Steven Krakowka | The Ohio State University (original) (raw)
Papers by Steven Krakowka
Journal of Veterinary Diagnostic Investigation, 2003
Journal of Veterinary Diagnostic Investigation, 2003
Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was a... more Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.
Journal of Veterinary Diagnostic Investigation, 2003
Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was a... more Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.
Veterinary Microbiology, 2009
Sera and selected tissue homogenates collected from gnotobiotic swine never exposed to the enviro... more Sera and selected tissue homogenates collected from gnotobiotic swine never exposed to the environment or other swine tissues were tested for the presence of porcine torque teno virus (TTV) DNAs by nested and non-nested polymerase chain reactions (PCR) using primers specific for the untranslated region of porcine genogroups (g) 1 and 2. Twenty-three of 105 (21.9%) gnotobiotic piglets were g1- and/or g2-TTV DNA positive. Twenty-three of 27 (85.2%) sow sera, collected at the time of Caesarian derivation of the litters contained either or both TTV genogroup DNAs. These data demonstrate that porcine TTV may be transmitted to piglets by the in utero route and that the incidence of fetal infection is high.
Canadian veterinary journal, 2007
Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus ... more Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus type 2 (PCV2) at 3 days of age and then given 1 of 6 different commercial Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins as either a single dose (7 d of age, 1 application products) or 2 doses (7 and 21 d of age, 2 application product). Control groups received PCV2 alone (n = 9) or were infected with PCV2 and immunized twice with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freund's adjuvant (ICFA) (n = 7). Five of 7 (71%) PCV2-infected piglets immunized with KLH/ICFA developed mild or overt PMWS, whereas none of 9 piglets infected with PCV2 alone developed PMWS. Five of 12 (42%) piglets vaccinated with a commercial bacterin containing mineral oil adjuvant developed PMWS following vaccination. None of the PCV2-infected piglets in the other bacterin-vaccinated groups developed PMWS in this model of PCV2-associated disease. This difference in prevalence of PMWS in pi...
Journal of General Virology, 1989
Nucleocapsid (NC) variants expressed by the Onderstepoort strain of canine distemper virus (CDV) ... more Nucleocapsid (NC) variants expressed by the Onderstepoort strain of canine distemper virus (CDV) were ultrastructurally and biochemically characterized. Three isolated variants were defined which corresponded to the three variants observed within the cytoplasm of infected cells. Dense NC (D-NC), isolated on discontinuous caesium chloride (CsCl) isopycnic gradients, had an average density of 1.2971 +/- 0.0042 g/ml. Ultrastructurally, D-NC were 1620.0 +/- 112.1 nm in length with a 20.1 +/- 1.3 nm outer and a 5.8 +/- 0.7 nm inner core diameter. The D-NC protein composition was 89.7% of a 61K protein (N), 8.4% of a 75K protein (P) and 1.9% of a 160K to 200K protein (L). A single species of nucleic acid, 15 kb in length, was isolated from D-NC. Light NC (L-NC), similarly isolated, had an average density of 1.2894 +/- 0.0040 g/ml. L-NC differed ultrastructurally from D-NC in that poor resolution of NC subunits, a larger outer diameter (32.0 +/- 2.8 nm), and a greater inner core diameter (10.4 +/- 0.6 nm) were observed. The average L-NC strand length was 1574.4 +/- 115.8 nm. The protein composition was the same as D-NC with the exception of an additional 70K protein, representing 4.0 to 7.7% of the total L-NC protein mass. A 15 kb nucleic acid was also identified in L-NC, although heightened sensitivity of encapsidated L-NC nucleic acid to non-specific nuclease degradation was observed. The ratio of D-NC to L-NC isolated from individual virus preparations varied and was independent of viral infectivity. A third NC variant, defective-NC (Df-NC), was also identified. This had the lowest density on CsCl gradients (1.2460 +/- 0.0046 g/ml). The Df-NC structures were truncated to a uniform length of 87.0 +/- 5.8 nm. Diameter measurements were between those of D-NC and L-NC, being 24.4 +/- 1.4 nm (outer) and 6.9 +/- 0.4 nm (inner core). Like L-NC, the 70K protein was present but in greater amounts, representing as much as 43.7% of the total Df-NC protein mass. RNase A-sensitive nucleic acid was isolated from Df-NC which ranged in size from 1.16 to 0.67 kb with a majority of the material being 0.86 kb in length. For both L-NC and Df-NC, canine CDV convalescent serum reacted with viral N and P proteins in Western blot analyses but not with the 70K protein, suggesting a host cellular origin for the latter.
