Experimental reproduction of postweaning multisystemic wasting syndrome (PMWS) in pigs in Sweden and Denmark with a Swedish isolate of porcine circovirus type 2   总被引：8，自引：0，他引：8  

Hasslung F  Wallgren P  Ladekjaer-Hansen AS  Bøtner A  Nielsen J  Wattrang E  Allan GM  McNeilly F  Ellis J  Timmusk S  Belák K  Segall T  Melin L  Berg M  Fossum C 《Veterinary microbiology》2005,106(1-2):49-60

An experimental model using 3-day-old snatch-farrowed colostrum-deprived piglets co-infected with porcine circovirus type 2 (PCV2) and porcine parvovirus (PPV) is at present one of the best methods to study factors affecting development of postweaning multisystemic wasting syndrome (PMWS). A Swedish isolate of PCV2 (S-PCV2) retrieved in 1993 from a healthy pig has been used in this model to reproduce PMWS in pigs from Northern Ireland. This virus has been present in the Swedish pig population for at least a decade without causing any known PMWS disease problems, despite its potential pathogenicity. The reasons for this are unknown, but could be related to genetics, absence of triggers for PCV2 upregulation (infectious agent and/or management forms) within Swedish pig husbandry. In order to confirm the pathogenicity of S-PCV2, Swedish and Danish pigs were experimentally infected with this isolate according to the established model. Swedish pigs were also infected with a reference isolate of PCV2 (PCV2-1010) to compare the severity of disease caused by the two isolates in Swedish pigs. Both Danish and Swedish pigs developed PMWS after the experimental infection with S-PCV2. Antibodies to PCV2 developed later and reached lower levels in serum from pigs infected with S-PCV2 than in pigs inoculated with PCV2-1010. In general, pigs infected with S-PCV2 showed more severe clinical signs of disease than pigs infected with PCV2-1010, but pigs from all PCV2-inoculated groups displayed gross and histological lesions consistent with PMWS. All pigs inoculated with PPV, alone or in combination with PCV2, displayed interleukin-10 responses in serum while only pigs infected with PPV in combination with PCV2 showed interferon-alpha in serum on repeated occasions. Thus, the pathogenicity of S-PCV2 was confirmed and a role for cytokines in the etiology of PMWS was indicated.  相似文献   

Evaluation of ovulation rate and ovarian phenotype in puberal heifers from a cattle population selected for increased ovulation rate     

Cushman RA  Allan MF  Snowder GD  Thallman RM  Echternkamp SE 《Journal of animal science》2005,83(8):1839-1844

Long-term selection for increased ovulation rate (1984 to 2002) has resulted in a unique ovarian phenotype in the MARC Twinner cattle population. Ovulation rate and frequency of bilateral ovulations were examined by rectal palpation in 29,547 estrous cycles for 3,910 heifers (12 to 18 mo of age) in this population. Bilateral ovulations (one corpus lutuem [CL] on each ovary) were of interest because bilateral twin pregnancies result in decreased dystocia and increased calf survival. Ovulation rate increased linearly at a rate of 0.026 CL per year, and it currently averages 1.48 +/- 0.04 CL per estrous cycle. Concurrent with the increase in ovulation rate, the frequency of triplet ovulations increased from 0% to 2.3 +/- 0.8% (P < 0.001). Ovulation rate of both the right and left ovary increased equally at a rate of 0.013 CL per year, and mean ovulation rate of the right ovary remained greater than mean ovulation rate of the left ovary throughout the study (0.66 vs. 0.55 +/- 0.003 CL per estrous cycle; P < 0.001). Although correlations were low, ovulation rate of one ovary was negatively correlated (P < 0.001; r = -0.07) with ovulation rate of the same ovary in the previous estrous cycle, but positively correlated (P < 0.001; r = 0.13) with the contralateral ovary of the previous estrous cycle. The proportion of bilateral ovulations averaged 55.7 +/- 0.7%, a value greater than the predicted 49.5% (P < 0.001). In addition to dystocia and retained placenta, triplet pregnancies increase the incidence of pregnancies gestating fetuses of opposite sexes and subsequent incidence of freemartins; thus, selection pressure on ovulation rate may need to be adjusted in the MARC Twinner population. The proportion of bilateral ovulations in the population is greater than expected, and this may be an economically important trait, which will respond to selection and be beneficial for improving bovine reproductive efficiency. Understanding factors controlling the increased functional activity of the right ovary and bilateral ovulations may provide further insights into the mechanisms controlling follicle selection and methods to improve reproductive management of cattle.  相似文献   

Experimental infection of 3-week-old conventional colostrum-fed pigs with porcine circovirus type 2 and porcine parvovirus   总被引：7，自引：0，他引：7  

Ostanello F  Caprioli A  Di Francesco A  Battilani M  Sala G  Sarli G  Mandrioli L  McNeilly F  Allan GM  Prosperi S 《Veterinary microbiology》2005,108(3-4):179-186

