cells have been described as a subset of intraepithelial lymphocytes (IELs). However, the relationship of IELs to DP cells in the peripheral blood of other species is unknown. Because of their unconventional phenotype and rarity in human and mice, most immunologists have ignored extrathymic CD4/CD8 DP lymphocytes. Nevertheless, their abundance in the peripheral blood of swine, monkeys and chickens makes it impossible to dismiss this lymphocyte population. Here are reports that have described extrathymic lymphocytes exhibiting a CD4+CD8dim phenotype in several species reviewed. Swine and monkey lymphocytes with this phenotype are represented by small resting cells that simultaneously express CD4 and CD8alpha molecules. The available evidence favors the notion that such DP T cells in swine are comprised predominantly of MHC class II restricted memory CD4+ helper T cells that after activation have acquired the ability to express the CD8alpha chain and then to maintain this DP phenotype. Moreover, porcine CD4/CD8 DP T cells appear to be comprised of memory cells due to their ability to respond to recall antigen, resilience to thymectomy, increase in proportion with age, expression of memory T cell markers, production of interferon-gamma and localization to inflammatory sites. Some of these characteristics are also descriptive of human and monkey CD4/CD8 DP T cells. Thus, in swine, humans and monkeys, these phenotypically distinct lymphocytes appear to represent a primed T cell subset. The possible functional significance of the simultaneous expression of the CD4 and CD8 co-receptors on mature T cells is discussed.

Tuberculosis, 2014

Tuberculosis is an important health concern for Asian elephant (Elephas maximus) populations worl... more Tuberculosis is an important health concern for Asian elephant (Elephas maximus) populations worldwide, however, mechanisms underlying susceptibility to Mycobacterium tuberculosis are unknown. Proliferative responses assessed via brominated uridine incorporation and cytokine expression measured by real-time RT-PCR were evaluated in peripheral blood mononuclear cell (PBMC) cultures from 8 tuberculosis negative and 8 positive Asian elephants. Cultures were stimulated with Mycobacterium bovis purified protein derivative (PPD-B), M. tuberculosis culture filtrate protein (CFP)-10, and Mycobacterium avium PPD (PPD-A). Following stimulation with PPD-B, proliferation was higher (a ¼ 0.005) in positive samples; no significant differences were detected following CFP-10 or PPD-A stimulation. Tumor necrosis factor (TNF)-a, interleukin (IL)-12, and interferon (IFN)-g expression was greater in samples from positive elephants following stimulation with PPD-B (a ¼ 0.025) and CFP-10 (a ¼ 0.025 TNF-a and IL-12; a ¼ 0.005 IFN-g). Stimulation with PPD-A also produced enhanced IL-12 expression in positive samples (a ¼ 0.025). Findings suggested that differences in immune cell function exist between tuberculosis positive and negative elephants. Proliferative responses and expression of TNF-a, IL-12, and IFN-g in response to stimulation with PPD-B and CFP-10 differ between tuberculosis positive and negative elephants, suggesting these parameters may be important to tuberculosis immunopathogenesis in this species.

Journal of Veterinary Diagnostic Investigation, 1991

The effect of altering the strain of the test virus used in the standardized pseudorabies virus n... more The effect of altering the strain of the test virus used in the standardized pseudorabies virus neutralization (VN) test on the sensitivity of the assay was evaluated. Comparative VN tests were performed using 4 different strains: the avirulent Bartha parental, the avirulent recombinant Bartha gIII Ka , the moderately virulent Shope (currently used for the VN test at the National Veterinary Services Laboratory, Ames, IA), and the highly virulent P2208 (Funkhauser). A radioimmunoassay and a Western immunoblotting technique were employed to verify the presence of anti-pseudorabies virus (PrV) antibodies in sera. Statistical analysis indicated that replacement of the Shope strain by the Bartha gIII Ka or the P2208 strain resulted in VN titers that were 4.23-and 2.00-fold higher, respectively. Despite these differences, specificity with regard to PrV diagnosis was unaltered. This apparent enhancement of the sensitivity of the PrV VN test would be beneficial for the serologic identification of PrV-infected animals during an eradication effort. Since its inception, the virus neutralization (VN) microtitration test 12 has been an important serologic means to identify virus-infected animals. The VN test has been standardized for the detection of anti-pseudorabies virus (PrV) antibodies in swine using the PrV-Shope strain 9 and has become the "gold standard" against which newly developed serologic diagnostic tests are compared. However, questions still remain concerning the sensitivity and the specificity of the standardized PrV VN test. In addition, serum toxicity to the cells used in the VN test continues to be a problem for both the practitioner and the diagnostician. Most states involved in a PrV eradication program use a serum dilution of 1:4 as the cutoff for reporting positive anti-PrV antibody VN titer results. Some states, such as Illinois, use the 1:8 dilution in their eradication effort. This criterion helps avoid some difficulties due to serum toxicity and what is empirically thought by some to be nonspecific results (false positives) at the lower serum dilutions. A number of serologic assays for pseudorabies diagnosis have been developed.

