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Abstract

Objective—To determine whether porcine genogroup 1 torque teno virus (g1-TTV) can infect and cause disease in gnotobiotic swine.

Sample Population—20 conventional baby pigs and 46 gnotobiotic baby pigs.

Procedures—Porcine g1-TTV was transmitted from conventional swine to gnotobiotic pigs via pooled leukocyte-rich plasmas (n = 18) that had positive results for g1-TTV DNA. Bone marrow–liver homogenates that had positive results for torque teno virus (TTV) were used in 4 serial passages in gnotobiotic pigs (2 pigs/passage). A pathogenesis experiment was conducted with in vivo passages of g1-TTV in various groups of gnotobiotic pigs.

Results—All g1-TTV inoculated pigs had no clinical signs but developed interstitial pneumonia, transient thymic atrophy, membranous glomerulonephropathy, and modest lymphocytic to histiocytic infiltrates in the liver after inoculation with the TTV-containing tissue homogenate; these changes were not detected in uninoculated control pigs or pigs injected with tissue homogenate devoid of TTV DNAs. In situ hybridization was used to identify g1-TTV DNAs in bone marrow mononuclear cells.

Conclusions and Clinical Relevance—Analysis of these data revealed that porcine g1-TTV was readily transmitted to TTV-naïve swine and that infection was associated with characteristic pathologic changes in gnotobiotic pigs inoculated with g1-TTV. Thus, g1-TTV could be an unrecognized pathogenic viral infectious agent of swine. This indicated a directly associated induction of lesions attributable to TTV infection in swine for a virus of the genus Anellovirus.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether 2 isolates of recently isolated swine-origin Helicobacter pylori-like bacteria are pathogenic in pigs and compare the signs of gastric disease induced by these isolates with those detected in H pylori- and Helicobacter heilmannii-in fected pigs.

Animals—36 neonatal gnotobiotic pigs.

Procedure—Groups of separately housed pigs were inoculated orally with swine-origin Helicobacter-like isolates 2662 or 1268, H pylori (human gastric pathogen), or a gastric homogenate from gnotobiotic swine containing H heilmannii. Noninoculated pigs were used as control animals. Clinical signs and development of homologous and heterologous antibodies against Helicobacter organisms were assessed. After euthanasia, gastric tissues were examined grossly and microscopically; Helicobacter organisms were detected by use of Warthin-Starry and immunohistochemical stains.

Results—Both porcine Helicobacter-like isolates colonized the stomachs of swine. Isolate 2662 was highly pathogenic; in 13 isolate 2662-inoculated pigs, gastroesophageal ulcerations developed in 9 and ulceration of the gastric glandular mucosa was detected in 5. Histologically, inflammatory gastritis consisting of multifocal to diffuse lymphocytic and plasmacytic cellular infiltrates and lymphoid follicle formation in the gastric lamina propria accompanied bacterial colonization of the gastric compartment. In contrast, H heilmannii was minimally pathogenic in that only modest inflammatory cell infiltrates were seen. Gastroesophageal or mucosal ulcers were not evident in pigs inoculated with H heilmannii.

Conclusions and Clinical Relevance—These data indicate that swine-origin H pylori-like bacteria can be pathogenic in pigs and suggest that porcine gastric disease may be mediated, in part, by colonization of the stomach by swine-origin H pylori-like bacteria. (Am J Vet Res 2005;66:945–952)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether genogroup 1 porcine torque teno virus (g1-TTV) can potentiate clinical disease associated with porcine circovirus type 2 (PCV2).

Sample population—33 gnotobiotic baby pigs.

Procedures—Pigs were allocated into 7 groups: group A, 5 uninoculated control pigs from 3 litters; group B, 4 pigs oronasally inoculated with PCV2 alone; group C, 4 pigs inoculated IP with first-passage g1-TTV alone; group D, 4 pigs inoculated IP with fourth-passage g1-TTV alone; group E, 6 pigs inoculated IP with first-passage g1-TTV and then oronasally inoculated with PCV2 7 days later; group F, 6 pigs inoculated IP with fourth-passage g1-TTV and then inoculated oronasally with PCV2 7 days later; and group G, 4 pigs inoculated oro-nasally with PCV2 and then inoculated IP with fourth-passage g1-TTV 7 days later.

Results—6 of 12 pigs inoculated with g1-TTV prior to PCV2 developed acute onset of postweaning multisystemic wasting syndrome (PMWS). None of the pigs inoculated with g1-TTV alone or PCV2 alone or that were challenge exposed to g1-TTV after establishment of infection with PCV2 developed clinical illness. Uninoculated control pigs remained healthy.

