Ratree Platt - Academia.edu (original) (raw)

Papers by Ratree Platt

Vaccine, Jul 1, 2009

The aim of this study was to evaluate the ability of a pentavalent (BVDV types 1 and 2, BHV-1, BR... more The aim of this study was to evaluate the ability of a pentavalent (BVDV types 1 and 2, BHV-1, BRSV, and PI-3) modified live virus (MLV) vaccine given to 1-2-, 4-5-, and 7-8-week-old calves with maternal antibodies to induce humoral and cellular immune responses and protect calves from virulent BVDV type 2. Eight calves in each age group were vaccinated and four served as controls. All calves were challenged intranasally with BVDV type 2, 12 weeks after vaccination. SVN titers to all five viruses declined in all groups after vaccination (except 4-5-week-old calves to BVDV type 1). After challenge, the SVN titers for both types of BVDV showed anamnestic responses in calves vaccinated at 4-5 and 7-8 weeks, but not at 1-2 weeks of age. In all groups, T cell subsets responded specifically to BVDV types 1 and 2 but not to BHV-1, BRSV, or PI-3 after vaccination by increasing their expression of activation markers (CD25, IFN-gamma and IL-4). All vaccinated calves were significantly protected from BVDV type 2 challenge.

Virology, Apr 1, 2016

Control of influenza A virus (IAV) in pigs is done by vaccination of females to provide maternall... more Control of influenza A virus (IAV) in pigs is done by vaccination of females to provide maternally-derived antibodies (MDA) through colostrum. Our aim was to evaluate if MDA interfere with IAV infection, clinical disease, and transmission in non-vaccinated piglets. In the first study, naïve sows were vaccinated with H1N2-δ1 whole inactivated virus (WIV) vaccine. In a follow-up study seropositive sows to 2009 pandemic H1N1 (H1N1pdm09) were boosted with H1N1pdm09 WIV or secondary experimental infection (EXP). MDA-positive pigs were challenged with homologous or heterologous virus, and MDA-negative control groups were included. WIV-MDA piglets were protected from homologous infection. However, piglets with WIV-derived MDA subsequently challenged with heterologous virus developed vaccine associated enhanced respiratory disease (VAERD), regardless of history of natural exposure in the sows. Our data indicates that although high titers of vaccine-derived MDA reduced homologous virus infection, transmission, and disease, MDA alone was sufficient to induce VAERD upon heterologous infection.

Virology, Sep 1, 2014

Live-attenuated influenza virus (LAIV) prime-boost vaccination previously conferred protection ag... more Live-attenuated influenza virus (LAIV) prime-boost vaccination previously conferred protection against heterologous H3N2 swine influenza challenge, including in piglets with maternally derived antibodies (MDA). Conversely, a whole-inactivated virus (WIV) vaccine was associated with enhanced disease. This study was aimed at identifying immune correlates of cross-protection. Piglets with and without MDA received intramuscular adjuvanted WIV or intranasal LAIV, and were challenged with heterologous H3N2. WIV induced cross-reactive IgG, inhibited by MDA, and a moderate T cell response. LAIV elicited mucosal antibodies and T cells cross-reactive to the heterologous challenge strain. The presence of MDA at LAIV vaccination blocked lung and nasal antibody production, but did not interfere with T cell priming. Even without mucosal antibodies, MDA-positive LAIV vaccinates were protected, indicating a likely role for T cells. Based on the data, one LAIV dose can induce cell-mediated immunity against antigenically divergent H3N2 influenza virus despite passive antibody interference with humoral immune responses.

