Snapshot of HIV pathogenesis in China

Generation and characterization of a bivalent protein boost for future clinical trials: HIV-1 subtypes CR01_AE and B gp120 antigens with a potent adjuvant

The RV144 Phase III clinical trial with ALVAC-HIV prime and AIDSVAX B/E subtypes CRF01_AE (A244) and B (MN) gp120 boost vaccine regime in Thailand provided a foundation for the future development of improved vaccine strategies that may afford protection against the human immunodeficiency virus type 1 (HIV-1). Results from this trial showed that immune responses directed against specific regions V1V2 of the viral envelope (Env) glycoprotein gp120 of HIV-1, were inversely correlated to the risk of HIV-1 infection. Due to the low production of gp120 proteins in CHO cells (2–20 mg/L), cleavage sites in V1V2 loops (A244) and V3 loop (MN) causing heterogeneous antigen products, it was an urgent need to generate CHO cells harboring A244 gp120 with high production yields and an additional, homogenous and uncleaved subtype B gp120 protein to replace MN used in RV144 for the future clinical trials. Here we describe the generation of Chinese Hamster Ovary (CHO) cell lines stably expressing vaccine HIV-1 Env antigens for these purposes: one expressing an HIV-1 subtype CRF01_AE A244 Env gp120 protein (A244.AE) and one expressing an HIV-1 subtype B 6240 Env gp120 protein (6240.B) suitable for possible future manufacturing of Phase I clinical trial materials with cell culture expression levels of over 100 mg/L. The antigenic profiles of the molecules were elucidated by comprehensive approaches including analysis with a panel of well-characterized monoclonal antibodies recognizing critical epitopes using Biacore and ELISA, and glycosylation analysis by mass spectrometry, which confirmed previously identified glycosylation sites and revealed unknown sites of O-linked and N-linked glycosylations at non-consensus motifs. Overall, the vaccines given with MF59 adjuvant induced higher and more rapid antibody (Ab) responses as well as higher Ab avidity than groups given with aluminum hydroxide. Also, bivalent proteins (A244.AE and 6240.B) formulated with MF59 elicited distinct V2-specific Abs to the epitope previously shown to correlate with decreased risk of HIV-1 infection in the RV144 trial. All together, these results provide critical information allowing the consideration of these candidate gp120 proteins for future clinical evaluations in combination with a potent adjuvant.

The evolutionary patterns of hepatitis C virus subtype 2a and 6a isolates linked to an outbreak in China in 2012

An HCV outbreak occurred in 2012 in China, affecting hundreds of patients. We characterized HCV subtype 2a and 6a sequences from 60 and 102 patients, respectively, and co-analyzed them with 82 local controls and 103 calibrating references. The close grouping of the patients׳ sequences contrasted sharply with the diversity of local controls. Scaled by the calibrating references, the emergence of patients׳ isolates was estimated at 2-5 years before sampling. In contrast, the controls intermingled with the calibrating references that were much older. For both subtypes, the major and minor clusters could be defined, with the closeness to indicate linked transmission.

CONCLUSION

HCV sequences from the study patients grouped into three subtype 2a and two subtype 6a clusters, in addition to three 6a solitary branches, representing descendants of eight earlier strains that were distinct and otherwise sporadic. Due to iatrogenic transmission through reusing needles, five strains were highly selected and preferentially spread.

Update on diversity and distribution of HIV-1 subtypes in Yunnan province

The aim of this study was to characterize updated HIV subtypes in Yunnan to determine their origins and distribution within the population. RT-PCR of both the gag and env genes were sequenced from Yunnan province inhabitants newly diagnosed with HIV-1. Sequence data from 290 samples were used for statistical analysis of subtype distribution and phylogenetic tree construction. Distribution data were adjusted to account for different geographical distributions of HIV-1 subtypes in the population. Phylogenetic analysis revealed six HIV-1 subtypes in Yunnan, including eight types of unique recombination forms (URFs). The most prevalent subtypes in this province, CRF07_BC (18·9%), CRF08_BC (39·1%), CRF01_AE (22·4%), and URFs (subtype C, 5·9% and subtype B, 4·5%), were all recombinants. We found significant differences in the distribution of these HIV-1 subtypes not only geographically, but also between various ethnic groups and with respect to transmission routes. Our findings indicate a complex population of HIV-1 subtypes, URFs, and recombinant subtypes in Yunnan province. This diversity could make the prevention and control of HIV infection in Yunnan more difficult due to the possibility of virus recombination or infection by multiple subtypes.

