Molecular epidemiology of HIV type 2 infections in South India

Epidemic characteristics of local HIV-2 transmission across Hunan province, China

OBJECTIVE

To elucidate the epidemiological features of HIV-2 in Hunan Province, China, utilizing sequence analysis.

METHODS

Thirteen individuals diagnosed with HIV-2 infection in Hunan Province, China, from 2017 to 2023 were included in this study. Amplification of HIV-2 env and pol regions was conducted, followed by Sanger sequencing. Phylogenetic and molecular transmission network analyses were performed to delineate molecular features and transmission dynamics.

RESULTS

All 14 individuals contracted HIV-2 through heterosexual intercourse, comprising 7 males and 7 females, with a median age of 58 years. Among them, three couples (HN001 and HN013, HN010 and HN011, HN008 and HN009) were identified, along with commercial sexual activity engagement reported for subject HN004. Notably, subjects HN001, HN003, HN008, and HN010 engaged in commercial sexual activities at the same location as subject HN004. Phylogenetic analysis of the pol gene revealed close proximity of sequences from all subjects to reference sequences from Gambia (Sub-type A). Employing a genetic distance threshold of 1.5 %, eight out of the 14 subjects formed a molecular transmission network, with HN002 and HN004 identified as central nodes.

CONCLUSION

From 2017 to 2023, all HIV-2-infected individuals in Hunan Province, China, acquired the virus through identifiable routes, indicating transmission of similar HIV-2 strains among them.

Partial pol Sequences from Drug Naive HIV-2 Infected Individuals from Maharashtra, India

HIV-2 is important due to its unique challenges in diagnosis, treatment, and drug resistance. The data on Indian HIV-2 pol gene as well as resistance to antiretroviral drugs are limited. Here we report sequence data of protease (PR) and reverse transcriptase (RT) genes from HIV-2 infected treatment naive individuals (N = 32) from Maharashtra, India. These sequences were found to be closely related to HIV-2 subtype A sequences from Guinea Bissau. We observed two unique residues at positions 14 and 70 in the PR region specific to Indian HIV-2. Mutations associated with resistance to RT and protease inhibitors were observed in 3 of 32 (9.37%) samples. To our knowledge, this is the first study from India to report drug resistance among treatment naive HIV-2 infected individuals. The results emphasize need for larger nationwide surveillance for HIV-2 drug resistance to better understand the primary drug resistance among HIV-2 infected individuals.

Drug resistance mutations and viral load in human immunodeficiency virus type 2 and dual HIV-1/HIV-2 infected patients in Ghana

Antiretroviral therapy (ART) and drug resistance studies worldwide have focused almost exclusively on human immunodeficiency virus type 1 (HIV-1). As a result, there is limited information on ART and drug resistance in HIV-2 patients. In Ghana, the HIV epidemic is characterized by the domination of HIV-1, with cocirculating HIV-2. We, therefore, sought to determine viral load and drug resistance mutations in HIV-2 patients to inform the clinical management of such individuals in Ghana.We used purposive sampling to collect blood from 16 consented patients, confirmed as HIV-2 or HIV-1/2 dual infections by serology. A 2-step real-time RT-PCR assay was used to determine plasma HIV-2 RNA viral loads. For drug resistance testing, nucleic acids were extracted from plasma and peripheral blood mononuclear cells. The reverse transcriptase and protease genes of HIV-2 were amplified, sequenced and analyzed for drug resistance mutations and HIV-2 group.HIV-2 viral load was detected in 9 of 16 patients. Six of these had quantifiable viral loads (range: 2.62-5.45 log IU/mL) while 3 had viral loads below the limit of quantification. Sequences were generated from 7 out of 16 samples. Five of these were classified as HIV-2 group B and 2 as HIV-2 group A. HIV-2 drug resistance mutations (M184V, K65R, Y115F) were identified in 1 patient.This study is the first to report HIV-2 viral load and drug resistance mutations in HIV-2 strains from Ghana. The results indicate the need for continuous monitoring of drug resistance among HIV-2- infected patients to improve their clinical management.