The Journal of Infectious Diseases, 1998
To determine the effect of oral adjuvant-assisted and parenteral vaccination, germ-free piglets w... more To determine the effect of oral adjuvant-assisted and parenteral vaccination, germ-free piglets were vaccinated orally with and without labile toxin adjuvant or parenterally and challenged with viable Helicobacter pylori. All prechallenge vaccination regimens induced anti-H. pylori antibodies and suppressed bacterial colonization, but no vaccination regime completely prevented infection. Parenteral vaccination given after infection had no effect on bacterial colonization. Lymphocytic gastritis was present in all piglets challenged with live bacteria regardless of vaccination status. Neutrophilic gastritis was present in vaccinated challenged piglets but not in infected, unvaccinated piglets. Gastritis was not present in uninfected control piglets regardless of vaccination status. In gnotobiotic piglets, vaccination suppresses but does not prevent infection by H. pylori, and parenteral vaccination does not cure infected piglets. Vaccination does not ameliorate gastritis due to H. pylori in piglets but does induce neutrophilic gastric inflammation in some infected piglets. Because of the importance of Helicobacter pylori in human gastric disease and the incomplete success associated with current methods of therapy, the potential utility of both preventative and curative vaccination for H. pylori has attracted increasing attention in recent years. Early studies in gnotobiotic piglets demonstrated that parenteral vaccination was only partly effective in suppressing bacterial colonization after subsequent challenge and that vaccination did not prevent gastritis but in fact increased its severity [1]. Subsequent experiments determined that oral vaccination of specific pathogen-free mice prevents colonization by either H. pylori or Helicobacter felis [2-11] and that oral vaccination can eliminate bacterial colonization in most mice in which infection is already established [10, 12, 13]. Oral vaccination was ineffective in gnotobiotic piglets, but the vaccination protocol used did not include any oral adjuvant and thus was not directly comparable to the murine experiments [1]. The purpose of this study was to compare the efficacy of 4 vaccination protocols in preventing establishment of H. pylori infection in gnotobiotic piglets and to evaluate the efficacy of parenteral vaccination in eliminating established infection. Methods Bacterial strains. H. pylori strains 26695 and N6 were used. Both are cagA-positive and VacA-positive human isolates that were
Veterinary Pathology, 2001
Porcine circovirus (PCV)-2, a newly described single-stranded circular DNA virus pathogen of swin... more Porcine circovirus (PCV)-2, a newly described single-stranded circular DNA virus pathogen of swine is the cause of postweaning multisystemic wasting syndrome (PMWS). In gnotobiotic piglets, PCV-2 infection alone produces asymptomatic infection without evidence of overt PMWS. Gnotobiotic piglets infected with PCV-2 were injected with keyhole limpet hemocyanin in incomplete Freund's adjuvant (KLH/ICFA), and the effects on virus production and development of PMWS were determined. In the first experiment, piglets were injected subcutaneously on the left hip and shoulder, and viral burden was assessed in regional lymph nodes draining the injection sites and in contralateral lymph nodes 13–14 days after infection. Immune activation increased the number of virus antigen-positive cells in draining lymph nodes and increased the amount of infectious virus recovered by 1–4 log10. In a second experiment, the effects of injections of KLH/ICFA with or without concurrent stimulation of peritoneal macrophages by intraperitoneal injections of thioglycollate broth on induction of PMWS was assessed. All immunized piglets developed moderate to severe PMWS, whereas none of the piglets infected with PCV-2 alone developed PMWS. In PMWS-affected piglets, extensive replication of PCV-2 was documented by both immunocytochemistry and quantitative viral titrations. Thus, immune activation is a key component of the pathogenesis of PCV-2-associated PMWS in swine.
