Immune response to avian reovirus in chickens and protection against experimental infection

Abstract

Objectives: To assess the efficacy of the vaccination procedure and the effect of the transfer of maternal antibodies to progeny chickens on reovirus pathogenicity. Design: To vaccinate chickens and challenge progeny chickens with high doses of homologous and heterologous viruses. Procedure: High doses of reovirus strains RAM-1, 1091 and 724 were used to induce tenosynovitis lesions. High doses were produced by concentration of viruses grown in cell culture. Then similar doses of viruses were used to challenge immunised chickens progeny. Result: Vaccination of breeding hens with the RAM-1 strain of avian reovirus, which resulted in the passive transfer of neutralising antibody to progeny chickens, completely prevented the development of tenosynovitis in 80% of progeny chickens infected with the homologous virus. Even though multiple injection of hens resulted in broadening of the normal type-specificity of the neutralising antibody response against heterologous serotypes of avian reovirus, only marginal protection against strains of two heterologous serotypes of avian reovirus was obtained. Conclusions: A model for assessing the efficacy of vaccination against avian reovirus strains on clinical signs such as tenosynovitis was developed that overcome the normal low virulence of Australian strains of avian reovirus. Breeding hens can be immunised with Australian strain of avian reovirus with passive transfer of antibody via the yolk to the progeny chickens. Although the neutralising antibody response to three injections of inactivated virus decreased the specificity of the neutralising antibody response against antigenically heterologous strains of avian reovirus, the protective immunity appeared to retain type-specificity.