Restoration of the otherwise compromised replication of HIV variants highly resistant to multiple protease inhibitors by amino acid insertions near Gag cleavage sites.
Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. WeOrA1272)
Mitsuya H, Tamiya S, Mardy S, Kavlick MF NCI/NIH, Bethesda, United States
The emergence of HIV variants highly resistant to multiple anti-HIV agents represents a major cause of "treatment failure". Here, we examined the virological and enzymatic significance of amino acid inserts near the Gag cleavage sites seen in primary clinical isolates derived from patients with AIDS who had received 7-11 anti-HIV agents including 3-4 protease inhibitors over 24-81 months and had lost response to any existing antiviral regimens at the time (HIV[MDR]). Of 6 full-sized infectious clones newly generated using such primary isolates which were highly resistant to a variety of anti-HIV agents including 5 currently clinically available protease inhibitors and harbored high numbers of drug-resistance-associated mutations, 4 clones had unique amino acid inserts; TGNS, SQVN, and AQQA near the p17/p24 Gag cleavage site and/or SRPE, APP, and PTAPPA near the p1/p6 cleavage site. Each insert proved to be a duplicate of the adjacent am ino acid stretch. The competitive HIV replication assay showed that such Gag-inserts mostly compromised the replication of wild-type HIV, whereas the HIV[MDR] clones containing the insert(s) replicated significantly better than HIV[MDR] clones lacking the insert(s). None of the inserts had significant effects on the viral budding; however, the otherwise reduced Gag processing by mutant protease was found to be substantially improved in the presence of the insert(s), while the Gag processing by wild-type protease was impaired with the insert(s) as assessed by Western blot analysis using anti-p24 and -p6 antibodies. These data show that the inserts seen near the Gag cleavage sites in HIV[MDR] restore the otherwise compromised enzymatic activity of mutant protease, thus enabling HIV[MDR] to be replication-competent.
Keywords: AEGIS, Genes, gag, Virus Replication, Anti-HIV Agents, Protease Inhibitors, Antiviral Agents, Humans, genetics, virology
