Avian metapneumovirus excretion in vaccinated and non-vaccinated specified pathogen free laying chickens

Vaccinated and non-vaccinated specified pathogen-free White Leghorn laying chickens were challenged at peak of lay by the intravenous or oculonasal route with a virulent avian metapneumovirus (aMPV) subtype B chicken strain. Severe clinical signs and a drop in egg production were induced in the non-vaccinated intravenously challenged birds whereas the vaccinates were not affected. Live virus excretion was demonstrated in the faeces and...