I nactivated vaccines now are commonly-used tools to stimulate the immune systems of layers and breeders. For viral antigens, inactivated vaccines are used primarily to induce a prolonged antibody response in birds which have previously received live virus vaccines. For bacterial antigens, these vaccines are typically used in birds which have not previously been vaccinated with a live bacterial...

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum, representing the four serovars known to occur in that country, was investigated. During this study an alternative challenge model for infectious coryza was used, in which the infectivity as well the virulence of different isolates could be evaluated. The challenge model consisted of the direct challe...

A total of 27 different isolates of Haemophilus paragallinarum were made from chickens between June 1991 and December 1992. All of these isolates were examined by ELISA, by means of a locally produced panel of three monoclonal antibodies (denoted F1, V1 and VF3). The isolates were all of the F1 antigenic type. Three of them showed a weak reaction with the F1 monoclonal antibody, while three oth...