3rd Conf Retro and Opportun Infect. 1996 Jan 28-Feb 1;:178. Unique
One of the striking differences between HIV and the type-B and -C
oncogenic retroviruses is its possession of six genes in addition to
gag, pol, and env. Accumulating evidence suggests that all six of these
genes are required for efficient virus replication in vivo. As such,
each may provide a novel target for future therapeutic strategies. An
update or our efforts to understand the molecular basis for the function
of two of these genes, rev and vif, will be presented. The rev protein
is essential for the nucleocytoplasmic transport of all unspliced
(intron containing) viral RNA. The protein itself has two discrete
domains: an amino-terminal region confers binding to substrate RNA as
well as nuclear localization whereas a carboxy-terminal region(the
activation domain) mediates interactions with cellular cofactors and is
required for Rev's own export out of the nucleus. We have recently
demonstrated that the activation domain acts as a specific and
autonomous nuclear export signal (NES), a finding that suggests that the
critical targeting information that drives rev-RNA complexes into the
cytoplasm resides within the Rev protein itself. Considerably less is
currently known regarding vif. It has, however, been established that
its presence in virus producing cells is required for the released
virions to be infectious. Our results suggest that viruses expressed in
the absence of vif are still able to penetrate target cells and initiate
reverse transcription as efficiently as wild type virus. However, the
reverse transcripts of vif-deficient virus infections fail to proceed to
provirus formation and appear to be degraded by later timepoints. One
explanation for this phenotype is that the viral pre-integration
complexes disassemble inappropriately, this model might be consistent
with the noted ultrastructural abnormalities of vif-deficient viruses.
*Genes, rev *Genes, vif HIV/GENETICS/*PHYSIOLOGY Transcription,
Genetic Virus Replication/*GENETICS ABSTRACT