American Journal of Reproductive Immunology and Microbiology, 1987

Recent technological advances have provided methods of detecting antigens encoded by the major hi... more Recent technological advances have provided methods of detecting antigens encoded by the major histocompatibility complex with greater precision, allowing the expression of such antigens on the components of the placenta to be clarified. Of specific interest is the expression of these antigens on trophoblast cells, the fetal-derived epithelial cells that confront maternal blood and tissues at the maternal-fetal interface. It is now clear that the different trophoblast subpopulations differentially express class I antigens, although none appear to express class II antigens. Class I antigens can be induced by exposure to interferons on some populations but apparently not others, suggesting that the regulation of their expression differs for subpopulations of trophoblast cells, depending on gestational stage and location. This restricted expression has important implications for maternal-fetal immune interactions during the different phases of pregnancy and perhaps also bears on physiological functions of the feto-placental unit, such as growth and differentiation.

Anaporc Revista De La Asociacion De Porcinocultura Cientifica, 2004

The Journal of Immunology

Veterinary Immunology and Immunopathology, 1994

The porcine T-cell population is unique in that there is a large percentage of CD+CD8+ dual expre... more The porcine T-cell population is unique in that there is a large percentage of CD+CD8+ dual expressing peripheral T-cells. This paper reviews the data available on these porcine T-cells and compares them to the much rarer dual expressing T-cells in humans. The percent of dual expressing cells increases with activation in in vitro culture with various antigens including pseudorabies virus. The percent of resting dual expressing cells also increases with the age of the pig. Flow-cytometric-sorted dual expressing cells responded in culture to the super antigen staphylococcal enterotoxin B. Selected CD4+CD8- cells cultured in vitro developed expression of CD8 and maintained the dual expressing phenotype for the 12 weeks of culture. Dual expressing cells freshly prepared from porcine blood did not express the IL-2 receptor as demonstrated by their failure to bind FITC-IL-2 and an anti-porcine IL-2 receptor monoclonal antibody. In response to activation with phorbol myristic acetate, CD4, but not CD8, was down regulated on the dual expressing T-cells. In summary, porcine dual expressing T-cells constitute a substantial percentage of the porcine peripheral T-cell pool. These cells appear to contain the majority of the memory T-cell with their frequency increasing with blood donor age and in vitro culture. Although the receptor specificity is not known, they have a functional receptor. Finally, the function of the two accessory molecules CD4 and CD8 in these cells is not known, but their regulation is distinct, thereby suggesting no equivalent roles in immune function.

Journal of the American Veterinary Medical Association, 1992

Immunosuppression suspected to be associated with retrovirus infection was diagnosed in an 18-mon... more Immunosuppression suspected to be associated with retrovirus infection was diagnosed in an 18-month-old female llama. The llama had a 6-month history of weight loss, intermittent lameness, and infections that were nonresponsive to treatment. Serial CBC indicated persistent nonregenerative anemia and leukopenia characterized by absolute neutropenia and lymphopenia. Functional hypoplasia of myeloid and erythroid cell lines was detected in serial bone marrow biopsy specimens. Notable pathologic findings included inadequate hematopoiesis, generalized lymphoid hypoplasia and plasma cell depletion, and pulmonary alveolar histiocytosis. Pneumocystis carinii cysts and viral particles of the size and morphologic features consistent with the retrovirus family were observed in lung sections examined by transmission electron microscopy. Antemortem macrophage and postmortem lymph node cultures were positive for reverse transcriptase activity.

