Elicitation of Neutralizing Antibody Responses to HIV-1 Immunization with Nanoparticle Vaccine Platforms.

A leading strategy for developing a prophylactic HIV-1 vaccine is the elicitation of antibodies that can neutralize a large fraction of circulating HIV-1 variants. However, a major challenge that has limited the effectiveness of current vaccine candidates is the extensive global diversity of the HIV-1 envelope protein (Env), the sole target for HIV-neutralizing antibodies. To address this challenge, various strategies incorporating Env diversity into the vaccine formulation have been proposed. Here, we assessed the potential of two such strategies that utilize a nanoparticle-based vaccine platform to elicit broadly neutralizing antibody responses. The nanoparticle immunogens developed here consisted of different formulations of Envs from strains BG505 (clade A) and CZA97 (clade C), attached to the N-termini of bacterial ferritin. Single-antigen nanoparticle cocktails, as well as mosaic nanoparticles bearing both Env trimers, elicited high antibody titers in mice and guinea pigs. Furthermore, serum from guinea pigs immunized with nanoparticle immunogens achieved autologous, and in some cases heterologous, tier 2 neutralization, although significant differences between mosaic and single-antigen nanoparticles were not observed. These results provide insights into the ability of different vaccine strategies for incorporating Env sequence diversity to elicit neutralizing antibodies, with implications for the development of broadly protective HIV-1 vaccines.

Deep Sequencing Reveals Compartmentalized HIV-1 in the Semen of Men with and without Sexually Transmitted Infection-Associated Urethritis.

Concurrent sexually transmitted infections (STI) can increase the probability of HIV-1 transmission primarily by increasing the viral load present in semen. In this study, we explored the relationship of HIV-1 in blood and seminal plasma in the presence and absence of urethritis and after treatment of the concurrent STI. Primer ID deep sequencing of the V1/V3 region of the HIV-1 env gene was done for paired blood and semen samples from antiretroviral therapy (ART)-naive men living in Malawi with (n = 19) and without (n = 5) STI-associated urethritis; for a subset of samples, full-length env genes were generated for sequence analysis and to test entry phenotype. Cytokine concentrations in the blood and semen were also measured, and a reduction in the levels of proinflammatory cytokines was observed following STI treatment. We observed no difference in the prevalence of diverse compartmentalized semen-derived lineages in men with or without STI-associated urethritis, and these viral populations were largely stable during STI treatment. Clonal amplification of one or a few viral sequences accounted for nearly 50% of the viral population, indicating a recent bottleneck followed by limited viral replication. We conclude that the male genital tract is a site where virus can be brought in from the blood, where localized sustained replication can occur, and where specific genotypes can be amplified, perhaps initially by cellular proliferation but further by limited viral replication.IMPORTANCE HIV-1 infection is a sexually transmitted infection that coexists with other STI. Here, we examined the impact of a concurrent STI resulting in urethritis on the HIV-1 population within the male genital tract. We found that viral populations remain largely stable even with treatment of the STI. These results show that viral populations within the male genital tract are defined by factors beyond transient inflammation associated with a concurrent STI.

HIV-1 genetic transmission networks among men who have sex with men in Kunming, China.

BACKGROUND: Yunnan has the greatest share of reported human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) cases in China. In recent years, HIV prevalence and incidence remained stubbornly high in men who have sex with men (MSM). To follow the dynamics of the HIV-1 epidemic among MSM, HIV-1 genetic characteristics and genetic transmission networks were investigated. METHODS: Blood samples from 190 newly diagnosed HIV-1 cases among MSM were continuously collected at fixed sites from January 2013 to December 2015 in Kunming City, Yunnan Province. Partial gag, pol and env genes were sequenced and used for phylogenetic and genotypic drug resistance analyses. The genetic characteristics of the predominant HIV-1 strains were analyzed by the Bayesian Markov Chain Monte Carlo (MCMC) method. The genetic transmission networks were identified with a genetic distance of 0.03 substitutions/site and 90% bootstrap support. RESULTS: Among the 190 HIV-1 positive MSM reported during 2013-2105, various genotypes were identified, including CRF01_AE (45.3%), CRF07_BC (35.8%), unique recombinant forms (URFs) (11.6%), CRF08_BC (3.2%), CRF55_01B (2.1%), subtype B (1.6%) and CRF59_01B (0.5%). The effective population sizes (EPS) for CRF01_AE and CRF07_BC increased exponentially from approximately 2001-2010 and 2005-2009, respectively. Genetic transmission networks were constructed with 308 pol sequences from MSM diagnosed during 2010-2015. Of the 308 MSM, 109 (35.4%) were identified in 38 distinct clusters. Having multiple male partners was associated with a high probability of identification in the genetic transmission networks. Of the 38 clusters, 27 (71.1%) contained individuals diagnosed in different years. Of the 109 individuals in the networks, 26 (23.9%) had ≥2 potential transmission partners (≥2 links). The proportion of MSM with ≥2 links was higher among those diagnosed from 2010-2012. The constituent ratios of their potential transmission partners by areas showed no significant difference among MSM from Kunming, other cities in Yunnan and other provinces. Additionally, surveillance drug resistance mutations (SDRMs) were identified in 5% of individuals. CONCLUSION: This study revealed the various HIV-a genotypes circulating among MSM in Kunming. MSM with more partners were more easily detected in transmission networks, and early-diagnosed MSM remained active in transmission networks. These findings suggested that the routine interventions should be combined with HIV testing and linkage to care and early antiretroviral therapy among HIV-positive MSM.

