Comparative study of the cell tropism of feline immunodeficiency virus isolates of subtypes A, B and D classified on the basis of the env gene V3-V5 sequence.

Feline immunodeficiency virus (FIV) isolates have been classified into subtypes A, B, C and D based on the env gene V3-V5 sequence. The cell tropism of seven new Japanese isolates and a Petaluma (prototype) isolate of FIV, which classified into subtypes A, B and D, for feline lymphoblastoid and feline fibroblastoid cell lines was compared. FeT-1 (CD4+/-, CD8-, AND CD9+2) and Kumi-1 (CD4+2, CD8- and CD9+2) cells were used as the interleukin-2 (IL-2)-dependent feline T-lymphocyte cell lines and FeT-J (CD4+, CD8+/- and CD9+2) and 3201 (CD4+2, CD8+ and CD9-) cells were used as the IL-2- independent feline T-lymphocyte cell lines. The feline fibroblastoid cell lines used were Crandell feline kidney (CrFK) and fewf-4 (both CD4-, CD8- and CD9+2) cells. All FIV isolates replicated in all lymphoblastoid cell lines used. All isolates showed the greatest cytopathogenicity for Kumi-1 cells. All isolates replicated even in the CD9-negative 3201 cells. More isolates caused persistent infection in IL-2-independent cell lines than in IL-2-dependent cell lines. The number of subtype B isolates that established persistent infection was limited, only one of four strains. Only the subtype A isolates replicated in CrFK cells, whereas none of the isolates replicated in fewf-4 cells, which have similar cell surface markers to CrFK cells. The subtype A viruses (CrFK/Petaluma, CrFK/Sendai-1) growing in CrFK cells showed greater cytopathogenicity for lymphoblastoid cell lines than did those (FL-4/Petaluma, Kumi-1/Sendai-1) growing in a lymphoblastoid cell line.