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J. Virol., 08 1997, 5871-5877, Vol 71, No. 8
C Aiken
Human immunodeficiency virus type 1 (HIV-1) normally enters cells by direct
fusion with the plasma membrane. In this report, HIV-1 particles capable of
infecting cells through an endocytic pathway are described. Chimeric
viruses composed of the HIV-1 core and the envelope glycoprotein of
vesicular stomatitis virus (VSV-G) were constructed and are herein termed
HIV-1(VSV) pseudotypes. HIV-1(VSV) pseudotypes were 20- to 130-fold more
infectious than nonpseudotyped HIV-1. Infection by HIV-1(VSV) pseudotypes
was markedly diminished by ammonium chloride and concanamycin A, a
selective inhibitor of vacuolar H+ ATPases, demonstrating that these
viruses require endosomal acidification to achieve productive infection.
HIV-1 is thus capable of performing all of the viral functions necessary
for infection when entry is targeted to an endocytic route. Maximal HIV-1
infectivity requires the presence of the viral Nef protein and the cellular
protein cyclophilin A (CyPA) during virus assembly. Pseudotyping by VSV-G
markedly suppressed the requirement for Nef. HIV-1(VSV) particles were also
resistant to inhibition by cyclosporin A; however, the deleterious effect
of a gag mutation inhibiting CyPA incorporation was not relieved by VSV-G.
These results suggest that Nef acts at a step of the HIV-1 life cycle that
is either circumvented or facilitated by targeting virus entry to an
endocytic pathway. The findings also support the hypothesis that Nef and
CyPA enhance HIV-1 infectivity through independent processes and
demonstrate a mechanistic difference between reduction of HIV-1 infectivity
by cyclosporin A and gag mutations that decrease HIV-1 incorporation of
CyPA.
Copyright © 1997, American Society for Microbiology
Pseudotyping human immunodeficiency virus type 1 (HIV-1) by the glycoprotein of vesicular stomatitis virus targets HIV-1 entry to an endocytic pathway and suppresses both the requirement for Nef and the sensitivity to cyclosporin A
Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2363, USA. chris.aiken@mcmail.vanderbilt.edu
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