Viral Immunology, Mar 1, 2004

Modified vaccinia virus Ankara (MVA) was used as a vector to express genes from bovine respirator... more Modified vaccinia virus Ankara (MVA) was used as a vector to express genes from bovine respiratory syncytial virus (BRSV). Using these recombinant viruses as recall antigens for cells from BRSV-immuned cattle proved to be problematic because non-recombinant MVA itself frequently stimulated high levels of T lymphocyte activation. This phenomenon was observed in a high percentage of cattle from multiple herds. Gamma delta TCR(+) T cells were more sensitive to activation by MVA than other classes of T cells. A serological assay for MVA neutralization detected low, fluctuating titers of serum virus neutralizing (SVN) activity toward MVA in some cattle, but these were lower titers than those observed in cattle that underwent MVA vaccination. T cell reactivity in non-vaccinated cattle did not correlate significantly (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05) with SVN activity, undermining the notion that any adaptive immune response was responsible for the observed T cell sensitivity. More probable explanations are that MVA has mitogenic or superantigenic properties, or that the virus induces gammadelta TCR(+) T cell activation through interactions with innate pattern recognition receptors.

American Journal of Veterinary Research, Jul 1, 2006

Veterinary Microbiology, Nov 1, 2001

Attempts to develop live vaccines to protect against enterotoxigenic Escherichia coli (ETEC) infe... more Attempts to develop live vaccines to protect against enterotoxigenic Escherichia coli (ETEC) infection by induction of both cell-mediated and mucosal immunity, and serum antibody responses have included use of recombinant Salmonella strains that produce K88 fimbrial antigens (Hone et al., 1988; Attridge et al., 1988; Morona et al., 1994). However, none of the recombinant Salmonella vectors has been licensed by the United States Department of Agriculture (USDA) for use as a live vaccine in pigs in the United States. A variant of Salmonella enterica ser. Choleraesuis strain 54 (SC54) is currently used as a safe and effective intranasal attenuated live vaccine in pigs. In order to expand the efficacy of this live vaccine strain, we sought to modify strain SC54 to express the K88 antigens of ETEC. To accomplish this, a plasmid-based system was used to integrate the K88 gene cluster into the chromosome of strain SC54 by site-specific recombination. The K88 antigens were expressed by strain SC54, and the gene cluster was stably maintained in the host.

Veterinary Pathology, Oct 7, 2010

The objective of this study was to develop an intestinal model of Mycobacterium avium subspecies ... more The objective of this study was to develop an intestinal model of Mycobacterium avium subspecies paratuberculosis (Map) infection in the calf for evaluation of mucosal pathology and local and systemic immunologic responses. Map was inoculated into Peyer's patches of young calves using a right flank surgical approach in standing calves to exteriorize the ileocecal junction. Inoculum doses ranging from 10 3 to 10 9 colony-forming units of strain K10 Map were injected through the serosal surface into Peyer's patches of the distal ileum near the ileocecal valve. Fecal samples were collected for culture from each calf weekly until termination of the study. Calves were necropsied at 7, 30, 60, and 90 days after infection, when inoculation sites, lymph nodes, spleen, and peripheral blood were collected for evaluation. Ileocecal lymph nodes were consistently colonized by Map in the 10 5 to 10 9 groups. The ileocecal valve was also colonized in 10 7 and 10 9 groups. This correlated with fecal culture results as infected calves intermittently shed Map in their feces throughout the study. Granulomatous lesions with giant cells and acid-fast bacilli at the ileocecal junction, ileocecal lymph nodes, and lamina propria of high-dose animals (10 7 and 10 9) were identified from each time point. Flow cytometry was used to detect antigen-specific production of interferon-g and interleukin-4 locally (ileocecal lymph node) and systemically (peripheral blood mononuclear cells), which defined distinct immunologic profiles in low-dose and high-dose calves. This study demonstrates intestinal Map infection via Peyer's patch inoculation, a novel model with many shared features of natural Map infection.