Virus Research, 2012

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant swine pathogen which... more Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant swine pathogen which exhibits considerable sequence diversity. In an attempt to identify highly conserved T-cell epitopes contained in proteins of this virus, we examined heptadecamer peptides spanning the sequence of the PRRSV nonstructural proteins (NSPs) 9 and 10, both of which are highly conserved, for their ability to elicit a recall proliferative and interferon-gamma response in peripheral blood mononuclear cells obtained from pigs immunized against the type-II PRRSV strain FL-12. These studies led to the identification of four peptides, two from each NSP9 and NSP10 that appear to contain T-cell epitopes. Comparison of the amino acid sequence of these four peptide sequences to the analogous sequences from a diverse sample of type-II PRRSV strains indicated that these sequences are highly conserved and thus contain highly conserved T-cell epitopes. The identified epitopes may be important in the formulation of immunogens to provide broad cross-protection against diverse PRRSV strains.

Virus Research, 2010

Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on ... more Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre-including this research content-immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

Veterinary Research, 2000

Several studies were conducted to evaluate the characteristics of the immunity induced by infecti... more Several studies were conducted to evaluate the characteristics of the immunity induced by infection with wild type PRRS virus or vaccination with a PRRS modified live virus (MLV) vaccine. By monitoring the kinetics of the immune response to virus we made several remarkable observations. As a result of either infection with wild type PRRS virus or vaccination with a PRRS MLV vaccine, an antibody response was readily detectable by ELISA within 2 weeks after the administration of virus. A striking observation resulting from this research is that the generation of immunity able to mediate virus-inhibitory function, i.e., virus neutralizing antibodies and interferon gamma (IFN-$\gamma$)-producing T cells, becomes detectable only several weeks after exposure of pigs to either wild type virus or a MLV vaccine. The presence of virus-specific IFN-$\gamma$-producing cells was not frankly detectable until 8 to 10 weeks after virus administration. However, even then the frequency was fairly low as compared to the frequency of virus-specific cells induced by an Aujeszky's disease virus (ADV) MLV vaccine. In animals inoculated with the wild-type PRRS virus, the frequency of PRRS virus-specific IFN-$\gamma$-producing cells increased gradually over time so that by 9-10 months after infection it was comparable to the frequency induced by the administration of an ADV MLV vaccine within 2-3 weeks. By 12 months after infection with wild-type PRRS virus the titer of antibodies against this virus declines significantly, becoming even undetectable by ELISA in at least 30% of the pigs. In contrast, the intensity and quality of the virus-specific IFN-$\gamma$ response increases in both quality and quantity. Of note was the observation that the IFN-$\gamma$ ELISPOT remained at the same level in all animals infected with the wild-type virus from 300 to 690 days post infection (latest time tested). In contrast, during this time the presence of anti-PRRS virus antibodies in the serum of these animals decreased, so that at 690 days after infection 80% of the animals became negative by PRRSV IDEXX ELISA test. This is despite the fact that the frequency of IFN-$\gamma$-producing cells remained at the same level as that of the measurement at 300 days post infection. Although the reason for the delayed PRRS virus-inhibitory immune response is unclear at this time, we have evidence indicating that accessory cell-derived cytokines such as IL-12 and IL-10 are able to enhance and suppress, respectively, the intensity of the virus-specific cellular immune response at least in vitro. The complexity of the regulation of the immune response of pigs to PRRS virus is clearly indicated by the concomitant gradual decline of humoral immunity while the cell-mediated immunity increases. The rational development of effective PRRS virus vaccines requires an understanding of the mechanisms that regulate the kinetics, quality and intensity of the humoral and cellular immunity against this virus. Given the economic losses attributed to this disease this information is urgently needed. Based on these observations, it seems reasonable to postulate that an intrinsic property of PRRS virus is responsible for the inefficient stimulation of potentially protective immunity at least in the short term, namely, virus-neutralizing antibodies and IFN-$\gamma$-producing T cells. Although the reason(s) behind the poor immunogenicity of PRRS virus are unknown, we are currently examining several possibilities. We believe that clarification of this issue is essential for the development and formulation of a highly immunogenic and effective PRRS vaccine