Sensitive detection of the K103N non-nucleoside reverse transcriptase inhibitor resistance mutation in treatment-naïve HIV-1 infected individuals by rolling circle amplification

Primary or transmitted antiretroviral drug resistance mutations pose a significant obstacle for optimizing antiviral treatment. When present at low-levels, resistance mutations are less likely to be detected by standard genotyping assays. This study utilizes a novel rolling circle amplification (RCA) method using padlock probes to achieve the sensitive, specific and low-level detection of the NNRTI resistance K103N from 59 HIV+ treatment-naïve patients from Beijing, China. Using standard genotyping methods, primary drug resistance mutations to either protease or RT inhibitors were found in 25% (15/59) of patients attending hospital clinics in Beijing. Among these 15 patients with antiretroviral (ARV) resistance mutations, standard sequence-based genotyping revealed that most (10/15) had the 103N. Using a highly sensitive RCA assay, 5 more patients among the 59 treatment-naïve cohort were found to have the 103N, but at low-levels, leading to an overall rate of 103N at 25.4% (15/59) in this population. The high prevalence of the 103N suggests that baseline resistance testing should be performed before treatment in this population. Importantly, the new RCA technology allows large-scale, sensitive detection of drug resistance mutations, including detection of minority populations with minimal equipment requirement.

The possible contribution of HIV-1-induced syncytia to the generation of intersubtype recombinants in vitro

OBJECTIVE

To develop a method for single syncytia isolation and delineate the possible contribution of syncytia to intersubtype recombination.

DESIGN

We dually infected whole peripheral mononuclear blood cells with subtype A and D viruses and studied syncytia in vitro and developed a method to isolate individual syncytia to further study HIV variants/dual infections, viral isolation, proviral copies in single syncytia and possible intersubtype recombination in dual cultures containing syncytia using real time PCR.

METHODS

Cell culture-based single syncytia isolation, PCR and cloning to determine the nature of HIV variants and real-time PCR to determine proviral copies per individual syncytium and intersubtype recombination in dual cultures. Viral coculture from single syncytia and p24 antigen determination for assessing viral replication in vitro.

RESULTS

Our results show the feasibility that not only can single syncytia be successfully isolated, but the viruses from individual syncytia can also be grown in vitro. They also demonstrate the ability of single syncytia to bring diverse HIV-1 subtypes together along with the possible contribution to intersubtype recombination in vitro. Up to 40% of single syncytia harbored both input HIV-1 subtypes and single syncytium could harbor as many as 2000 proviral DNA copies, which exceeds the limit seen in a single cell.

CONCLUSION

These analyses are unique in experimentally confirming the previously held belief that single syncytia can harbor multiple HIV strains and that they can serve as a breeding ground for heterozygous virions and this may contribute toward viral diversity and intersubtype recombination.

Complex patterns of the HIV-1 epidemic in Kuala Lumpur, Malaysia: Evidence for expansion of circulating recombinant form CRF33_01B and detection of multiple other recombinants

The HIV protease-reverse transcriptase (PR-RT) (1047 bp), gp120-env (891 bp) and gp41-env (547 bp) regions from the plasma of 115 HIV-1-infected patients in Kuala Lumpur (KL), Malaysia were sequenced. Detailed phylogenetic and bootscanning analyses were performed to determine the mosaic structure of the HIV-1 strains and their recombination breakpoint(s). Among the 50 patient samples in which all three regions could be amplified, the HIV-1 CRF01_AE subtype (46%) was predominant followed by subtypes B (10%) and B' (6%). A total of 9/50 (18%) patients were infected with a CRF01_AE/B inter-subtype recombinant, displaying a recombinant form (RF)(PR-RT), CRF01_AE(gp120-env) and CRF01_AE(gp41-env). This RF was derived from the Thai variants of CRF01_AE and B' subtype, with two distinct B' subtype segments in the backbone of CRF01_AE, similar to the newly identified CRF33_01B. In addition, one sample demonstrated a close structural relationship with the new CRF33_01B in the PR-RT region but displayed B' segment in part of the env region (RF(PR-RT), CRF01_AE/B'(gp120-env) and B'(gp41-env)) indicating continuing evolution of CRF33_01B. The remaining 18% of samples were identified as unique recombinant forms (URFs).

The influence of social and sexual networks in the spread of HIV and syphilis among men who have sex with men in Shanghai, China

OBJECTIVES

To analyze characteristics of social and sexual networks and their role as risk factors for HIV and syphilis among men who have sex with men (MSM) in Shanghai, China.

DESIGN

: A cross-sectional study.

METHODS

We recruited 477 participants using a snowball sampling method. We administered a face-to-face questionnaire and provided testing and counseling for HIV and syphilis.

RESULTS

The prevalences of HIV and markers for syphilis were 1.47% (95% confidence interval [CI]: 0.59 to 3.01) and 13.47% (95% CI: 10.53 to 16.88), respectively. The independent factors associated with lower risk for syphilis infection were having a contact network, overlap of social and sexual networks, meeting other MSM at the gym or through the Internet, having 3 to 5 lifetime male anal sex partners, and having a female steady sex partner. A larger male sexual network size, having been married, being more knowledgeable about HIV, having 6 or more lifetime male anal sex partners, and having steady male or female sex partners were independently associated with having unprotected anal or vaginal intercourse.

CONCLUSIONS

Significant associations were found between network characteristics and syphilis infection and unprotected sex. Network-based interventions should be developed to reduce this HIV risk among MSM in China.