Characterization of the Infectious Bursal Agent

GUMBORO disease was first diagnosed as an infectious disease in the fall of 1957 by Cosgrove (1962). Later, two virus agents were isolated from birds believed to be suffering from the Gumboro disease syndrome, Winterfield et al. (1961). The first was isolated from kidneys of affected birds and it was designated the “Gray” agent that caused nephrosis but was believed to be a variant type of infectious bronchitis virus (IBV). The virus was of low virulence for the respiratory tract (Winterfield et al., 1961; Winterfield and Hitchner, 1962; and Winterfield, 1963). A second agent was isolated later by the same research group from the bursa of affected birds and was designated infectious bursal agent (IBA). Thus, Winterfield et al. (1962) concluded that at least two different agents were involved in Gumboro disease. The Winterfield group then differentiated the signs and gross pathology of birds infected by the two agents, namely…