Canadian Journal of Veterinary Research Revue Canadienne De Recherche Veterinaire, Jul 1, 2010
The objective of this study was to improve the visual localization of urease activity of Helicoba... more The objective of this study was to improve the visual localization of urease activity of Helicobacter pylori-like organisms (HPLO) on swine gastric mucosa by in vitro optimization of the urea concentration and pH indicator of a urease test reagent. Five 21-day-old conventional pigs were infected orally with HPLO (3 pigs) or Brucella broth alone (2 pigs). At 17 d after infection the pigs were euthanized and their stomachs excised and tested for HPLO by a modified urease test formulation sprayed onto the gastric mucosa, as well as confirmatory culture and isolation of HPLO from urease-positive sites. This study showed improved detection of HPLO in porcine gastric mucosa with the use of a modified urease test formulation containing 5% urea and the pH indicator bromocresol purple compared with the use of a conventional formulation of 2% urea and phenol red. This test can readily be applied to achieve a presumptive diagnosis of HPLO in cases of gastritis or gastric esophageal ulceration in pigs.
Canadian Journal of Veterinary Research Revue Canadienne De Recherche Veterinaire, Oct 1, 2012
I n t r o d u c t i o n Porcine circovirus type 2 (PCV2) is a small, nonenveloped, singlestranded... more I n t r o d u c t i o n Porcine circovirus type 2 (PCV2) is a small, nonenveloped, singlestranded DNA virus (1). It has been incriminated as a necessary cause of postweaning multisystemic wasting syndrome (PMWS) (2). This disease, which has a high case-fatality rate (3), typically develops in piglets between 8 and 16 wk of age. Clinical signs include progressive emaciation, dyspnea, and enlarged superficial lymph nodes. The virus is also associated with a number of other diseases, such as porcine dermatopathy and nephropathy syndrome (4), reproductive disorders (5), proliferative and necrotizing pneumonia (6), and porcine respiratory disease complex (7). Recently, a sharp increase in PCV2-associated deaths was reported in Canada (8,9). The virus is stable (10) and ubiquitous in the swine population (3), which makes eradication very difficult. Vaccination represents an attractive means to control endemic infection and has
Infection and …, 1997
To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gn... more To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets.
Infection and …, 1997
To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gn... more To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets.
Infection and …, 1987
Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesi... more Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesis of human gastritis, dyspepsia, and gastroduodenal ulceration. Previous attempts to reproduce the diseases in conventional laboratory animal species have been unsuccessful. To determine if neonatal gnotobiotic piglets were susceptible to C. pylori, we orally challenged two litters (n = 17) with 109 CFU after pretreating them with
Infection and …, 1987
Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesi... more Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesis of human gastritis, dyspepsia, and gastroduodenal ulceration. Previous attempts to reproduce the diseases in conventional laboratory animal species have been unsuccessful. To determine if neonatal gnotobiotic piglets were susceptible to C. pylori, we orally challenged two litters (n = 17) with 109 CFU after pretreating them with
American Journal of Veterinary Research, 2005
Scandinavian Journal of Gastroenterology, 1995
Urease-negative Helicobacter pylori generated by insertional mutagenesis fails to colonize gnotob... more Urease-negative Helicobacter pylori generated by insertional mutagenesis fails to colonize gnotobiotic piglets, and this effect is largely independent of gastric pH. The purpose of this study was to determine whether urease-negative H. pylori colonized gastric explants ex vivo. Gastric mucosal explants derived from neonatal germ-free piglets were inoculated with either wild-type H. pylori or one of two mutants derived by insertional mutagenesis. All three bacterial strains colonized explants. The level of colonization increased over the duration of the experiment, reaching 10(8)-10(9) cfu/g gastric mucosa by 72 h after inoculation. Morphologic evidence of colonization was similar to that observed in gnotobiotic piglets. Colonization of explants was not affected by lack of urease. These results contrast with previous findings showing that urease activity is essential for colonization of piglets by H. pylori. Thus, urease-dependent colonization is dependent on an intact gastric microenvironment.
