Incidence, characterisation and prophylaxis of nephropathogenic avian infectious bronchitis viruses
Meulemans, G.; Carlier, M.C.; Gonze, M.; Petit, P.; Vandenbroeck, M.
Veterinary Record 120(9): 205-206
1987
ISSN/ISBN: 0042-4900 PMID: 3033872 Document Number: 286495
Since 1984 the number of infectious bronchitis (IB) associated nephritis infections in Belgian broiler flocks has increased. From January to August 1986, 18 flocks, including 7 vaccinated with H120 strain at one-day-old were infected by nephrogenic TB virus. Neutralization tests using M41 virus antiserum on 4 isolates of the nephrogenic IB virus showed they did not belong to the Massachussetts serotype. Three of 10 isolates of the virus killed with 7 days, 50% of 10-week-old specific pathogen free (SPF) chickens infected by intravenous inoculation. Infection of different aged SPF chickens by eye drop inoculation of a third egg passage of one of these isolates (strain 1648) showed there was a decrease in pathogenic effect as the age at infection increased. Mortality was 57.9% with infection at 1 day old, 50% with infection at 7 days old and 30% with infection at 14 days old. The protection afforded by vaccination was evaluated in 23 SPF chickens given H120 vaccine at one-day-old and 24 non vaccinated chickens. The chickens were challenged at 12 days of age by eye drop inoculation with nephrogenic IB virus strain 1648. Two (8.7%) vaccinated and 7 (29.2%) unvaccinated birds died with nephritic lesions demonstrating partial protection by the vaccine.