Pathologically and serologically different avian nephritis virus isolates implicated in etiology of baby chick nephropathy.

Three virus isolates (WG-3, -4, and -5) from chicks affected by baby chick nephropathy were orally inoculated into 1-day-old specific-pathogen-free chicks of lines PDL-1 and 15I. Additional chicks were orally inoculated with avian nephritis virus (ANV) strain G-4260. Chicks inoculated with isolates WG-3, -4, and -5 died between 2 and 6 days postinoculation (PI), with mortality ranging from 0% to 53.3%. Pathological findings in the dead chicks included nephrosis in chicks inoculated with WG-3, -4, and -5, and nephritis and visceral urate deposition in chicks inoculated with G-4260. The stability of the WG-5 isolate, as well as the size of the particles and the nucleic acid type, were also similar to those of the G-4260 strain. All of the examined chicks inoculated with WG-3, -4, and -5 had interstitial nephritis at 14 days PI. Therefore, the three virus isolates were considered to be ANV. However, there was no serological relationship between the isolates and ANV (G-4260 and M-8 strains).