A virus suspected of causing high death rates in fledgling budgerigars in Georgia and Texas aviaries was isolated in budgerigar embryo fibroblasts inoculated with tissue homogenates from affected birds. Virus was most easily recovered from tissues containing many intranuclear inclusion bodies. Cytopathic effect on fibroblasts of all four isolates was characterized by a swollen nucleus followed by rounding and detachment of the affected cell from the monolayer. Properties suggesting the B-931 isolate belongs to the papovaviridae family are (1) presence of DNA; (2) insensitivity to treatment with CHCl3; and (3) presence of cubic viral particles 42 to 49 nm in diameter in the nucleus of infected chicken embryo fibroblasts. The isolate did not hemagglutinate erythrocytes of chickens, turkeys, budgerigars, guinea pigs, or type O humans and was basically stable against heating and freeze-thawing. An examination of fledgling budgerigars from infected aviaries demonstrated that sick birds carried more virus than healthy birds.

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Specific-pathogen-free (SPF) chicks infected with infectious bursal disease (IBDV) virus at one day of age or midway (7 days) through a two-week immunization program for Eimeria tenella showed significantly less (P less than or equal to 0.05) protection against coccidal challenge as measured by lesion scores than chicks given IBDV after 14 days of coccidial immunization. The chicks showed complete protection to later coccidial challenge administered on Day 21. Bursae were markedly smaller from IBDV-infected chicks than from uninfected controls, and pathological changes were extensive. Virus-neutralization tests demonstrated that titers to IBD were higher in chicks exposed to the virus than in unexposed controls.

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