Precise mapping of recombination breakpoints suggests a common parent of two BC recombinant HIV type 1 strains circulating in China

Distinct Rates and Transmission Patterns of Major HIV-1 Subtypes among Men who Have Sex with Men in Guangxi, China

The diversity and transmission patterns of major HIV-1 subtypes among MSM population in Guangxi remains unknown. Understanding the characteristics is crucial for effective intervention strategies. Between 2016 and 2021, we recruited individuals newly diagnosed with HIV-1 from MSM population in Guangxi. HIV-1 pol region was amplified and sequenced, and constructed molecular network, assessed clustering rate, cluster growth rate, spatial clustering, and calculating the basic reproductive number (R0) based on sequences data. We identified 16 prevalent HIV-1 subtypes among Guangxi MSM, with CRF07_BC (53.1%), CRF01_AE (26.23%), and CRF55_01B (12.96%) predominating. In the network, 618 individuals (66.17%) formed 59 clusters. Factors contributing to clustering included age < 30 years (AOR = 1.35), unmarried status (AOR = 1.67), CRF07_BC subtype (AOR = 3.21), and high viral load (AOR = 1.43). CRF07_BC had a higher likelihood of forming larger clusters and having higher degree than CRF01_AE and CRF55_01B. Notably, CRF07_BC has higher cluster growth rate and higher basic reproductive number than CRF01_AE and CRF55_01B. Our findings underscore CRF07_BC as a prominent driver of HIV-1 spread among Guangxi's MSM population, highlighting the viability of targeted interventions directed at specific subtypes and super clusters to control HIV-1 transmission within this population.

Geographic Transmission and Epidemic History of HIV-1 CRF01_AE, CRF07_BC, and HCV Subtype-6w among Taiwanese Persons Who Inject Drugs

Persons who inject drugs (PWID) and their risk-related behaviors (e.g., unprotected sex and sharing needles/syringes/other injection equipment) have caused severe public health problems, especially in the rapid spread of HIV-1 and HCV. Here, we reconstructed the epidemic history of HIV-1 circulating recombinant form (CRF) 01_AE, CRF07_BC, and HCV subtype-6w among Taiwanese PWID. The timescales were estimated using phylogenetic and Bayesian coalescent analyses. The results revealed that CRF01_AE started to circulate in the Taiwanese PWID population in central Taiwan at 1992.5 (95% credible region: 1988.8–1995.9) and spread to other regions of Taiwan, while CRF07_BC was first identified in southern Taiwan at 2000.0 (95% CR: 1997.8–2002.2) and then spread northward to central-northern Taiwan. All HCV-6 strains were from Asia (that is, China, Myanmar, Taiwan, and Vietnam) and originated in 1928.1 (95% CR: 1890.2–1966.0). Furthermore, subtype-6w isolates from different regions of Taiwan appeared to share a common source that existed in the mid-1990s (95% CR: 1985.0–2001.8) or thereabouts. The routes of drug trafficking and the resulting high prevalence of HIV-1/HCV co-infections among PWID might have contributed to the virus transmission and promoted its spread worldwide. Long-term monitoring and policy implementation in at-risk populations would be useful for disease control.

Multiple CRF01_AE/CRF07_BC Recombinants Enhanced the HIV-1 Epidemic Complexity Among MSM in Shenyang City, Northeast China

The transmission of Unique Recombinant Forms (URFs) has complicated the molecular epidemic of HIV-1. This increasing genetic diversity has implications for prevention surveillance, diagnosis, and vaccine design. In this study, we characterized the HIV-1 URFs from 135 newly diagnosed HIV-1 infected cases between 2016 and 2020 in Shenyang, northeast China and analyzed the evolutionary relationship of them by phylogenetic and recombination approaches. Among 135 URFs, we found that the CRF01_AE/CRF07_BC recombinants were the most common (81.5%, 110/135), followed by CRF01_AE/B (11.9%, 16/135), B/C (3.7%, 5/135), and others (3.0%, 4/135). 94.8% (128/135) of patients infected by URFs were through homosexual contact. Among 110 URFs_0107, 60 (54.5%) formed 11 subclusters (branch support value = 1) and shared the consistent recombination structure, respectively. Four subclusters have caused small-scale spread among different high-risk populations. Although the recombination structures of URFs_0107 are various, the hotspots of recombinants gathered between position 2,508 and 2,627 (relative to the HXB2 position). Moreover, the CRF07_BC and CRF01AE fragments of URFs_0107 were mainly derived from the MSM population. In brief, our results reveal the complex recombinant modes and the high transmission risk of URFs_0107, which calls for more attention on the new URFs_0107 monitoring and strict control in the areas led by homosexual transmission route.

First complete-genome documentation of HIV-1 intersubtype superinfection with transmissions of diverse recombinants over time to five recipients

Human immunodeficiency virus type 1 (HIV-1) recombinants in the world are believed to be generated through recombination between distinct HIV-1 strains among coinfection or superinfection cases. However, direct evidence to support transmission of HIV-1 recombinants from a coinfected/superinfected donor to putative recipient is lacking. Here, we report on the origin and evolutionary relationship between a set of recombinants from a CRF01_AE/CRF07_BC superinfected putative donor and diverse CRF01_AE/CRF07_BC recombinants from five putative recipients. Interviews on sociodemographic characteristics and sexual behaviors for these six HIV-1-infected men who have sex with men showed that they had similar ways of partner seeking: online dating sites and social circles. Phylogenetic and recombination analyses demonstrated that the near-full-length genome sequences from six patients formed a monophyletic cluster different from known HIV-1 genotypes in maximum likelihood phylogenetic trees, were all composed of CRF01_AE and CRF07_BC fragments with two common breakpoints on env, and shared 4-7 breakpoints with each other. Moreover, 3' half-genomes of recombinant strains from five recipients had identical/similar recombinant structures with strains at longitudinal samples from the superinfected donor. Recombinants from the donor were paraphyletic, whereas five recipients were monophyletic or polyphyletic in the maximum clade credibility tree. Bayesian analyses confirmed that the estimated time to the most recent common ancestor (tMRCA) of CRF01_AE and CRF07_BC strains of the donor was 2009.2 and 2010.7, respectively, and all were earlier than the emergence of recombinants from five recipients. Our results demonstrated that the closely related unique recombinant forms of HIV-1 might be the descendent of a series of recombinants generated gradually in a superinfected patient. This finding highlights the importance of early initiation of antiretroviral therapy as well as tracing and testing of partners in patients with multiple HIV-1 infection.

HIV drug resistance and HIV transmission risk factors among newly diagnosed individuals in Southwest China

Background

The widespread use of antiretroviral therapy (ART) has resulted in the development of transmitted drug resistance (TDR), which reduces ART efficacy. We explored TDR prevalence and its associated risk factors in newly diagnosed individuals in Guangxi.

Methods

We enrolled 1324 participants who were newly diagnosed with HIV-1 and had not received ART at voluntary counselling and testing centres (VCT) in Guangxi, China, who had not received ART. Phylogenetic relationship, transmission cluster, and genotypic drug resistance analyses were performed using HIV-1 pol sequences. We analysed the association of demographic and virological factors with TDR.

Results

In total, 1151 sequences were sequenced successfully, of which 83 (7.21%) showed evidence of TDR. Multivariate logistic regression analysis revealed that there was significant difference between the prevalence of TDR and unmarried status (adjusted odds ratio (aOR) = 2.41, 95% CI: 1.23–4.71), and CRF08_BC subtype (aOR = 2.03, 95% CI: 1.13–3.64). Most cases of TDR were related to resistance to non-nucleoside reverse transcriptase inhibitors (4.87%) and V179E was the most common mutation detected. We identified a total of 119 HIV transmission clusters (n = 585, 50.8%), of which 18 (15.1%) clusters showed evidence of TDR (36, 41.86%). Three clusters were identified that included drug-resistant individuals having a transmission relationship with each other. The following parameters were associated with TDR transmission risk: Unmarried status, educational level of junior high school or below, and CRF08_BC subtype may be a risk of the transmission of TDR.

