No abstract

No abstract

Infectious bursal disease virus of chickens was purified, and its structure was examined by the negative-staining technique in the electron microscope. The buoyant density of infectious bursal disease virus in CsCl was found to be 1.34 g/cm3. The morphological details suggest that the capsid of the virion consists of a single layer of 32 capsomeres arranged in 5:3:2 symmetry. The virion measured about 55 nm in diameter and had no envelope.

No abstract

Chickens were infected with infectious bursal disease (IBD) virus in ovo or at different times posthatching to 6 weeks of age. The B- and T-cell responses in the lymphoid tissues and blood were examined sequentially to 8 weeks of age by using indirect immunofluorescence. The proportion of B-cells was consistently lower in infected birds than in controls, especially in chicks infected as embryos or at 1 day old. The proportion of T-cells increased following these early infections but was slightly lower in spleen and blood of birds infected at 1, 4, and-6 weeks of age. Serum IgM levels dropped significantly after infection, regardless of the time of infection. IgG levels decreased following early infection but increased after infection at 1 week old or more. The results strongly suggest that B-cells are the target for IBD virus infection.