Defective rev response element (RRE) and rev gene in HAART treated AIDS patients with discordance between viral load and CD4+ T-cell counts.
BACKGROUND
Highly Active Antiretroviral Therapy (HAART) has emerged as one the most effective method for treating AIDS patients. However, after variable period of treatment, many AIDS patients on HAART show elevated PCR viral load without a corresponding decline in CD4+ T-cells. Our earlier studies have revealed that the viruses present in the plasma of such patients are not infectious.


OBJECTIVE
The aim of this study is to characterize the changes in the regulatory genes of HIV-1, namely tat, rev and rev response element (RRE) isolated from the plasma of such AIDS patients and to assess their role in role in affecting viral infectivity, hence its contribution, in the 'contradictory phenomenon' of high viral load and high CD4+ T-cell counts.


METHODS
The viral RNA was isolated from the plasma of HAART patients when they exhibited high plasma viral load and high CD4+ T-cell counts. The target regulatory genes were amplified by RT-PCR and sequenced. Sequences were also obtained from the proviral DNA from the peripheral blood mononuclear cells (PBMCs) of the study subjects. The sequences were compared with the wild type viral sequence to look for the changes induced in them due to HAART regime.


CONCLUSIONS
Our data revealed that RRE was missing in the viral particles isolated from the plasma of all study subjects. In two patients, the second exon of the rev gene was missing thereby leading to defective Rev protein. In another patients, Rev synthesis was prematurely stopped due to G135T substitution in the amino terminal domain. No such changes were observed in the corresponding proviral DNA. These changes are likely to result in the assembly of non-infectious virus due to lack of envelope proteins. Absence of RRE and Rev protein also leads to transport and packaging of multiply spliced transcripts into the virions instead of complete genomic RNA.
Saurya
Shreesh
S
Department of Haematology, University of Cambridge Clinical School, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK. ssaurya@hammer.imm.ox.ac.uk
Lichtenstein
Zelman
Z
Karpas
Abraham
A
D000595:Amino Acid Sequence; D023241:Antiretroviral Therapy, Highly Active; D018791:CD4 Lymphocyte Count; D015694:Gene Products, rev / Q000187:drug effects / Q000235:genetics; D015757:Genes, rev / Q000187:drug effects; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology* / Q000821:virology; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D020218:Response Elements / Q000187:drug effects / Q000235:genetics; D019562:Viral Load; D054321:rev Gene Products, Human Immunodeficiency Virus
D015694:Gene Products, rev; D054321:rev Gene Products, Human Immunodeficiency Virus