In vitro evaluation of novel reverse transcriptase inhibitors TAF (tenofovir alafenamide) and OBP-601 (2,3-didehydro-3-deoxy-4-ethynylthymidine) against multi-drug resistant primary isolates of HIV-2

New antiretroviral drugs are needed to treat HIV-2 infected patients failing therapy. Herein, we evaluate the activity of novel reverse transcriptase inhibitors tenofovir alafenamide (TAF) and OBP-601(2,3-didehydro-3-deoxy-4-ethynylthymidine) against primary isolates from HIV-2 infected patients experiencing virologic failure. TAF and OBP-601 were tested against twelve primary isolates obtained from nine drug-experienced patients failing therapy and three drug naïve patients using a single-round infectivity assay in TZM-bl cells. The RT-coding region of pol was sequenced and the GRADE algorithm was used to identify resistance profiles and mutations. TAF and OBP-601 inhibited the replication of almost all isolates at a median EC₅₀ of 0.27 nM and 6.83 nM, respectively. Two isolates showed moderate-level resistance to OBP-601 or TAF and two other isolates showed high-level resistance to OBP-601 or to both drugs. With one exception, all resistant viruses had canonical nucleoside reverse transcriptase inhibitors (NRTIs)-associated resistance mutations (K65R, N69S, V111I, Y115F, Q151M and M184V). Our results show that TAF has potent activity against most multi-drug resistant HIV-2 isolates and should be considered for the treatment of HIV-2 infected patients failing therapy.

Hiv-2 molecular epidemiology

The Simian Immunodeficiency Virus of sooty mangabeys (SIVsmm) has been revealed to be at the origin of Human Immunodeficiency Virus type 2 (HIV-2) in humans, firstly detected from two Portuguese patients in 1986. HIV-2 is mainly restricted to West Africa where it infects up to 1 to 2 million people. HIV-2 is also present in Europe, mainly Portugal and France, India and United States of America. Two major HIV-2 groups, groups A and B, were generated by two independent transmission events involving infected sooty mangabeys from the Taï forest in Ivory Coast. Seven other HIV-2 groups have been described, but each has only been identified in one patient. To date, no subtypes have been formally described but some preliminary data suggest that HIV-2 group A may be divided in two distinct subtypes with distinct geographical origins. To date only two recombinant forms have been described: one circulating recombinant form (CRF01_AB) and one unique recombinant form. In this review, we focused mainly on molecular data available and their insights about HIV-2 origins, diversity, drug resistance and global epidemiology.

Dolutegravir in HIV-2-Infected Patients With Resistant Virus to First-line Integrase Inhibitors From the French Named Patient Program

BACKGROUND

Dolutegravir has shown in vitro activity against human immunodeficiency virus type 2 (HIV-2). We report safety and efficacy data of regimens containing dolutegravir (50 mg twice daily) in antiretroviral-experienced, HIV-2-infected patients.

METHODS

HIV-2-infected patients experiencing virological failure to raltegravir received dolutegravir with optimized background antiretroviral combinations within the French Named Patient Program (NPP). Plasma HIV-2 RNA (pVL) was assessed at time of dolutegravir initiation (baseline), month 3, and month 6. Antiretroviral trough plasma concentrations (C12h) were determined using liquid chromatography coupled with tandem mass spectrometry.

RESULTS

Thirteen HIV-2-infected-patients, with a median duration of 15 years' infection and given 16 previous antiretroviral regimens, were included in NPP. Median follow-up was 9 months (min-max, 3-15 months). Median baseline pVL and CD4 cell count were 9544 copies/mL (inter quartile range [IQR], 3096-23 120 copies/mL) and 100 cells/µL (IQR, 77-171 cells/µL), respectively. Available integrase genotypic resistance patterns were Y143C/G/H/R (n = 5), Q148R/K (n = 2), and N155H (n = 4). Optimized background antiretroviral regimens conferring a genotypic sensitivity score ≤2 in 10 patients included nucleoside reverse transcriptase inhibitors associated with darunavir/ritonavir (n = 12), saquinavir/ritonavir (n = 2), and maraviroc (n = 3). At months 3 and 6, pVL was undetectable in 6 of 13 and 4 of 12 patients, respectively, and median CD4 count was 161 (101-188) cells/µL and 167 (135-1353) cells/µL, respectively. Median dolutegravir C12h was 4086 (1756-5717 ng/mL) ng/mL in 9 patients. No serious events were notified except 1 death from progressive multifocal leukoencephalopathy at month 4.