This report describes an experimental infection with porcine circovirus type 2 (PCV2) in combination with porcine parvovirus (PPV) in 3-week-old conventional colostrum-fed pigs with maternal antibodies to both viruses. Two groups of four pigs each were inoculated with PCV2 and PPV. One of the groups received also a commercial inactivated vaccine against porcine pleuropneumonia to evaluate possible effects of the stimulation of the immune system of pigs on the infection. Another group of four pigs was kept as uninfected control. Clinical signs, rectal temperatures and body weights were recorded. Serum antibody titers to PCV2 and PPV were determined at weekly intervals. Pigs were killed 42 days after inoculation and tissue samples were examined for the presence of gross and microscopic lesions. Tissues were also analyzed for the presence of PCV2 and PPV DNA by PCR, and for the presence of PCV2 antigen by immunohistochemistry (IHC). All the pigs had serum antibodies to PCV2 and PPV at the beginning of the trial. None of them developed clinical symptoms or pathological lesions typical of post-weaning multisystemic wasting syndrome (PMWS), a disease associated to PCV2 infection. However, IHC and/or PCR analyses showed that clinically silent PCV2 infection developed in five of the eight inoculated pigs, regardless of the administration of the vaccine. In particular, PCV2 DNA and/or antigen were detected in most of the tissues examined in the two pigs with the lowest titer of maternal PCV2 antibodies at the beginning of the trial. PPV DNA was not detected in any of the samples examined. The five pigs with PCR and/or IHC evidence of PCV2 infection had a mean weight gain during the experiment lower than that of the inoculated PCR-negative pigs considered together and that of the control pigs. In conclusion, it would appear that passive immunity against PCV2 can play a role in preventing the development of PMWS, but is not able to prevent the establishing of clinically silent PCV2 infections. The dissemination and persistence of the virus in the tissues may depend on the level of PCV2 antibodies at the time of inoculation.  相似文献   

Identification of a novel herpesvirus from a California desert tortoise (Gopherus agassizii)     

Johnson AJ  Pessier AP  Wellehan JF  Brown R  Jacobson ER 《Veterinary microbiology》2005,111(1-2):107-116

Herpesviruses are significant pathogens of tortoises, causing upper respiratory tract disease and necrotizing stomatitis, with infections often associated with high mortality rates. Herpesvirus infection in a captive California desert tortoise (Gopherus agassizii) was detected by light microscopic observation of intranuclear inclusion bodies in various tissues followed by transmission electron microscopic observation of herpesvirus-like particles, and amplification of herpesvirus nucleic acid sequences using polymerase chain reaction. Using an indirect enzyme linked immunosorbent assay, anti-tortoise herpesvirus antibodies were detected one month after initial onset of clinical signs. This novel herpesvirus is distinct from the previously described tortoise herpesvirus (tortoise herpesvirus-1, THV-1) sharing 83% sequence identity of 60 amino acids of a portion of the DNA polymerase gene and 79% sequence identity across 120 amino acids of a portion of the ribonucleotide reductase gene. Similar to THV-1, this novel herpesvirus, tortoise herpesvirus-2 (THV-2), also clusters with the alphaherpesviruses.  相似文献   

PMWS: an emerging disease identified in archived porcine tissues     

Staebler S  Sydler T  Buergi E  McCullough K  McNeilly F  Allan G  Pospischil A 《Veterinary journal (London, England : 1997)》2005,170(1):132-134

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Effects of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies     

Paul AJ  Hutchens DE  Firkins LD  Keehan CM 《American journal of veterinary research》2004,65(3):277-278

OBJECTIVE: To evaluate the safety of dermal application of 10.0% imidacloprid-0.08% ivermectin in ivermectin-sensitive Collies at dose rates of 3 to 5 times the proposed maximum therapeutic dose. ANIMALS: 15 Collies (5 males and 10 females) that were confirmed as ivermectin-sensitive dogs. PROCEDURE: Dogs were assigned to 3 treatment groups (control, 3X, or 5X group) in a randomized block design on the basis of the maximal ivermectin-sensitivity score obtained during preliminary screening. Dogs in groups 3X and 5X were treated at 3 and 5 times the maximum label dose, respectively. Control dogs received an application of an equal volume of a nonmedicated solution. Observation and scoring on all days were conducted to specifically include neurologic signs typical of ivermectin toxicosis, including lethargy, ataxia, abnormal mydriasis, and abnormal salivation. RESULTS: None of the dogs had clinical abnormalities during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study indicates that dermal application of 10.0% imidacloprid-0.08% ivermectin is safe for use in ivermectin-sensitive Collies at dose rates of 3 or 5 times the proposed maximum therapeutic dose.  相似文献   

Attenuation of an avian pathogenic Escherichia coli strain due to a mutation in the rpsL gene     

Amoako KK  Prysliak T  Potter AA  Collinson SK  Kay WW  Allan BJ 《Avian diseases》2004,48(1):19-25