Conclusions and Clinical Relevance—These data implicated g1-TTV as another viral infection that facilitates PCV2-induced PMWS. This raises the possibility that torque teno viruses in swine may contribute to disease expression currently associated with only a single infectious agent.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether feline vaccine siteassociated sarcomas (VSS) contain a higher amount of endogenous FeLV (enFeLV) RNA, compared with feline nonvaccine site-associated sarcomas (non-VSS).

Sample Population—Formalin-fixed paraffin-embedded (FFPE) tissues from 50 VSS and 50 cutaneous non-VSS.

Procedure—RNA was extracted from FFPE sections of each tumor, and regions of the long terminal repeat (LTR) and envelope (env) gene of enFeLV were amplified by use of reverse transcriptase-polymerase chain reaction (RT-PCR). The density of each RT-PCR product band for enFeLV was compared with that of a constitutively expressed gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). An integrated density value (IDV) was determined by use of densitometry, and the IDV ratio for enFeLV to GAPDH was calculated for each enFeLV primer set.

Results—The median (interquartile range) of the IDV ratio for the enFeLV LTR primer set was 0.52 (0.26 to 1.17) for the VSS group and 0.84 (0.21 to 1.53) for the non-VSS group. The median (interquartile range) of the IDV ratio for the enFeLV env primer set was 0.60 (0.37 to 0.91) for the VSS group and 0.59 (0.36 to 1.09) for the non-VSS group.

Conclusions—Because the amount of enFeLV RNA within the LTR and env gene was not significantly different between the VSS and non-VSS groups, enFeLV replication or expression is unlikely to be involved in VSS development. (Am J Vet Res 2001;62:1990–1994)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the use of a polymerase chain reaction (PCR) method for detection of feline immunodeficiency virus (FIV) DNA, using formalin-fixed paraffin- embedded (FFPE) tissues, and to use this method to evaluate tissues obtained from vaccine site-associated sarcomas (VSS) of cats for FIV DNA.

Sample Population—50 FFPE tissue blocks from VSS of cats and 50 FFPE tissue blocks from cutaneous non-vaccine site-associated fibrosarcomas (non-VSS) of cats.

Procedure—DNA was extracted from FFPE sections of each tumor and regions of the gag gene of FIV were amplified by a PCR, using 3 sets of primers. Sensitivity of the method was compared between frozen and FFPE tissues, using splenic tissue obtained from a cat that had been experimentally infected with FIV.

Results—We did not detect FIV DNA in VSS or non- VSS tissues. Sensitivity of the PCR method was identical for frozen or FFPE tissues.

Conclusions and Clinical Relevance—It is possible to detect FIV DNA in FFPE tissues by use of a PCR. We did not find evidence to support direct FIV involvement in the pathogenesis of VSS in cats. (Am J Vet Res 2000;61:1037–1041)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate a group of vaccine site-associated sarcomas (VSS) for the presence of feline foamy virus (FeFV) DNA, using polymerase chain reaction (PCR) methods.

Sample Population—50 formalin-fixed paraffin embedded (FFPE) tissue blocks from VSS of cats.

Procedure—DNA was extracted from FFPE sections of each tumor, and regions of the gag and pol genes of FeFV were amplified by use of PCR methods, using 1 primer set for each region. Sensitivity of the method was compared between fresh and FFPE cells, using mouse kidney tissue that was injected with FeFVinfected cultured cells and using agarose-cell pellets.

Results—Feline foamy virus DNA was not detected in VSS tissues. Sensitivity of the method was 10 times greater in fresh versus FFPE mouse tissues. Sensitivity of the method in fresh FeFV-infected cultured cells versus FFPE agarose-cell pellets was equal when fixation was 24 or 48 hours and 10 times greater when fixation was 72 hours or 1 week.

Conclusion and Clinical Relevance—A PCR-based method can be successfully applied to FFPE tissues for FeFV DNA detection. Results suggest there is no direct FeFV involvement in the pathogenesis of VSS in cats. (Am J Vet Res 2002;63:60–63)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether a Helicobacter sp similar to Helicobacter pylori in the stomachs of humans could be isolated from the stomachs of pigs.

Animals—4 young conventionally reared and 21 gnotobiotic pigs.

Procedure—Gastric mucosal homogenates (10% wt/vol) from 4 young conventionally reared pigs were cultured on Skirrow medium under microaerophilic conditions to assess the presence of Helicobacter spp. Colonies with morphologic features compatible with Helicobacter organisms were selected, tested for urease activity, and subpassaged on Skirrow medium. Isolates were examined via SDS-PAGE electrophoresis and reciprocal western blot analyses involving convalescent sera from monoinfected gnotobiotic pigs.

