Isolation of non-cytopathic viruses implicated in the aetiology of nephritis and baby chick nephropathy and serologically related to avian nephritis virus.

Three embryo-lethal agents were isolated from broiler chickens having either stunting syndrome or baby chick nephropathy. The agents replicated at low levels in chick kidney cells, but a cytopathic effect was not seen. Their presence was detected by embryo mortalities after yolk sac inoculations. All three agents caused nephritis and growth suppression when inoculated into 1-day-old chicks, and one agent caused increased incidence of baby chick nephropathy. This, and one other agent, were serologically closely related to avian nephritis virus G-4260. Picornavirus-like particles were present in the kidneys of infected birds. The histopathology of baby chick nephropathy was similar to, although more severe than, the nephritis seen in clinically normal birds. The strain of birds used to produce chick kidney cells influenced the ability of G-4260 to form a cytopathic effect and plaques. Strain of bird also influenced the lesions produced on chorio-allantoic membranes after inoculation of G-4260 and the above isolates.