Acta Neuropathol, 1980
Three weeks after inoculation of 24-day-old gnotobiotic dogs with Snyder-Hill canine distemper vi... more Three weeks after inoculation of 24-day-old gnotobiotic dogs with Snyder-Hill canine distemper virus, white matter samples were taken from the primary predilection sites for canine distemper virus-associated demyelination. The plasmalogenase activity in extracts was nearly 6-fold greater than control values for a dog with extensive demyelination and was not detectable in tissue from a dog with non-demyelinating lesions. Acid and neutral phospholipases A1 and A2 were assayed in homogenates and extracts with phosphatidyl ethanolamine substrates. Phospholipase A2 activities at both pH 4.3 and pH 6.8 were less in the dog with severe demyelinating lesions than in dogs with less severe lesions. Phospholipase A1 activities were generally similar for all four dogs. The marked elevation of plasmalogenase activity in demyelinating tissue may be associated with a release from the plasmalogens of arachidonic acid which is converted to oxygenated metabolites that may then be responsible for the inflammation. Phospholipases acting on phosphatidyl ethanolamine do not seem to be involved in the pathogenesis of demyelination associated with canine distemper virus.
Journal of Neuroimmunology, Jan 31, 1989
In order to determine the infectivity of various viremic blood fractions for central nervous syst... more In order to determine the infectivity of various viremic blood fractions for central nervous system (CNS) endothelia, viremic plasma, platelets and mononuclear cells were prepared from canine distemper virus (CDV)-infected dogs and infused into the right carotid arteries of CDV-naive gnotobiotic dogs. All blood fractions were infectious for endothelia as determined by indirect immunofluorescence examination for viral antigen in recipients. Virus-positive platelets, even though possessing only trace amounts (1.0 x 10(1) TCID50/ml) of in vitro titratable virus, were the most effective fraction for infection of vascular endothelium. These data confirm the important role of vascular endothelia in establishing CNS infection in this disease and implicate virus-positive platelets and leukocytes in the initiation of this phenomenon.
Journal of Veterinary Diagnostic Investigation, 2003
Journal of Veterinary Diagnostic Investigation, 2003
Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was a... more Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.
Journal of Veterinary Diagnostic Investigation, 2003
Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was a... more Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.
Veterinary Microbiology, 2009
Sera and selected tissue homogenates collected from gnotobiotic swine never exposed to the enviro... more Sera and selected tissue homogenates collected from gnotobiotic swine never exposed to the environment or other swine tissues were tested for the presence of porcine torque teno virus (TTV) DNAs by nested and non-nested polymerase chain reactions (PCR) using primers specific for the untranslated region of porcine genogroups (g) 1 and 2. Twenty-three of 105 (21.9%) gnotobiotic piglets were g1- and/or g2-TTV DNA positive. Twenty-three of 27 (85.2%) sow sera, collected at the time of Caesarian derivation of the litters contained either or both TTV genogroup DNAs. These data demonstrate that porcine TTV may be transmitted to piglets by the in utero route and that the incidence of fetal infection is high.
Canadian veterinary journal, 2007
Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus ... more Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus type 2 (PCV2) at 3 days of age and then given 1 of 6 different commercial Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins as either a single dose (7 d of age, 1 application products) or 2 doses (7 and 21 d of age, 2 application product). Control groups received PCV2 alone (n = 9) or were infected with PCV2 and immunized twice with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freund's adjuvant (ICFA) (n = 7). Five of 7 (71%) PCV2-infected piglets immunized with KLH/ICFA developed mild or overt PMWS, whereas none of 9 piglets infected with PCV2 alone developed PMWS. Five of 12 (42%) piglets vaccinated with a commercial bacterin containing mineral oil adjuvant developed PMWS following vaccination. None of the PCV2-infected piglets in the other bacterin-vaccinated groups developed PMWS in this model of PCV2-associated disease. This difference in prevalence of PMWS in pi...