Higher viral load and genetic diversity of HIV-1 in seminal compartments than in blood of seven Chinese men who have sex with men and have early HIV-1 infection.

To date, there have been no reports characterizing HIV-1 in the semen of Chinese men who have sex with men (MSM) with early infection. In this study, genetic diversity and viral load of HIV-1 in the seminal compartments and blood of Chinese MSM with early HIV-1 infection were examined. Viral load and genetic diversity of HIV-1 in paired samples of semen and blood were analyzed in seven MSM with early HIV-1 infection. HIV-1 RNA and DNA were quantitated by real-time PCR assays. Through sequencing the C2-V5 region of the HIV-1 env gene, the HIV-1 genotype and genetic diversity based on V3 loop amino acid sequences were determined by using Geno2pheno and PSSM programs co-receptor usage. It was found that there was more HIV-1 RNA in seminal plasma than in blood plasma and total, and more 2-LTR circular and integrated HIV-1 DNA in seminal cells than in peripheral blood mononuclear cells from all seven patients with early HIV-infection. There was also greater HIV-1 genetic diversity in seminal than in blood compartments. HIV-1 in plasma displayed higher genetic diversity than in cells from the blood and semen. In addition, V3 loop central motifs, which present some key neutralizing antibody epitopes, varied between blood and semen. Thus, virological characteristics in semen may be more representative when evaluating risk of transmission in persons with early HIV infection.

Differentiating founder and chronic HIV envelope sequences.

Significant progress has been made in characterizing broadly neutralizing antibodies against the HIV envelope glycoprotein Env, but an effective vaccine has proven elusive. Vaccine development would be facilitated if common features of early founder virus required for transmission could be identified. Here we employ a combination of bioinformatic and operations research methods to determine the most prevalent features that distinguish 78 subtype B and 55 subtype C founder Env sequences from an equal number of chronic sequences. There were a number of equivalent optimal networks (based on the fewest covarying amino acid (AA) pairs or a measure of maximal covariance) that separated founders from chronics: 13 pairs for subtype B and 75 for subtype C. Every subtype B optimal solution contained the founder pairs 178-346 Asn-Val, 232-236 Thr-Ser, 240-340 Lys-Lys, 279-315 Asp-Lys, 291-792 Ala-Ile, 322-347 Asp-Thr, 535-620 Leu-Asp, 742-837 Arg-Phe, and 750-836 Asp-Ile; the most common optimal pairs for subtype C were 644-781 Lys-Ala (74 of 75 networks), 133-287 Ala-Gln (73/75) and 307-337 Ile-Gln (73/75). No pair was present in all optimal subtype C solutions highlighting the difficulty in targeting transmission with a single vaccine strain. Relative to the size of its domain (0.35% of Env), the α4ß7 binding site occurred most frequently among optimal pairs, especially for subtype C: 4.2% of optimal pairs (1.2% for subtype B). Early sequences from 5 subtype B pre-seroconverters each exhibited at least one clone containing an optimal feature 553-624 (Ser-Asn), 724-747 (Arg-Arg), or 46-293 (Arg-Glu).

Deep Sequencing of the HIV-1 env Gene Reveals Discrete X4 Lineages and Linkage Disequilibrium between X4 and R5 Viruses in the V1/V2 and V3 Variable Regions.

