Mother to child transmission of HIV‐1 in a Thai population: Role of virus characteristics and maternal humoral immune response

The objective of this study was to investigate factors influencing mother to child transmission of HIV‐1 in Thailand, where HIV‐1 CRF01_AE, the major subtype in Southeast Asia, predominates. Samples from 84 HIV‐1 infected, anti‐retroviral treatment‐naïve, non‐breast feeding mothers, 28 who transmitted HIV‐1 to their babies (transmitters) and 56 who did not (non‐transmitters), were studied for maternal humoral immune response and virus characteristics. Maternal humoral immune response was measured by lymphocyte phenotyping; neutralizing antibodies to laboratory HIV‐1 MN strain and two clinical isolates; peptide binding antibody to gp41 and V3 from strains CRF01_AE, B, and MN; autologous antibodies; and quasispecies diversity. Virus characteristics studied were viral load, co‐receptor usage, and viral replication capacity. No significant difference between transmitters and non‐transmitters was found for any parameter of maternal humoral immune response. However, viral load and viral replication capacity were significantly higher in transmitters versus non‐transmitters and were not correlated with each other. This suggests that viral replication capacity may be a transmission factor independent of viral load, which is already well established as a risk factor for transmission of HIV‐1. All except four viral isolates used the CCR5 co‐receptor. This is one of few studies of vertical transmission in a population where HIV‐1 CRF01_AE predominates. The data suggest that in this population the maternal humoral immune response was not important in preventing transmission at parturition, but that virus characteristics were key factors, and that viral replication capacity may contribute to birth‐associated mother to child transmission of HIV‐1. J. Med. Virol. 81:768–778, 2009. © 2009 Wiley‐Liss, Inc.     

Characterization of mutations in CRF01_AE virus isolates from antiretroviral treatment-naive and -experienced patients in Singapore

OBJECTIVE: To determine the frequency of drug resistance mutations among antiretroviral treatment-naive and -experienced patients infected with CRF01_AE virus. DESIGN: Prospective observational study. METHODS: We recruited antiretroviral-experienced HIV-infected patients with suspected drug resistance and consecutive newly diagnosed drug-naive patients. Viral sequencing was performed using standard methods. Frequencies of mutations in CRF01_AE virus isolates were compared with reference data for subtype B virus. RESULTS: Sequences were obtained for CRF01_AE virus isolates from 69 patients with treatment exposure and 35 treatment-naive patients. Treatment-naive patients had numerous polymorphisms but no major drug resistance mutations. There were differences between CRF01_AE and subtype B viruses in several drug resistance mutations including the following: D67N, L210F, K101E, V106M, V179I/D, G190A/S/E, and G48V (which were more common in CRF01_AE virus) and M41L, T215Y, and V82A (which were less common in CRF01_AE virus). CONCLUSIONS: The pattern of treatment-related mutations in CRF01_AE virus differs from that in subtype B virus at a number of positions determining drug resistance. Understanding these differences is important for interpreting results of resistance tests and determining treatment choices.     

An adenovirus-based HIV subtype B prime/boost vaccine regimen elicits antibodies mediating broad antibody-dependent cellular cytotoxicity against non-subtype B HIV strains

Although HIV subtype B predominates in North America and Western Europe, most HIV infections worldwide are non-subtype B. Globally effective AIDS vaccines need to elicit broad immunity against multiple HIV strains. In this study, 10 chimpanzees were intranasally primed sequentially with adenovirus type 5 (Ad5)- and Ad7-HIVMNenv/rev recombinants and boosted twice intramuscularly with heterologous oligomeric HIVSF162 gp140DeltaV2 protein in MF59 adjuvant. Sera were evaluated for binding, neutralizing, and antibody-dependent cellular cytotoxicity (ADCC) against HIV clades A, B, C, and CRF01_AE. The vaccine regimen elicited high-titered HIV subtype A, B, C and CRF01_AE gp120-binding antibodies. Sera from 7 of 10 vaccinated chimpanzees cross-neutralized the heterologous South African subtype C primary HIVTV-1 isolate. Significant cross-clade neutralization against other subtype A, C and E isolates was not observed. Sera from all animals mediated ADCC of cells coated with gp120 from HIV subtypes A and B. Nine of 10 animals also exhibited ADCC activity against HIV subtype C and CRF01_AE gp120-coated targets. This subtype B Ad-HIV recombinant prime/envelope protein boost regimen is a promising approach for eliciting broad ADCC activity against diverse HIV clades. Incorporating additional non-subtype B envelope genes and protein boosts in a multivalent strategy may be required to elicit broader neutralizing antibodies against non-subtype B HIV strains.     