Veterinary Research, 2000

An understanding of the role that different types of immune effector mechanisms have in mediating... more An understanding of the role that different types of immune effector mechanisms have in mediating protective immunity against virus diseases of swine is key to the development of effective vaccines for this species. The abundant literature available on the efficacy of vaccines against Aujeszky's disease virus (ADV) has provided evidence that inactivated ADV vaccines are not as effective as modified live virus (MLV) vaccines at stimulating protective immunity. The fact that similar titers of virus-neutralizing antibodies are present in pigs receiving either type of vaccine has fueled the speculation that cell-mediated immunity must therefore be responsible for mediating protection from disease. Certainly, the lesser ability of inactivated ADV vaccines to provide protective immunity must reflect the inability of this type of vaccine to induce sufficient levels of immune effector mechanism(s) important for protection. However, the exact nature of this deficit is unknown. We have examined this issue by measuring the serum titer of virus-neutralizing antibodies and the frequency of ADV-specific interferon-gamma (IFN-$\gamma$)-producing cells in the peripheral blood mononuclear cells of pigs after immunization with either inactivated or MLV ADV vaccines. We found that while both MLV and inactivated vaccines are able to induce similar levels of neutralizing antibodies, an inactivated vaccine is not as effective as a MLV vaccine at stimulating ADV-specific IFN-$\gamma$-producing cells. Indeed we found a correlation between the intensity of this response and the level of protective immunity. This correlation was further confirmed by the observation that pigs immunized with inactivated virus in combination with either human recombinant IL-12 or an oil-in-water adjuvant, develop an enhanced IFN-$\gamma$ response and level of protective immunity, as compared to pigs receiving the inactivated virus alone. In contrast, the titer of virus neutralizing antibodies produced in response to the inactivated vaccine was mildly affected by either of these adjuvants. The data obtained clearly show that there are differences in the quality and quantity of the immunity induced by a live versus an inactivated ADV vaccine. While inactivated commercial vaccines are equally efficient as a MLV vaccine at inducing humoral immunity, they only induce a weak and transient virus-specific IFN-$\gamma$ response. In contrast, a MLV vaccine induces a robust virus-specific IFN-$\gamma$ response. In all of the different ADV vaccine formulations tested in our experiments, a high level of protective immunity correlated with the presence of a strong IFN-$\gamma$ response, while the titer of virus-neutralizing antibodies did not. Although the results from this study do not rule out a role for humoral immunity in protection, they do suggest that cell-mediated immunity participate in providing a high degree of protective immunity. The data presented argue in favor of the notion that the level of cell-mediated immunity is a major factor in determining the level of protection from ADV-induced disease. At the very minimum, a strong IFN-$\gamma$ response in a pig is a good predictor that the animal has developed a strong protective immune response against this virus

Veterinary Microbiology, 2000

In¯uenza is a common respiratory disease in pigs, and since swine in¯uenza viruses are zoonotic p... more In¯uenza is a common respiratory disease in pigs, and since swine in¯uenza viruses are zoonotic pathogens, they also pose human health risks. Pigs infected with in¯uenza virus mount an effective immune response and are protected from subsequent challenge, whereas the currently available, inactivated-virus vaccine does not consistently confer complete protection to challenge. To develop and evaluate new vaccination strategies, it is imperative to fully understand the immune responses that are associated with protection following natural infection. Therefore, we have evaluated the phenotype and kinetics of immune responses to primary and re-challenge infection with H1N1 swine in¯uenza virus in the pig. Through the use of isotype-speci®c antibody secreting cell ELISPOT assays, interferon-g ELISPOT assays and isotype-speci®c ELISAs on serum, nasal wash and bronchoalveolar lavage samples, we de®ned the humoral and cellular immune responses, both locally in the respiratory tract and systemically, to this viral infection. Virus-speci®c serum IgG, IgA, and HI titers all peaked 2±3 weeks after primary infection and did not substantially increase after re-challenge. The predominant virus-speci®c isotype in serum was IgG. Pigs responded with virus-speci®c IgG and IgA in both the upper (nasal washes) and lower (bronchoalveolar lavages) airways; IgA was the predominant isotype in both sites. Despite the fact that the pigs were completely protected from re-challenge, the antibody titers in the nasal washes increased. Results of the antibody-secreting cell ELISPOT assays demonstrated that the numbers of both IgG and IgA secreting cells in the nasal mucosa were dramatically higher than in any other tissue examined. In contrast, IFN-g secreting cells were predominantly localized to the spleen and tracheobronchial lymph nodes. These data will be helpful in the future development and evaluation of novel vaccines.