Conclusions

Our findings indicated that moderate TDR prevalence and highlighted the importance of continuous TDR monitoring and designing of strategies for TDR mitigation.

Patterns and risk of HIV-1 transmission network among men who have sex with men in Guangxi, China

The prevalence of HIV-1 in Guangxi is very high, and the rate of HIV-1 infection among men who have sex with men (MSM) has been increasing. Therefore, it is necessary to explore the patterns and risk factors of HIV transmission in Guangxi. For this purpose, individuals diagnosed with HIV-1 during 2013-2018 in Guangxi were recruited. Phylogenetic relationship, transmission clusters, and genotypic drug resistance analyses were performed based on HIV-1 pol sequences. Related factors were analysed to assess for their association with HIV-1 transmission. CRF07_BC (50.4%) and CRF01_AE (33.4%) were found to be the predominant subtypes. The analysed 1633 sequences (50.15%, Guangxi; 49.85%, other provinces) were segregated into 80 clusters (size per cluster, 2-704). We found that 75.3% of the individuals were in three clusters (size ˃ 100), and 73.8% were high-risk spreaders (links ≥ 4). Infection time, marital status, and subtype were significantly associated with HIV-1 transmission. Additionally, 80.2% of recent infections were linked to long-term infections, and 46.2% were linked to other provinces. A low level of transmitted drug resistance was detected (4.8%). Our findings indicated superclusters and high-risk HIV-1 spreaders among the MSM in Guangxi. Effective strategies blocking the route of transmission should be developed.

The evolutionary and transmission characteristic of HIV-1 CRF07_BC in Nanjing, Jiangsu

To understand the epidemiology, evolutionary and transmission characteristics of HIV-1 CRF07_BC in Nanjing, China. One hundred and fifty-nine patients with HIV-1 CRF07_BC were recruited. DNA sequencing, phylogenetic analysis, and molecular transmission cluster analysis were conducted to determine the molecular epidemiology and evolutionary characteristics. Of these HIV-1-infected patients, 95.6% were male, and men who sex with men (76.7%) were the main transmission route. Only 34.0% of these cases were born in Nanjing, and most of them (64.8%) reported having multiple sex partners in the last 6 months. The maximum likelihood phylogenetic analyses of HIV-1 CRF07_BC revealed two lineages. Overall, 67.3% of Nanjing sequences were connected to at least one other individual distributed in 11 clusters, and the average degree was 21.2 with range (1-178). The clustered patients were more likely to be male. The time to a most recent common ancestor for the early HIV-1 CRF07_BC circulating in Nanjing was estimated to be 1998.71[1997.36-2001.07]. The mean estimated evolutionary rate for the epidemic cluster was slightly lower at 2.38[2.12-2.65]  ×  10-3 per site per year with the relaxed exponential clock model. HIV-1 CRF07_BC was transmitted into Nanjing more than 20 years ago from Yunnan and has become one of the most predominant subtypes with a higher evolutionary rate than before.

HIV-1 Transmissions Among Recently Infected Individuals in Southwest China are Predominantly Derived from Circulating Local Strains

Although the Guangxi region accounts for 10% of all HIV-1 cases new reported in 2011 in China, the sources of the transmitted HIV-1 strains are virtually unknown. To determine the extent to which recent HIV infections were derived from already circulating local strains as opposed to recently introduced strains, we performed a cross-sectional molecular epidemiological investigation of recent infections across Guangxi during 2012-2013. HIV-1 nucleotide sequences were amplified and sequenced. Phylogenetic analyses of pol gene regions were used to determine HIV-1 transmission source strains. Based on 229 sequences generated, the subtype/CRF distribution was as follows: CRF01_AE (61.1%), CRF07_BC (18.8%), CRF08_BC (16.6%), CRF55_01B (3.1%), and subtype B' (0.4%). In total, 213 of 229 (93.0%) sequenced transmission strains were derived from already-circulating local strains. Multivariate logistic regression analysis showed that only an age of 18-25 years was significantly associated with transmission from outside Guangxi (compared to >25 years, AOR: 5.15, 95% CI: 1.18-22.48, p < 0.01). This is the first study to use a Bayesian discrete phylogeographic approach to analyze transmission source strains in China. Our results provide useful data for designing evidence-based prevention strategies and methods for combating the rapid spread of sexually transmitted HIV in Guangxi.

Profiling the neutralizing antibody response in chronically HIV-1 CRF07_BC-infected intravenous drug users naïve to antiretroviral therapy

Characterizing neutralizing antibody (NAb) responses in individuals infected with diverse HIV-1 strains is necessary to reveal the novel targets for regional preventive and therapeutic strategies development. We evaluated the prevalence, breadth, and potency of NAb responses in 98 CRF07_BC-infected individuals using a large, multi-subtype panel of 30 tier 2-3 Env-pseudotyped viruses. Furthermore, we compared the neutralization pattern of CRF07_BC-infected people with that of subtype B’-infected individuals in China. Of the 98 plasma samples tested, 18% neutralized more than 80% of viruses in the panel, and 53% neutralized more than 50%, suggesting the presence of broadly NAbs in these individuals. A preferential intra-subtype neutralization of CRF07_BC was found. Notably, CRF07_BC-infected individuals generated higher neutralization titers against intra-subtype viruses than subtype B’-infected individuals with longer infection length. However, subtype B’-infected individuals mounted broader neutralization responses against inter-subtype viruses than CRF07_BC infection with shorter infection time, indicating the transition from narrow autologous to broad heterologous neutralization over time. Neutralization activity of the top six plasmas from each cohort was attributable to IgG fraction, and half of them developed CD4 binding site antibody reactivity. Heatmap analysis identified three statistically robust clusters of plasmas that offer valuable resources for further in-depth virological and immunological study.

Accumulation of MxB/Mx2-resistant HIV-1 Capsid Variants During Expansion of the HIV-1 Epidemic in Human Populations

Recent studies have identified human myxovirus resistance protein 2 (MxB or Mx2) as an interferon induced inhibitor of HIV-1 replication. However, whether HIV-1 can overcome MxB restriction without compromise of viral fitness has been undefined. Here, we have discovered that naturally occurring capsid (CA) variants can render HIV-1 resistant to the activity of MxB without losing viral infectivity or the ability to escape from interferon induction. Moreover, these MxB resistant HIV-1 variants do not lose MxB recognition. Surprisingly, MxB resistant CA variants are most commonly found in the Clade C HIV-1 that is the most rapidly expanding Clade throughout the world. Accumulation of MxB resistant mutations is also observed during HIV-1 spreading in human populations. These findings support a potential role for MxB as a selective force during HIV-1 transmission and evolution.

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Naturally occurring HIV-1capsid variants confer HIV-1 resistance to MxB.

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MxB-resistant capsid A116 is a major variant in HIV-1 Subtype C.

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HIV-1 capsid variant A116 is accumulating during expansion of the HIV-1 epidemic in China.

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MxB-resistant HIV-1 capsid variants maintain interaction with MxB.

Interferon (IFN) is a key component of the innate immune response to exogenous pathogens. Human MxB has been identified as a potent inhibitor of HIV-1 induced by interferon. How HIV-1 escapes from MxB inhibition is not clear. This study demonstrates that capsid variations detected in primary HIV-1 isolates can mediate MxB resistance. MxB resistant capsid mutations can accumulate during HIV-1 transmission and are mostly enriched in Clade C HIV-1 that is the most rapidly expanding Clade throughout the world. Identification of the critical role of these capsid mutations in overcoming a host restriction factor may provide opportunities for the development of therapeutic interventions.

