RECOMBINANT FOWLPOX VIRUSES COEXPRESSING CHICKEN TYPE-I IFN AND NEWCASTLE-DISEASE VIRUS HN AND F GENES - INFLUENCE OF IFN ON PROTECTIVE EFFICACY AND HUMORAL RESPONSES OF CHICKENS FOLLOWING IN OVO OR POSTHATCH ADMINISTRATION OF RECOMBINANT VIRUSES

We have constructed recombinant (r) fowl pox viruses (FPVs) coexpressi ng chicken type I interferon (IFN) and/or hemagglutinin-neuraminidase (HN) and fusion (F) proteins of Newcastle disease virus (NDV). We admi nistered rFPVs and FPV into embryonated chicken eggs at 17 days of emb ryonation or in chickens after hatch. Administration of FPV or rFPVs d id not influence hatchability and survival of hatched chicks. In ovo o r after hatch vaccination of chickens with the recombinant viruses res ulted in protection against challenge with virulent FPV and NDV. Chick ens vaccinated with FPV or FPV-NDV recombinant had significant lower b ody weight 2 weeks following vaccination. This loss in body weight was not detected in chickens receiving FPV-IFN and FPV-NDI/-IFN recombina nts. Chickens vaccinated with FPV coexpressing IFN and NDV genes produ ced less antibodies against NDV in k comparison with chickens vaccinat ed with FPV expressing NDVgenes. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.