Veterinary Immunology and Immunopathology, 1999

Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucohemorrhagic diarrhoea r... more Serpulina hyodysenteriae infection of pigs, swine dysentery, causes a mucohemorrhagic diarrhoea resulting in significant economic losses to swine producers. The pathogenesis of this disease is poorly understood. Regardless, commercial vaccines have been developed and are in use. Thus, the present study was designed to examine cellular immune responses induced by parenteral S. hyodysenteriae vaccination. Significant antigen-specific interferon-gamma (IFN-gamma) and blastogenic responses were detected from peripheral blood lymphocytes isolated from vaccinated pigs. However, poor IFN-gamma responses were detected from colonic lymph node lymphocytes from these same pigs despite significant antigen-specific blastogenic responses. In addition, peripheral blood IFN-gamma responses were diminished by either in vitro depletion of CD4 expressing cells or by in vitro treatment with porcine IL-10. Colonic lymph node IFN-gamma responses were not inhibited by treatment with porcine IL-10. Vaccination also resulted in increased percentages of both mucosal and peripheral blood CD8 single positive cells with concurrent decreases in percentages of CD4 single positive cells as compared to percentages of these same populations from non-vaccinated pigs. In conclusion, these studies show that parenteral S. hyodysenteriae vaccination results in cellular immune responses detectable both peripherally (systemic immunity) as well as at the site of infection (mucosal immunity). However, it appears that regulatory mechanisms affecting IFN-gamma production in response to S. hyodysenteriae antigen differ between peripheral and colonic compartments.

Veterinary Immunology and Immunopathology, 1998

After initial evaluation of the 176 new and 19 control monoclonal antibodies (mAb) submitted to t... more After initial evaluation of the 176 new and 19 control monoclonal antibodies (mAb) submitted to the Second International Swine CD Workshop, 57 were assigned to the T-cell/activation marker subgroup. These 57 mAb were further analyzed using flow cytometry on whole blood lymphocytes, splenocytes, Peyer's patch lymphocytes, in vitro cell lines, broncho-alveolar lavage cells, Con A and PHA blasts, fetal cell populations, and by 2-color flow cytometry against mAb to porcine CD2, CD4, and CD8. Finally, the molecular weights of the target antigens were characterized when possible. As a result of these analyses, 23 mAb were distributed into 7 CD clusters. Newly confirmed mAb assignments included: two CD2; one CD4; two CD5; one wCD6; and one wCD25. Three new mAb were found that reacted with wCD8, one of which defined a new epitope, wCD8c. For the first time, mAb against porcine CD3 were identified, including 6 mAb that reacted with three different epitopes. Several new mAb reacted with antigens whose expression varied depending on the activation state of the test cell. These will require further characterization in order to assign a CD number.

Veterinary Immunology and Immunopathology, 1999

Mature T lymphocytes expressing the alphabeta T cell receptor are generally classified as either ... more Mature T lymphocytes expressing the alphabeta T cell receptor are generally classified as either CD4+ or CD8+, based on the mutually exclusive expression of these two lymphocyte coreceptors. Contrary to this conventional division, there is considerable evidence that significant numbers of CD4/CD8 double positive (DP) lymphocytes exist in the peripheral blood and secondary lymphoid tissues of swine, chickens and monkeys. Although CD4/CD8 DP T cells are rarely present in human peripheral blood the relative percentage of this lymphocyte population can increase spontaneously in healthy individuals and in persons suffering from certain disease conditions. DP can also be found among those T cells infiltrating arthritic joints, rejected kidney grafts and certain tumors. In humans, and rats, CD4/CD8 DP T cells appear transiently following activation of their progenitors. Murine DP cells have been described as a subset of intraepithelial lymphocytes (IELs). However, the relationship of IELs to DP cells in the peripheral blood of other species is unknown. Because of their unconventional phenotype and rarity in human and mice, most immunologists have ignored extrathymic CD4/CD8 DP lymphocytes. Nevertheless, their abundance in the peripheral blood of swine, monkeys and chickens makes it impossible to dismiss this lymphocyte population. Here are reports that have described extrathymic lymphocytes exhibiting a CD4+CD8dim phenotype in several species reviewed. Swine and monkey lymphocytes with this phenotype are represented by small resting cells that simultaneously express CD4 and CD8alpha molecules. The available evidence favors the notion that such DP T cells in swine are comprised predominantly of MHC class II restricted memory CD4+ helper T cells that after activation have acquired the ability to express the CD8alpha chain and then to maintain this DP phenotype. Moreover, porcine CD4/CD8 DP T cells appear to be comprised of memory cells due to their ability to respond to recall antigen, resilience to thymectomy, increase in proportion with age, expression of memory T cell markers, production of interferon-gamma and localization to inflammatory sites. Some of these characteristics are also descriptive of human and monkey CD4/CD8 DP T cells. Thus, in swine, humans and monkeys, these phenotypically distinct lymphocytes appear to represent a primed T cell subset. The possible functional significance of the simultaneous expression of the CD4 and CD8 co-receptors on mature T cells is discussed.

