Phylogenetic Analysis of HIV-1 CRF65_CPX Reveals Yunnan Province Is Still a Source Contributing to the Spread of HIV-1 in China

The origin, dissemination, and molecular networks of HIV-1 CRF65_cpx strain in Hainan Island, China

BACKGROUND

HIV-1 CRF65_cpx strain carries drug-resistant mutations, which raises concerns about its potential for causing virologic failure. The CRF65_cpx ranks as the fourth most prevalent on Hainan Island, China. However, the origin and molecular epidemiology of CRF65_cpx strains in this area remain unclear. This study aims to estimate the spatial origins and dissemination patterns of HIV-1 CRF65_cpx in this specific region.

METHODS

Between 2018 and 2021, a total of 58 pol sequences of the CRF65_cpx were collected from HIV-positive patients on Hainan Island. The available CRF65_cpx pol sequences from public databases were compiled. The HIV-TRACE tool was used to construct transmission networks. The evolutionary history of the introduction and dissemination of HIV-1 CRF65_cpx on Hainan Island were analyzed using phylogenetic analysis and the Bayesian coalescent-based approach.

RESULTS

Among the 58 participants, 89.66% were men who have sex with men (MSM). The median age was 25 years, and 43.10% of the individuals had a college degree or above. The results indicated that 39 (67.24%) sequences were interconnected within a single transmission network. A consistent expansion was evident from 2019 to 2021, with an incremental annual addition of four sequences into the networks. Phylodynamic analyses showed that the CRF65_cpx on Hainan Island originated from Beijing (Bayes factor, BF = 17.4), with transmission among MSM on Hainan Island in 2013.2 (95%HPD: 2012.4, 2019.5), subsequently leading to an outbreak. Haikou was the local center of the CRF65_cpx epidemic. This strain propagated from Haikou to other locations, including Sanya (BF > 1000), Danzhou (BF = 299.3), Chengmai (BF = 27.0) and Tunchang (BF = 16.3). The analyses of the viral migration patterns between age subgroups and risk subgroups revealed that the viral migration directions were from "25-40 years old" to "17-24 years old" (BF = 14.6) and to "over 40 years old" (BF = 17.6), and from MSM to heterosexuals (BF > 1000) on Hainan Island.

CONCLUSION

Our analyses elucidate the transmission dynamics of CRF65_cpx strain on Hainan Island. Haikou is identified as the potential hotspot for CRF65_cpx transmission, with middle-aged MSM identified as the key population. These findings suggest that targeted interventions in hotspots and key populations may be more effective in controlling the HIV epidemic.

Characteristics of Four Novel Recombinant Strains from the Backbone of CRF55_01B and CRF65_cpx in Beijing by Near Full-Length Genome

The HIV-1 epidemic was mainly driven by men who have sex with men (MSM) recently in Beijing, China, with high genetic diversity. Novel recombinant strains were frequently reported at 3.4%-9.9%. It is imperative to interpret the recombinant modes and the putative transmission sources by near full-length genome (NFLG). Four individuals from the MSM population were identified as novel recombinant strains during surveillance of pretreatment drug resistance. NFLG sequences were harvested by near end-point dilution and nested PCR with two overlapping half fragments. Phylogenetic inference was performed with subtyping reference sequences and major parental strain sequences, to explore the patterns of genetic recombinant and potential sources of parent strains. The breakpoints were determined using SimPlot 3.5 to draw genome mosaic map, and the potential parental strains were confirmed by Mega 6.0 using segmental neighbor-joining trees. BL19487-00 and BL1948-00 sequences were obtained from epidemiologically linked individuals and shared similar breakpoints (HXB2 nt 4,497 ± 8 to 4,722) with substitution of subtype B pol gene segment in the backbone of CRF55_01B. BL3104-00 and BL4307-00 carried seven and eight breakpoints, respectively, in the backbone of CRF65_cpx with g5 CRF01_AE substitutions. The recombinant fragments were located around gag, pol, and env genes, with vpr-tat and nef-3'-LTR genes only for BL4307-00. No transmitted drug resistance was observed with the four unique recombinant forms (URFs), except for some drug resistance associated mutations. The advent of URFs around CRF55_01B and CRF65_cpx identified in recent years implied that the sexual behaviors were active and the epidemic of HIV was complicated among MSM in Beijing. Molecular epidemiological surveillance and precise control should be reinforced for this population.

