Biological and physico‐chemical properties of the infectious bursal disease virus (IBDV)

Abstract

Some biological properties of an egg-adapted strain of IBDV, PV1, have been studied. By immunofluorescent staining the strain is serologically identical to another egg-adapted strain, MU2, and to three pathogenic strains of IBDV. All five strains do not react with antisera prepared against known avian viruses of various groups, including Reoviruses. The egg-adapted strain PV1 replicates in chick embryo fibro-blasts and in RK13 cells, with the formation of plaques. The PV1 strain, highly neuropathogenic for newborn mice, is not neuropathogenic for newborn chicks. Various physico-chemical characteristics of IBDV have been studied in comparison to Crawley Reovirus, namely resistance to 5-iodo-2-deoxyuridine, heat-resistance, stability over a wide pH range, resistance to photodynamic inactivation and UV irradiation, sensitivity to Actinomycin D. As Reoviruses, IBDV is a naked RNA Virus, sensitive to Actinomycin D. It is more resistant than Reoviruses to heat, UV irradiation and photodynamic in-activation. All these findings are discussed in relationship to the taxonomic position of IBDV. Cytological observations are reported on cells infected with IBDV and the growth curve is described.