Biology Reference
In-Depth Information
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HIV and Molecular Biology of the
Virus-Host Interplay
Massimo Clementi
Department of Biomedical Sciences, University of Trieste, Trieste, Italy
INTRODUCTION
The precise understanding of the molecular mechanisms in each step of the
human immunode®ciency virus ( HIV ) life cycle has provided an essential basis
for designing antiviral compounds and strategies aimed at blocking viral repli-
cation and preventing or delaying disease progression. As in other retroviral
infections, the replication cycle of HIV can be described as proceeding in two
phases. The ®rst phase includes entry of the virion into the cell cytoplasm,
synthesis of double-stranded DNA (provirus) using the single-stranded genome
RNA as a template, transfer of the proviral DNA to the nucleus, and inter-
gration of the DNA into the host genome. The second phase includes synthesis
of new copies of the viral genome, expression of viral genes, virion assembly by
encapsidation of the genome by precursors of the HIV structural proteins,
budding, and ®nal processing of the viral proteins. Whereas the former phase
is mediated by proteins that are present within the virion and occurs in the
absence of viral gene expression, the latter, leading to production of infectious
virions, is a complex process requiring the interplay of viral and cellular factors.
The precise understanding of the molecular mechanisms of HIV replication
and the use of new technologies in virology has lead to exciting discoveries on
many aspects of the biology of this virus. In particular, a growing body of new
data on the HIV replication mechanisms together with the results from molec-
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