The apoptotic potential of different HIV-1 subtype C Tat mutations in cell culture

[摘要] The efficiency in which HIV-1 can infect, spread and evade the attack of therapeuticagents can be attributed to a high mutation rate and frequent recombination events.These factors have collectively contributed to the diversity observed in HIV-1 andresulted in a multitude of subtypes, sub-subtypes, circulating recombinant forms(CRF's) and unique recombinant forms (URF's). The aim of this study was toinvestigate HIV-1 diversity in Cape Town using a small cohort of treatment naivepatients being investigated for HIV Associated Neurocognitive Disorders (HAND).Four different genomic domains: gag, pol, accessory and gp41 genes weresequenced to subtype the virus. HIV-1 tat was further investigated because thedicysteine motif has been reported to play a role in HAND. Viral RNA and proviralDNA was extracted from 64 patients and used for the amplification and sequencingof the genes. Rega and jpHMM online tools were used to identify HIV-1 subtypesand recombinants while Neighbor-joining phylogenetic trees were constructed forphylogenetic analysis. The pol gene was further investigated using SCUEAL todetect possible intra-subtype recombination and was also screened for the presenceof transmitted drug resistance. In addition tat sequence datasets retrieved from theLos Alamos sequence database were investigated and compared with the newlygenerated sequences for the detection of point mutations and amino acid signaturepatterns.Sequencing identified most of the samples as subtype C; however six inter-subtyperecombinants (AE, A1G, A1CU and two BC) and 9 intra-subtype C recombinantswere identified. In addition 13% of pol sequences were identified with resistancemutations. Signature pattern analysis identified a high level of variability in the tatsequences: 68% were identified with C30S31; 29% with the C30C31 mutation and asingle sequence with a novel mutation C30A31. Functional analysis of thesemutations indicated that all mutations investigated were capable of inducingapoptosis in cell culture. The C30C31 mutation generated the highest level ofapoptosis, closely followed by the C30A31 mutation. However no statisticalsignificance could be detected between tat mutations and the observed levels ofapoptosis.

[发布机构] Stellenbosch University