Effect of fowl adenovirus on replication of vaccine strain of Marek’s disease virus in chickens

Abstract

Abstract The aim of the study was to determine the effect of field strain, serotype 7 (FAdV-7 JN-5/10), of fowl adenovirus infection on the replication of Rispens/CVI988 strain of Marek’s disease virus. Ninety one-day-old SPF chickens were divided into six groups. The chickens from group I were vaccinated against Marek’s disease (MD) and 24 h later infected with the adenovirus; chickens from group II were vaccinated and infected simultaneously; chickens from group III were infected with the adenovirus and 24 h after the infection vaccinated against MD. The chickens from groups IV-VI were: control of infection (IV), control of vaccination (V), and neither vaccinated nor infected (VI). After 3, 7, 14, 21, and 28 d post infection, the number of copies of pp38 gene of Rispens strain and hexon gene of FAdV strain was determined in the bursa of Fabricius and liver using real-time PCR. The results indicated that in all cases the replication of Rispens strain was reduced to about 1.0 log10 - 3.5 log10 in chickens infected with the adenovirus and vaccinated against MD compared with the chickens only vaccinated. Sixty-three one-day-old SPF chickens infected with adenovirus and vaccinated against MD were challenged with vv MD virus field strain. The protection index in this experiment was 55.6%-77.8%.