Replicative Capacity Differences of Thymidine Analog Resistance Mutations in Subtype B and C Human Immunodeficiency Virus Type 1

Armstrong, Kimberly L.; Lee, Tun‐Hou; Essex, M.

doi:10.1128/jvi.02645-08

Cited by 21 publications

(13 citation statements)

References 22 publications

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“…The difference in viral DNA accumulation between viruses carrying RT from subtype B and C isolates may eventually determine the overall level of viral replication, that is consistent with the published data on subtype-associated effect of RT on viral replicative fitness [29]. …”

Section: Resultssupporting

confidence: 87%

Subtype-associated differences in HIV-1 reverse transcription affect the viral replication

et al. 2010

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BackgroundThe impact of the products of the pol gene, specifically, reverse transcriptase (RT) on HIV-1 replication, evolution, and acquisition of drug resistance has been thoroughly characterized for subtype B. For subtype C, which accounts of almost 60% of HIV cases worldwide, much less is known. It has been reported that subtype C HIV-1 isolates have a lower replication capacity than B; however, the basis of these differences remains unclear.ResultsWe analyzed the impact of the pol gene products from HIV-1 B and C subtypes on the maturation of HIV virions, accumulation of reverse transcription products, integration of viral DNA, frequency of point mutations in provirus and overall viral replication. Recombinant HIV-1 viruses of B and C subtypes comprising the pol fragments encoding protease, integrase and either the whole RT or a chimeric RT from different isolates of the C and B subtypes, were used for infection of cells expressing CXCR4 or CCR5 co-receptors. The viruses carrying different fragments of pol from the isolates of B and C subtypes did not reveal differences in Gag and GagPol processing and viral RNA incorporation into the virions. However, the presence of the whole RT from subtype C, or the chimeric RT containing either the polymerase or the connection and RNase H domains from C isolates, caused significantly slower viral replication regardless of B or C viral backbone. Subtype C RT carrying viruses displayed lower levels of accumulation of strong-stop cDNA in permeabilized virions during endogenous reverse transcription, and decreased accumulation of both strong-stop and positive strand reverse transcription products in infected cells and in isolated reverse transcription complexes. This decreased accumulation correlated with lower levels of viral DNA integration in cells infected with viruses carrying the whole RT or RT domains from subtype C isolates. The single viral genome assay analysis did not reveal significant differences in the frequency of point mutations between the RT from B or C subtypes.ConclusionsThese data suggest that the whole RT as well as distinct polymerase and connection-RNase H domains from subtype C HIV-1 confer a lower level of accumulation of reverse transcripts in the virions and reverse transcription complexes as compared to subtype B, resulting in a lower overall level of virus replication.

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Section: Resultssupporting

confidence: 87%

Subtype-associated differences in HIV-1 reverse transcription affect the viral replication

et al. 2010

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“…The HIV subtype C molecular clone MJ4 was used as the backbone virus for all clones (30). The subtype B sample in this study is the RT from HXB2 (36), replacing the RT in MJ4 so that the viruses are identical except for RT (1). The consensus C sequence for RT from the Los Alamos HIV database (23) was used as the template to create the consensus C RT used in this study.…”

Section: Methodsmentioning

confidence: 99%

Replicative Fitness Costs of Nonnucleoside Reverse Transcriptase Inhibitor Drug Resistance Mutations on HIV Subtype C