Molecular epidemiology of HIV-1 subtypes in southern China

The driving forces of the HIV-1 epidemic in Guangxi, China were assessed by investigating virologic and epidemiologic data from a cohort of longitudinally followed injection drug users (IDUs) in Binyang and Pingxiang, major urban areas along 2 separate drug routes in the province. Sera and interview data were obtained in September and October of 2000. Sequence analysis of HIV-1 was performed on the gag-pol region (HXB2 nt 1850-3005) and C2 to V4 env (HXB2 nt 6704-7626). Sequence data demonstrated that 88% of the infections in Pingxiang were CRF01_AE, whereas 96% in Bin-yang were CRF08_BC. Three recently infected subjects in Pingxiang were infected with CRF08_BC, and 1 chronically infected subject had evidence of a recombinant virus. Intersubject distances were statistically greater for CRF01_AE-infected subjects than CRF08_BC-infected subjects for all regions except V4. The epidemic in Binyang is similar to previously described IDU-based epidemics, with a strong founder effect with little variation in V3. The epidemic in Pingxiang may have had multiple introductions of the CRF01_AE epidemic into the city and greater spread through sexual transmission, resulting in greater variation in V3 than typically seen in purely parenterally based epidemics.     

Distinguishing molecular forms of HIV-1 in Asia with a high-throughput, fluorescent genotyping assay, MHAbce v.2

High-resolution HIV-1 genotyping of large sample sets is crucial to define the evolving and dynamic epidemics in Asia. Here we present MHAbce v.2, a multi-region hybridization assay that individually discriminates subtypes B, C, CRF01_AE, and virtually all of their described recombinants, based on real-time PCR using subtype-specific TaqMan probes in 8 regions throughout the viral genome. In a validation panel (n=70), the assay performed with a sensitivity of 95.7% and specificity of 99.8%. The assay was field-tested on samples from a retrospective MTCT cohort (n=180; Lampang Province, Northern Thailand; 1996-1998). 177/180 of the samples were typeable, and 94.4% were typed as CRF01_AE. The remaining strains represented even proportions of subtype B and B/CRF01_AE recombinants and were confirmed by sequencing, revealing early links between the heterosexual and IDU HIV-1 epidemics in Thailand. MHAbce v.2, with an area of application including China, India, Southeast Asia, and the Pacific Rim, can be used to develop a comprehensive and detailed picture of this important component of the HIV/AIDS pandemic.     

Temporal trends and molecular epidemiology of HIV-1 infection in Taiwan from 1988 to 1998

Eight hundred and seventy-nine HIV-1-infected patients (comprising 46% of reported HIV-1/AIDS cases in Taiwan) were recruited for this study of the molecular epidemiology of HIV-1 in Taiwan from 1988 to 1998. HIV-1 subtypes were determined using a modified peptide-enzyme immunoassay complemented with DNA sequencing and phylogenetic analysis. Of the 807 HIV-1 infected men, 68.2% were infected with HIV-1B, 29.5% with HIV-1 circulating recombinant form (CRF)01_AE and 2.3% with other subtypes. Of the 72 HIV-1-infected women, 72.2% were infected with HIV-1 CRF01_AE, 13.9% with HIV-1B, and 13.9% with other subtypes. All of 8 foreign-born, Southeast Asian women and 6 of 7 (85.7%) Taiwan-native female commercial sex workers were infected with HIV-1 CRF01_AE. Fourteen of the 33 (42.4%) heterosexual married men with CRF01_AE had transmitted HIV-1 to their wives, whereas only 1 of 17 (5.9%) men with HIV-1 B had transmitted HIV-1 to their spouses (p < .01). Of 18 heterosexual male injecting drug users, 1 of 12 (8.5%) with HIV-1B and 5 of 6 (83.3%) with HIV-1 CRF01_AE had had sexual contact with female commercial sex workers (p < .01). Therefore, in this population, CRF01_AE was preferentially associated with heterosexual risk groups, a finding compatible with differences in transmission capability between B and non-B subtypes.     

