engleski

Assessment of avian antibody and cytokine responses to virus

Viruses are responsible for some of the major diseases in poultry, a well known example being avian influenza which can cause lethal infection even in humans. Many viral infections in poultry are controlled by vaccination. Assessment of avian antibodies to viruses is therefore routinely used for both, detection of field infection and evaluation of post vaccinal immunity. This assessment is based on detection and, in most cases, quantification of specific avian antibodies. The main drawback of such an approach is a time gap between the infection/vaccination and the point when specific antibodies are produced in detectable amounts, which usually takes a week or more. Several viral infections in poultry cause severe immunosuppression, although the antibody response to the causative virus remains unaffected. Immunosuppressed birds are therefore more susceptible to other infections but also poorly respond to vaccination. Reasoning that immunosuppression should be reflected by reduced production of cytokines in response to a viral antigen, we have developed competitive nucleic acid hybridization microtiter plate assays for chicken interferon alpha (ChIFN-alpha) and ChIFN- gamma mRNA. Our results suggest that suspected immunosuppression in a commercial flock could be assessed within 2-3 days by challenging birds with inactivated Newcastle disease virus (NDV) and measuring the abundance of ChIFN-alpha and ChIFN- gamma mRNA in blood obtained 2-4 h later. In addition, we have successfully employed existing quantitative RT-PCRs for detection of ChIFN-gamma mRNA and chicken interleukin 2 mRNA in chicken primary cell culture to measure their abundance in the blood of chickens vaccinated with live and inactivated NDV. Results of these studies enhance understanding of avian mechanisms of adaptive immunity which evolved divergently from better known analogous mechanisms in mammals. Nevertheless, assessment of specific avian immunity to different viruses still requires detection and quantification of specific avian antibodies.

avian; antibody; cytokine; virus

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