A DETERMINANT OF FELINE IMMUNODEFICIENCY VIRUS INVOLVED IN CRANDELL FELINE KIDNEY-CELL TROPISM

Viral progeny of the molecular clone 19k1 of feline immunodeficiency v irus (FIV) can infect feline T-cells but not Crandell feline kidney (C rFK) cells. In contrast, the biological isolate FIV-AM6c, which was Cr FK adapted by co-cultivation of FIV-AM6 infected thymocytes with CrFK cells, can infect both thymocytes and CrFK cells. The envelope gene of FIV-AM6c was amplified by polymerase chain reaction using DNA from in fected CrFK cells, and subsequently cloned and sequenced, To map viral determinants of CrFK cell tropism, chimeric viruses with a 19k1 backg round containing envelope gene fragments of FIV-AM6c were constructed. CrFK cells were transfected with DNA of these chimeric clones and co- cultivated with thymocytes. After 3 days the CrFK cells and the thymoc ytes were cultured separately. FIV antigen could be detected in most o f the thymocyte cultures within 14 days and in one of the CrFK culture s after 52 days. The resulting virus from this CrFK culture can infect both CrFK cells and thymocytes. The results of this study indicate th at the envelope region contains determinants of CrFK tropism. The dela y in replication indicates that also determinants other than those ide ntified here are involved in CrFK cell tropism. More chimeric clones a re being studied at present to map these determinants.