Abstract:
HIV-1 Rev response element (RRE) is essential for efficient expression of
intron-containing transcripts of HIV-1. Although the element is situated in the
relatively conserved region of the virus, certain degree of variation was observed. The
objective of this study is to determine the range of HIV-1 RRE variation in its primary
sequence, the secondary structure and the functional variability. From 894 RRE
sequence analysis, primary sequence variation was found to be scattered throughout
the RRE region, while only a few contributed to the secondary structure alteration.
Pilot investigation of RRE function on a set of 10 primary isolates showed
considerable level of variation in RRE activity. Both the mechanisms in unspliced
RNA nuclear export and translation enhancement contributed to differences in RRE
activity. In a cohort study of 21 HIV-1 infected individuals, functional variability of
RRE was assessed at two different time points during follow up period. Although
RRE activity did not correlate with rates of CD4+ cell decline at the early time point,
there was a statistically significant difference between progressor and slow/nonprogressor
groups at the late time point (P = 0.004, Mann-Whitney U test, 2-tailed).
Furthermore, RRE activity at the late time point showed an inverse correlation with
rates of CD4+ cell decline based on Spearman’s correlation coefficient, (r = - 0.624, P
= 0.01). These results suggested that variation of RRE may play important roles in
modulation of virus replication and disease progression.