Bronquitis infecciosa aviar: respuesta a programas de vacunacion en broilers.
1992
Ulloa J. | Garate O. | Cubillos M. | Manzur P.
The immune response against infectious Bronchitis Virus was studied in two Broiler vaccination programs. Eighty day-old chicks were divided into two groups of 40 chickens each and vaccinated by eyedrop with H120. A second H120 vaccine dose was administered, as coarse drop spray, when chicks were 14 and 20 days old respectively. A third group without vaccination was considered control. Antibody titres were determined weekly by haemagglutination inhibition (HI) and serum neutralization (SN) until 47 days of age. Experimental groups were challenged when chickens were 50 days old with IBV strain Mass 41, to evaluate protection. A high maternal antibody transference to progeny which lasted for approximately 19 days, at titres considered specific, was observed. Vaccinated groups did not present seraconversion after both antigenic stimulations. However, the persistence of antibody titres after the first vaccination was higher than in the control group. Antibody titres determined by HI and SN were significatively correlated. Protection in vaccinated groups was partial four days after challenge. No relation was observed between protection and serum antibody titres. Results allowed us to conclude that age difference for the second vaccination had no effects on the protection at slaughter age.
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