The HIV-1 V3 domain on field isolates: participation in generation of escape virus in vivo and accessibility to neutralizing antibodies

Summary The V3 domain is highly variable and induces HIV neutralizing antibodies (NA). Here we addressed the issues of 1) the participation of mutations in V3 in generation of neutralization resistant escape virus in vivo and 2) the applicability of synthetic V3 peptides corresponding to field isolates to induce neutralizing immune sera. Seven peptides corresponding to the V3 region of primary and escape virus from 3 HIV-1 infected patients were synthesized and used for antibody (Abs) studies and immunizations. The anti-V3 Abs titre in patient serum was generally low against peptides corresponding to autologous virus isolated later than the serum sample in contrast to the titre against peptides corresponding to virus isolated earlier than the serum sample. Furthermore, neutralizing anti-V3 monoclonal antibodies (MAbs) raised against V3 peptides from laboratory strains of HIV-1 showed distinct binding patterns against V3 peptides corresponding to sequential primary and escape field isolates, with the strongest reactivity against late isolated escape virus. These observations suggest that the neutralization epitope was influenced by the appearance of mutations. When used as immunogen in rabbits, V3 peptides corresponding to field isolates were highly immunogenic but failed to induce neutralizing or gp120-precipitating Abs. On the contrary, V3 peptide corresponding to the laboratory strain HXB2 induced HIV neutralizing, gp120-precipitating immune serum. In conclusion, these data suggest a participation of the V3 domain in the immunoselection of escape virus, and that V3 on early field virus is less accessible to NA than that on laboratory strains.     

北京市性传播HIV-1感染者流行毒株gag基因序列测定和亚型分析

目的 了解北京市性传播HIV-1感染者流行毒株亚型特点和流行规律.方法 随机采集北京市2008年新确证性传播HIV感染者的抗凝全血标本100份,分离血浆,提取病毒RNA,用套式聚合酶链反应扩增病毒gag基因,并进行序列测定和亚型分析.结果 系统进化分析确定北京市性传播HIV-1感染者流行毒株存在8个亚型或流行重组型,分别为B亚型22份,B'亚型8份,C亚型1份,CRF01_AE 38份,CRF02_AG 2份,CRF07 BC 9份,CRF08_BC 3份,疑似C/CRF01_AE重组型1份.结论 CRF01_AE和B亚型分别占45.2%和26.2%,为性传播感染者主要的亚型,应该加强我市HIV-1亚型流行情况的监测.

Abstract：

Objective To investigate the subtype distribution and sequence characteristics of HIV-1 strains prevalent among sexual infectors in Beijing. Methods We collected the blood samples from 100HIV sexual infectors in Beijing during 2008 and separated plasma specimens. RNA was extracted from the plasma and the gag gene was amplified by RT-PCR and nest-PCR. The PCR products were sequenced directly and phylogenetic analyses of gag gene was performed using the MEGA4 software. Results Among 100 HIV-1 plasma samples,84 gag gene fragments were amplified and analyzed. Eight HIV subtypes including B(22 strains), B'(8 strains),C( 1 strain) ,CRF01_AE (38 strains) ,CRF02_AG (2 strains) ,CRF07_BC(9 strains) ,CRF08_BC(3 strains) and C/CRF01_AE recombinant like strain( 1 strain) were identified circulating in Beijing. Conclusion CRF01 _AE and subtype B were predominant in Beijing account for 45.2% and 26.2% and the surveillance of HIV gene variation should be paid more attention.     

A phase 1/2 comparative vaccine trial of the safety and immunogenicity of a CRF01_AE (subtype E) candidate vaccine: ALVAC-HIV (vCP1521) prime with oligomeric gp160 (92TH023/LAI-DID) or bivalent gp120 (CM235/SF2) boost

BACKGROUND: The development of an effective HIV-1 vaccine is critical to control the pandemic. A prime-boost HIV-1 vaccine trial assessing safety and immunogenicity was conducted in Thailand as part of an evaluation of candidate regimens for a phase 3 efficacy trial. METHODS: ALVAC-HIV (vCP1521), expressing circulating recombinant form 01_AE (CRF01_AE) gp120/subtype B LAI and subtype B Gag/Protease boosted with recombinant envelope oligomeric CRF01_AE gp160 (ogp160) or bivalent CRF01_AE/subtype B gp120 CM235/SF2, was evaluated in a phase 1/II trial of 130 HIV-negative Thai adults. RESULTS: One hundred forty volunteers were enrolled, and 130 completed all safety and immunogenicity visits. Reactogenicity was common but generally mild, and there was no significant difference in the adverse event rate between vaccine and placebo recipients (P = 0.26). There were 7 serious adverse events during the follow-up period, none of which were vaccine related. Cumulative HIV-specific, CD8-mediated, cytotoxic T-lymphocyte responses were observed in 11 (25%) of 44 subjects who received ALVAC boosted by bivalent gp120 and in 5 (11%) of 45 subjects who received ALVAC boosted by ogp160, but these differences were not statistically significant compared with those in placebo recipients (P = 0.62 and P = 0.37, respectively). HIV-specific lymphoproliferative responses were detected in 84% of subunit-boosted vaccine recipients and in 10% of placebo recipients. Neutralizing antibody responses to CRF01_AE and subtype B laboratory strains were seen in 95% of ogp160-boosted and 100% of gp120 B/E-boosted vaccinees, respectively. CONCLUSIONS: These 2 different prime-boost regimens seem to be safe and displayed cell-mediated immune responses consistent with those in other trials of canarypox vectors.     

