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Like other pathogens that readily persist in animal hosts, members of the Bornaviridae family have evolved effective mechanisms to evade the innate immune response. The prototype of this virus family, Borna disease virus employs an unusual replication strategy that removes the triphosphates from the 5′ termini of the viral RNA genome. This strategy allows the virus to avoid activation of RIG-I and other innate immune response receptors in infected cells. Here we determined whether the newly discovered avian bornaviruses (ABV) might use a similar strategy to evade the interferon response. We found that de novo infection of QM7 and CEC32 quail cells with two different ABV strains was efficiently inhibited by exogenous chicken IFN-α. IFN-α also reduced the viral load in QM7 and CEC32 cells persistently infected with both ABV strains, suggesting that ABV is highly sensitive to type I IFN. Although quail cells persistently infected with ABV contained high levels of viral RNA, the supernatants of infected cultures did not contain detectable levels of biologically active type I IFN. RNA from cells infected with ABV failed to induce IFN-β synthesis if transfected into human cells. Furthermore, genomic RNA of ABV was susceptible to 5′-monophosphate-specific RNase, suggesting that it lacks 5′-triphospates like BDV. These results indicate that bornaviruses of mammals and birds use similar strategies to evade the host immune response. [ABSTRACT FROM AUTHOR]

In this study, an indirect Newcastle disease virus enzyme-linked immunosorbent assay (ELISA) for waterfowl was evaluated concerning its efficiency and its suitability to monitor the antibody response in Muscovy ducks (Cairina moschata) and domestic geese (Anser anser var. domestica) following vaccination with a commercial inactivated NDV vaccine for chickens. Three weeks after vaccination seroconversion was already evident in the ELISA. Comparison of the ELISA results with those of the haemagglutination inhibition (HI) test provided a positive linear correlation between both tests (Pearson's product-moment correlation; r=0.652; P<0.001). However, a discrepancy of test results was evident in weeks 7 and 10, with 10 sera of vaccinated birds evaluated negative by HI test but positive by ELISA. Eight of these sera were confirmed to yield avian paramyxovirus specific reactivity by western blot analysis. Relative diagnostic sensitivity and specificity were determined to be 100.0% and 91.7% for the ELISA, compared with 91.1% and 97.2% for the HI test. Thus, the established ELISA represents a suitable alternative to the HI test in the monitoring of the immune response of waterfowl after vaccination, particularly for the analysis of high sample numbers. Further on, the results emphasize the immunogenicity of the inactivated Newcastle disease virus vaccine in domestic geese and Muscovy ducks. [ABSTRACT FROM AUTHOR]

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Background: Campylobacter jejuni is considered as a chicken commensal. The gut microbiota and the immune status of the host may affect its colonization. Infectious bursal disease virus (IBDV) is an immunosuppressive virus of chickens, which allows secondary pathogens to invade or exacerbates their pathogenesis. To investigate the effect of IBDV-induced immunosuppression on the pathogenesis of C. jejuni, broiler chickens were inoculated with a very virulent (vv) strain of IBDV at 14 days post hatch followed by C. jejuni inoculation at 7 (Experiment A) or 9 (Experiment B) days post virus (IBDV) inoculation. Results: vvIBDV-infection led to a depression in caecal lamina propria B lymphocytes and the anti-C. jejuni-antibody response starting at 14 days post C. jejuni inoculation (pbi). The C. jejuni-colonization pattern was comparable between mono-inoculated groups of both experiments, but it varied for vvIBDV + C. jejuni co-inoculated groups. In Experiment A significant higher numbers of colony forming units (CFU) of C. jejuni were detected in the caecum of co-inoculated birds compared to C. jejuni-mono-inoculated birds in the early phase after C. jejuni-inoculation. In Experiment B the clearance phase was affected in the co-inoculated group with significantly higher CFU at 21 days pbi compared to the mono-inoculated group (P < 0.05). No major differences were seen in numbers local lamina propria T lymphocyte populations between C. jejuni-inoculated groups with or without vvIBDV-infection. Interestingly, both pathogens affected the microbiota composition. The consequences of these microflora changes for the host have to be elucidated further. Conclusion: Our data suggests that the timing between viral and bacterial infection might affect the outcome of C. jejuni colonization differently. Our results confirm previous studies that anti-Campylobacter-antibodies may specifically be important for the clearance phase of the bacteria. Therefore, as vvIBDV is widely distributed in the field, it may have a significant impact on the colonization and shedding rate of C. jejuni in commercial poultry flocks. Subsequently, successful IBDV-control strategies may indirectly also benefit the gut-health of chickens. [ABSTRACT FROM AUTHOR]