Tuberculosis, 2014

Tuberculosis is an important health concern for Asian elephant (Elephas maximus) populations worl... more Tuberculosis is an important health concern for Asian elephant (Elephas maximus) populations worldwide, however, mechanisms underlying susceptibility to Mycobacterium tuberculosis are unknown. Proliferative responses assessed via brominated uridine incorporation and cytokine expression measured by real-time RT-PCR were evaluated in peripheral blood mononuclear cell (PBMC) cultures from 8 tuberculosis negative and 8 positive Asian elephants. Cultures were stimulated with Mycobacterium bovis purified protein derivative (PPD-B), M. tuberculosis culture filtrate protein (CFP)-10, and Mycobacterium avium PPD (PPD-A). Following stimulation with PPD-B, proliferation was higher (a ¼ 0.005) in positive samples; no significant differences were detected following CFP-10 or PPD-A stimulation. Tumor necrosis factor (TNF)-a, interleukin (IL)-12, and interferon (IFN)-g expression was greater in samples from positive elephants following stimulation with PPD-B (a ¼ 0.025) and CFP-10 (a ¼ 0.025 TNF-a and IL-12; a ¼ 0.005 IFN-g). Stimulation with PPD-A also produced enhanced IL-12 expression in positive samples (a ¼ 0.025). Findings suggested that differences in immune cell function exist between tuberculosis positive and negative elephants. Proliferative responses and expression of TNF-a, IL-12, and IFN-g in response to stimulation with PPD-B and CFP-10 differ between tuberculosis positive and negative elephants, suggesting these parameters may be important to tuberculosis immunopathogenesis in this species.

Journal of Veterinary Diagnostic Investigation, 1991

The effect of altering the strain of the test virus used in the standardized pseudorabies virus n... more The effect of altering the strain of the test virus used in the standardized pseudorabies virus neutralization (VN) test on the sensitivity of the assay was evaluated. Comparative VN tests were performed using 4 different strains: the avirulent Bartha parental, the avirulent recombinant Bartha gIII Ka , the moderately virulent Shope (currently used for the VN test at the National Veterinary Services Laboratory, Ames, IA), and the highly virulent P2208 (Funkhauser). A radioimmunoassay and a Western immunoblotting technique were employed to verify the presence of anti-pseudorabies virus (PrV) antibodies in sera. Statistical analysis indicated that replacement of the Shope strain by the Bartha gIII Ka or the P2208 strain resulted in VN titers that were 4.23-and 2.00-fold higher, respectively. Despite these differences, specificity with regard to PrV diagnosis was unaltered. This apparent enhancement of the sensitivity of the PrV VN test would be beneficial for the serologic identification of PrV-infected animals during an eradication effort. Since its inception, the virus neutralization (VN) microtitration test 12 has been an important serologic means to identify virus-infected animals. The VN test has been standardized for the detection of anti-pseudorabies virus (PrV) antibodies in swine using the PrV-Shope strain 9 and has become the "gold standard" against which newly developed serologic diagnostic tests are compared. However, questions still remain concerning the sensitivity and the specificity of the standardized PrV VN test. In addition, serum toxicity to the cells used in the VN test continues to be a problem for both the practitioner and the diagnostician. Most states involved in a PrV eradication program use a serum dilution of 1:4 as the cutoff for reporting positive anti-PrV antibody VN titer results. Some states, such as Illinois, use the 1:8 dilution in their eradication effort. This criterion helps avoid some difficulties due to serum toxicity and what is empirically thought by some to be nonspecific results (false positives) at the lower serum dilutions. A number of serologic assays for pseudorabies diagnosis have been developed.