Viral Immunology, Dec 1, 2006

The ability of porcine reproductive and respiratory syndrome virus (PRRSV) to suppress T cell exp... more The ability of porcine reproductive and respiratory syndrome virus (PRRSV) to suppress T cell expression of CD25 (alpha chain of interleukin [IL]-2 receptor), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) was determined by flow cytometry in naive porcine T cells in response to mitogen (concanavalin A) and cytokine inducers (phorbol 12-myristate 13-acetate plus ionomycin [PMA/I]). Four PRRSV isolates of varying clinical virulence and three different types of porcine myeloid antigen-presenting cells (APCs) were used. T cells cultured with monocytes infected with virulent PRRSV (VR-2385, SDSU-73, and VR-2332), but not with a vaccine strain (Ingelvac PRRS MLV; Boehringer Ingelheim Vetmedica, St. Joseph, MO), demonstrated significantly reduced CD25 expression (%CD25(+)) and IFN-gamma expression (%IFN-gamma (+)) compared with T cells incubated with uninoculated monocyte cultures. T cells cultured with monocytes infected with all four PRRSV isolates demonstrated significantly reduced %TNF-alpha (+). The significant reduction of %CD25(+), %IFN-gamma (+), and %TNF-alpha (+) was not detected in T cells cultured with monocyte-derived macrophages (MDMs) and immature monocyte-derived dendritic cells (MDCs) infected with any PRRSV isolates. Heat-inactivated PRRSV did not induce significantly reduced T cell responses in any APC cultures. The reduction of T cell response in monocyte cultures was not due to PRRSV-induced T cell death. Gene expression of IL-10 detected by semiquantitative reverse transcriptase-polymerase chain reaction was significantly increased in virulent PRRSV-infected monocyte cultures after PMA/I, but not concanavalin A, stimulation compared with IL-10 gene expression from uninoculated monocyte cultures. Increased IL-10 gene expression contributed to significantly reduced %IFN-gamma (+) and %TNF-alpha (+), but not %CD25(+), as determined by IL-10 neutralization assay. This study reports that PRRSV has the ability to suppress T cell responses. The suppressive ability of PRRSV is associated with viral virulence and is mediated by virus-infected monocytes, but not by virus-infected MDMs and immature MDCs.

Veterinary Immunology and Immunopathology, Jul 1, 2010

Vaccination against Johne's disease with an inactivated, oil-adjuvanted Mycobacterium avium ssp. ... more Vaccination against Johne's disease with an inactivated, oil-adjuvanted Mycobacterium avium ssp. paratuberculosis (MAP) bacterin can reduce clinical signs in infected herds; however, the development of indurated swelling at the injection site limits vaccine acceptability to producers. This study determined whether a reduced dose of vaccine antigen, with a full dose of adjuvant, would produce comparable T cell-mediated immune responses with smaller lesions. T cell responses induced by in vitro stimulation with MAP antigen from calves vaccinated with full, half, and quarter doses of antigen were evaluated 2, 4, and 9 months after vaccination by multi-parameter flow cytometry (FCM) and the whole blood interferon-g (WB IFN-g) assay. The WB IFN-g responses were significantly elevated in vaccinated animals, but did not differ significantly between doses. FCM demonstrated antigen-specific responses for both IFN-g and IL-4 in the CD4 T cell population from vaccinated animals, while CD8 T cells and gd T cells mainly responded with increased IFN-g. Dose may have affected some T cell subset parameters at some time points, but intradermal skin test responses, WB IFN-g production, IFN-g responses by T cell subsets in FCM were not significantly different between full, half, or quarter doses of antigen. Injection site lesions were smaller in animals vaccinated with a lower dose of antigen, but reached statistical significance (P < 0.05) in the half dose group only.

