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.
Objective—To determine whether 2 isolates of
recently isolated swine-origin Helicobacterpylori-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)
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.
Objective—To compare antibody responses to
intranasal and SC Bordetella bronchiseptica vaccines
in seropositive dogs.
Design—Randomized controlled study.
Animals—40 young adult Beagles vaccinated against
Procedure—Dogs were randomly assigned to 1 of 4
groups (intranasal vaccine, SC vaccine, intranasal and
SC vaccines, no vaccine) and vaccinated on day 0.
Serum and salivary B bronchiseptica-reactive antibody
responses were measured on days 0 through 7,
10, 14, 21, and 28.
Results—Dogs that were vaccinated with the SC vaccine,
alone or in combination with the intranasal vaccine,
had a significant increase in serum concentration
of B bronchiseptica-reactive IgG beginning on day 5
and persisting through day 28. Dogs that were vaccinated
with the intranasal vaccine alone had a significant
increase in serum concentration of B bronchiseptica-
reactive IgG beginning on day 10 and persisting
through day 28, but serum IgG concentration in these
dogs was significantly less than concentration in dogs
that received the SC vaccine. Neither vaccine had a
demonstrable effect on salivary concentrations of B
bronchiseptica-reactive IgA or IgG. On day 10, all vaccinated
groups had significantly higher serum IgA concentrations
than did unvaccinated control dogs.
Conclusions and Clinical Relevance—Results suggest
that the SC B bronchiseptica vaccine may be
used to stimulate antibody responses in seropositive
dogs. There was no apparent benefit to administering
these vaccines simultaneously. Intranasal vaccines
may not be effective for booster vaccination of dogs
previously exposed to or immunized against B bronchiseptica.
Dogs should be vaccinated at least 5 days
prior to exposure to B bronchiseptica. (J Am Vet Med
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
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)
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.
Objective—To determine whether porcine dermatitis and nephropathy syndrome (PDNS) could be experimentally induced in gnotobiotic swine.
Sample Population—Plasma samples from 27 sows and 20 conventional weaned piglets were obtained, and 30 gnotobiotic pigs were used in experiments.
Procedures—3 experiments were conducted. Groups of 3-day-old gnotobiotic pigs were inoculated with pooled plasma samples obtained from healthy feeder pigs in a herd that was in the initial phases of an outbreak of respiratory disease; gross and histologic lesions of PDNS were detected in the inoculated pigs. In a second experiment, 2- and 3-day-old gnotobiotic pigs were inoculated with porcine reproductive respiratory syndrome virus (PRRSV) and with PRRSV-negative tissue homogenate containing genogroup 1 torque teno virus (g1-TTV). Lesions of PDNS were detected.
Results—Pigs inoculated with pooled plasma or the combination of tissue-culture–origin PRRSV and g1-TTV tissue homogenate developed systemic hemostatic defects, bilaterally symmetric cutaneous hemorrhages, generalized edema, icterus, bilaterally symmetric renal cortical hemorrhage, dermal vasculitis with hemorrhage, and interstitial pneumonia consistent with a clinical and pathologic diagnosis of PDNS. The PRRSV RNAs and g1-TTV DNAs were detected in plasma; all pigs seroconverted to PRRSV, and all had negative results for porcine circovirus type 2 when tested by use of PCR assays.
Conclusions and Clinical Relevance—These data suggested that PDNS is a manifestation of disseminated intravascular coagulation in swine. For the experimental conditions reported here, combined infection with g1-TTV and PRRSV was implicated in the genesis of these lesions.