CANINE-DISTEMPER VIRUS FROM DISEASED LARGE FELIDS - BIOLOGICAL PROPERTIES AND PHYLOGENETIC-RELATIONSHIPS

Specific pathogen free (SPF) domestic cats were inoculated with tissue homogenate obtained from a Chinese leopard (Panthera pardus japonensi s) that had died in a North American zoo from a natural infection with canine distemper virus (CDV). The cats developed a transient cell-ass ociated CDV viraemia along with pronounced lymphopenia but did not sho w any clinical symptoms. Plasma neutralizing-antibody titres against t he homologous CDV (A92-27/4, isolated from the Chinese leopard) were c onsistently higher than against the CDV vaccine strain 'Bussell'. The Chinese leopard CDV isolate showed in vitro biological properties remi niscent of virulent, wild-type CDV strains. Sequence analysis of the H gene of two large felid CDV isolates from the USA (A92-27/4 and A92-6 ) revealed up to 10% amino acid changes including up to four additiona l potential N-linked glycosylation sites in the extracytoplasmic domai n as compared to CDV vaccine strains. Phylogenetic analysis was perfor med using the entire coding region of the H gene and a 388 bp fragment of the P gene of several morbillivirus species. Evidence was obtained that recent CDV isolates from different species in the United States (including isolates from large felids), Europe and Africa are signific antly distinct from CDV vaccine strains. All wild-type CDV isolates an alysed clustered according to geographical distribution rather than to host species origin. By sequence analysis a CDV epizootic among large felids in a Californian safari park was linked to a virus which most likely originated fi-om feral non-felid carnivores.