Results—Urease- and catalase-positive, gram-negative, microaerophilic, small, curved rod bacteria were isolated from the gastric mucosa of young healthy pigs. The first isolate (2662) was structurally and immunologically closely related to H pylori isolated from humans. The second isolate (1268) displayed an SDS-PAGE profile dissimilar to that of H pylori and isolate 2662, yet it shared limited immunologic crossreactivity with these microbes.

Conclusions and Clinical Relevance—Findings of this study indicate that development of gastric mucosal ulcers and ulceration of the nonglandular pars esophagea in pigs may be associated with gastric colonization by swine-origin Helicobacter spp, which are similar to H pylori isolated from humans. (Am J Vet Res 2005;66:938–944)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether vaccine site-associated sarcomas (VSS) from cats contain polyomavirus antigen or DNA.

Sample Population—50 formalin-fixed paraffinembedded tissue blocks of VSS from cats.

Procedure—Sections from each tissue block were evaluated for polyomavirus antigen by use of an avidin-biotin-complex immunohistochemical staining method, using rabbit anti-murine polyomavirus polyclonal antiserum as the primary antibody. The DNA was extracted from sections of each tissue block, and a polymerase chain reaction assay was performed, using primers designed to amplify regions of the bovine polyomavirus genome and consensus polyomavirus primers designed to detect unknown polyomaviruses.

Results—Polyomavirus antigen and DNA were not detected in any of the VSS.

Conclusions and Clinical Relevance—Results suggest that polyomaviruses likely do not have any direct involvement in the pathogenesis of VSS in cats. (Am J Vet Res 2001;62:828–832)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To investigate the role of tumor suppressor gene p53 mutation in feline vaccine site-associated sarcoma (VSS) development and to evaluate the relationship between p53 nucleotide sequence and protein expression.

Sample Population—Formalin-fixed paraffinembedded tissues of 8 feline VSS with dark p53 immunostaining (high p53 expression) and 13 feline VSS with faint or no staining (normal p53 expression).

Procedure—DNA was extracted from neoplastic and normal tissue from each paraffin block. The following 3 regions of the p53 gene were amplified by polymerase chain reaction: 379 base pair (bp) region of exon 5, intron 5, and exon 6, 108 bp region of exon 7, and 140 bp region of exon 8. Amplified p53 products were sequenced and compared with published feline p53. The p53 mutations identified were correlated with p53 mutations predicted by immunostaining.

Results—Neoplastic cells of 5 of 8 (62.5%) VSS that had high p53 expression harbored single missense mutations within the p53 gene regions examined. The p53 gene mutations were not detected in the 13 tumors with normal p53 immunostaining. Nonneoplastic tissues adjacent to all 21 VSS lacked mutations of these p53 gene regions.

Conclusions—The p53 gene mutations were restricted to neoplastic tissue and, therefore, were unlikely to predispose to VSS. However, p53 mutations may have contributed to cancer progression in 5 of the 21 VSS. There was very good (κ quotient = 0.67 with a confidence limit of 0.3 to 1.0), although not complete, agreement between prediction of mutation by p53 immunostaining and identification of mutations by sequencing of key p53 gene regions. (Am J Vet Res 2000;61:1277–1281)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the prevalence of antibodies against a swine-origin Helicobacter pylori–like organism (HPLO) and H pylori in conventionally reared swine.

Animals—640 conventionally reared swine of various ages from 16 high-health farms in Canada, 20 sows from Ohio, and 35 gnotobiotic swine.

Procedures—Blood was collected from the cranial vena cava. Sera were collected and tested via ELISA for antibodies against antigen prepared from a swine-origin HPLO and human H pylori strain 26695.

Results—Antibodies reactive with a swine HPLO, H pylori, or both were detected in 483 of 640 swine from all 16 farms in western Canada. Seroprevalence varied with age and was low (5.6%) in suckling (≤ 4-week-old) swine and increasingly high in swine ranging from > 4 weeks old to adulthood.

Conclusions and Clinical Relevance—Findings suggested that colonization by a swine-origin HPLO, H pylori, or both and resultant seroconversion, like that of H pylori infection in humans, were common in commercial swine operations. Furthermore, data indicated that gastric infection was acquired at an early age. The relationships to gastric colonization by HPLOs and clinical manifestations of disease such as gastritis and gastroesophageal ulceration remain to be determined.

Full access
in American Journal of Veterinary Research