Evidence for a bovine origin of the polyomavirus detected in foetal rhesus monkey kidney cells, FRhK-4 and -6.

Rabbit antisera to the stump-tailed macaque polyomavirus (STMV) which had been shown by immunoelectron microscopy and indirect immunofluorescence to react with the polyomavirus found in FRhK-4 cells (FRKV), also gave precipitin lines in counter-immunoelectrophoresis (CIE) and double diffusion in gel (GD) when reacted with FRKV. The reactions in GD showed identity with that of a rabbit antiserum to FRKV. Naturally occurring antibody to FRKV (anti-FRKV) was found by CIE in 48 per cent of 353 cattle, 1/106 pigs and 1/20 goats but not in any of 13 other species including 45 rhesus monkeys and 97 humans. Each of 9 anti-FRKV positive samples from cattle, the goat serum, but not the pig serum gave a line of identity with the rabbit antiserum to FRKV in GD against FRKV. Detection of anti-FRKV in colostrum deprived newborn calves and in commercial foetal calf sera (FBS) indicates that intra-uterine infection of cattle with FRKV may occur. FRKV adapted readily to growth in secondary calf kidney cultures and grew more rapidly and to higher titres than in the FRhK-4 cultures. We conclude that FRKV is probably another strain of STMV and that the natural hosts of these viruses are cattle and not primates. Evidence of intra-uterine infection of cattle implies that infectious FRKV may be present in some FBS and may thus have gained entry into various susceptible cell lines, particularly primate kidney.