CONCLUSIONS

Optimized dolutegravir-containing antiretroviral regimens supported by good plasma exposure provide a substantial initial efficacy rate for salvage therapy in heavily antiretroviral-experienced HIV-2-infected patients with virus harboring resistance to first-generation integrase inhibitors. Larger numbers of patients and longer follow-up are needed to confirm these findings.

Antiretroviral therapy and drug resistance in human immunodeficiency virus type 2 infection

One to two million people worldwide are infected with the human immunodeficiency virus type 2 (HIV-2), with highest prevalences in West African countries, but also present in Western Europe, Asia and North America. Compared to HIV-1, HIV-2 infection undergoes a longer asymptomatic phase and progresses to AIDS more slowly. In addition, HIV-2 shows lower transmission rates, probably due to its lower viremia in infected individuals. There is limited experience in the treatment of HIV-2 infection and several antiretroviral drugs used to fight HIV-1 are not effective against HIV-2. Effective drugs against HIV-2 include nucleoside analogue reverse transcriptase (RT) inhibitors (e.g. zidovudine, tenofovir, lamivudine, emtricitabine, abacavir, stavudine and didanosine), protease inhibitors (saquinavir, lopinavir and darunavir), and integrase inhibitors (raltegravir, elvitegravir and dolutegravir). Maraviroc, a CCR5 antagonist blocking coreceptor binding during HIV entry, is active in vitro against CCR5-tropic HIV-2 but more studies are needed to validate its use in therapeutic treatments against HIV-2 infection. HIV-2 strains are naturally resistant to a few antiretroviral drugs developed to suppress HIV-1 propagation such as nonnucleoside RT inhibitors, several protease inhibitors and the fusion inhibitor enfuvirtide. Resistance selection in HIV-2 appears to be faster than in HIV-1. In this scenario, the development of novel drugs specific for HIV-2 is an important priority. In this review, we discuss current anti-HIV-2 therapies and mutational pathways leading to drug resistance.

Novel agents for the treatment of HIV-2 infection

Many of the antiretrovirals used against HIV-1 are either ineffective or less effective in HIV-2 infection. There is in vitro evidence of the potency of maraviroc and several investigational agents against HIV-2. We conclude that, whilst specific boosted protease inhibitors combined with nucleoside analogues should still be considered the mainstays of HIV-2 treatment, maraviroc, T-1249, TAK-779 and AMD3100, as well as raltegravir, could contribute to regimens for treatment-experienced individuals. Factors bearing on the use and timing of these alternative agents are discussed.

Revealing the dimer dissociation and existence of a folded monomer of the mature HIV-2 protease

Purification and in vitro protein-folding schemes were developed to produce monodisperse samples of the mature wild-type HIV-2 protease (PR2), enabling a comprehensive set of biochemical and biophysical studies to assess the dissociation of the dimeric protease. An E37K substitution in PR2 significantly retards autoproteolytic cleavage during expression. Furthermore, it permits convenient measurement of the dimer dissociation of PR2(E37K) (elevated K(d) approximately 20 nM) by enzyme kinetics. Differential scanning calorimetry reveals a T(m) of 60.5 for PR2 as compared with 65.7 degrees C for HIV-1 protease (PR1). Consistent with weaker binding of the clinical inhibitor darunavir (DRV) to PR2, the T(m) of PR2 increases by 14.8 degrees C in the presence of DRV as compared with 22.4 degrees C for PR1. Dimer interface mutations, such as a T26A substitution in the active site (PR2(T26A)) or a deletion of the C-terminal residues 96-99 (PR2(1-95)), drastically increase the K(d) (>10(5)-fold). PR2(T26A) and PR2(1-95) consist predominantly of folded monomers, as determined by nuclear magnetic resonance (NMR) and size-exclusion chromatography coupled with multiangle light scattering and refractive index measurements (SMR), whereas wild-type PR2 and its active-site mutant PR2(D25N) are folded dimers. Addition of twofold excess active-site inhibitor promotes dimerization of PR2(T26A) but not of PR2(1-95), indicating that subunit interactions involving the C-terminal residues are crucial for dimer formation. Use of SMR and NMR with PR2 facilitates probing for potential inhibitors that restrict protein folding and/or dimerization and, thus, may provide insights for the future design of inhibitors to circumvent drug resistance.