UNLABELLED: HIV-1 requires the CD4 receptor and a coreceptor (CCR5 [R5 phenotype] or CXCR4 [X4 phenotype]) to enter cells. Coreceptor tropism can be assessed by either phenotypic or genotypic analysis, the latter using bioinformatics algorithms to predict tropism based on the env V3 sequence. We used the Primer ID sequencing strategy with the MiSeq sequencing platform to reveal the structure of viral populations in the V1/V2 and C2/V3 regions of the HIV-1 env gene in 30 late-stage and 6 early-stage subjects. We also used endpoint dilution PCR followed by cloning of env genes to create pseudotyped virus to explore the link between genotypic predictions and phenotypic assessment of coreceptor usage. We found out that the most stringently sequence-based calls of X4 variants (Geno2Pheno false-positive rate [FPR] of ≤2%) formed distinct lineages within the viral population, and these were detected in 24 of 30 late-stage samples (80%), which was significantly higher than what has been seen previously by using other approaches. Non-X4 lineages were not skewed toward lower FPR scores in X4-containing populations. Phenotypic assays showed that variants with an intermediate FPR (2 to 20%) could be either X4/dual-tropic or R5 variants, although the X4 variants made up only about 25% of the lineages with an FPR of <10%, and these variants carried a distinctive sequence change. Phylogenetic analysis of both the V1/V2 and C2/V3 regions showed evidence of recombination within but very little recombination between the X4 and R5 lineages, suggesting that these populations are genetically isolated. IMPORTANCE: Primer ID sequencing provides a novel approach to study genetic structures of viral populations. X4 variants may be more prevalent than previously reported when assessed by using next-generation sequencing (NGS) and with a greater depth of sampling than single-genome amplification (SGA). Phylogenetic analysis to identify lineages of sequences with intermediate FPR values may provide additional information for accurately predicting X4 variants by using V3 sequences. Limited recombination occurs between X4 and R5 lineages, suggesting that X4 and R5 variants are genetically isolated and may be replicating in different cell types or that X4/R5 recombinants have reduced fitness.

Genotypic prediction of tropism of highly diverse HIV-1 strains from Cameroon.

BACKGROUND: The use of CCR5 antagonists involves determination of HIV-1 tropism prior to initiation of treatment. HIV-1 tropism can be assessed either by phenotypic or genotypic methods. Genotypic methods are extensively used for tropism prediction. However, their validation in predicting tropism of viral isolates belonging to group M non-B subtypes remains challenging. In Cameroon, the genetic diversity of HIV-1 strains is the broadest reported worldwide. To facilitate the integration of CCR5 antagonists into clinical practice in this region, there is a need to evaluate the performance of genotypic methods for predicting tropism of highly diverse group M HIV-1 strains. METHODS: Tropism of diverse HIV-1 strains isolated from PBMCs from Cameroon was determined using the GHOST cell assay. Prediction, based on V3 sequences from matched plasma samples, was determined using bioinformatics algorithms and rules based on position 11/25 and net charge applied independently or combined according to Delobel's and Garrido's rules. Performance of genotypic methods was evaluated by comparing prediction generated with tropism assigned by the phenotypic assay. RESULTS: Specificity for predicting R5-tropic virus was high, ranging from 83.7% to 97.7% depending on the genotypic methods used. Sensitivity for X4-tropic viruses was fairly low, ranging from 33.3% to 50%. In our study, overall, genotypic methods were less able to accurately predict X4-tropic virus belonging to subtype CRF02_AG. In addition, it was found that of the methods we used the Garrido rule has the highest sensitivity rate of over 50% with a specificity of 93%. CONCLUSION: Our study demonstrated that overall, genotypic methods were less sensitive for accurate prediction of HIV-1 tropism in settings where diverse HIV-1 strains co-circulate. Our data suggest that further optimization of genotypic methods is needed and that larger studies to determine their utility for tropism prediction of diverse HIV-1 strains may be warranted.

HIV latency. Proliferation of cells with HIV integrated into cancer genes contributes to persistent infection.

