Studies on origin of retroviruses from wild carnivore

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In Socialist Republic of Vietnam (Vietnam), there are lots of camivors (feuds) which are not present in Japan. Three retroviruses (feline leukemia virus (FIV), feline immunodeficiency virus (FIV), and feline syncytial virus (FSV)) are known to infect domestic cats. The purpose of this study is to isolate and identify retroviruses from several feuds in Vietnam and to compare them with known retroviruses. We surveyed domestic and leopard cats in the vicinity of Hanoi and HoChiMinh city.In the vicinity of Hanoi, we could not find any incidence of infection of FIV or FeLV in both domestic and leopard cats. However, we found that 29% of domestic cats and 71% of leopard cats were infected with FSV.We isolated 9 strains of FSV and conducted phylogenetic analysis. All the isolates except one isolate formed a cluster in the phylogenetic tree. Form the result, we considered that FSV has been present in Vietnam from the earliest time or FIV of domestic cats infect leopard cats recently, or vice versa.In the vicinity of HoChiMinh city, we could not find any incidence of infection of FeLV in both domestic and leopard cats. Contrary to the result obtained in the vicinity of Hanoi city, we found that 22% of domestic cats were ***ected with FIV whereas no leopard cats were infected with the virus. In addition, we found that 78% of domestic cats and 25% of leopard cats were infected with FSV.We succeeded in isolation of five strains of FIV and determined the nucleotide sequence of the V3-V5 legion of env gene. The phylogenetic analysis revealed that five strains belonged to subtype C and one strain belonged to subtype D.FIV Subtype C is reported to be prevalent in Canada and Taiwan. From the results obtained here, we considered that FIV invaded southern Vietnam recently from other countries including Canada and Taiwan, or domestic cats in southern Vietnam retained FIV subtype C from the earliest time.