EVOLUTION OF CANINE PARVOVIRUS INVOLVED LOSS AND GAIN OF FELINE HOST-RANGE

Canine parvovirus (CPV) type-2 emerged as a new virus infecting dogs i n 1978, and it was probably derived as a variant of feline panleukopen ia virus or of a closely related virus infecting another carnivore. CP V type-2 was subsequently replaced in nature by antigenically variant viruses (CPV type-2a and CPV type-2b) which now coexist in dog populat ions worldwide. We show that CPV type-2 isolates did not replicate in cats, but that both CPV type-2a and CPV type-2b isolates replicated ef ficiently. About 10% of the viruses isolated from cats with natural pa rvovirus disease were antigenically indistinguishable from CPV type-2a or type-2b. The capsid protein gene sequence of a 1990 feline parvovi rus isolate (''FPV-24'') was essentially identical to the sequence of CPV type-2b viruses from dogs. The loss and reacquisition of the felin e host range in CPV was most likely due in each case to small numbers of changes in a region of the virus capsid where three protein monomer s interact. (C) 1996 Academic Press, Inc.