Geographic origin and evolutionary history of China's two predominant HIV-1 circulating recombinant forms, CRF07_BC and CRF08_BC

To determine the origin and evolutionary history of two predominant and closely-related circulating recombinant forms (CRF07_BC and CRF08_BC), recombinant structures and phylogenies of 7 unique recombinant forms comprised of subtypes of B’ (Thai B linage) and C (designated URFs_BC) from archival specimens of injection drug users (IDUs) collected in 1996 to 1998 from western Yunnan and 4 circulating recombinant forms with B’/C recombinants recently identified (designated nCRFs_BC) in China were compared with those of CRF07_BC and CRF08_BC. The results showed that 5 of 7 URFs_BC and all the nCRFs_BC shared recombination breakpoints with CRF07_BC and/or CRF08_BC. Yunnan URFs_BC consistently occupied the basal branch positions compared with CRF07_BC, CRF08_BC, and nCRFs_BC in phylogenetic trees. The estimated most recent common ancestors (tMRCA) for Yunnan URFs_BC were from ~1987, approximately half a decade earlier than those for CRF07_BC (~1994) and CRF08_BC (~1992). Discrete phylogeographic and spatial diffusion analysis revealed that both CRF07_BC and CRF08 BC came from western Yunnan in the early 1990s. Our results provide compelling evidence for western Yunnan as the geographic origin of CRF07_BC and CRF08_BC, which emerged from a swarm of URFs_BC by a series of recombination events in western Yunnan in the early 1990s.

Comprehensive Characterization of the Transmitted/Founder env Genes From a Single MSM Cohort in China

BACKGROUND

The men having sex with men (MSM) population has become one of the major risk groups for HIV-1 infection in China. However, the epidemiological patterns, function of the env genes, and autologous and heterologous neutralization activity in the same MSM population have not been systematically characterized.

METHODS

The env gene sequences were obtained by the single genome amplification. The time to the most recent common ancestor was estimated for each genotype using the Bayesian Markov Chain Monte Carlo approach. Coreceptor usage was determined in NP-2 cells. Neutralization was analyzed using Env pseudoviruses in TZM-bl cells.

RESULTS

We have obtained 547 full-length env gene sequences by single genome amplification from 30 acute/early HIV-1--infected individuals in the Beijing MSM cohort. Three genotypes (subtype B, CRF01_AE, and CRF07_BC) were identified and 20% of the individuals were infected with multiple transmitted/founder (T/F) viruses. The tight clusters of the MSM sequences regardless of geographic origins indicated nearly exclusive transmission within the MSM population and limited number of introductions. The time to the most recent common ancestor for each genotype was 10-15 years after each was first introduced in China. Disparate preferences for coreceptor usages among 3 genotypes might lead to the changes in percentage of different genotypes in the MSM population over time. The genotype-matched and genotype-mismatched neutralization activity varied among the 3 genotypes.

CONCLUSIONS

The identification of unique characteristics for transmission, coreceptor usage, neutralization profile, and epidemic patterns of HIV-1 is critical for the better understanding of transmission mechanisms, development of preventive strategies, and evaluation of vaccine efficacy in the MSM population in China.

Genetic Characterization of a Novel HIV-1 Circulating Recombinant Form (CRF74_01B) Identified among Intravenous Drug Users in Malaysia: Recombination History and Phylogenetic Linkage with Previously Defined Recombinant Lineages

In many parts of Southeast Asia, the HIV-1 epidemic has been driven by the sharing of needles and equipment among intravenous drug users (IDUs). Over the last few decades, many studies have proven time and again that the diversity of HIV-1 epidemics can often be linked to the route of infection transmission. That said, the diversity and complexity of HIV-1 molecular epidemics in the region have been increasing at an alarming rate, due in part to the high tendency of the viral RNA to recombine. This scenario was exemplified by the discovery of numerous circulating recombinant forms (CRFs), especially in Thailand and Malaysia. In this study, we characterized a novel CRF designated CRF74_01B, which was identified in six epidemiologically unlinked IDUs in Kuala Lumpur, Malaysia. The near-full length genomes were composed of CRF01_AE and subtype B', with eight breakpoints dispersed in the gag-pol and nef regions. Remarkably, this CRF shared four and two recombination hotspots with the previously described CRF33_01B and the less prevalent CRF53_01B, respectively. Genealogy-based Bayesian phylogenetic analysis of CRF74_01B genomic regions showed that it is closely related to both CRF33_01B and CRF53_01B. This observation suggests that CRF74_01B was probably a direct descendent from specific lineages of CRF33_01B, CRF53_01B and subtype Bʹ that could have emerged in the mid-1990s. Additionally, it illustrated the active recombination processes between prevalent HIV-1 subtypes and recombinants in Malaysia. In summary, we report a novel HIV-1 genotype designated CRF74_01B among IDUs in Kuala Lumpur, Malaysia. The characterization of the novel CRF74_01B is of considerable significance towards the understanding of the genetic diversity and population dynamics of HIV-1 circulating in the region.

HIV-1 genetic characteristics and transmitted drug resistance among men who have sex with men in Kunming, China

BACKGROUND

Yunnan has been severely affected by HIV/AIDS in China. Recently, the reported prevalence of HIV-1 among men who have sex with men (MSM) in Yunnan was high in China. To monitor dynamic HIV-1 epidemic among Yunnan MSM, HIV-1 genetic characteristics and transmitted drug resistance (TDR) were investigated.

METHODS

Blood samples from 131 newly HIV-1 diagnosed MSM were continuously collected at fixed sites from January 2010 to December 2012 in Kunming City, Yunnan Province. Partial gag, pol and env genes were sequenced. Phylogenetic, evolutionary and genotypic drug resistance analyses were performed.

RESULTS

Multiple genotypes were identified among MSM in Kunming, including CRF01_AE (64.9%), CRF07_BC (25.2%), unique recombinant forms (URFs, 5.3%), subtype B (3.1%) and CRF08_BC (1.5%). CRF01_AE and CRF07_BC were the predominant strains. The mean of genetic distance within CRF01_AE were larger than that within CRF07_BC. The estimated introducing time of CRF01_AE in Yunnan MSM (1996.9) is earlier than that of CRF07_BC (2002.8). In this study, subtype B was first identified in Yunnan MSM. CRF08_BC seems to be the distinctive strain in Yunnan MSM, which was seldom found among MSM outside Yunnan. The proportion of URFs increased, which further contributed to genetic diversity among MSM. Strikingly, genetic relatedness was found among these strains with MSM isolates from multiple provinces, which suggested that a nationwide transmission network may exist. TDR-associated mutations were identified in 4.6% individuals. The multivariate analysis revealed that non-native MSM and divorced/widowed MSM were independently associated with a higher TDR rate.

CONCLUSION

This work revealed diverse HIV-1 genetics, national transmission networks and a baseline level of TDR in MSM. These findings enhance our understanding of the distribution and evolution of HIV-1 in MSM, and are valuable for developing HIV prevention strategies for MSM.