Antiretroviral treatment (ART) of HIV infection suppresses viral replication. Yet if ART is stopped, virus reemerges because of the persistence of infected cells. We evaluated the contribution of infected-cell proliferation and sites of proviral integration to HIV persistence. A total of 534 HIV integration sites (IS) and 63 adjacent HIV env sequences were derived from three study participants over 11.3 to 12.7 years of ART. Each participant had identical viral sequences integrated at the same position in multiple cells, demonstrating infected-cell proliferation. Integrations were overrepresented in genes associated with cancer and favored in 12 genes across multiple participants. Over time on ART, a greater proportion of persisting proviruses were in proliferating cells. HIV integration into specific genes may promote proliferation of HIV-infected cells, slowing viral decay during ART.

Neurocognitive impairment in HIV-1 clade C- versus B-infected individuals in Southern Brazil.

HIV-1 clade C isolates show reduced Tat protein chemoattractant activity compared with clade B. This might influence neuropathogenesis by altering trafficking of monocytes into the CNS. A previous study suggested low rates of HIV-associated dementia in clade C-infected individuals. The present study evaluated neurocognitive impairment rates in clade B- and C-infected individuals from the same local population. HIV+ and HIV- participants were recruited from the same geographic region in Southern Brazil. We evaluated neuropsychological (NP) impairment using a screening instrument (the International HIV Dementia Scale (IHDS)), as well as a Brazilian Portuguese adaptation of a comprehensive battery that has demonstrated sensitivity to HIV-associated neurocognitive disorders (HAND) internationally. NP performance in controls was used to generate T scores and impairment ratings by the global deficit score (GDS) method. Clade assignments were ascertained by sequencing pol and env. Blood and cerebrospinal fluid were collected from all HIV+ participants. HIV+ and HIV- participants were comparable on demographic characteristics. HIV+ participants overall were more likely to be impaired than HIV- by the IHDS and the GDS. Clade B- and C-infected individuals were demographically similar and did not differ significantly in rates of impairment. The prevalence of pleocytosis, a marker of intrathecal cellular chemotaxis, also did not differ between clade B and C infections. Clade B and C HIV-infected individuals from the same geographic region, when ascertained using comparable methods, did not differ in their rates of neurocognitive impairment, and there was no evidence of differences in CNS chemotaxis.

Prevalence of transmitted HIV drug resistance in Iran between 2010 and 2011.

OBJECTIVE: Drug-resistant (DR) HIV emerges during combined antiretroviral treatment (cART), creating concern about widespread transmission of DR-HIV as cART is expanded in resource-limited countries. The aim of this study was to determine the predominant HIV-1 subtypes and prevalence of transmitted DR mutations among antiretroviral-naïve patients in Iran. DESIGN: To monitor transmission of DR HIV, a threshold surveillance based on the world health organization (WHO) guidelines was implemented in Iran. METHODS: For this HIVDR threshold surveillance study, blood samples were collected from 50 antiretroviral-naïve HIV-1-infected patients. Antiretroviral-resistant mutations were determined by sequencing HIV-1 protease, reverse transcriptase and integrase regions. The HIV-1 subtype was determined by sequencing the p17 and C2-V5 regions of the gag and env genes, respectively. RESULTS: Phylogenetic analyses of the sequenced regions revealed that 45 (95.7%) of 47 samples that were successfully obtained were CRF35_AD. The remaining two cases were subtype B (2.1%) and CRF01_AE (2.1%). Consistent results were obtained also from Env and Gag sequences. Regarding prevalence of transmitted DR viruses, two cases were found to harbor reverse transcriptase-inhibitor-resistant mutations (4.3%). In addition, although not in the WHO list for surveillance of transmitted mutations, 13 minor protease-inhibitor-resistant mutations listed in the International AIDS Society-USA panel of drug resistance mutations were found. No DR mutations were detected in the integrase region. CONCLUSIONS: Our study clarified that CRF35_AD is the major subtype among HIV-1-infected patients in Iran. According to the WHO categorization method of HIVDR threshold survey, the prevalence of transmitted drug resistant HIV in Iran was estimated as moderate (5-15%).

High concordance between the position-specific scoring matrix and geno2pheno algorithms for genotypic interpretation of HIV-1 tropism: V3 length as the major cause of disagreement.

The agreement between the position-specific scoring matrix (PSSM) and geno2pheno as tools for genotypic interpretation of HIV-1 tropism using 800 clinical specimens was assessed. There was an overall concordance of 88%. Disagreement was found mostly in specimens with short V3 lengths (<35 amino acids). Thus, consideration of V3 lengths should improve the predictability of HIV-1 tropism using genotypic algorithms.

