A novel mutation, D404N, in the connection subdomain of reverse transcriptase of HIV-1 CRF08_BC subtype confers cross-resistance to NNRTIs

Impacts of HIV-1 Subtype Diversity on Long-Term Clinical Outcomes in Antiretroviral Therapy in Guangxi, China

BACKGROUND

Comprehensively estimating the impacts of HIV-1 subtype diversity on long-term clinical outcomes during antiretroviral therapy (ART) can help inform program recommendations.

METHODS

The HIV-1 sequence data and clinical records of 5950 patients from all 14 prefectures in Guangxi, China, during 2008-2020 were included. Evolutional trends of CD4+ T-lymphocyte count and viral load were explored, and the effects of HIV-1 subtypes on clinical outcomes were estimated by the Cox proportional hazards model. The polymorphisms involved in drug resistance mutation were analyzed.

RESULTS

Compared with patients with CRF07_BC, patients with CRF01_AE and CRF08_BC showed poor immunologic and virologic responses to antiretroviral therapy. Although the median expected time from ART initiation to virologic suppression for all patients was approximately 12 months, patients with CRF01_AE and CRF08_BC had a long time to achieve immune recovery and a short time to occur immunologic failure, compared with patients with CRF07_BC. Adjusted analysis showed that both CRF01_AE and CRF08_BC were the negative factors in immune recovery and long-term mortality. In addition, CRF08_BC was a negative factor in virologic suppression and a risk factor of virologic failure. This poor virologic response might result from the high prevalence of drug resistance mutation in CRF08_BC.

CONCLUSIONS

Compared with patients with CRF07_BC, patients with CRF01_AE could benefit more from immediate ART, and patients with CRF08_BC are more suitable for PI-based regimens. These data emphasize the importance of routine HIV-1 genotyping before ART, immediate ART, and personalized ART regimens to improve the prognosis for patients undergoing ART.

Drug resistance-related mutations T369V/I in the connection subdomain of HIV-1 reverse transcriptase severely impair viral fitness

Fitness is a key parameter in the measurement of transmission capacity of individual drug-resistant HIV. Drug-resistance related mutations (DRMs) T369V/I and A371V in the connection subdomain (CN) of reverse transcriptase (RT) occur at higher frequencies in the individuals experiencing antiretroviral therapy failure. Here, we evaluated the effects of T369V/I and A371V on viral fitness, in the presence or in the absence of thymidine analogue resistance-associated mutations (TAMs) and assessed the effect of potential RT structure-related mechanism on change in viral fitness. Mutations T369V/I, A371V, alone or in combination with TAMs were introduced into a modified HIV-1 infectious clone AT1 by site-directed mutagenesis. Then, experiments on mutant and wild-type virus AT2 were performed separately using a growth-competition assay, and then the relative fitness was calculated. Structural analysis of RT was conducted using Pymol software. Results showed that T369V/I severely impaired the relative virus fitness, and A371V compensated for the viral fitness reduction caused by TAMs. Structural modeling of RT suggests that T369V/I substitutions disrupt powerful hydrogen bonds formed by T369 and V365 in p51 and p66. This study indicates that the secondary DRMs within CN might efficiently damage viral fitness, and provides valuable information for clinical surveillance and prevention of HIV-1 strains carrying these DRMs.

Novel Mutations L228I and Y232H Cause Nonnucleoside Reverse Transcriptase Inhibitor Resistance in Combinational Pattern

The emergence of drug resistance mutations is increasing after the implementation of highly active antiretroviral therapy. To characterize two novel mutations L228I and Y232H in the primer grip of reverse transcriptase (RT) of HIV-1 circulating recombination form 08_BC (CRF08_BC) subtype, both mutant clones were constructed to determine their impacts on viral phenotypic susceptibility and replication capacity (RC). Results showed that the novel mutation, L228I, conferred a low-level resistance to etravirine by itself. L228I in combination with Y188C displayed a high level of cross-resistance to both nevirapine (NVP) and efavirenz (EFV). The copresence of A139V and Y232H induced a moderate level of resistance to NVP and EFV. Mutations Y188C/L228I, A139V, Y232H, and A139V/Y232H reduced more than 55% of viral RC compared with that of the wild-type (WT) reference virus. Modeling study suggested that the copresence of Y188C/L228I or A139V/Y232H might induce conformational changes to RT, which might result in reduced drug susceptibility and viral RC due to abolished hydrogen bonding or complex interaction with vicinal residues. Our results demonstrated that L228I and Y232H were novel accessory nonnucleoside reverse transcriptase inhibitor resistance-related mutations and provided valuable information for clinicians to design more effective treatment to patients infected with HIV-1 subtype CRF08_BC.