engleski

IMMUNE STATUS ASSESSMENT BY ABUNDANCE OF INTERFERON (IFN ALPHA AND GANINIA mRNA IN CHICKEN BLOOD

Immune supression of poultry is a serious problem that is not easily monitored. Ideally and practically, a test for immune status should be done with samples collected on one trip to a poultry house. Whereas mRNA in whole blood is sensitive to degradation by ribonucleases, rapid dissolution in Catrimox 14, a cationic detergent, will preserve mRNA for two weeks from 4 to 37 C. Thus, IFN mRNA induced by immune challenge can be collected in 4 hr, and safely transported to a lab for analysis. We have developed a competitive nucleic acid hybridization test for mRNA of chicken IFN alpha and gamma that can be done in microtitre plates. DNA probes for the mRNA were produced with plasmids provided by Drs. J. W. Lowenthal (CSIRO, Australia), M. J. Sekellick and P. I. Marcus (U. Conn., USA). Sample RNA from whole blood was allowed to bind to immobilized capture probe and compete with labelled probe added in excess of the capture probe. Signal was inversely proportional with competition by the mRNA. Specific-pathogen-free chickens had no detectable message before immunization with inactivated Newcastle disease virus (NDV). Kinetics of induction of the mRNA were the same for both IFN, reaching maximum levels in about 6 hr, and returning to baseline in 7 days. Induction was the same from one day to 4 wk of age, indicating that immaturity of immune responses in the very young is a post-transcriptional event. Chickens were injected intracoelomically with 1, 2.5 and 5 mg cyclophosphamide for 3 days before NDV immunization at 2 wk of age, and samples for IFN mRNA were taken 4 hr later. Levels of mRNA were decreased in dose related fashion, and they correlated with antibody responses one week later. The test can be used for evaluation of immune status of chickens, and for research into the molecular events responsible for immune suppression. Supported by a grant from the US Poultry & Egg Association.

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