Journal of General Virology, 1989
Nucleocapsid (NC) variants expressed by the Onderstepoort strain of canine distemper virus (CDV) ... more Nucleocapsid (NC) variants expressed by the Onderstepoort strain of canine distemper virus (CDV) were ultrastructurally and biochemically characterized. Three isolated variants were defined which corresponded to the three variants observed within the cytoplasm of infected cells. Dense NC (D-NC), isolated on discontinuous caesium chloride (CsCl) isopycnic gradients, had an average density of 1.2971 +/- 0.0042 g/ml. Ultrastructurally, D-NC were 1620.0 +/- 112.1 nm in length with a 20.1 +/- 1.3 nm outer and a 5.8 +/- 0.7 nm inner core diameter. The D-NC protein composition was 89.7% of a 61K protein (N), 8.4% of a 75K protein (P) and 1.9% of a 160K to 200K protein (L). A single species of nucleic acid, 15 kb in length, was isolated from D-NC. Light NC (L-NC), similarly isolated, had an average density of 1.2894 +/- 0.0040 g/ml. L-NC differed ultrastructurally from D-NC in that poor resolution of NC subunits, a larger outer diameter (32.0 +/- 2.8 nm), and a greater inner core diameter (10.4 +/- 0.6 nm) were observed. The average L-NC strand length was 1574.4 +/- 115.8 nm. The protein composition was the same as D-NC with the exception of an additional 70K protein, representing 4.0 to 7.7% of the total L-NC protein mass. A 15 kb nucleic acid was also identified in L-NC, although heightened sensitivity of encapsidated L-NC nucleic acid to non-specific nuclease degradation was observed. The ratio of D-NC to L-NC isolated from individual virus preparations varied and was independent of viral infectivity. A third NC variant, defective-NC (Df-NC), was also identified. This had the lowest density on CsCl gradients (1.2460 +/- 0.0046 g/ml). The Df-NC structures were truncated to a uniform length of 87.0 +/- 5.8 nm. Diameter measurements were between those of D-NC and L-NC, being 24.4 +/- 1.4 nm (outer) and 6.9 +/- 0.4 nm (inner core). Like L-NC, the 70K protein was present but in greater amounts, representing as much as 43.7% of the total Df-NC protein mass. RNase A-sensitive nucleic acid was isolated from Df-NC which ranged in size from 1.16 to 0.67 kb with a majority of the material being 0.86 kb in length. For both L-NC and Df-NC, canine CDV convalescent serum reacted with viral N and P proteins in Western blot analyses but not with the 70K protein, suggesting a host cellular origin for the latter.
The Journal of Infectious Diseases, 1998
To determine the effect of oral adjuvant-assisted and parenteral vaccination, germ-free piglets w... more To determine the effect of oral adjuvant-assisted and parenteral vaccination, germ-free piglets were vaccinated orally with and without labile toxin adjuvant or parenterally and challenged with viable Helicobacter pylori. All prechallenge vaccination regimens induced anti-H. pylori antibodies and suppressed bacterial colonization, but no vaccination regime completely prevented infection. Parenteral vaccination given after infection had no effect on bacterial colonization. Lymphocytic gastritis was present in all piglets challenged with live bacteria regardless of vaccination status. Neutrophilic gastritis was present in vaccinated challenged piglets but not in infected, unvaccinated piglets. Gastritis was not present in uninfected control piglets regardless of vaccination status. In gnotobiotic piglets, vaccination suppresses but does not prevent infection by H. pylori, and parenteral vaccination does not cure infected piglets. Vaccination does not ameliorate gastritis due to H. pylori in piglets but does induce neutrophilic gastric inflammation in some infected piglets. Because of the importance of Helicobacter pylori in human gastric disease and the incomplete success associated with current methods of therapy, the potential utility of both preventative and curative vaccination for H. pylori has attracted increasing attention in recent years. Early studies in gnotobiotic piglets demonstrated that parenteral vaccination was only partly effective in suppressing bacterial colonization after subsequent challenge and that vaccination did not prevent gastritis but in fact increased its severity [1]. Subsequent experiments determined that oral vaccination of specific pathogen-free mice prevents colonization by either H. pylori or Helicobacter felis [2-11] and that oral vaccination can eliminate bacterial colonization in most mice in which infection is already established [10, 12, 13]. Oral vaccination was ineffective in gnotobiotic piglets, but the vaccination protocol used did not include any oral adjuvant and thus was not directly comparable to the murine experiments [1]. The purpose of this study was to compare the efficacy of 4 vaccination protocols in preventing establishment of H. pylori infection in gnotobiotic piglets and to evaluate the efficacy of parenteral vaccination in eliminating established infection. Methods Bacterial strains. H. pylori strains 26695 and N6 were used. Both are cagA-positive and VacA-positive human isolates that were
