Lack of antibodies to porcine circovirus type 2 virus in beef and dairy cattle and horses in western Canada.
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Porcine circovirus type 2 (PCV2) is a recently recognized agent that is consistently associated with postweaning multisystemic wasting disease in swine. There are conflicting data concerning the ability of this virus to infect and cause disease in other species. To determine if normal cattle, cattle affected with various illnesses, and normal horses in endemic areas of PCV2 infection in swine have had PCV2 infections, 100 randomly selected bovine sera, 100 equine sera, and 100 colostrum samples from clinically normal dairy cattle were examined for the presence of antibodies to porcine circoviruses by using ELISAs. All samples tested were negative for antibodies to porcine circoviruses. As well, a seronegative neonatal Holstein calf and 6 seronegative, 6-month-old beef calves that were experimentally infected with PCV2 failed to develop antibodies to the virus. These results suggest that natural infection of cattle and horses with PCV2 does not occur, or is a rare event, in western Canada. (+info)
Association of porcine circovirus 2 with reproductive failure in pigs: a retrospective study, 1995-1998.
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In order to determine if vertically transmitted porcine circovirus (PCV) has played a role in reproductive failure in pigs in areas of endemic infection, archival fixed tissues were examined by polymerase chain reaction (PCR) and immunohistochemistry. Tissues tested were from routine cases of abortion or reproductive failure submitted between 1995 and 1998 to the diagnostic laboratory at the Western College of Veterinary Medicine, Saskatoon. They originated from 29 high-health herds in the provinces of Alberta and Saskatchewan and comprised a total of 36 individual submissions. Porcine circovirus type 1 (PCV1) was not detected by PCR in any submitted tissues. Porcine circovirus type 2 (PCV2) was not detected by PCR or immunohistochemistry in any of the submitted tissue. The effect of extended formalin fixation on the detection of PCV2 by PCR was assessed and fixation for up to one week had no gross effect on sensitivity of detection using this PCR technique. Failure to detect porcine circoviruses in cases of reproductive failure prior to 1999 in areas of endemic infections, suggests that reproductive disease may be a new clinical manifestation of PCV2 infection, and that vertical transmission may not have been the primary mechanism of initial dissemination of the virus in the pig population. (+info)
Multiple porcine circovirus 2-associated abortions and reproductive failure in a multisite swine production unit.
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Porcine circovirus type 2 was detected in several stillborn and nonviable neonatal piglets presenting with chronic passive congestion, cardiac hypertrophy, and severe diffuse myocarditis. The presence of the virus in the heart and other tissues of affected piglets was confirmed by polymerase chain reaction, immunohistochemistry, and virus isolation techniques. Other reproductive losses and associated infectious agents in the herd are discussed. (+info)
Colocalization of porcine reproductive and respiratory syndrome virus and porcine circovirus 2 in porcine dermatitis and nephrology syndrome by double-labeling technique.
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Simultaneous detection of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus 2 (PCV2) was achieved by a double-labeling technique using a combination of immunohistochemistry and in situ hybridization in five pigs with naturally occurring porcine dermatitis and nephropathy syndrome (PDNS). Both PRRSV and PCV2 were isolated from a homogenate of pooled skin and kidney from three pigs. PRRSV RNA was demonstrated by reverse transcription polymerase chain reaction (PCR) in skin, kidney, lymph node, and tonsil homogenates from all pigs. PCV2 DNA was demonstrated by PCR in kidney, lymph node, tonsil, liver, and lung homogenates from all pigs. For double-labeling studies, the tissue samples were processed sequentially, first by immunohistochemistry and then by in situ hybridization. The most consistent and intense staining for PRRSV and PCV2 was in the kidney, lymph node, and tonsil. PRRSV antigen and PCV2 DNA were also detected in the skin. This morphologic study is the first to confirm the presence of both PRRSV and PCV2 in the same tissues in pigs with naturally occurring PDNS. (+info)
Postweaning multisystemic wasting syndrome induced after experimental inoculation of cesarean-derived, colostrum-deprived piglets with type 2 porcine circovirus.
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Cesarean-derived, colostrum-deprived pigs (n = 23) were inoculated intranasally and subcutaneously with a low cell culture passage of type 2 porcine circovirus. In 11 pigs, a persistent fever that lasted 7-17 days began 12-15 days after inoculation with virus. Additional signs of disease in those 11 pigs included depression (11 of 11 pigs), palpable enlargement of inguinal, prefemoral, and popliteal lymph nodes (11 of 11), icterus (6 of 11), and hyperpnea (2 of 11). The remaining 12 pigs had fever that occurred intermittently for 2-4 days between days 12 and 20 postinoculation. Overt signs of disease in those pigs were limited to palpable enlargement of inguinal and popliteal lymph nodes (9 of 12 pigs). When compared with control pigs of similar age, the average daily rate of weight gain for all pigs inoculated with virus was less over a 2-week period that began 2 weeks post inoculation. At postmortem examination, lymph node enlargement was seen in 14 of 14 pigs euthanized between days 20 and 28 postinoculation. Lymph node enlargement was especially prominent in pigs that developed a persistent fever. Microscopic lesions noted in pigs that developed a persistent fever included cellular depletion in lymphoid tissues; hepatic cell necrosis; and lymphogranulomatous inflammation of lymph nodes, Peyer's patches of the intestine, liver, kidney, and heart. Virus was isolated with varying frequency from nasal, rectal, or tonsil swab specimens, buffy coat, serum, urine, and lung lavage fluid obtained antemortem or postmortem. Virus was isolated from or viral DNA was detected in a variety of tissues obtained postmortem up to 125 days postinoculation. Antibody against type 2 porcine circovirus usually was detected in serum between 15 and 20 days postinoculation; however, antibody against virus was not detected in serum from 4 pigs euthanized 20-24 days postinoculation. Direct contact with pigs inoculated with virus 42 days previously resulted in transmission of virus to 3 of 3 control pigs. (+info)
Genome sequence determinations and analyses of novel circoviruses from goose and pigeon.
