Polymerase chain reaction and partial sequencing of a British isolate (T637) of feline immunodeficiency virus.

We have used the polymerase chain reaction (PCR) and direct sequencing of the amplified products to obtain information of the molecular nature of an FIV isolate, T637. Cats experimentally infected with T637 have progressed to clinical immunodeficiency disease. The 5' long terminal repeat (LTR), most of the genes coding for internal proteins (GAG) and surface proteins (ENV), and part of the polymerase (POL) gene have been sequenced. The LTR of T637 has 92% nucleic acid identity with the prototype strain, FIV-Petaluma and the Glasgow isolate, FIV-14, 89% with a Swiss isolate, FIVZ2, and 95% with the PPR isolate. Both GAG and POL genes of T637 share extensive homology with Petaluma and PPR. In the ENV gene, T637 has 91% nucleic acid homology with Petaluma and 86% with PPR, and an overall amino acid homology of between 81-87%. For the surface (SU) region of the ENV gene product, T637 has 89% amino acid homology with Petaluma and FIVZ2 and 86% with PPR.