The diseases caused by pathogenic Escherichia coli constitute a major economic loss to the poultry industry. The development of a live oral E. coli vaccine to prevent or reduce diseases in poultry had been the objective of our work. Four spontaneous streptomycin-dependent (str-dependent) mutants were generated from a virulent avian strain that contains a mutation in the fur region of the chromosome. Genetic analysis of the mutants indicated that the str-dependent phenotype was due to a base change of C --> T at base 272 in the rpsL gene. The mutants were tested for attenuation using the day-old chick model. Day-old birds, in groups of 20, were either challenged with 10(6) colony-forming units (CFU) of the str-dependent mutant, the parent strain (containing the fur mutation), or the wild-type strain without the fur mutation. The parent strain and the wild-type strain were highly virulent, and 80% or more of the birds died. None of the birds challenged with the str-dependent mutants died, indicating attenuation of the mutants. The protective effect of the mutant as a live vaccine against the challenge with 10(6) CFU of the wild-type strain EC317 was investigated. Vaccination by both aerosol (day 1) and oral (days 14 and 28) routes using 10(8) CFU of the str-dependent mutant (EC1598) had no effect on the occurrence of cellulitis in the birds. Two vaccinations given as aerosol on day 1 and given orally on day 14 also had no significant effect on the occurrence of systemic lesions. Three immunizations on days 1, 14, and 28 resulted in a significant reduction in the number of birds with systemic lesions. Antibody titers prior to challenge were not predictive of outcome of challenge.  相似文献   

PCV-2 infection in swine; more than just postweaning multisystemic wasting syndrome   总被引：3，自引：0，他引：3  

Allan G  McNeilly F  Krakowa S  Ellis J 《Veterinary journal (London, England : 1997)》2003,166(3):222-223

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Association of lymphopenia with porcine circovirus type 2 induced postweaning multisystemic wasting syndrome (PMWS)   总被引：15，自引：0，他引：15  

Nielsen J  Vincent IE  Bøtner A  Ladekaer-Mikkelsen AS  Allan G  Summerfield A  McCullough KC 《Veterinary immunology and immunopathology》2003,92(3-4):97-111

The composition of peripheral blood leukocyte populations was studied following experimental PCV2-infection in 3-week-old piglets. Four of 10 PCV2-infected piglets developed clinical and pathological symptoms consistent with postweaning multisystemic wasting syndrome (PMWS) between 14 and 21 days post-inoculation (p.i.), and were characterised as PMWS-affected. Only these four PMWS-affected piglets, but neither the non-symptomatic infected nor control animals, developed a clear leukopenia. Kinetic analysis demonstrated a clear loss of both CD21(+) B and CD3(+) T lymphocytes in the PMWS-affected piglets. By CD3/CD4/CD8 triple labelling, the influence of PCV2 infection on all T cell sub-populations was discernible. A loss of CD3(+)CD4(+)CD8(+) memory/activated Th lymphocytes was particularly notable. However, all T lymphocyte sub-populations-CD3(+)CD4(+)CD8(+) memory Th, CD3(+)CD4(+)CD8(-) nai;ve Th, CD3(+)CD4(-)CD8(+) Tc and CD3(+)CD4(-)CD8(-) gammadelta TCR(+) lymphocytes-were susceptible to PCV2 infection-induced lymphopenia. CD3(-)CD4(-)CD8(+) NK cells were also depleted in the PMWS-affected animals, but granulocytes and monocytes were less affected. In conclusion, PCV2 infection induces primarily a lymphopenia, but only in animals which subsequently develop PMWS. The lymphopenia can be identified early p.i., particularly with the B lymphocytes. Memory/activated Th lymphocytes might be affected more than the other T cell sub-populations, but as time progressed a collapse of both T and B cell populations was clear.  相似文献   

In vitro studies on the infection and replication of porcine circovirus type 2 in cells of the porcine immune system   总被引：13，自引：0，他引：13  

Gilpin DF  McCullough K  Meehan BM  McNeilly F  McNair I  Stevenson LS  Foster JC  Ellis JA  Krakowka S  Adair BM  Allan GM 《Veterinary immunology and immunopathology》2003,94(3-4):149-161

Porcine circovirus type 2 (PCV2) nucleic acid and/or antigens are consistently observed in cells of monocytic morphology in lesions of pigs affected by post-weaning multisystemic wasting syndrome (PMWS). In this study, PCV2 antigen was detected in the cytoplasm of monocytes, pulmonary macrophages (PMs) and monocyte-derived macrophages exposed to the virus in vitro, by immunofluorescence analysis (IFA) and the phenotype of these cells confirmed by detection of monocytic cell surface markers using flow cytometry. Viral antigen was not observed in lymphocytic cells. Replication of the virus in PMs was investigated further by comparison to that observed in the continuous pig kidney cell line (PK15A) using quantitative virus titration, quantitative PCR and by the detection of double stranded DNA intermediates of viral replication by Southern blotting analyses. Although increases in viral DNA and levels of infectious virus progeny and the presence of replicative intermediates, indicative of viral replication, were observed in PK15A cells, no such changes were observed in PMs in spite of the fact that infectious virus, viral antigen and viral DNA persisted in the cells for at least the duration of the experiment. These results suggest that in vivo, monocytic cells may not represent the primary target for PCV2 replication.  相似文献