Veterinary Pathology, 2001
Porcine circovirus (PCV)-2, a newly described single-stranded circular DNA virus pathogen of swin... more Porcine circovirus (PCV)-2, a newly described single-stranded circular DNA virus pathogen of swine is the cause of postweaning multisystemic wasting syndrome (PMWS). In gnotobiotic piglets, PCV-2 infection alone produces asymptomatic infection without evidence of overt PMWS. Gnotobiotic piglets infected with PCV-2 were injected with keyhole limpet hemocyanin in incomplete Freund's adjuvant (KLH/ICFA), and the effects on virus production and development of PMWS were determined. In the first experiment, piglets were injected subcutaneously on the left hip and shoulder, and viral burden was assessed in regional lymph nodes draining the injection sites and in contralateral lymph nodes 13–14 days after infection. Immune activation increased the number of virus antigen-positive cells in draining lymph nodes and increased the amount of infectious virus recovered by 1–4 log10. In a second experiment, the effects of injections of KLH/ICFA with or without concurrent stimulation of peritoneal macrophages by intraperitoneal injections of thioglycollate broth on induction of PMWS was assessed. All immunized piglets developed moderate to severe PMWS, whereas none of the piglets infected with PCV-2 alone developed PMWS. In PMWS-affected piglets, extensive replication of PCV-2 was documented by both immunocytochemistry and quantitative viral titrations. Thus, immune activation is a key component of the pathogenesis of PCV-2-associated PMWS in swine.
Canadian Journal of Veterinary Research Revue Canadienne De Recherche Veterinaire, Jul 1, 2010
The objective of this study was to improve the visual localization of urease activity of Helicoba... more The objective of this study was to improve the visual localization of urease activity of Helicobacter pylori-like organisms (HPLO) on swine gastric mucosa by in vitro optimization of the urea concentration and pH indicator of a urease test reagent. Five 21-day-old conventional pigs were infected orally with HPLO (3 pigs) or Brucella broth alone (2 pigs). At 17 d after infection the pigs were euthanized and their stomachs excised and tested for HPLO by a modified urease test formulation sprayed onto the gastric mucosa, as well as confirmatory culture and isolation of HPLO from urease-positive sites. This study showed improved detection of HPLO in porcine gastric mucosa with the use of a modified urease test formulation containing 5% urea and the pH indicator bromocresol purple compared with the use of a conventional formulation of 2% urea and phenol red. This test can readily be applied to achieve a presumptive diagnosis of HPLO in cases of gastritis or gastric esophageal ulceration in pigs.
Canadian Journal of Veterinary Research Revue Canadienne De Recherche Veterinaire, Oct 1, 2012
I n t r o d u c t i o n Porcine circovirus type 2 (PCV2) is a small, nonenveloped, singlestranded... more I n t r o d u c t i o n Porcine circovirus type 2 (PCV2) is a small, nonenveloped, singlestranded DNA virus (1). It has been incriminated as a necessary cause of postweaning multisystemic wasting syndrome (PMWS) (2). This disease, which has a high case-fatality rate (3), typically develops in piglets between 8 and 16 wk of age. Clinical signs include progressive emaciation, dyspnea, and enlarged superficial lymph nodes. The virus is also associated with a number of other diseases, such as porcine dermatopathy and nephropathy syndrome (4), reproductive disorders (5), proliferative and necrotizing pneumonia (6), and porcine respiratory disease complex (7). Recently, a sharp increase in PCV2-associated deaths was reported in Canada (8,9). The virus is stable (10) and ubiquitous in the swine population (3), which makes eradication very difficult. Vaccination represents an attractive means to control endemic infection and has
Infection and …, 1997
To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gn... more To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets.