HIV-1 diversity, drug-resistant mutations, and viral evolution among high-risk individuals in phase II HIV vaccine trial sites in southern China

HIV-1 prevalence in Guangxi, China, has been growing since 1996, when the first case was reported. Over half of HIV-1 positive patients in Guangxi Province were injecting drug users (IDUs), possibly because of the province’s location near drug-trafficking routes. Since a phase II HIV vaccine trial is ongoing there, a current characterization of the subtypes of HIV-1 among IDUs in Guangxi would provide critical information for future HIV vaccine trials, as well as further control and prevention of HIV-1 transmission. Thus, we conducted a molecular epidemiological investigation of HIV-1 samples from 2008–2010 among IDUs in multiple cities in Guangxi Province. Our results, based on the gag/pol fragment, indicated a very high proportion (78.47%) of HIV-1 CRF08_BC recombinants, some CRF01_AE (15.38%) recombinants, and a low proportion of CRF07_BC (6.15%) recombinants among the IDUs. The high proportion of CRF08 HIV-1 strains among recent IDUs matches the vaccine candidate constructs. However, future vaccine development should also incorporate CRF01-targeted vaccine candidates. Distinct Env sequence evolution patterns were observed for CRF08_BC and CRF01_AE, indicating that different local selection pressures have been exerted on these two HIV-1 subtypes. Unique drug-resistant mutations were also detected, and our data indicate that HIV treatment programs should consider pre-existing drug-resistant mutations.

Molecular evolution of the HIV-1 Thai epidemic between the time of RV144 immunogen selection to the execution of the vaccine efficacy trial

The RV144 HIV-1 vaccine trial (Thailand, 2003 to 2009), using immunogens genetically matched to the regional epidemic, demonstrated the first evidence of efficacy for an HIV-1 vaccine. Here we studied the molecular evolution of the HIV-1 epidemic from the time of immunogen selection to the execution of the efficacy trial. We studied HIV-1 genetic diversity among 390 volunteers who were deferred from enrollment in RV144 due to preexisting HIV-1 infection using a multiregion hybridization assay, full-genome sequencing, and phylogenetic analyses. The subtype distribution was 91.7% CRF01_AE, 3.5% subtype B, 4.3% B/CRF01_AE recombinants, and 0.5% dual infections. CRF01_AE strains were 31% more diverse than the ones from the 1990s Thai epidemic. Sixty-nine percent of subtype B strains clustered with the cosmopolitan Western B strains. Ninety-three percent of B/CRF01_AE recombinants were unique; recombination breakpoint analysis showed that these strains were highly embedded within the larger network that integrates recombinants from East/Southeast Asia. Compared to Thai sequences from the early 1990s, the distance to the RV144 immunogens increased 52% to 68% for CRF01_AE Env immunogens and 12% to 29% for subtype B immunogens. Forty-three percent to 48% of CRF01_AE sequences differed from the sequence of the vaccine insert in Env variable region 2 positions 169 and 181, which were implicated in vaccine sieve effects in RV144. In conclusion, compared to the molecular picture at the early stages of vaccine development, our results show an overall increase in the genetic complexity of viruses in the Thai epidemic and in the distance to vaccine immunogens, which should be considered at the time of the analysis of the trial results.

Emerging variability in HIV-1 genetics among recently infected individuals in Yunnan, China

Background

Yunnan has the longest endured Human Immunodeficiency Virus-1 (HIV-1) epidemic in China, and the genetic diversity of HIV-1 constitutes an essential characteristic of molecular epidemiology in this region. To obtain a more comprehensive picture of the dynamic changes in Yunnan’s HIV-1 epidemic, a cross-sectional molecular epidemiological investigation was carried out among recently infected individuals.

Methodology/Principal Findings

We sequenced partial gag (HXB2∶781–1861) and env (HXB2∶7002–7541) genes from 308 plasma samples of recently infected patients. With phylogenetic analysis, 130 specimens generated interpretable genotyping data. We found that the circulating genotypes included: CRF08_BC (40.8%), unique recombinant forms (URFs, 27.7%), CRF01_AE (18.5%), CRF07_BC (9.2%), subtype B (2.3%) and C (1.5%). CRF08_BC was the most common genotype, and was predominant in both intravenous drug users (IDUs) and heterosexually transmitted populations. CRF08_BC and CRF07_BC still predominated in eastern Yunnan, but CRF08_BC showed increasing prevalence in western Yunnan. Strikingly, the URFs raised dramatically in most regions of Yunnan. Seven different types of URFs were detected from 12 prefectures, suggesting that complicated and frequent recombination is a salient feature of Yunnan’s HIV-1 epidemic. Among URFs, two BC clusters with distinctive recombination patterns might be potential new CRF_BCs. CRF01_AE was no longer confined to the prefectures bordering Myanmar, and had spread to the eastern part of Yunnan, especially the capital city of Kunming, with a large number of infections in the transient population. The ratios of the main genotypes showed no statistical differences between infected IDUs and heterosexually transmitted infections.

Conclusions/Significance

The changing patterns of the dominant HIV-1 genotypes in Yunnan indicate the complex evolving dynamic nature of the epidemic. Understanding new trends in molecular epidemiology of HIV-1 infection is critical for adjusting current prevention strategies and vaccine development in Yunnan.

A new migration map of HIV-1 CRF07_BC in China: analysis of sequences from 12 provinces over a decade

BACKGROUND

As one of prevalence HIV-1 strains in IDUs in Asia, the origination and full transmission map of CRF07_BC is of great interested and remains unclear. In the study, we collected 769 CRF07_BC derived sequences (including 45 sequences generated in our laboratory) from 12 provinces in China for reconstructing transmission map. Meanwhile, ample historic epidemic evidences were also reviewed to assist sequences analysis.

METHODOLOGY/PRINCIPAL FINDINGS

In the study, we collected 769 CRF07_BC derived sequences and identified 138 independent sequences from 12 provinces in China for subsequent phylogeographic tree analysis, Bayes Factor test and the estimation of state tMRCA. The analyses demonstrated that CRF07_BC was originated in 1993 in IDU in Yunnan province and then initially spread to Guangxi (eastern neighbor to Yunnan) in 1994, to Xinjiang (northwest) in 1995 and to Sichuan (northern neighbor to Yunnan) in 1996. The subsequent transmissions occurred from Yunnan to Liaoning (northeast) in 1997 and to Jiangsu in 1998. Interestingly, after the early introduction of CRF07_BC into Guangxi, Xinjiang and Sichuan, these three regions served as secondary epicenters for further spreading into Gansu, Ningxia, Qinghai, Beijing and Hunan during 1999-2001. These analyzed results are in accordance with early epidemic investigations.

CONCLUSIONS/SIGNIFICANCE

Our data not just reconstructed the migration map of CRF07_BC, but also firstly revealed the active roles of these secondary epicenters in the dynamic migration of CRF07_BC in China.

Molecular epidemiology of human immunodeficiency virus type 1 in Guangdong province of southern China

Background

Although the outbreak of human immunodeficiency virus type 1 (HIV-1) in Guangdong has been documented for more than a decade, the molecular characteristics of such a regional HIV-1 epidemic remained unknown.

Methodology/Principal Findings

By sequencing of HIV-1 pol/env genes and phylogenetic analysis, we performed a molecular epidemiologic study in a representative subset (n  = 200) of the 508 HIV-1-seropositive individuals followed up at the center for HIV/AIDS care and treatment of Guangzhou Hospital of Infectious Diseases. Of 157 samples (54.1% heterosexual acquired adults, 20.4% needle-sharing drug users, 5.7% receivers of blood transfusion, 1.3% men who have sex with men, and 18.5% remained unknown) with successful sequencing for both pol and env genes, 105 (66.9%) HIV-1 subtype CRF01_AE and 24 (15.3%) CRF07_BC, 9 (5.7%) B’, 5 (3.2%) CRF08_BC, 5 (3.2%) B, 1 (0.6%) C, 3 (1.9%) CRF02_AG, and 5 (3.2%) inter-region recombinants were identified within pol/env sequences. Thirteen (8.3%) samples (3 naïves, 6 and 5 received with antiretroviral treatment [ART] 1–21 weeks and ≥24 weeks respectively) showed mutations conferring resistance to nucleoside/nonnucleoside reverse transcriptase inhibitors or protease inhibitors. Among 63 ART-naïve patients, 3 (4.8%) showed single or multiple drug resistant mutations. Phylogenetic analysis showed 8 small clusters (2–3 sequences/cluster) with only 17 (10.8%) sequences involved.

Conclusion/Significance

This study confirms that sexual transmission with dominant CRF01_AE strain is a major risk for current HIV-1 outbreak in the Guangdong’s general population. The transmission with drug-resistant variants is starting to emerge in this region.

HIV type 1 subtypes based on the pol gene and drug resistance mutations among antiretroviral-naive patients from Guangxi, Southern China

We investigated the distribution of HIV-1 subtypes and the prevalence of HIV-1 drug resistance among HIV-infected antiretroviral-naive patients in Guangxi, southern China. A total of 144 subjects from Liuzhou or Nanning, two cities having the most HIV-infected cases in Guangxi, were enrolled. HIV-1 pol fragments were amplified and sequenced from plasma of all patients. In all, 124 sequences were obtained, with 67 from Liuzhou and 57 from Nanning. All sequences were subtyped by phylogenetic analysis and analyzed for antiretroviral resistance using the HIVdb program. Our data showed that the sequences from Liuzhou were subtyped as CRF01_AE (77.6%), CRF07_BC(20.9%), and BC (1.5%), respectively, and the sequences from Nanning as CRF01_AE (78.9%), CRF08_BC (15.8%), B (3.5%), and C (1.8%), respectively. Of the sequences 11.9% from Liuzhou and 28.1% from Nanning harbored drug resistance-associated mutations, but there were only two sequences with mutations associated with significantly reduced phenotypic susceptibility to antiretroviral drugs.

Near full-length genomic characterization of a HIV type 1 BC recombinant strain from Manipur, India

Genetic complexity of HIV-1 is brought about by recombination between HIV-1 subtypes which leads to the development of epidemiologically significant founder strains. In the present study, the near full-length genome sequence of an HIV-1 isolate from an injecting drug user of Manipur (India) was determined, which evidenced the presence of a novel HIV-1 BC recombinant strain. Near full-length genome was amplified by polymerase chain reaction using primer walking approach. The recombination break points were detected using bootscan and simplot analyses. This isolate exhibited a mosaic structure consisting of subtype C backbone with subtype B insertions at the upstream of pol gene (3026-3259) and the downstream of env gene which spanned till the nef gene (8183-8961). Phylogenetic relationships determined with neighbor-joining trees, revealed that the subtype C sequences clustered with sequences from Indian subtype C HIV-1 strains, and the subtype B sequences clustered with HIV-1 subtype B strains from Thailand. This finding may create a complex scenario of HIV-1 epidemic among the injecting drug users of Manipur in near future.

Phylodynamic inference of infectious diseases caused by HIV, enterovirus 71 and the 2009 swine-origin human influenza virus

The rapidly evolving nature of viruses, particularly RNA viruses, exhibit complex phylodynamic behaviors, accumulating mutations across the genome on a timescale observable by humans. Phylodynamic investigations provide unique and quantitative evolutionary data on the origin, progression in terms of time and space, and epidemic and transmission history of pathogens. This review describes recent phylodynamic conjectures on three distinct categories of human viruses, including HIV, enterovirus 71 and the swine-origin pandemic influenza virus H1N1, which are of enormous importance to public health.

Phylogeographic analyses reveal a crucial role of Xinjiang in HIV-1 CRF07_BC and HCV 3a transmissions in Asia

Background

China faces an increasing prevalence of two HIV-1 circulating recombinant forms (CRFs) 07_BC and 08_BC. Both CRFs_BC were previously demonstrated to originate in Yunnan and spread to Liaoning from Yunnan via injection drug use (IDU) in China. Supposing it is true, we are unable to answer why only CRF07_BC, rather than both CRFs_BC together, was transmitted to Xinjiang.

Methodology/Principal Findings

We investigated the phylogeography of CRF07_BC and CRF08_BC using multiple HIV-1 genomic regions with Bayesian phylogeography method. Phylogenetic reconstructions showed that all CRF07_BC sequences were divided into two clades, Yunnan and Xinjiang, and all strains from other regions of mainland China clustered within the Xinjiang clade. Significant geographic diffusion links of Xinjiang with other regions (including Liaoning, Beijing, Jiangsu and Guangdong) were supported by Bayes factor tests. The temporal dynamics analyses showed that CRF07_BC spread from Xinjiang to Liaoning in 1996.10, and to Jiangsu in 2000.9. The analyses of CRF08_BC not only confirmed the previous conclusion on temporal and spatial dynamics of CRF08_BC, but also indicated that the CRF08_BC strains from Guangdong and Shanghai originated from Yunnan. The analyses of HCV 3a showed that it was introduced into Xinjiang in the early 1980s, and spread from Xinjiang to Yunnan in 1990.10 and to Jiangsu in 1999.2, and further from Yunnan to Guangxi in 1995.3. The temporal and spatial dynamics of HCV 3a were similar to some extent to that of HIV-1 CRF07_BC and/or CRF08_BC, suggesting a possible association in migration patterns between HCV and HIV-1 through IDU. In addition, HCV 3a spread from Xinjiang to Pakistan, implying a drug trafficking route linking them.

Conclusions/Significance

Xinjiang, as the most important transfer station for drug trafficking from Golden Crescent to other regions of China, plays a very crucial role in the transmission of viruses (e.g., HIV-1 and HCV) through IDU in Asia.

Identification and characterization of two new HIV type 1 Unique (B/C) recombinant forms in China

Recombination was most important in the generation of new viral strains and in the increase of HIV diversity. There were more and more new HIV-1 strains. Not only circulating recombinant forms (CRFs) but also unique recombinant forms (URFs) have been reported around the world. CRF07_BC and CRF08_BC were the two predominant CRFs circulated in Yunnan Province, southwest China. In the present study, we identified two new HIV Type 1 unique (B/C) recombinant gorms in Yunnan Province by nucleotide sequencing in two halves of HIV genome. Although the genomic structures of the two B/C recombinants were different from previously identified CRFs (CRF07_BC and CRF08_BC) and URFs in Yunnan Pprovince, they have several common recombination sites with CRF07_BC and CRF08_BC.

RecDraw: a software package for the representation of HIV-1 recombinant structures

The crucial role of recombination in HIV-1 biology is being increasingly recognized. In vitro studies have shown that up to 30 strand-transfer events may occur per viral replication cycle. Thus, recombination may surpass mutation as a major mechanism driving HIV-1 evolution. Currently, recombinant strains comprise 37% of the full-genome HIV-1 sequence database, including sequences representing 47 Circulating Recombinant Forms (CRFs) and more than 250 different Unique Recombinant Forms (URFs). Mapping of recombination breakpoints helps establish relationships among strains that are related by descent, such as CRF07_BC and CRF08_BC in China, and sheds light on their origin and epidemic spread. Additionally, unrelated recombinants sharing common breakpoints may reflect recombination hotspots within the viral genome. Here we present a software tool, RecDraw, for the graphical representation and efficient comparison of recombinant HIV-1 structures and breakpoints. RecDraw is a platform-flexible, Java stand-alone application available through http://www.hivresearch.org/research.php?ServiceID = 5&SubServiceID = 6 .

Rapid identification of human immunodeficiency virus type 1 CRF01_AE and BC recombinants by subtype-specific PCR

A subtype-specific PCR approach is described for the identification of HIV-1 intersubtype CRF01_AE and BC recombinants, the two predominant subtypes in Southern China. Primers were designed based on the env and gag regions of the HIV-1 genome. Nested PCRs with primers targeting the env region were performed to amplify subtype C, CRF01_AE, or BC recombinants. To differentiate BC recombinants from subtype C virus, a BC recombinant specific gag PCR was then performed. In order to identify the CRF07_BC and CRF08_BC recombinant forms, an additional PCR step was included. Four HIV-1 samples of known subtype, 77 samples with unknown-subtype, and 30 HIV-negative control samples were tested by the new assay. The results of this PCR-based subtyping approach were compared with that of a sequence-based phylogenetic analysis. In total, 73 (94.8%) samples were amplified by the subtype-specific PCR reactions, of which 39 were identified as CRF01_AE, 14 as CRF07_BC, and 20 as CRF08_BC. The sensitivity of this assay was 90.7% for the CRF01_AE recombinant and 100% for BC recombinants. The specificity was 100% when used to identify 30 HIV-negative samples. The reproducibility was 93.8% for CRF01_AE, and 100% for BC recombinants. This subtype-specific PCR technique represents a simple, rapid, and low-cost assay for the identification of HIV-1 CRF01_AE and BC recombinants in Southern China.

Reconstructing the epidemic history of HIV-1 circulating recombinant forms CRF07_BC and CRF08_BC in East Asia: the relevance of genetic diversity and phylodynamics for vaccine strategies

HIV-1 CRF07_BC and CRF08_BC are closely related circulating recombinant forms (CRFs) with serious public health consequences in China. The temporal and spatial dynamics of these CRFs were determined by estimating their times of divergence, using phylogenetic and Bayesian coalescent methods. Studies of the timelines of CRF07_BC and CRF08_BC trace the expansion of these strains back their origins to Yunnan province. The present study highlights the relevance of incorporating evolutionary and molecular epidemiological analyses into an in-depth understanding of the genesis of HIV epidemic, providing information for determining regional and global public health policies, including future vaccine strategies.

Near full-length genomic characterization of a novel HIV type 1 subtype B/C recombinant strain from Yunnan, China

Recombination contributes substantially to the genetic diversity of HIV-1, and mosaic strains arise frequently, especially in populations in which multiple subtypes circulate. Yunnan, which borders the "Golden triangle" region of Southeast Asia in the south, was considered as the epicenter of China. B, CRF01_AE, CRF07_BC, and CRF08_BC are all currently involved in the HIV-1 epidemiology in the area, which suggested the possible emergence of a new recombination. This study presented a near full-length genomic analysis of a novel HIV-1 recombination involving B and C. Different from the reported CRF07_BC and CRF08_BC, the new recombination revealed more breakpoints. This is the first report of a novel recombination involving subtype B and C in Yunnan, China. More work is needed to determine the epidemiologic significance of the new recombination.

Distinct circulating recombinant HIV-1 strains among injecting drug users and sex workers in Afghanistan

Little information is available regarding a circulating HIV genotype among high-risk groups in Afghanistan; we describe HIV genotypes among injecting drug users (IDUs) and sex workers (SWs) in four Afghan cities. Participants completed behavioral questionnaires and HIV testing. Western blot-confirmed specimens had peripheral mononuclear blood cells isolated for genotyping. Analysis of recombinants was done by bootscanning and manual sequence alignment. The single SW sample harbored a CRF01_AE strain. Of 10 IDUs available for analysis, all were CRF35_AD and from Hirat. Analyzed subregions (gag p17 and env C1-C5) revealed close homology between the Hirat specimens. Three distinct subclusters comprising two or three strains were identified, whereas two other strains were generally equidistant from previously identified Kabul strains. Results suggest that the nascent HIV epidemic among IDUs in Hirat is largely, if not entirely, subtype CRF35_AD, and the close homology suggests recent infection; harm reduction should be supported to avert further transmission.

Distribution of CCR5-Delta32, CCR2-64I, SDF1-3'A, CX3CR1-249I, and CX3CR1-280M in Chinese populations

Polymorphisms of CCR5, CCR2, SDF, and CX3CR1 were reported to be involved in HIV-1 infection or the development of disease progression to AIDS. Cohort studies showed that CCR5-Delta32, SDF1-3'A, and CCR2-64I were protective, which could provide resistance to HIV-1 infection or delay disease progression, although the effect of SDF1-3'A homozygosity in the later stage of progression to AIDS was still controversial. The two SNPs of CX3CR1-249I and 280M were independent risk factors, which could accelerate the progression to AIDS. In this study, we surveyed the frequency distributions of the five alleles in Chinese populations using PCR and PCR-RFLP. We found that the frequencies of the alleles varied substantially from population to population. We also observed that there was a large discrepancy between these alleles among populations of the north and south. Populations in the same language-speaking family or with the same origin shared similar allele distributions. Furthermore, genotype distributions were found to be in accordance with Hardy-Weinberg equilibrium and a significant linkage disequilibrium was observed between 249I and 280M. The comprehensive genotype analysis of the three-locus CCR5-Delta32, CCR2-64I, SDF1-3'A, and CX3CR1-249I-280M haplotypes for the first time provides host genetic information for future studies of HIV infection and disease progression in Chinese populations.

Temporal and spatial dynamics of human immunodeficiency virus type 1 circulating recombinant forms 08_BC and 07_BC in Asia

Human immunodeficiency virus type 1 (HIV-1) CRF08_BC and CRF07_BC are two major recombinants descended from subtypes B' and C. Despite their massive epidemic impact in China, their migration patterns and divergence times remain unknown. Phylogenetic and population genetic analyses were performed on 228 HIV-1 sequences representing CRF08_BC, CRF07_BC, and subtype C strains from different locations across China, India, and Myanmar. Genome-specific rates of evolution and divergence times were estimated using a Bayesian Markov chain Monte Carlo framework under various evolutionary models. CRF08_BC originated in 1990.3 (95% credible region [CR], 1988.6 to 1991.9) in Yunnan province before spreading to Guangxi (south) and Liaoning (northeast) around 1995. Inside Guangxi region, the eastward expansion of CRF08_BC continued from Baise city (west) to Binyang (central) between 1997 and 1998 and later spread into Pingxiang around 1999 in the south, mainly through injecting drug users. Additionally, CRF07_BC diverged from its common ancestor in 1993.3 (95% CR, 1991.2 to 1995.2) before crossing the border into southern Taiwan in late 1990s. Phylogenetic analysis indicates that both CRF08_BC and CRF07_BC can trace their origins to Yunnan. The parental Indian subtype C lineage likely entered China around 1981.2 (95% CR, 1976.7 to 1985.9). Using a multiple unlinked locus model, we also showed that the dates of divergence calculated in this study may not be significantly affected by intrasubtype recombination among different lineages. This is the first phylodynamic study depicting the spatiotemporal dynamics of HIV/AIDS in East Asia.

Dynamic analysis of genetic diversity of gag and env regions of HIV-1 CRF07_BC recombinant in intravenous drug users in Xinjiang Uvghur Autonomous Region, China

The aim of this study was to investigate the genetic variation of HIV-1 CRF07_BC, the most prevalent circulating strain in intravenous drug users (IDUs) in China. We studied the diversity in the C2-V5 region of the HIV-1 env gene and in the p17-p24 region of the HIV-1 gag gene from the same samples in 12 IDUs who were divided into two groups according to the length of infection time. Two IDUs were longitudinally monitored from the time of seroconversion for 2-2.5 years. The viral divergence from the founder strain and the viral population diversity between sequential time points were analyzed in two men. The data show that the divergence of the env gene is higher than that of gag in general, while the diversity of the gag gene is sometimes higher than that of env during the course of HIV evolution. In addition, env and gag gene diversity increased over time. The observed patterns and associations may enhance our understanding of HIV-1 evolution.

Analysis of putative N-linked glycosylation sites and variable region of envelope HIV-1 CRF07_BC recombinant in intravenous drug users in Xinjiang Autonomous Region, China

To investigate more closely the determinants of transmission and escape in HIV-1 internal proteins, we analyzed the characterization of putative N-linked glycosylation sites (PNGSs) and the variable loop of CRF07_BC recombinant human immunodeficiency virus type 1 (HIV-1), isolated from intravenous drug users (IDUs). We studied the characterization of PNGSs and the variable loop in the C1-C5 and V1-V4 regions of the HIV-1 env gene in 12 intravenous drug users (IDUs) who were divided into two groups according to the length of infection time. In addition, two IDUs were longitudinally monitored from the time of seroconversion for 1.5 and 2.5 years. The longitudinal characterization within the individuals on PNGSs and the variable loop in the C1-C5 and V1-V4 region were also observed. Based on the above analysis, we found that PNGSs and the variable loop appeared to increase over time within IDU transmission of CRF07_BC recombinant HIV-1. We argue that limited PNGSs and the length of variable loops may be involved in selective transmission and escape.

Evidence of a novel B/C recombinant exhibiting unique breakpoints of near full-length HIV type 1 genome from Northeastern India

Despite the predominance of the HIV-1 clade C in India, the presence of other subtypes and recombinants has been reported. Here we report the identification of a novel HIV-1 B/C recombinant isolated from Northeast India and characterized near full length genome of the recombinant virus. Bootscan analysis of the nearly full-length genome showed a unique mosaic structure consisting of a subtype B backbone with three subtype C genome insertions. Breakpoint analyses revealed insertion of fragments belonging to subtype C at positions 1853-2223 in gag and 3025-3759 and 3998-5073 in pol. Phylogenetic analysis revealed that the segments of subtype B clustered with sequences of subtype B viruses reported from Thailand whereas segments of subtype C clustered with sequences of subtype C viruses reported from India. We report the mosaic structure that is distinct to HIV-1 B/C recombinant viruses reported to date.

Chronology of the HIV-1 CRF07_BC expansion in East Asia

The HIV-1 epidemic among injecting drug users (IDU) in Taiwan is caused primarily by CRF07_BC infections. Evolutionary analyses, which utilize outgroup reference strains from northwestern China (Xinjiang), reveal that CRF07_BC was introduced into southern Taiwan in 1998-2001 and spread to central-northern Taiwan in 2001-2003, causing the largest HIV/AIDS epidemic in Taiwan. The separate introduction of CRF07_BC into Xinjiang occurred in 1992-1995. This study illustrates the temporal dynamics of CRF07_BC spread among IDU across east Asia.

Genotypic analysis of the protease and reverse transcriptase of HIV type 1 isolates from recently infected injecting drug users in western China

The partial pol gene was analyzed to determine circulating HIV-1 subtypes and the prevalence of drug resistance among recently infected injecting drug users in the west of China. Phylogenetic and bootscanning analyses showed that all 25 sequences belonged to CRF07_BC. No major drug resistance mutations were found, while the CRF07_BC sequences harbored a few highly prevalent polymorphic positions in both the protease and reverse transcriptase regions. It is notable that D60E, L63P and I93L substitutions, which were more common in HIV-1 isolates from PI-treated than untreated patients, were present in most of the isolates. Compared with subtype B, the CRF07_BC strains had a decreased genetic barrier for the V106M mutation, which is selected by efavirenz and leads to high-level resistance to all present nonnucleoside RT inhibitors. Further studies are needed to determine the impact of genetic features of CRF07-BC on antitretroviral susceptibility and evolution of drug resistance mutations.

Identification of 3 phylogenetically related HIV-1 BG intersubtype circulating recombinant forms in Cuba

BG intersubtype recombinants represented 11.6% of HIV-1 isolates in a recent survey in Cuba based on pol sequences, most of them forming a single clade further subdivided into 3 subclades. Here, we analyze 8 near full-length genomes and 1 gag-pol sequence from epidemiologically unlinked Cuban BG recombinants from these 3 subclades (3 from each). Near full-length sequences were also obtained from 3 subtype G and 2 subtype B Cuban viruses. Phylogenetic relationships were estimated via maximum likelihood, and mosaic structures of the recombinants were inferred with the bootscanning, MaxChi, Genconv, and GARD methods. For the near full-length genomes, all recombinants formed a strongly supported clade further subdivided into the same subclades previously defined in pol. Mosaic structures were identical within each subclade and different among subclades, although 5 breakpoints were coincident among all recombinants. Individual phylogenetic trees for nonrecombinant fragments (concatenated B and G subtype segments) indicated a common ancestry for the parental viruses and their relationships to local subtype B and G strains. These results allow us to identify 3 new BG intersubtype circulating recombinant forms in Cuba derived from a common recombinant ancestor, which originated from B and G subtype parental strains circulating in Cuba.

A nascent HIV type 1 epidemic among injecting drug users in Kabul, Afghanistan is dominated by complex AD recombinant strain, CRF35_AD

Injecting drug use (IDU), common in global centers of heroin production, confers significant risk for HIV-1 infection. Once introduced into IDU networks, an explosive rise in HIV-1 infection typically occurs, fueled principally by needle sharing. New HIV-1 epidemics in IDUs have occurred in Russia, China, Thailand, Spain, Iran, and in other countries, and some have spread into other risk groups in their respective countries. In Afghanistan, the introduction of HIV-1 into IDU networks has begun, but a recent report of 3% HIV-1 prevalence suggests that the epidemic is still at an early stage. Here we establish, by complete genome sequencing and phylogenetic analysis of four viral strains from Afghan IDUs, that all are the same complex recombinant strain, combining HIV-1 subtypes A and D and herein termed CRF35_AD. Published partial HIV-1 sequences from an HIV-1 epidemic among IDUs in Iran, already at 23.2% HIV-1 prevalence, are either CRF35_AD or a related recombinant. Voluntary HIV-1 screening and harm reduction programs in Afghanistan, applied now, could limit the spread of HIV-1, both in IDUs and in other social networks.

Identification of CRF34_01B, a second circulating recombinant form unrelated to and more complex than CRF15_01B, among injecting drug users in northern Thailand

In Thailand, the circulating HIV-1 strains include CRF01_AE, subtype B, and their recombinants. Genotyping and full-genome sequencing had previously identified circulating recombinant form CRF15_01B within a cohort of 347 HIV-1-infected individuals enrolled in the Opiate Users Research (OUR) study in northern Thailand. Using an improved MHAbce in six to eight genome regions and archived OUR serum samples, seven strains were identified with a new and complex 01/B recombinant pattern in common, different from that of CRF15_01B. Complete sequencing of three strains, amplified from serum as overlapping half-genomes, confirmed their common recombinant structure, mostly CRF01_AE, but with segments of subtype B in pol and gp41, plus a region of frequent 01/B crossovers in pol. OUR strains 1969P, 2275P, and 2478P were from individuals without direct epidemiological linkage and thus establish CRF34_01B. More comprehensive HIV-1 prevention and treatment programs in IDU can help to limit the growing complexity of HIV-1 strains in Thailand.

Molecular epidemiology of HIV type 1 subtypes in Taiwan: outbreak of HIV type 1 CRF07_BC infection in intravenous drug users

In Taiwan, sexual transmission is responsible for most HIV-1 infections with two dominant subtypes, subtype B and CRF01_AE, distributing among homosexual and heterosexual groups, respectively. Recently, intravenous drug use has become an emerging route of HIV-1 transmission and contributed to a significant increase of HIV-1 infection. To characterize the HIV isolates responsible for the outbreak among intravenous drug users (IDUs), phylogenetic analysis was performed to analyze the protease/RT sequences amplified from HIV-1-infected IDUs at National Taiwan University Hospital and Taipei City STD Control Center. CRF07_BC, which is circulating in northern China, was demonstrated to account for the majority of HIV-1 infection in IDUs in the past 2 years. Although these Taiwanese CRF07_BC sequences shared the same breakpoint positions as those described in the CRF07_BC reference sequences, they formed a unique cluster in the phylogenetic tree, suggesting they originated from a founder virus. This finding was further supported by the relative low genetic diversity and unique sequence features. Our results demonstrated the emergence of CRF07_BC and its association with the HIV-1 outbreak among IDUs between 2004 and 2005 in Taiwan. This finding not only helps us to have a better understanding of the HIV evolution in Asia, but also has important implications for vaccine design in the future.

Dominance of HIV-1 subtype CRF01_AE in sexually acquired cases leads to a new epidemic in Yunnan province of China

BACKGROUND

Dating back to the first epidemic among injection drug users in 1989, the Yunnan province has had the highest number of human immunodeficiency virus type 1 (HIV-1) infections in China. However, the molecular epidemiology of HIV-1 in Yunnan has not been fully characterized.

METHODS AND FINDINGS

Using immunoassays, we identified 103,015 accumulated cases of HIV-1 infections in Yunnan between 1989 and 2004. We studied 321 patients representing Yunnan's 16 prefectures from four risk groups, 11 ethnic populations, and ten occupations. We identified three major circulating subtypes: C/CRF07_BC/CRF08_BC (53%), CRF01_AE (40.5%), and B (6.5%) by analyzing the sequence of p17, which is part of the gag gene. For patients with known risk factors, 90.9% of injection drug users had C/CRF07_BC/CRF08_BC viruses, whereas 85.4% of CRF01_AE infections were acquired through sexual transmission. No distinct segregation of CRF01_AE viruses was found among the Dai ethnic group. Geographically, C/CRF07_BC/CRF08_BC was found throughout the province, while CRF01_AE was largely confined to the prefectures bordering Myanmar. Furthermore, C/CRF07_BC/CRF08_BC viruses were found to consist of a group of viruses, including C, CRF08_BC, CRF07_BC, and new BC recombinants, based on the characterization of their reverse transcriptase genes.

CONCLUSIONS

This is the first report of a province-wide HIV-1 molecular epidemiological study in Yunnan. While C/CRF07_BC/CRF08_BC and CRF01_AE are codominant, the discovery of many sexually transmitted CRF01_AE cases is new and suggests that this subtype may lead to a new epidemic in the general Chinese population. We discuss implications of our results for understanding the evolution of the HIV-1 pandemic and for vaccine development.

Global epidemiology of HIV

HIV is among the most generically variable of human pathogens. A comprehensive and detailed description of HIV strains in the pandemic is an important foundation for diagnosis, treatment, and prevention. The current sequence database for HIV includes almost 800 complete genome sequences, documenting HIV-1 groups M, O, and N, and HIV-2. Among HIV-1 group M strains, responsible for the vast majority of HIV infections worldwide, 743 sequences represent 9 genetic subtypes, 16 circulating recombinant forms (CRF) that are spreading in populations, and a variety of unique recombinant forms (URF), identified so far only from a single individual. The global distribution of HIV is complex and dynamic with regional epidemics harboring only a subset of the global diversity. HIV strains differ enormously in terms of global prevalence. Six strains account for the majority of HIV infections: HIV-1 subtypes A, B, C, D, and two of the CRF, CRF01-AE and CRF02_AG, respectively. Many of the known subtypes and recombinant forms are currently rare in the epidemic, but could spread more widely if favorable conditions arise. HIV-2 is largely restricted to West Africa at relatively low prevalence there. Groups O and N of HIV-1 are very rare in the pandemic. The goal of universal coverage of HIV-1 strains by diagnostic tests can be met by minimizing false negative test rates for the six globally prevalent HIV-1 group M strains and HIV-2, and by evaluating systematically coverage of rare subtypes and recombinant forms.

Identification of conserved lentiviral sequences as landmarks of genomic flexibility

Considering that recombinations produce quasispecies in lentivirus spreading, we identified and localized highly conserved sequences that may play an important role in viral ontology. Comparison of entire genomes, including 237 human, simian and non-primate mammal lentiviruses and 103 negative control viruses, led to identify 28 Conserved Lentiviral Sequences (CLSs). They were located mainly in the structural genes forming hot spots particularly in the gag and pol genes and to a lesser extent in LTRs and regulatory genes. The CLS pattern was the same throughout the different HIV-1 subtypes, except for some HIV-1-O strains. Only CLS 3 and 4 were detected in both negative control HTLV-1 oncornaviruses and D-particle-forming simian viruses, which are not immunodeficiency inducers and display a genetic stability. CLSs divided the virus genomes into domains allowing us to distinguish sequence families leading to the notion of ‘species self’ besides that of ‘lentiviral self’. Most of acutely localized CLSs in HIV-1s (82%) corresponded to wide recombination segments being currently reported. To cite this article: M.L.J. Moncany et al., C. R. Biologies 329 (2006).

Molecular epidemiology of HIV Type 1 in preparation for a Phase III prime-boost vaccine trial in Thailand and a new approach to HIV Type 1 genotyping

To characterize HIV-1 genotypes in candidate populations for a prime-boost phase III vaccine trial in Thailand, specimens from prevalent and incident HIV-1 infections from a family planning clinic population in Rayong Province and a community cohort in Chon Buri Province, collected from 1998 to 2001, were genotyped. A new multiregion hybridization assay, MHAbce, capable of distinguishing HIV-1 CRF01_AE, subtype B, and subtype C and their recombinants, was developed and applied to prevalent infections. Most incident and selected prevalent infections were studied by complete genome sequencing. By MHAbce, 168 of 194 prevalent infections were genotyped. Of these, 90.5% were CRF01_AE, 2.4% were subtype B, and 7.2% showed discordant or dual probe reactivity, indicative of recombination or dual infection, respectively. Among 23 incident infections, 20 were sequenced. Eighteen CRF01_AE, one subtype B, and one CRF01/B recombinant strains were seen. Two CRF01/B and one CRF01/C recombinant were identified among selected prevalent infections. These results indicate that incident and prevalent HIV-1 infections in Rayong and Chon Buri during 1998-2001 were 90% CRF01_AE, 3% subtype B, and 7% either recombinant or dual. This study frames the genetic diversity of HIV-1 in these cohorts in their preparatory phase for the ongoing ALVACHIV (vCP1521) prime, AIDSVAX B/E boost, phase III vaccine trial and will provide a benchmark for interpretation and analysis.

Circulating and unique recombinant forms of HIV type 1 containing subsubtype A2

HIV-1 strains containing subsubtype A2 are relatively rare in the pandemic but have been repeatedly identified in Kenya, where candidate vaccines based in part on subtype A, but not A2 strains, may be evaluated. Among the most recent is CRF16_A2D, a circulating recombinant form (CRF) whose prototypes are complete or partial HIV-1 sequences from Kenya, Korea, and Argentina. Using samples from blood bank discards in Kenya and complete genome sequencing, this report further documents CRF16_A2D and related recombinants and identifies a second CRF, CRF21_A2D. The two A2-containing CRFs, and two recombinants related to CRF16_A2D, share common structural elements but appear to have been independently derived. Concerted selection may have influenced the emergence and spread of certain A2-containing strains in Kenya. The second complete subtype C sequence from Kenya is also reported here. Monitoring of A2-containing recombinants and subtype C strains, both relatively rare in Kenya, may be informative in the course of cohort development and evaluation of candidate vaccines.