淮安市经异性性传播的HIV感染者中HIV-1病毒基因亚型特征分析

目的 了解淮安市经异性性传播HIV感染者中HIV-1病毒基因亚型分布及其流行特征.方法 从60名异性性传播HIV-1感染者血液中提取DNA或RNA,用巢式PCR或RT-PCR方法扩增gag、env基因区片段,测定序列并分析.结果 60份标本中,确定了48份标本的基因亚型,发现有4种HIV-1亚型和重组型.其中CRF01_AE亚型占62.5％,CRF07_BC亚型占22.9％,CRF08_BC亚型占6.3％,B亚型占6.3％.结论淮安市异性性传播感染HIV者中,流行着CRF01_AE、CRF07_BC、CRF08_BC、B亚型这4种亚型病毒株,CRF01_AE为主要流行亚型.     

Phylodynamic analysis of the dissemination of HIV-1 CRF01_AE in Vietnam

To estimate the epidemic history of HIV-1 CRF01_AE in Vietnam and adjacent Guangxi, China, we determined near full-length nucleotide sequences of CRF01_AE from a total of 33 specimens collected in 1997-1998 from different geographic regions and risk populations in Vietnam. Phylogenetic and Bayesian molecular clock analyses were performed to estimate the date of origin of CRF01_AE lineages. Our study reconstructs the timescale of CRF01_AE expansion in Vietnam and neighboring regions and suggests that the series of CRF01_AE epidemics in Vietnam arose by the sequential introduction of founder strains into new locations and risk groups. CRF01_AE appears to have been present among heterosexuals in South-Vietnam for more than a decade prior to its epidemic spread in the early 1990s. In the late 1980s, the virus spread to IDUs in Southern Vietnam and subsequently in the mid-1990s to IDUs further north. Our results indicate the northward dissemination of CRF01_AE during this time.     

Subtype CRF01_AE dominate the sexually transmitted human immunodeficiency virus type 1 epidemic in Guangxi,China

Human immunodeficiency virus type 1 (HIV‐1) infection by sexual transmission in Guangxi, China had increased dramatically. However, limited information is available on the genetic characterization of the HIV‐1 epidemic. In this study, HIV‐1 seropositive drug‐naïve patients infected by heterosexual transmission were enrolled. The full length gag and pol genes were sequenced followed by phylogenetic analysis, recombinant analysis and drug resistant analysis. Multiple subtypes were identified, including CRF01_AE (80.1%), CRF07_BC (6.4%), CRF08_BC (10.2%), subtype B (1.7%), and URFs (1.7%). In the phylogenetic tree, two large CRF01_AE clusters were identified. One cluster is originating from Vietnam strains as being reported previously in intravenous drug users. One novel cluster was identified and showed close relationship to strains from Fujian province. Inter‐subtype recombination among CRF01_AE, subtype B and C was identified. Low level drug‐resistance in drug‐naïve heterosexually transmitted infections was found. The results suggested that multiple originating CRF01_AE strains dominated the HIV‐1 epidemic in heterosexual transmission in Guangxi province. J. Med. Virol. 85:388–395, 2013. © 2013 Wiley Periodicals, Inc.     

The spread of HIV-1 subtypes B and CRF01_AE among injecting drug users in Bangkok, Thailand

The HIV epidemic among injecting drug users (IDUs) in Bangkok was initially dominated by HIV subtype B and later by the recombinant CRF01_AE. The present study investigates the distribution of the 2 variants in time and how it is affected by changes in injecting risk behavior and treatment. A mathematic model describing the spread of HIV subtype B and CRF01_AE among IDUs was developed, and data from the AIDSVAX B/E cohort of IDUs in Bangkok were used. From the model, it was calculated that during 1999 to 2003, the annual incidence of HIV was around 0.6 and 2.7 to 3.9 infections per 100 person-years for subtype B and CRF01_AE, respectively. Of the new infections, 18% and 72% are first infections with subtype B and CRF01_AE, respectively, and 9% are superinfections. With increases in risk behavior, the fraction of superinfections rises. If treatment reduces the infectivity of CRF01_AE more than that of subtype B, the fraction of subtype B infections should increase. Subtype B should remain prevalent in a small but considerable fraction of the population for a long time. Changes in risk behavior and the introduction of treatment may alter the distribution of subtypes, but CRF01_AE should remain dominant.     

