PATHOGENICITY, ATTENUATION, AND IMMUNOGENICITY OF INFECTIOUS BURSAL DISEASE VIRUS

An investigation was conducted in specific-pathogen-free chickens on t he pathogenicity of bursa-derived and tissue culture-attenuated classi c (STC) and variant (IN) serotype 1 strains of infectious bursal disea se virus. The IN bursa-derived virus caused bursal inflammation, necro sis, and atrophy earlier than the bursa-derived STC virus. Both viruse s lost their pathogenicity after four passages in BGM-70 cells. A stat istically significant level (P < 0.05) of protection was observed in S PF chickens vaccinated with the attenuated IN virus used as a live or inactivated vaccine followed by homologous (IN) and heterologous (STC) challenge with bursa-derived viruses.