Infection and …, 1997
To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gn... more To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets.
Infection and …, 1987
Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesi... more Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesis of human gastritis, dyspepsia, and gastroduodenal ulceration. Previous attempts to reproduce the diseases in conventional laboratory animal species have been unsuccessful. To determine if neonatal gnotobiotic piglets were susceptible to C. pylori, we orally challenged two litters (n = 17) with 109 CFU after pretreating them with
Infection and …, 1987
Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesi... more Campylobacter pylori, a gram-negative microaerophiic bacterium, has been implicated in the genesis of human gastritis, dyspepsia, and gastroduodenal ulceration. Previous attempts to reproduce the diseases in conventional laboratory animal species have been unsuccessful. To determine if neonatal gnotobiotic piglets were susceptible to C. pylori, we orally challenged two litters (n = 17) with 109 CFU after pretreating them with
American Journal of Veterinary Research, 2005
Scandinavian Journal of Gastroenterology, 1995
Urease-negative Helicobacter pylori generated by insertional mutagenesis fails to colonize gnotob... more Urease-negative Helicobacter pylori generated by insertional mutagenesis fails to colonize gnotobiotic piglets, and this effect is largely independent of gastric pH. The purpose of this study was to determine whether urease-negative H. pylori colonized gastric explants ex vivo. Gastric mucosal explants derived from neonatal germ-free piglets were inoculated with either wild-type H. pylori or one of two mutants derived by insertional mutagenesis. All three bacterial strains colonized explants. The level of colonization increased over the duration of the experiment, reaching 10(8)-10(9) cfu/g gastric mucosa by 72 h after inoculation. Morphologic evidence of colonization was similar to that observed in gnotobiotic piglets. Colonization of explants was not affected by lack of urease. These results contrast with previous findings showing that urease activity is essential for colonization of piglets by H. pylori. Thus, urease-dependent colonization is dependent on an intact gastric microenvironment.
Acta Neuropathol, 1980
Three weeks after inoculation of 24-day-old gnotobiotic dogs with Snyder-Hill canine distemper vi... more Three weeks after inoculation of 24-day-old gnotobiotic dogs with Snyder-Hill canine distemper virus, white matter samples were taken from the primary predilection sites for canine distemper virus-associated demyelination. The plasmalogenase activity in extracts was nearly 6-fold greater than control values for a dog with extensive demyelination and was not detectable in tissue from a dog with non-demyelinating lesions. Acid and neutral phospholipases A1 and A2 were assayed in homogenates and extracts with phosphatidyl ethanolamine substrates. Phospholipase A2 activities at both pH 4.3 and pH 6.8 were less in the dog with severe demyelinating lesions than in dogs with less severe lesions. Phospholipase A1 activities were generally similar for all four dogs. The marked elevation of plasmalogenase activity in demyelinating tissue may be associated with a release from the plasmalogens of arachidonic acid which is converted to oxygenated metabolites that may then be responsible for the inflammation. Phospholipases acting on phosphatidyl ethanolamine do not seem to be involved in the pathogenesis of demyelination associated with canine distemper virus.
Journal of Neuroimmunology, Jan 31, 1989
In order to determine the infectivity of various viremic blood fractions for central nervous syst... more In order to determine the infectivity of various viremic blood fractions for central nervous system (CNS) endothelia, viremic plasma, platelets and mononuclear cells were prepared from canine distemper virus (CDV)-infected dogs and infused into the right carotid arteries of CDV-naive gnotobiotic dogs. All blood fractions were infectious for endothelia as determined by indirect immunofluorescence examination for viral antigen in recipients. Virus-positive platelets, even though possessing only trace amounts (1.0 x 10(1) TCID50/ml) of in vitro titratable virus, were the most effective fraction for infection of vascular endothelium. These data confirm the important role of vascular endothelia in establishing CNS infection in this disease and implicate virus-positive platelets and leukocytes in the initiation of this phenomenon.