Phylogenetic Analysis of Sequences in the HIV Database Revealed Multiple Potential Circulating Recombinant Forms in China

HIV recombination contributes greatly to its diversity and produces many circulating recombinant forms (CRFs) and unique recombinant forms (URFs). In China, 24 CRFs have been reported to date, and CRFs cause more than 80% of HIV infections. However, the prevalence of CRFs might still be underestimated, as a high level of onward transmission of URFs has been reported. In this study, we analyzed all Chinese pol region (2,253-3,252) sequences in the HIV Database to evaluate potential new CRFs in China. HIV-1 genotypes were verified by the Context-based Modeling for Expeditious Typing (COMET) tool. Maximum-likelihood (ML) trees were constructed based on sequences with unassigned genotypes. Cluster Picker 1.2.1 was used to identify transmission clusters. Meanwhile, a jumping-profile hidden Markov model (jpHMM) was used to perform recombination breakpoint analysis. Beast 1.7.5 was used to estimate the time of the most recent common ancestor of new CRFs. In the HIV databases, CRF01_AE was the most prevalent genetic form in China, accounting for 39.69% of all national infections, followed by CRF07_BC (20.47%), subtype B (17.50%), CRF08_BC (6.60%), subtype C (6.28%), CRF55_01B (2.06%), and other CRFs (1.77%). The URFs were responsible for 5.31% of all infections nationwide. Among URFs, genomes comprising BC, 01BC, 01B, and 01C were dominant. Finally, 17 potential CRFs and 1 novel CRF were identified. BEAST analysis indicates that novel CRF originated around in 2009. The data highlight that more CRFs have been spreading in China. HIV-1 pol sequences that are commonly used to explore drug resistance are helpful for the surveillance of epidemics of different HIV-1 genotypes.

Natural presence of the V179D and K103R/V179D mutations associated with resistance to nonnucleoside reverse transcriptase inhibitors in HIV-1 CRF65_cpx strains

BACKGROUND

There is increasing evidence that HIV-1 genetic diversity can have an impact on drug resistance. The aim of this study is to investigate the epidemiological situation of CRF65_cpx and the impact of natural polymorphisms of this variant on genotypic resistance.

METHODS

We used the BLAST search program followed by phylogenetic analysis to identify additional CRF65_cpx pol sequences from the Los Alamos HIV Sequence Database. Maximum likelihood phylogeny was estimated to clarify the epidemiological relationship of CRF65_cpx strains. Genotypic resistance was determined by submitting sequences to the Stanford HIV Drug Resistance Database.

RESULTS

A total of 32 CRF65_cpx pol sequences were obtained. The CRF65_cpx strains were detected in seven provinces with large geographic distance. Yunnan CRF65_cpx sequences were mainly derived from a heterosexual risk group, whereas the CRF65_cpx sequences in other provinces were almost exclusively derived from an MSM population. With one exception of V179E, the other 31 strains harbored V179D mutation. The combination of V179D and K103R, conferring intermediate resistance to EFV and NVP, was detected in seven treatment-naive MSM patients.

CONCLUSIONS

This study confirmed the expansion CRF65_cpx in China. Furthermore, we found the natural presence of the V179D and K103R/V179D mutations associated with resistance to NNRTIs in HIV-1 CRF65_cpx. Our findings highlight the contribution of polymorphic mutations to drug resistance and underscore the challenges in treating patients harboring CRF65_cpx strains.

Brief Report: Onward Transmission of Multiple HIV-1 Unique Recombinant Forms Among Men Who Have Sex With Men in Beijing, China

BACKGROUND

Unique recombinant forms (URFs) were generated in dually infected or multiply infected individuals, and some of URFs can be transmitted to many people resulting in the emergence of circulating recombinant forms (CRFs). We examined whether there was evidence for onward transmission of multiple URFs among men who have sex with men (MSM) in Beijing.

METHODS

A total of 146 MSM subjects with acute/early HIV-1 infection were recruited from the Beijing PRIMO clinical cohort between September 2010 and July 2012. HIV-1 full-length gag and partial pol, env genes were amplified and sequenced separately. Phylogenetic analysis and recombination analysis were performed to determine the viral genotypes. Single genome amplification and direct sequencing were used to confirm onward transmission of URFs.

RESULTS

CRF01_AE was the most common genotype (51.9%), followed by CRF07_BC (23.0%), subtype B (14.8%), URFs (7.4%), CRF65_cpx (2.2%), and CRF55_01B (0.7%). Multiple forms of URFs were identified, including CRF01_AE/BC, CRF01_AE/B, and CRF01_AE/C. Nine of the 10 individuals harboring URFs were infected by onward transmission of URFs. The remaining one individual was coinfected with CRF01_AE and CRF07_BC variants.

CONCLUSIONS

We introduced a new method to provide evidence for onward transmission of URF strains by examining the absence of intersubtype coinfection among early infected individuals. Onward transmission of multiple URFs was found among MSM in Beijing, China. Our findings call for a program of continuous molecular surveillance and have implications to prevention programs among MSM in China.

