A SINGLE AMINO-ACID SUBSTITUTION IN THE TRANSMEMBRANE ENVELOPE GLYCOPROTEIN OF FELINE IMMUNODEFICIENCY VIRUS ALTERS CELLULAR TROPISM

The cellular tropism of the feline immunodeficiency virus (FIV) is aff ected by changes in variable region 3 (V3) of the surface (SU) envelop e glycoprotein (Verschoor, E. J., et al., J. Virol. 69:4752-4757, 1995 ). By using high-dose DNA transfection, an FIV molecular clone with a non-CRFK-tropic V3 acquired the ability to replicate in CRFK cells. A single point mutation from a methionine to a threonine in the ectodoma in of its transmembrane (TM) envelope glycoprotein was responsible for this change in viral tropism, This substitution is located in the put ative SU interactive region, between the fusion peptide and the membra ne-spanning region. Our results show that this region of the TM envelo pe glycoprotein constitutes an additional determinant for cell tropism .