MOLECULAR CHARACTERIZATION OF FELINE IMMUNODEFICIENCY VIRUS GENOME OBTAINED DIRECTLY FROM ORGANS OF A NATURALLY INFECTED CAT WITH MARKED NEUROLOGICAL SYMPTOMS AND ENCEPHALITIS

Feline immunodeficiency virus (FIV) was first isolated from cats with immunodeficiency syndrome. Recently, neurological abnormalities and br ain lesions were shown in cats infected with FIV. To investigate the F IV genome associated with central nervous system (CNS) lesions, provir al DNA sequences from the V3-V6 region of the FIV env gene were direct ly amplified from uncultured necropsy tissues of a 2-year-old naturall y FIV-infected cat with marked neurological symptoms and. encephalitis . By in situ hybridization, FIV RNA was detected mainly in the astrocy tes. Fifteen clones isolated from cerebrum, bone marrow and lymph node samples showed only a small number of mutations or deletions in this reg:ion. A representative clone, JN-BR1, was distantly related to the previous Japanese strain (TM2) belonging to the subtype B. However, it was relatively close to the Petaluma strain which is known to infect feline brain-derived culture cells and induce brain lesions in inocula ted cats. By phylogenetic analysis, the JN-BR1 strain was placed in su btype A that included Petaluma strain and several other American and E uropean strains. The JN-BR1 strain derived from brain with encephaliti s in this study and the Petaluma strain may share a common genetic str ucture that is related to their neuropathogenicity.