Viral genetic determinants of non progressive HIV-1 subtype C infection in antiretroviral drug naive children
Date
2009-09-08T10:05:00Z
Authors
Tzitzivacos, Demetrio Basil
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Objectives: Characterization of HIV-1 from slow progressors (SP) is important to
facilitate vaccine and antiviral drug development. In order to identify virus attenuations
that may contribute to slower rates of disease progression, the full viral genomes from
primary isolates of six slow progressing HIV-positive children were sequenced.
Methods: Primary virus biological phenotypes were determined by growth in CCR5- and
CXCR4-expressing U87.CD4 cell lines. Proviral DNA was isolated from co-cultured
PBMCs, and the near full-length genomes and LTR regions were PCR amplified,
sequenced and analysed. Predicted amino acid (aa) sequences for all the HIV-1 proteins
were extensively analyzed.
Results: All primary HIV-1 isolates utilized CCR5, and were determined to be HIV-1
subtype C by phylogenetic analysis. Predicted aa sequence analysis revealed open
reading frames for all HIV-1 genes which encoded for proteins of the expected length,
with several exceptions. For example, isolate LT5 had a 2 aa insertion in the Vpr
mitochondriotoxic domain. Isolate LT21 contained an additional 5aa in the C-terminus of
tat exon 2, while the integrase enzyme in isolate LT39 had an additional 3aa at the Cterminus.
Rev from isolates LT45 and LT46 did not have the characteristic subtype C
16aa truncation, and in addition, had a further 3aa. In addition, altered functional
domains was noted in several isolates, such as the cAMP-dependent kinase PKA
phosphorylation site in Nef (LT5), a Vpr mutation involved in decreasing pro-apoptotic
activity (LT42), and the Nef ExxxLL motif involved in the interaction with AP-1 and AP-2
(LT46).
Conclusions: The slower HIV disease progression in these six children may be attributed
to altered protein functions. For example, LT46 Nef is unable to bind AP-1 and AP-2 and
therefore inactive on CD4 endocytosis. The biological relevance of these findings
requires further investigation.
Description
M.Med. Faculty of Health Sciences, University of the Witwatersrand, 2008
Keywords
viral genetic determinants, HIV-1