Veterinary Immunology and Immunopathology, Mar 1, 2008

The objective of this research project was to evaluate the antibody and cell-mediated immune resp... more The objective of this research project was to evaluate the antibody and cell-mediated immune responses to a multivalent vaccine containing killed bovine viral diarrhea virus (BVDV) types 1 and 2. Twenty castrated male crossbred beef cattle (350-420 kg body weight) seronegative to BVDV were randomly divided into two groups of 10 each. Group 1 served as negative mock-vaccinated control. Group 2 was vaccinated subcutaneously twice, 3 weeks apart, with modified live bovine herpesvirus 1, parainfluenza 3 virus and bovine respiratory syncytial virus diluted in diluent containing killed BVDV type 1 (strain 5960) and type 2 (strain 53637) in an adjuvant containing Quil A, Amphigen, and cholesterol. Serum samples were collected from all cattle at days À21, 0, and days 21, 28, 35, 56 and 70 post-vaccination. Standard serum virus neutralization tests were performed with BVDV type 1 (strain 5960) and type 2 (strain 125C). Anticoagulated blood samples were collected at day 0, and days 28, 35, 56 and 70 post-vaccination. Peripheral blood mononuclear cells (PBMCs) were isolated, stimulated with live BVDV type 1 (strain TGAN) and type 2 (strain 890) and cultured in vitro for 4 days. Supernatants of cultured cells were collected and saved for interferon gamma (IFNg) indirect enzymelinked immunosorbent assay (ELISA). Four-color flow cytometry was performed to stain and identify cultured PBMC for three T cell surface markers (CD4, CD8, and gd TCR) and to detect the activation marker CD25 (a chain of IL-2 receptor) expression. The net increase in %CD25+ cells (D%CD25+) of each T cell subset of individual cattle was calculated. The results of all postvaccination weeks of each animal were plotted and the areas under the curve of each T cell subset were statistically analyzed and compared between groups. The mean area under the curve of the D%CD25+ data for days 0-70 of all subsets, except CD4ÀCD8+gd TCRÀ (cytotoxic) T cell subset of both BVDV types 1 and 2 stimulated cells, of the vaccinated group were significantly higher than the control group (P < 0.05). IFNg production by PBMC from the vaccinated group showed significantly higher results (P < 0.05) than the control group in the BVDV types 1 and 2 stimulated cells for at least some time points after vaccination. The vaccinated group also had significantly (P < 0.0001) higher neutralizing antibody titers than the control group from day 28 onward.

American Journal of Veterinary Research, Dec 1, 2006

Objective-To monitor by use of 5-color flow cytometry the antigen-specific responses of subsets o... more Objective-To monitor by use of 5-color flow cytometry the antigen-specific responses of subsets of peripheral T cells in cattle inoculated with a killed Mycobacterium avium subsp paratuberculosis (MAP) vaccine and to compare results with those for 2 established cell-mediated immunity assays. Animals-45 female Holstein cattle with negative results for MAP in skin tests conducted at time of inoculation with MAP. Procedures-Cattle were allocated to 4 groups. Cattle of group 1 (n = 12) were 0 to 3 months old and inoculated with a killed MAP vaccine. The 10 cattle of group 2 were the same age as those in group 1 but were not inoculated with MAP vaccine. The 11 cattle of group 3 were 9 to 12 months old and inoculated with killed MAP vaccine. The 12 cattle of group 4 were the same age as those in group 3 but were not inoculated with MAP vaccine. Results-Flow cytometry identified T-cell subsets that responded specifically to the recall antigen. Results of assays for CD25 expression and wholeblood interferon-γ had the strongest correlation with results for skin tests as well as results with each other. Intracellular expression of interferon-γ was not correlated as well with results for the other tests. Conclusions and Clinical Relevance-Flow cytometry can be useful for characterizing the immune response after administration of MAP vaccine and should be evaluated with regard to its sensitivity and specificity when used in detecting cattle naturally infected with MAP.