Armstrong

Lee

Essex

2011

Antimicrob Agents Chemother

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Single-dose nevirapine (NVP) is quite effective in preventing transmission of the human immunodeficiency virus (HIV) from mother to child; however, many women develop resistance to NVP in this setting. Comparing outcomes of clinical studies reveals an increased amount of resistance in subtype C relative to that in other subtypes. This study investigates how nonnucleoside reverse transcriptase inhibitor (NNRTI) drug resistance mutations of subtype C affect replication capacity. The 103N, 106A, 106M, 181C, 188C, 188L, and 190A drug resistance mutations were placed in a reverse transcriptase (RT) that matches the consensus subtype C sequence as well as the HXB2 RT, as a subtype B reference. The replicative fitness of each mutant was compared with that of the wild type in a head-to-head competition assay. The 106A mutant of subtype C would not grow in the competition assay, making it the weakest virus tested. The effect of the 106M mutation was weaker than those of the 181C and 188C mutations in the consensus C RT, but in subtype B, this difference was not seen. To see if the 106A mutation in a different subtype C background would have a different replicative profile, the same NNRTI resistance mutations were added to the MJ4 RT, a reference subtype C molecular clone. In the context of MJ4 RT, the 106A mutant was not the only mutant that showed poor replicative fitness; the 106M, 188C, and 190A mutants also failed to replicate. These results suggest that NNRTIs may be a cost-effective alternative for salvage therapy if deleterious mutations are present in a subtype C setting.The emergence of drug-resistant mutants is common among HIV-infected patients undergoing antiviral therapy. Clinically, the standard practice is to drop the antiviral to which the resistance has developed from the treatment regimen in such drug failure cases. However, a notable exception to this is the continuing use of lamivudine (3TC) as a salvage regimen because the 184V mutation linked to 3TC treatment has decreased replication ability relative to that of the wild type (WT) in subtype B (7). Mechanistically, Back et al. (2) found that the 184V mutant is less processive than wild-type RT under conditions of limiting deoxynucleoside triphosphates (dNTPs), and in primary lymphoid cells, the mutant is less fit than wildtype virus. These studies were extended further in vivo by Paredes et al. (35), who looked at multidrug-resistant virus from patients who were ending 3TC treatment. They used an allele-specific PCR assay to track the reversion of the M184V sequence and found that there was a fitness cost of 4 to 8% for the 184V mutation compared to that of the viral sequence that grew without 3TC drug pressure. Taken together, these studies illustrate how clinical management of HIV-infected patients can benefit from the study of the fitness cost of HIV drugresistant mutants.The use of antiretroviral drugs is increasing in the developing world. In particular, the use of single-dose nevirapine (NVP) has been shown to be an effective means of mitigat...

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“…They also showed that the TAM-2 mutant D67N/K70R/T215F had the slowest replication levels between both subtypes [25]. This might explain why D67N and K70R emerged first and then T215I was selected instead of 215F in 66% of replicates.…”

Section: Discussionmentioning

confidence: 97%

Differential In Vitro Kinetics of Drug Resistance Mutation Acquisition in HIV-1 RT of Subtypes B and C

et al. 2012

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BackgroundHIV-1 subtype B is the most prevalent in developed countries and, consequently, it has been extensively studied. On the other hand, subtype C is the most prevalent worldwide and therefore is a reasonable target for future studies. Here we evaluate the acquisition of resistance and the viability of HIV-1 subtype B and C RT clones from different isolates that were subjected to in vitro selection pressure with zidovudine (ZDV) and lamivudine (3TC).Methods/Principal FindingsMT4 cells were infected with chimeric virus pseudotyped with RT from subtype B and C clones, which were previously subjected to serial passage with increasing concentrations of ZDV and 3TC. The samples collected after each passage were analyzed for the presence of resistance mutations and VL. No differences were found between subtypes B and C in viral load and resistance mutations when these viruses were selected with 3TC. However, the route of mutations and the time to rebound of subtype B and C virus were different when subjected to ZDV treatment. In order to confirm the role of the mutations detected, other clones were generated and subjected to in vitro selection. RT subtype B virus isolates tended to acquire different ZDV resistance mutations (Q151M and D67N or T215Y, D67D/N and F214L) compared to subtype C (D67N, K70R, T215I or T215F).Conclusions/SignificanceThis study suggests that different subtypes have a tendency to react differently to antiretroviral drug selection in vitro. Consequently, the acquisition of resistance in patients undergoing antiretroviral therapy can be dependent on the subtypes composing the viral population.

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Replicative Capacity Differences of Thymidine Analog Resistance Mutations in Subtype B and C Human Immunodeficiency Virus Type 1

Cited by 21 publications

References 22 publications

Subtype-associated differences in HIV-1 reverse transcription affect the viral replication

Subtype-associated differences in HIV-1 reverse transcription affect the viral replication

Replicative Fitness Costs of Nonnucleoside Reverse Transcriptase Inhibitor Drug Resistance Mutations on HIV Subtype C

Differential In Vitro Kinetics of Drug Resistance Mutation Acquisition in HIV-1 RT of Subtypes B and C

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