Adaptation of infectious bursal disease virus in chicken embryo fibroblastcell culture and its fine structure

Two outbreaks of suspected infectious bursal disease (IBD) at university po ultry farms were investigated. On the basis of epidemiological data, charac teristic gross and microscopic changes in different organs including bursa of Fabricius (BF) and spleen, presence of IBD virus antigen in BF and demon stration of intracytoplasmic virus particles of 59.2 nm diameter in infecte d chicken embryo fibroblast cells by transmission electron microscopy confi rmed the outbreak as IBD. The type and distribution of lesions and mortalit y up to 23.2% is highly suggestive of involvement of IBD virus of moderate virulence. Neutralization of cell culture grown virus with reference antise ra revealed the identity of virus as IBDV serotype 1.