Veterinary Immunology and Immunopathology, Jul 1, 2016

The objective of this study was to investigate the impact of oral meloxicam (MEL) and longdistanc... more The objective of this study was to investigate the impact of oral meloxicam (MEL) and longdistance transportation on cell-mediated immunity (CMI) in preconditioned steers receiving a booster vaccination on arrival. We hypothesized that steers treated with MEL at 1 mg/kg body weight, 6 hours before night-time transport, would be less immunocompromised on arrival (day 0) and after 7 days, and that CMI following vaccination with a modified live bovine viral diarrhea virus (BVDV) recall antigen would be increased. Brahman crossbreed steers, 13 to 17 months of age (n=87), were randomly assigned to one of four treatment groups: MEL, transported (MTR) (n=22), MEL, non-transported (MNT) (n=22), lactose placebo, transported (CTR) (n=21), and lactose placebo, non-transported (CNT) (n=22). MTR and CTR steers were transported for approximately 16 hours non-stop on a truck from Mississippi to Iowa (approximately 1,300 km), whereas steers in the MNT and CNT groups remained in Mississippi as non-transported controls. Body weight was measured and jugular blood was collected at −1, 0, and 7 days from all steers at the same time, regardless of location. Multi-parameter flow cytometry (MP-FCM) was used to identify T-cell subsets and detect the expression of three activation markers (CD25 [interleukin (IL)-2 receptor], intracellular interferon-gamma [IFNγ], and IL-4) after in vitro stimulation with BVDV recall antigen. Plasma cortisol concentration was measured on day −1, 0, and 7 as a marker of transport-associated stress. Serum antibody titer to BVDV was assessed on day −1 and day 7 post-booster vaccination. Whole-blood samples were analyzed using MP-FCM on days 0 and 7. Results were log transformed and analyzed using repeated measures of analysis of variance. Compared with non-transported controls, transport led to an increase in BVDV-induced expression of CD25, IFNγ, and IL-4 in CD4 + , CD8 + , and γδ + Tcell subsets (P<0.05). MEL treatment mitigated the transportation-associated increase in CD25 3 expression by peripheral blood mononuclear cells (PBMCs), CD4 + , and γδ + T cells. CMI outputs for the MTR group were less than those of the CTR group (P<0.05); however, the MTR and NT groups did not differ (P>0.10). A treatment*transport interaction was noted for the increase in IL-4 expression by CD8 + T cells after transport, with a significant difference between the CTR and MTR groups at day 7. In conclusion, the use of oral MEL prior to transport appears to have inhibitory or homeostatic effects, but further research is needed to validate the effect of MEL treatment on specific T-cell subsets in transported cattle. Abbreviations: acid citrate dextrose solution (ACD); bovine respiratory disease (BRD); bovine viral diarrhea virus (BVDV); cell-mediated immunity (CMI); lactose placebo, non-transport (CNT); lactose placebo (CONT); lactose placebo, transport (CTR); expression index (EI); meloxicam (MEL); mean fluorescent intensity (MFI); modified live virus (MLV); meloxicam, non-transport (MNT); multi-parameter flow cytometry (MP-FCM); meloxicam, transport (MTR); nonsteroidal anti-inflammatory drug (NSAID); non-transport (NT); transport (TR);

This manuscript has t)een reproduced from the microfilm master. UMI films the text directly from ... more This manuscript has t)een reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of ttiis reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletkxi. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and contirujing from left to right in equal sections with small overiaps. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrattons appearing in this copy for an additional charge. Contact UMI directly to order.

Veterinary immunology and immunopathology, 2017

The objective of this study was to determine and compare the humoral and cellular immune response... more The objective of this study was to determine and compare the humoral and cellular immune responses of calves exposed to a single dose of Bovela(®) bovine viral diarrhea virus (BVDV) live double deleted vaccine or a field strain virus (FSV) of BVDV type 2 (strain 890). Thirty seronegative, colostrum-deprived 5 month-old Holstein steer calves that tested negative for persistent BVDV by ear notch immunohistochemistry and seronegative to BVDV types 1 and 2 were used. Calves were screened by multi-parameter flow cytometry (MP-FCM) 1 week before vaccination to ensure that they were negative for T cell responses to the BVDV types 1 and 2 viruses in the Bovela(®) vaccine. Calves were assigned to 3 treatment groups: control (PBS), FSV inoculated, and Bovela(®) vaccinated. The humoral response was tested by standard serum virus neutralization (SVN) test to BVDV types 1 (Singer strain) and 2 (strain 125). The response by CD4, CD8, and gamma delta (γδ TCR) T cells was evaluated by MP-FCM using ...

