ISOLATION OF A NOVEL SUBGROUP-B FELINE LEUKEMIA-VIRUS FROM A CAT INFECTED WITH FELV-A

Proviruses were cloned directly from a cat that developed neurological disorders approximately 28 months after inoculation with a molecularly cloned, minimally pathogenic subgroup A feline leukemia virus (FeLV-A). In addition to FeLV-A proviruses that were nearly identical to the inoculated virus, we detected a subgroup a-like variant in brain, bone marrow, and lymph node that apparently had acquired the major portion of its extracellular envelope gene (gp70) from endogenous FeLV-related sequences. A similar recombinant was also detected, by PCR, at low levels in bone marrow from an early time postinfection (2.5 months). A full-length proviral variant with this recombinant structure cloned from brain tissue encoded a replication-defective virus. A chimera encoding the 5'gag-pol portion of FeLV-A and the 3'env- LTR portion of the defective brain-derived clone was replication-competent and had the extended host range properties of FeLV-B. (C) 1994 Academic Press, Inc.