Selection of Human Immunodeficiency Virus Type 1 Variants with an Insertion Mutation in the p6^gag and p6^pol Genes under Highly Active Antiretroviral Therapy

Abstract

We detected several types of human immunodeficiency virus type 1 (HIV‐1) variants with an insertion mutation in the p6gag and p6pol genes in eight of twenty‐two (36.4%) patients who possessed drug‐resistant viruses under highly active antiretroviral therapy (HAART). It was characteristic that a conserved proline‐rich motif “PTAPP” in the N‐terminus of p6gag protein was completely or partially duplicated in all cases. Five among the eight cases were retrospectively investigated in terms of the occurrence of dynamic change in the gag gene between the inserted and wild‐type HIV‐1 in the course of HAART. The longitudinal analysis revealed the following: 1) The inserted‐type viruses were selected over the wild‐type during HAART in three cases in which the both types coexisted in the beginning of the therapy. 2) In two cases in which the inserted‐type HIV‐1 alone was detected before the beginning of HAART, the inserted‐type HIV‐1 alone was continuously detected during the therapy. The inserted‐type HIV‐1 was also detected in four of thirty‐nine (10.3%) therapy‐naive patients. However, the frequency of inserted‐type HIV‐1 detection in the HAART‐receiving patients is significantly higher than that in the therapy‐naive patients (P=0.02). These results suggest that this type of insertion mutation is a polymorphism of the p6gag and p6pol genes, however, it consequently gave an advantage on proliferation and/or survival of the HIV‐1 variant under the presence of antiretroviral drugs.

Amino Acid Insertions near Gag Cleavage Sites Restore the Otherwise Compromised Replication of Human Immunodeficiency Virus Type 1 Variants Resistant to Protease Inhibitors

“…Of 114 wild-type HIV-1 isolates in the database, insertions of more than three amino acids occurred in four regions as follows: 5 (4.4%) near the p17/p24 cleavage site, 6 (5.3%) near the p2/p7 cleavage site, 6 (5.3%) near the p1/p6 cleavage site, and 15 FIG. 4 (19) demonstrated that certain insertions such as APP were identified in wild-type viruses at low percentages; however, with antiviral therapy started, more virions were found to harbor such insertions, suggesting that these insertions represent "polymorphisms" that are associated with drug resistance. Pettit et al have shown that the proteolytic processing of the Gag precursor by the viral protease occurs in a sequential manner and that the rates of cleavage at the five major Gag cleavage sites, including the p17/p24 and p1/p6 sites, differ by as much as 400-fold when full-length Gag protein is digested with wild-type HIV-1 protease in vitro (29).…”

Novel Cytotoxic T-Lymphocyte Escape Mutation by a Three-Amino-Acid Insertion in the Human Immunodeficiency Virus Type 1 p6 Pol and p6 Gag Late Domain Associated with Drug Resistance

“…Mechanistically, the SPT/APP site may be a hot spot for template-primer misalignment during reverse transcriptase-mediated reactions (5). Of note, however, PIC1362 developed the SPT/APP insertion without ever receiving antiviral treatment, and the repeat has been noted previously in viral isolates from antiretroviral-treatment-naïve patients (17), which we speculate may have resulted from CTL selection.…”

Quantitative SNP‐Detection Method for Estimating HIV‐1 Replicative Fitness: Application to Protease Inhibitor‐Resistant Viruses

“…Viral RNA at each time point was purified from total harvested culture supernatant using a High Pure RNA Isolation Kit (Roche, Tokyo). DNA fragments containing the protease gene of wild-type and mutated HIV-1 were amplified by reverse transcriptionnested polymerase chain reaction (RT-nested PCR) and purified from the reaction mixture, as previously described (8). Finally, the population of each virus was differentially determined using a quantitative SNPdetection method developed for this study.…”

“…Template DNAs (1,539 bp) used in generating standard curves and those used in a kinetics analysis were amplified by PCR with K4 and U12 primers (8), in which each plasmid of the infectious clone was individually added to a reaction mixture. Amplified DNAs were purified using a QIAquick gel extraction kit (Qiagen, Tokyo), and DNA concentrations were determined from triplicate measurements by a BioSpec-1600 spectrometer (Shimadzu, Kyoto, Japan).…”