Virology, Jan 11, 2016

Analytical and quantitative cytopathology and histopathology, 2013

To characterize baseline canine lymphocyte phenotypes including lymphocytes coexpressing multiple... more To characterize baseline canine lymphocyte phenotypes including lymphocytes coexpressing multiple markers by novel 7-color multiparameter flow cytometry. Fresh canine peripheral blood lymphocytes of 79 healthy 26-week-old Beagle or Beagle-mix dogs were stained and analyzed. The high number of samples and acquired flow data (averaging 1.9 x 10(5) cells/sample) allowed the detection of minor lymphocyte subsets coexpressing multiple lymphocyte markers. The averaged percentages of major lymphocyte subsets of CD3+, CD4+, CD8+, CD21+ and gammadelta TCR+ cells from this study were 74.0, 43.6, 14.3, 9.6, and 0.2, respectively, which were comparable but uniquely different from other reports as they were simultaneously detected in the same sample. We demonstrated that the commonly used CD21 and CD3 monoclonal antibody (mAb) clones, previously recommended not to be used in the same staining, could and should be used together with the proper steps of lymphocyte gating. We found a high percentag...

Virology, 2014

Viral Immunology, 2004

Veterinary Microbiology, 2001

Veterinary Immunology and Immunopathology, 2006

Various vaccine adjuvant candidates were assessed with the modified-live porcine reproductive and... more Various vaccine adjuvant candidates were assessed with the modified-live porcine reproductive and respiratory syndrome virus (MLV PRRSV) (Ingelvac 1 PRRS MLV) vaccine. Their influence on humoral-mediated immune (HMI) and cell-mediated immune (CMI) responses as well as protection from virulent PRRSV challenge (MN-184) was evaluated. Ninety seronegative pigs were randomly divided into nine groups of 10 pigs. One group received MLV vaccine alone. Five groups received MLV vaccine with either bacterial endotoxin-derived adjuvant (ET), mixed open reading frame 5 (ORF5) peptides derived from various PRRSV isolates, porcine interferon alpha (IFNa), polyinosinic-polycytidylic acid stabilized with polylysine and carboxymethylcellulose (poly-ICLC), or porcine interleukin-12 (IL-12). One group did not receive MLV vaccine but was immunized with ORF5 peptides conjugated with cholera toxin (ORF5 peptide/CT). Two groups served as challenged and unchallenged non-vaccinated controls. Four-color flow cytometry was utilized to simultaneously identify three major porcine Tcell surface markers (CD4, CD8, and gd TCR) and detect activation marker CD25 (a chain of IL-2 receptor) or intracellular IFNg. The MLV PRRSV vaccine alone successfully primed CD4 À CD8 + gd À T-cells as demonstrated by a significant increase in %IFNg + cells when live PRRSV was used as a recall antigen. Booster immunizations of mixed ORF5 peptides and coadministration of IL-12 with MLV PRRSV vaccine significantly enhanced IFNg expression by some T-cell subsets (CD4 À CD8 + gd + and CD4 À CD8 À gd + for mixed ORF5 peptides and CD4 + CD8 + gd À and CD4 À CD8 + gd + for IL-12). All groups receiving MLV-vaccine with or without adjuvants had reduced lung lesions after challenge. The group immunized with only ORF5 peptide/CT did not have significant T-cell recall responses and was not protected from challenge. Expression of IFNg by several T-cell subsets correlated with reduced lung lesions and viremia, whereas expression of CD25 did not. Expression of