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The genomes of novel circoviruses from goose and pigeon, which were isolated using degenerate primer and inverse primer PCR methods, were cloned and sequenced. Comparative nucleotide (nt) sequence analyses showed that the goose circovirus (GCV) and pigeon circovirus (PiCV) possessed genomes which were 1821 and 2037 or 2036 nt, respectively, and which had features in common with the genomes of porcine circoviruses types 1 and 2 (PCV1, PCV2) and psittacine beak and feather disease virus (BFDV), such that they can now be assigned to the genus Circovirus of the family Circoviridae. Common features include the possession of (i) a potential stem-loop/nonanucleotide motif with which the initiation of rolling circle replication of the virus DNA is associated; (ii) two major ORFs, located on the virus (V1 ORF) and complementary (C1 ORF) strands, which encode the replication-associated protein (Rep) and capsid protein, respectively; (iii) high levels of amino acid identity (41.2--58.2%) shared with other circovirus Rep proteins; and (iv) direct/inverted repeat sequences within the putative intergenic region. On the basis of nt and amino acid sequence identities, GCV is substantially less closely related to BFDV than PiCV is to BFDV. (+info)
Experimental reproduction of severe disease in CD/CD pigs concurrently infected with type 2 porcine circovirus and porcine reproductive and respiratory syndrome virus.
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Three-week-old cesarean-derived colostrum-deprived (CD/CD) pigs were inoculated with porcine circovirus type 2 (PCV2, n = 19), porcine reproductive and respiratory syndrome virus (PRRSV, n = 13), concurrent PCV2 and PRRSV (PCV2/PRRSV, n = 17), or a sham inoculum (n = 12) to compare the independent and combined effects of these agents. Necropsies were performed at 7, 10, 14, 21, 35, and 49 days postinoculation (dpi) or when pigs became moribund. By 10 dpi, PCV2/PRRSV-inoculated pigs had severe dyspnea, lethargy, and occasional icterus; after 10 dpi, mortality in this group was 10/11 (91%), and all PCV2/ PRRSV-inoculated pigs were dead by 20 dpi. PCV2-inoculated pigs developed lethargy and sporadic icterus, and 8/19 (42%) developed exudative epidermitis; mortality was 5/19 (26%). PRRSV-inoculated pigs developed dyspnea and mild lethargy that resolved by 28 dpi. Microscopic lesions consistent with postweaning multisystemic wasting syndrome (PMWS) were present in both PCV2- and PCV2/PRRSV-inoculated pigs and included lymphoid depletion, necrotizing hepatitis, mild necrotizing bronchiolitis, and infiltrates of macrophages that occasionally contained basophilic intracytoplasmic inclusion bodies in lymphoid and other tissues. PCV2/ PRRSV-inoculated pigs also had severe proliferative interstitial pneumonia and more consistent hepatic lesions. The most severe lesions contained the greatest number of PCV2 antigen-containing cells. PRRSV-inoculated pigs had moderate proliferative interstitial pneumonia but did not develop bronchiolar or hepatic lesions or lymphoid depletion. All groups remained seronegative to porcine parvovirus. The results indicate that 1) PCV2 coinfection increases the severity of PRRSV-induced interstitial pneumonia in CD/CD pigs and 2) PCV2 but not PRRSV induces the lymphoid depletion, granulomatous inflammation, and necrotizing hepatitis characteristic of PMWS. (+info)
Nucleotide sequence analysis of a novel circovirus of canaries and its relationship to other members of the genus Circovirus of the family Circoviridae.
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The circular, single-stranded DNA genome of a novel circovirus of canaries, tentatively named canary circovirus (CaCV), was cloned and sequenced. Sequence analysis indicated that the genome was 1952 nucleotides (nt) in size and had the potential to encode three viral proteins, including the putative capsid and replication-associated (Rep) proteins. The CaCV genome shared greatest sequence similarity (58.3% nt identity) with the newly characterized columbid circovirus (CoCV) and was more distantly related to the two porcine circovirus strains, PCV1 and PCV2, beak and feather disease virus (BFDV) and a recently isolated goose circovirus (GCV) isolate (46.8-50.9% nt identity). In common with other members of the Circovirus genus, several nt structures and amino acid motifs thought to be implicated in virus replication were identified on the putative viral strand. Phylogenetic analysis of both the capsid and Rep protein-coding regions provided further evidence that CaCV is more closely related to CoCV and BFDV and more distantly related to GCV, PCV1 and PCV2. (+info)