Lack of Correlation between Infectivity, Serologic Response and Challenge Results in Immunization with an Avian Infectious Bronchitis Vaccine

Open Access
Publisher Website
Google Scholar
Abstract
Summary: White Leghorn chickens of two different ages and sources were vaccinated with diluted and undiluted infectious bronchitis (IB) vaccine. Statistical evaluation of the results showed: Incubation period was prolonged by the presence of congenital passive antibodies, and by using a vaccine that was diluted 100-fold.The combined factors of age and dose level affected vaccination reaction in that per cent of infectivity was highest and reactions were most severe in older birds receiving undiluted vaccine.Congenital passive immunity interfered with the development of active antibodies in that geometric mean serum neutralization titers peaked lower and later in birds having maternal antibodies than in birds from a susceptible source.Per cent of resistance on two challenge dates (7 weeks and 6 months after vaccination) was higher in the older birds vaccinated with the undiluted vaccine.There was no difference between immune and susceptible sources in immunity over the long run (at 6 months) in chicks vaccinated against IB within their 1st week of life.None of the six groups of birds showed any correlation between infectivity and serologic responses, between infectivity and challenge results, or between serologic responses and challenge results.

This publication has 0 references indexed in Scilit: