Susceptibility of HIV-1 subtypes B', CRF07_BC and CRF01_AE that are predominantly circulating in China to HIV-1 entry inhibitors

Background

The B′, CRF07_BC and CRF01_AE are the predominant HIV-1 subtypes in China. It is essential to determine their baseline susceptibility to HIV entry inhibitors before these drugs are used in China.

Methodology/Principal Findings

The baseline susceptibility of 14 representative HIV-1 isolates (5 CRF07_BC, 4 CRF01_AE, and 5 B′), most of which were R5 viruses, obtained from drug-naïve patients to HIV entry inhibitors, including two fusion inhibitors (enfuvirtide and C34), two CCR5 antagonists (maraviroc and TAK779) and one CXCR4 antagonist (AMD3100), were determined by virus inhibition assay. The sequences of their env genes were amplified and analyzed. These isolates possessed similar susceptibility to C34, but they exhibited different sensitivity to enfuvirtide, maraviroc or TAK779. CRF07_BC isolates, which carried polymorphisms of A578T and V583I in the N-terminal heptad repeat and E630Q, E662A, K665S, A667K and S668N in the C-terminal heptad repeat of gp41, were about 5-fold less sensitive than B′ and CRF01_AE isolates to enfuvirtide. Subtype B′ isolates with a unique polymorphism site of F317W in V3 loop, were about 4- to 5-fold more sensitive than CRF07_BC and CRF01_AE isolates to maraviroc and TAK779. AMD3100 at the concentration as high as 5 µM exhibited no significant inhibitory activity against any of the isolates tested.

Conclusion

Our results suggest that there are significant differences in baseline susceptibility to HIV entry inhibitors among the predominant HIV-1 subtypes in China and the differences may partly result from the naturally occurring polymorphisms in these subtypes. This study provides useful information for rational design of optimal therapeutic regimens for HIV-1-infected patients in China.     

柳州和南宁HIV-1亚型分布及耐药情况调查

为了解柳州和南宁两市HIV-1亚型分布和耐药情况,在柳州和南宁招募HIV感染者和AIDS患者共304名,采集外周静脉血,从血浆中提取HIVRNA,扩增HIVpol基因并测序。将获得的序列进行系统进化树分析,结果表明柳州的HIV-1毒株中存在CRF01_AE和CRF07_BC两种亚型,其中CRF01_AE毒株占75.2%,CRF07_BC毒株占24.8%;南宁的HIV-1毒株中存在CRF01_AE、CRF08_BC、B亚型和C亚型共4种亚型,其中CRF01_AE和CRF08_BC仍是南宁最主要的亚型,CRF01_AE占85.8%,CRF08_BC占11.5%。根据所得的序列资料进行HIV-1耐药性分析,计算耐药率。计算结果表明,柳州未治疗和治疗研究对象的耐药率分别为3.3%和8.7%,南宁未治疗和治疗研究对象的耐药率分别为1.4%和27.5%。     

Increased rate of CD4+ T-cell decline and faster time to antiretroviral therapy in HIV-1 subtype CRF01_AE infected seroconverters in Singapore

Background

It remains controversial as to whether HIV-1 subtypes influence disease progression. Singapore offers a unique opportunity to address this issue due to the presence of co-circulating subtypes. We compared subtype CRF01_AE and non-CRF01_AE infected patients, with regards to estimated annual rate of CD4+ T-cell loss and time from estimated data of seroconversion (EDS) to antiretroviral therapy (ART).

Methods

We recruited ART-naive patients with known dates of seroconversion between October 2002 and December 2007 at the Singapore Communicable Disease Centre, the national reference treatment centre. Multilevel mixed-effects models were used to analyse the rate of CD4+ T-cell decline. Time from EDS to ART was analyzed with the Kaplan-Meier survival method and compared with Cox proportional hazards models.

Results

54 patients with previously assigned HIV-1 subtypes (24 CRF01_AE, 17 B, 8 B'', 1 CRF33_01B, 3 CRF34_01B and 1 G) were observed for 89 patient-years. Subtype CRF01_AE and non-CRF01_AE infected patients did not differ in age, gender, risk factor, rate of symptomatic seroconversion, baseline CD4+ T-cell count, log₁₀ viral load or haemoglobin concentration. The estimated annual rate of CD4+ T-cell loss was 58 cells/mm³/year (95% CI: 7 to 109; P = 0.027) greater in subtype CRF01_AE infected patients compared to non-CRF01_AE patients, after adjusting for age, baseline CD4+ T-cell count and baseline log₁₀ viral load. The median time from EDS to ART was 1.8 years faster comparing CRF01_AE to non-CRF01_AE infected patient with a 2.5 times (95% CI: 1.2-5.0; P = 0.013) higher hazard for ART initiation, after controlling for age, baseline CD4+ T-cell count and baseline log₁₀ viral load.

Conclusions

Infecting subtype significantly impacted the rate of CD4+ T-cell loss and time to treatment in this cohort. Studies to understand the biological basis for this difference could further our understanding of HIV pathogenesis.     

HIV-1 Genetic Diversity and Its Impact on Baseline CD4+T Cells and Viral Loads among Recently Infected Men Who Have Sex with Men in Shanghai,China

The HIV-1 epidemic among men who have sex with men (MSM) has been spreading throughout China. Shanghai, a central gathering place for MSM, is facing a continuously increasing incidence of HIV-1 infection. In order to better understand the dynamics of HIV-1 diversity and its influence on patient’s immune status at baseline on diagnosis, 1265 newly HIV-1-infected MSM collected from January 2009 to December 2013 in Shanghai were retrospectively analyzed for genetic subtyping, CD4+T cell counts, and viral loads. HIV-1 phylogenetic analysis revealed a broad viral diversity including CRF01_AE (62.13%), CRF07_BC (24.51%), subtype B (8.06%), CRF55_01B (3.24%), CER67_01B (0.95%), CRF68_01B (0.4%), CRF08_BC (0.08%) and CRF59_01B (0.08%). Twenty-four unique recombination forms (URFs) (1.98%) were identified as well. Bayesian inference analysis indicated that the introduction of CRF01_AE strain (1997) was earlier than CRF07_BC strain (2001) into MSM population in Shanghai based on the time of the most recent common ancestor (tMRCA). Three epidemic clusters and five sub-clusters were found in CRF01_AE. Significantly lower CD4+T cell count was found in individuals infected with CRF01_AE than in those infected with CRF07_BC infection (P<0.01), whereas viral load was significantly higher those infected with CRF01_AE than with CRF07_BC (P<0.01). In addition, the patients with >45 years of age were found to have lower CD4+T cell counts and higher viral loads than the patients with <25 years of age (P<0.05). This study reveals the presence of HIV-1 subtype diversity in Shanghai and its remarkable influence on clinical outcome. A real-time surveillance of HIV-1 viral diversity and phylodynamics of epidemic cluster, patient’s baseline CD4+T cell count and viral load would be of great value to monitoring of disease progression, intervention for transmission, improvement of antiretroviral therapy strategy and design of vaccines.     

Molecular Epidemiology of HIV-1 in Jilin Province,Northeastern China: Emergence of a New CRF07_BC Transmission Cluster and Intersubtype Recombinants

Objective

To investigate the HIV-1 molecular epidemiology among newly diagnosed HIV-1 infected persons living in the Jilin province of northeastern China.

Methods

Plasma samples from 189 newly diagnosed HIV-1 infected patients were collected between June 2010 and August 2011 from all nine cities of Jilin province. HIV-1 nucleotide sequences of gag P17–P24 and env C2–C4 gene regions were amplified using a multiplex RT-PCR method and sequenced. Phylogenetic and recombination analyses were used to determine the HIV-1 genotypes.

Results

Based on all sequences generated, the subtype/CFR distribution was as follows: CRF01_AE (58.1%), CRF07_BC (13.2%), subtype B’ (13.2%), recombinant viruses (8.1%), subtype B (3.7%), CRF02_AG (2.9%), subtype C (0.7%). In addition to finding CRF01_AE strains from previously reported transmission clusters 1, 4 and 5, a new transmission cluster was described within the CRF07_BC radiation. Among 11 different recombinants identified, 10 contained portions of gene regions from the CRF01_AE lineage. CRF02_AG was found to form a transmission cluster of 4 in local Jilin residents.

Conclusions

Our study presents a molecular epidemiologic investigation describing the complex structure of HIV-1 strains co-circulating in Jilin province. The results highlight the critical importance of continuous monitoring of HIV-infections, along with detailed socio-demographic data, in order to design appropriate prevention measures to limit the spread of new HIV infections.     

HIV RNA and proviral HIV DNA can be detected in semen after 6 months of antiretroviral therapy although HIV RNA is undetectable in blood

The risk of sexual transmission of HIV is strongly correlated with amounts of genital HIV RNA. Few studies have reported amounts of HIV RNA and HIV DNA in semen in HIV‐infected Chinese patients undergoing antiviral treatment (ART). In this observational study, the amounts of HIV RNA and HIV DNA in semen were assessed after six months of ART in HIV‐infected Chinese individuals, when HIV RNA was undetectable in blood . This study included 19 HIV‐infected Chinese men undergoing ART for six months. Amounts of HIV in paired semen and blood samples were assessed using real‐time PCR. The C2‐V5 region of the HIV envelope (env) genes was cloned and sequenced and genotype and co‐receptor usage predicted based on the sequence. It was found that HIV RNA was undetectable in the plasma of most patients (17/19), whereas HIV RNA could be detected in the semen of most patients (16/19). HIV DNA could be detected in both semen and blood. Genetic diversity of HIV between the seminal and blood compartments was identified. Thus, amounts of HIV RNA and HIV DNA remain high in semen of HIV‐infected Chinese patients after six months of ART treatment, even when HIV RNA was undetectable in blood.     

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.     

A Comprehensive Mapping of HIV-1 Genotypes in Various Risk Groups and Regions across China Based on a Nationwide Molecular Epidemiologic Survey

Background

China is experiencing a dynamic HIV/AIDS epidemic. While serology based surveillance systems have reported the spread of HIV/AIDS, detailed tracking of its transmission in populations and regions is not possible without mapping it at the molecular level. We therefore conducted a nationwide molecular epidemiology survey across the country.

Methods

HIV-1 genotypes were determined from 1,408 HIV-positive persons newly diagnosed in 2006. The prevalence of each genotype was estimated by weighting the genotype’s prevalence from each province- and risk-specific subpopulation with the number of reported cases in the corresponding subgroups in that year.

Results

CRF07_BC (35.5%), CRF01_AE (27.6%), CRF08_BC (20.1%), and subtype B'' (9.6%) were the four main HIV-1 strains in China. CRF07_BC and CRF08_BC were the primary drivers of infection among injecting drug users in northeastern and southeastern China, respectively, and subtype B'' remained dominant among former plasma donors in central China. In contrast, all four strains occurred in significant proportions among heterosexuals nationwide, pointing to an expansion of the HIV-1 epidemic from high-risk populations into the general population. CRF01_AE also replaced subtype B as the principal driver of infection among men-who-have-sex-with-men.

Conclusions

Our study provides the first comprehensive baseline data on the diversity and characteristics of HIV/AIDS epidemic in China, reflecting unique region- and risk group-specific transmission dynamics. The results provide information critical for designing effective prevention measures against HIV transmission.     

Higher frequency of premature stop codon mutations at vpu gene of human immunodeficiency virus type 1 CRF01_AE compared with those of other subtypes

Our previous study demonstrated the anti-apoptosis function of the human immunodeficiency virus type 1 (HIV-1) vpu gene product in normal CD4+ T lymphocytes. In this study, using sequences obtained from the HIV sequence database, we compared vpu sequences from 184 preparations of various subtypes of HIV-1 from diverse geographical regions. Our analysis revealed that CRF01_AE isolates had premature stop codon mutations at the vpu gene at a much higher rate (36%) than other subtypes (0-9%). The premature stop codon mutations in vpu existed mostly at two amino acid residues: the methionine initiation codon and the boundary between the transmembrane (TM) and cytoplasmic domains. The mutations at the latter site were more often detected in CRF01_AE. The higher mutation rates at vpu in CRF01_AE were confirmed by sequence comparison of polymerase chain reaction products newly obtained directly from the DNA extracted from peripheral blood mononuclear cells (PBMCs), but not from the RNA from the plasma, in CRF01_AE- and subtype B-infected individuals. This finding may indicate the possibility that the more abundant population of HIV-1 CRF01_AE is able to induce apoptosis in CD4+ T lymphocytes than the populations of other subtypes.     

The role of conventional antibodies targeting the CD4 binding site and CD4-induced epitopes in the control of HIV-1 CRF01_AE viruses

HIV-1 CRF01_AE viruses are highly prevalent in Southeast Asia. However, vulnerability sites in Env of CRF01_AE viruses have not been investigated sufficiently. We examined the sensitivity of CRF01_AE viruses from Japan and Vietnam, together with subtype B viruses from Japan, to neutralization and Fc-mediated signaling. Neutralization coverage of broadly neutralizing antibodies (bnAbs), 2G12 and b12, was significantly low against CRF01_AE viruses, compared with subtype B viruses. In contrast, the conventional antibody targeting the CD4 binding site (CD4bs), 49G2, showed better neutralization and Fc-mediated signaling activities against CRF01_AE viruses than subtype B viruses. Fc-mediated signaling activity of anti-CD4 induced (CD4i) antibody, 4E9C, was also detected against CRF01_AE viruses more than subtype B viruses. These results suggest that conventional antibodies against CD4bs and CD4i may play an important role in the control of CRF01_AE viruses.     

Genotypes and Transmitted Drug Resistance among Treatment-Naive HIV-1-Infected Patients in a Northwestern Province,China: Trends from 2003 to 2013

Background

Transmitted drug resistance (TDR) reduces the efficacy of initial antiretroviral treatment and has become a public health concern. Little information is available regarding the genetic diversity of HIV-1 and the prevalence of TDR among treatment-naïve patients in a northwestern province of China since the implementation of national free antiretroviral therapy (ART).

Methods

Blood samples from 372 HIV-1 treatment-naive patients were collected between 2003 and 2013 in Shaanxi province. Viral RNA was extracted for nested PCR, and phylogenetic reconstruction and recombination analyses were performed to characterize patterns of the HIV-1 subtypes. Genotypic drug resistance testing was performed using an in-house assay to determine trends in the prevalence of HIV-1 transmitted drug resistance.

Results

Multiple genotypes were identified among the patients in Shaanxi, including B (25.0%), C (0.3%), G (0.3%), and CRF01_AE (39.2%), CRF07_BC (32.7%), CRF08_BC (0.8%), CRF55_01B (1.1%), and URFs (0.6%). The subtypes were associated with the transmission routes (χ² = 77.113, p<0.01). In this study, a low baseline CD4⁺ T cell count and a high viral load were found among CRF01_AE-infected patients compared with patients who were infected with non-CRF01_AE (p<0.01) through sexual transmission; however, the CRF01_AE subtype was not associated with a low baseline CD4⁺ T cell count or a high viral load in Chinese patients infected through blood transmission (p = 0.249). The overall TDR rate in this population was 4.4% between 2003 and 2013. A univariate logistic regression model revealed that a low CD4 T cell count (≤100 cells/µL) was associated with the development of drug-resistant strains.

Conclusion

Our work revealed diverse HIV-1 subtype distributions in Shaanxi province. We identified a low and stable TDR time trend among ART-naive patients. These findings enhance our understanding of HIV-1 genetic diversity and provide some guidelines for the improvement and implementation of a comprehensive public health strategy of HIV-1 TDR prevention.     

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.     

南宁市HIV-1/AIDS人群治疗前pol区遗传特性及蛋白结构分析

为探讨南宁市某县艾滋病病毒1型(HIV-1)感染人群中治疗前pol区遗传特性及蛋白结构变化情况,本研究通过RT-PCR扩增pol区部分序列并进行测序,将序列同源比对构建系统进化树;分型确定毒株亚型和斯坦福大学HIV耐药性数据库比对,分析耐药相关位点;SWISS-MODEL蛋白质同源数据库进行建模分析氨基酸的突变对蛋白质结构和功能的影响。本研究在90份HIV-1标本中获得46个pol区有效序列,共发现4种亚型,其中CRF01_AE占76.08%(35/46)、CRF08_BC占15.22%(7/46)、CRF07_BC占(3/46)6.52%、CRF59_01B1占2.17%(1/46);46个序列中有4例(8.69%)出现耐药突变位点,没有针对核苷酸反转录酶抑制剂(NRTI)的耐药突变;针对蛋白酶类抑制剂(PIs)1例,PR蛋白酶的柔性部位I47V位点发生突变,β折叠结构的I84V位点发生突变,都是异亮氨酸突变为缬氨酸;针对非核苷酸反转录酶抑制剂(NNRTI)有3例,2例位于活性中心的Y181C位点由酪氨酸突变为半胱氨酸,1例位于转角处的E138G位点由谷氨酸突变为甘氨酸。研究表明,南宁市某县HIV-1病毒CRF01_AE重组亚型比例最大,未经抗病毒治疗HIV1感染者中已经出现pol区耐药突变株,突变位点主要位于活性中心及柔性部位,传播水平已经处于中等流行状态。深入分析蛋白质与抑制剂相互作用机制,有助于为艾滋病抗病毒及耐药性监测方案提供科学依据。     

Patients Infected with CRF07_BC Have Significantly Lower Viral Loads than Patients with HIV-1 Subtype B: Mechanism and Impact on Disease Progression

The circulating recombinant form (CRF) 07_BC is the most prevalent HIV-1 strain among injection drug users (IDUs) in Taiwan. It contains a 7 amino-acid deletion in its p6^gag. We conducted a cohort study to compare viral loads and CD4 cell count changes between patients infected with subtype B and CRF07_BC and to elucidate its mechanism. Twenty-one patients infected with CRF07_BC and 59 patients with subtype B were selected from a cohort of 667 HIV-1/AIDS patients whom have been followed up for 3 years. Generalized estimated equation was used to analyze their clinical data and the results showed that patients infected with CRF07_BC had significantly lower viral loads (about 58,000 copies per ml less) than patients with subtype B infection (p = 0.002). The replicative capacity of nine CRF07_BC and four subtype B isolates were compared and the results showed that the former had significantly lower replicative capacity than the latter although all of them were CCR5- tropic and non-syncytium inducing viruses. An HIV-1-NL4-3 mutant virus which contains a 7 amino-acid deletion in p6^gag (designated as 7d virus) was generated and its live cycle was investigated. The results showed that 7d virus had significantly lower replication capacity, poorer protease-mediated processing and viral proteins production. Electron microscopic examination of cells infected with wild-type or 7d virus demonstrated that the 7d virus had poorer and slower viral maturation processes: more viruses attached to the cell membrane and higher proportion of immature virions outside the cells. The interaction between p6^gag and Alix protein was less efficient in cells infected with 7d virus. In conclusion, patients infected with CRF07_BC had significantly lower viral loads than patients infected with subtype B and it may due to the deletion of 7 amino acids which overlaps with Alix protein-binding domain of the p6^gag.     

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.     

Characteristics of HIV-1 Molecular Epidemiology in Suzhou,China, from 2009 to 2014

正Dear Editor,Human immunodeficiency virus(HIV)and acquired immunodeficiency syndrome(AIDS)remain major public health problems in China,where approximately 780,000people currently live with HIV,according to the 2012 China AIDS Response Progress Report.Suzhou was an early epidemic region in Jiangsu province and the current situation of     

Genetic and neutralization sensitivity of diverse HIV-1 env clones from chronically infected patients in China

As HIV-1 continues to spread in China from traditional high risk populations to the general public, its genetic makeup has become increasingly complex. However, the impact of these genetic changes on the biological and neutralization sensitivity of the virus is unknown. The current study aims to characterize the genetic, biological, and neutralization sensitivity of HIV-1 identified in China between 2004 and 2007. Based on a total of 107 full-length envelope genes obtained directly from the infected patients, we found that those viruses fell into three major genetic groups: CRF01_AE, subtype B', and subtype C/CRF07_BC/CRF08_BC/B'C. Pseudotyped viruses built upon the viable env genes have demonstrated their substantial variability in mediating viral entry and in sensitivity to neutralization by subtype-specific plasma pools and broadly neutralizing monoclonal antibodies (bnmAb). Many viruses are resistant to one or more bnmAb, including those known to have high potency against diverse viruses from outside China. Sequence and structural analysis has revealed several mechanisms by which these resistant viruses escape recognition from bnmAb. We believe that these results will help us to better understand the impact of genetic diversity on the neutralizing sensitivity of the viruses and to facilitate the design of immunogens capable of eliciting antibodies with potency and breadth similar to those of bnmAb.     

Unique CRF01_AE Gag CTL epitopes associated with lower HIV-viral load and delayed disease progression in a cohort of HIV-infected Thais

Cytotoxic T Lymphocytes (CTLs) play a central role in controlling HIV-replication. Although numerous CTL epitopes have been described, most are in subtype B or C infection. Little is known about CTL responses in CRF01_AE infection. Gag CTL responses were investigated in a cohort of 137 treatment-naïve HIV-1 infected Thai patients with high CD4+ T cell counts, using gIFN Enzyme-Linked Immunospot (ELISpot) assays with 15-mer overlapping peptides (OLPs) derived from locally dominant CRF01_AE Gag sequences. 44 OLPs were recognized in 112 (81.8%) individuals. Both the breadth and magnitude of the CTL response, particularly against the p24 region, positively correlated with CD4+ T cell count and inversely correlated with HIV viral load. The breadth of OLP response was also associated with slower progression to antiretroviral therapy initiation. Statistical analysis and single peptide ELISpot assay identified at least 17 significant associations between reactive OLP and HLA in 12 OLP regions; 6 OLP-HLA associations (35.3%) were not compatible with previously reported CTL epitopes, suggesting that these contained new CTL Gag epitopes. A substantial proportion of CTL epitopes in CRF01_AE infection differ from subtype B or C. However, the pattern of protective CTL responses is similar; Gag CTL responses, particularly against p24, control viral replication and slow clinical progression.