FELINE CORONAVIRUS TYPE-II STRAIN-79-1683 AND STRAIN-79-1146 ORIGINATE FROM A DOUBLE RECOMBINATION BETWEEN FELINE CORONAVIRUS TYPE-I AND CANINE CORONAVIRUS

Recent evidence suggests that the type II feline coronavirus (FCoV) st rains 79-1146 and 79-1683 have arisen from a homologous RNA recombinat ion event between FCoV type I and canine coronavirus (CCV). In both ca ses, the template switch apparently took place between the S and M gen es, giving rise to recombinant viruses which encode a CCV-like S prote in and the M, N, 7a, and 7b proteins of FCoV type I (K. Motowaka, T. H ohdatsu, H. Hashimoto, and H. Koyama, Microbiol. Immunol. 40:425-433, 1996; H. Vennema, A. Poland, K. Floyd Hawkins, and N. C. Pedersen, Fel ine Pract. 23:40-44, 1995). In the present study, we have looked for a dditional FCoV-CCV recombination sites. Four regions in the pol gene w ere selected for comparative sequence analysis of the type II FCoV str ains 79-1683 and 79-1146, the type I FCoV strains TN406 and UCD1, the CCV strain K378, and the TGEV strain Purdue. Our data show that the ty pe II FCoVs have arisen from double recombination events: additional c rossover sites were mapped in the ORF1ab frameshifting region of strai n 79-1683 and in the 5' half of ORF1b of strain 79-1146.