Natural presence of V179E and rising prevalence of E138G in HIV-1 reverse transcriptase in CRF55_01B viruses

There is increasing evidence that naturally occurring HIV-1 genetic diversity can have an impact on drug resistance. Recently, our previous study has demonstrated the natural presence of the V179D and K103R/V179D mutations associated with resistance to nonnucleoside reverse transcriptase inhibitors (NNRTIs) in HIV-1 CRF65_cpx strains. The aim of this study is to investigate the presence of natural drug-resistance mutations (DRMs) in other HIV-1 subtypes or CRFs circulating in China. A total of 14,403 pol sequences from China were retrieved from the Los Alamos HIV Sequence Database, 10,041 of which were treatment naïve and presented substantial genetic diversity. Besides the natural presence of V179D and K103R/V179D in CRF65_cpx, the natural presence of V179E was found in CRF55_01B. In all but one of the 228 patients infected with CRF55_01B, NNRTI resistance mutation V179E was present and the combination of V179E and E138G was detected in 14 treatment-naïve patients, with a rate of 6.2%. A significant trend for increasing prevalence of E138G mutation in CRF55_01B strains over time was observed (p < .001). Phylogenetic analysis was conducted to clarify the epidemiological relationship of CRF55_01B strains. Most of the sequences containing E138G mutation scattered in the big CRF55_01B cluster, which indicated the rising prevalence of E138G was mainly due to multiple mutation events rather than local transmission clusters of a particular variant containing E138G mutation. Our findings highlight the importance of molecular surveillance of CRF55_01B strains and the urgent need for implementation of effective preventive measures to reduce the transmission of CRF55_01B.

Identification of a Novel HIV-1 Unique Recombinant Form Comprising CRF01_AE, Subtype B', and CRF65_cpx Among Men Who Have Sex with Men in Jilin, China

The current HIV-1 epidemic in China is featured by diverse subtypes and continual emergence of new recombinant viruses. This study identified a novel unique recombinant form (URF), JL16013, among men who have sex with men (MSM) in Jilin, China. The JL16013 virus was different from all known subtypes and set up a distinct branch on the phylogenetic tree. This virus had a CRF01_AE backbone with two subtype B' fragments and one CRF65_cpx fragment inserted into gag, pol, env, and nef regions, suggesting that this novel URF might have originated from the CRF01_AE, subtype B', and CRF65_cpx viruses that were cocirculating in Jilin province. This was the first report of the CRF01_AE/B'/CRF65_cpx recombinant in China. Identification of this URF indicated the severity and complexity of the HIV-1 epidemic among MSM in Jilin province. Timely surveillance of new HIV-1 infections and new recombinants among the MSM population is urgently required.

Identification of a New HIV-1 Circulating Recombinant Form CRF65_cpx Strain in Jilin, China

This study reported a new HIV-1 circulating recombinant form CRF65_cpx virus isolated from a man who have sex with men (MSM) in Jilin, China. The near full-length genome of this virus was composed of 14 mosaic gene fragments derived from CRF01_AE, subtype B' (Thai B) and subtype C, highly similar to the CRF65_cpx viruses recently identified in Yunnan and Anhui of China. Phylogenetic tree analysis suggested that this CRF65_cpx strain was not generated among MSM in Jilin, but originated in southern regions of China and spread to Jilin by MSM population. The emergence of CRF65_cpx in Jilin indicated HIV-1 epidemic in this area was more and more complicated and the MSM population has become the important source for generation of new recombinant viruses. Real-time surveillance of new HIV-1 infections among MSM population is quite required.

Geographically-stratified HIV-1 group M pol subtype and circulating recombinant form sequences

Accurate classification of HIV-1 group M lineages, henceforth referred to as subtyping, is essential for understanding global HIV-1 molecular epidemiology. Because most HIV-1 sequencing is done for genotypic resistance testing pol gene, we sought to develop a set of geographically-stratified pol sequences that represent HIV-1 group M sequence diversity. Representative pol sequences differ from representative complete genome sequences because not all CRFs have pol recombination points and because complete genome sequences may not faithfully reflect HIV-1 pol diversity. We developed a software pipeline that compiled 6,034 one-per-person complete HIV-1 pol sequences annotated by country and year belonging to 11 pure subtypes and 70 CRFs and selected a set of sequences whose average distance to the remaining sequences is minimized for each subtype/CRF and country to generate a Geographically-Stratified set of 716 Pol Subtype/CRF (GSPS) reference sequences. We provide extensive data on pol diversity within each subtype/CRF and country combination. The GSPS reference set will also be useful for HIV-1 pol subtyping.

Genetic Characterization of a Unique Recombinant Strain Identified in Yunnan with Genome Comprising B and C

Since the first identification of HIV-1 outbreak in Dehong, Yunnan province has been the epidemic center of HIV in China. Owing to the special geographic location and the frequent population mobility, Yunnan province contained complex HIV subtype distribution. Many new circulating recombinant forms (CRFs) and unique recombinant forms (URFs) have been found in recent years. In this study, a unique HIV-1 recombinant strain genome (YN10134) was characterized from an HIV-positive female in Yunnan, China. This virus genome had a complex intersubtype recombinant structure with eight breakpoints, composed of subtypes B and C. Although the sequence had a similar breakpoint with CRF07_BC in the start position in Env, the phylogenetic analysis showed that the segment was not originated from CRF07_BC. The identification of the URF indicated the severity of the HIV epidemic in Yunnan province and the urgent need for epidemiological surveillance of the new recombination.