Human Immunodeficiency Virus Type 1 Subtypes Prevalence in Central China

Purpose

To study the epidemic characteristics, transmission sources and routes of various subtypes of human immunodeficiency virus type 1 (HIV-1) and sequence variations in Henan, central China. To provide theoretical foundation for Acquired Immune Deficiency Syndrome (AIDS) prevention strategy in this region where the primary HIV transmission route was through former paid blood donation.

Materials and Methods

HIV-1 gene env and gag were amplified by nested polymerase chain reaction (PCR) from uncultured peripheral blood mononuclear cells (PBMCs) obtained from 1,287 HIV-1 confirmed samples in Henan.

Results

Among 1,287 samples, 5 HIV-1 strains were found including subtypes B'' (95.9%), C (0.47%) and recombinant subtypes CRF 07_BC (1.09%), CRF 08_BC (1.79%) and CRF 01_AE (0.78%). Phylogenetic tree analysis found that 1,234 Henan subtype B'' were closely related to those commonly found in Thailand, and were distantly related to other international subtypes. The dominant strain in former blood plasma donors (FPDs) was subtype B'', and the dominant strains in sexual transmission were subtype B'' and BC. Among HIV patients who were most likely infected through routes other than paid blood donation, the percentage of non-B'' subtypes was much higher than those of FPD.

Conclusion

These findings suggest that the prevailing strain of HIV-1 in Henan is subtype B'', similar to the B'' subtype found in Thailand. In addition, for the first time we found subtypes C and recombinant subtypes CRF07_BC, CRF08_BC and CRF01_AE in this region. Indicating that the subtype feature of HIV-1 became more complicated than before in central China.     

Maternal HIV-1 antibody and vertical transmission in subtype C virus infection

The role of maternal humoral immune response and viral load was analyzed in relation to the incidence of mother-to-child transmission (MTCT) of infants born to HIV-1 subtype C infected mothers. High levels of viral RNA in the serum correlated with MTCT as did high titers of subtype C consensus V3 peptide binding antibodies (BA) and neutralizing antibody (NA) to subtype B HIV-1MN. Logistic regression analysis showed that maternal viral load and V3 peptide subtype C BA were independent predictors for MTCT, odds ratio (OR) = 2.22 and OR = 2.52, respectively. No correlation between NA to homologous HIV-1 subtype C virus and MTCT was found. BA to V3 peptides may provide a rapid inexpensive method that can be used to determine the risk of HIV-1 MTCT.     

Epitopes corresponding to the envelope genetic subtype are present on the surface of free virions of HIV-1 group M primary isolates and can be detected in neutralization assays with extended incubation phases

The hypothesis is that there are neutralizing epitopes on the surface of free virions of human immunodeficiency virus type 1 (HIV-1) that correspond to the genetic subtype of the envelope glycoprotein. Assays with extended incubation and reduced absorption phases are required to demonstrate neutralization with antibodies to these epitopes. These assays quantify virus infectivity, rather than reductions in release of antigen into culture supernatants. Neutralizing antibodies reduce virus infectivity by at least 80%, as scored by the presence/absence of antigen released after 14 days in culture of mitogen-transformed peripheral blood mononuclear cells (PBMCs). The epitopes are shared within different subtypes of group M, but not group O, isolates. Individual plasma, selected from three, independent panels of seropositive individuals, cross-neutralize within each subtype as well as the combinations of A with C, B with D or G, and C with CRF01_AE. Isolates within subtype B show the greatest variation in their resistance to neutralization, ranging from highly sensitive to highly resistant. No highly sensitive subtype D isolates were identified. Isolates from subtypes A, C, and CRF01_AE were all resistant. The strategic implication for vaccine design is that antibodies to a limited number of epitopes can neutralize more than 90% of the HIV-1 isolates that are circulating currently in the world. Also, since only antibodies that produce an all-or-nothing loss in virus infectivity can reasonably be expected to prevent the viremic phase after in vivo infection, assays with extended incubation, and culture phases should be used to monitor current efficacy trials.