[Molecular epidemiology of HIV-1 strains in the Moscow Region].

The Moscow Region is one of the HIV-1-affected subjects of the Russian Federation; there were 34613 HIV-1-infected subjects as of October 31, 2009. To characterize the molecular epidemiology of HIV-1 in the Moscow Region, the investigators obtained and studied HIV-1 variants from 61 infected subjects of the region, who were major risk groups: intravenous drug users (IDUs) and hetero- and homosexually infected persons. Genetic analysis of HIV-1 variants was carried out by sequencing the gag genes (729 nucleotides in length, including full-length protein p17 and partial p24) andlor env (270 nucleotides in length, V3 region) with further phylogenetic analysis. The findings demonstrated that HIV-1 subtype A variants are dominant in the Moscow Region and detectable in 93.5% of IDUs and 100% of heterosexually infected persons. Phylogenetically (and accordingly epidemiologically) unrelated HIV-1 subtype B strains were revealed in 4 patients, including 2 IDUs.

Entecavir therapy induces de novo HIV reverse-transcriptase M184V mutation in an antiretroviral therapy-naive patient.

Recently, entecavir was introduced as a potent drug against hepatitis B virus infection. Initially, it was suggested not to have any effect on human immunodeficiency virus (HIV) infection. This guideline was revised in 2007 because of a report showing that the M184V mutation was selected in an hepatitis B virus and HIV-coinfected patient previously treated with lamivudine. Our investigation revealed findings similar to those preveiously reported but in an antiretroviral therapy-naive patient coinfected with HIV and hepatitis B virus. After 26 weeks of entecavir therapy, the M184V mutation dominated the plasma viral population. Thus, entecavir should only be used for coinfected patients who simultaneously receive suppressive therapy against HIV infection.

Clade specific neutralising vaccines for HIV: an appropriate target?

The enormous diversity of the human immunodeficiency virus (HIV) has led to the idea that designing vaccines to specific geographic regions, or clades, could simplify the complexity of the task. Yet, despite the sequence diversity, all HIV viruses known to date interact with the same cellular receptors (CD4 and/or a coreceptor, CCR5 or CXCR4). In this review we examine the existing evidence to support a clade-specific vaccine strategy for induction of neutralising antibodies. We concentrate on lessons learnt from natural infection of humans. In short, the vast majority of studies to date indicate that neutralisation of HIV-1 is not clade specific. Potent sera tend to neutralise a range of heterologous viruses with no apparent clade preference, and none of the human neutralising monoclonal antibodies so far generated demonstrate significant clade preference. All but one of the most broadly neutralising antibodies are to functional regions involved in receptor interactions and plasma membrane fusion. Given these facts, we suggest that vaccine approaches that focus on 'clade-specific' and 'clade-generic' vaccines will logically converge on the same functionally conserved envelope structures. It still remains to be determined whether or not the task of designing a 'clade-generic' vaccine could be simplified by focusing on the viral envelopes with 'transmitting phenotypes'.

[Sequence analysis of gag and env genes of HIV type 1 circulating in former blood donors of Fuyang city, Anhui province].

OBJECTIVE: To determine the subtype and analyze the genetic characteristics of the HIV-1 predominantly circulating in the former blood donors of Fuyang city, Anhui province. METHODS: Whole blood samples were collected from 294 HIV-positive former blood donors of Fuyang city, 157 males and 137 females, aged 42 +/- 8. The fragments of HIV-1 env and gag genes were amplified by nested-PCR from the whole blood samples and thereafter sequenced. The env and gag sequences derived from 244 and 245 HIV infected individuals respectively were analyzed by using MEGA software, and related researches were also done according to the disease progression of the HIV infected individuals. RESULTS: Phylogenetic trees showed that both the env and gag strains were clustered with the Thailand B reference strains. The internal nucleotide distances of the env and gag genes were 9.11% and 3.59% respectively. The nucleotide distances of both env and gag genes significantly increased as the CD4 T-cell counts decreased or as the viral load rose (both P < 0.001). The V3 loop tip motifs were dramatically dominated by GPGQ in the long-time non-progressors, and by GPGR in the slow progressors (P = 0.038). CONCLUSION: The predominant strains circulating in the HIV-1 infected former blood donors of Fuyang city are of the Thailand B clade. Low CD4 T-cell count and high viral load are associated with the increase of genetic distances among viral isolates. The V3 loop tip motif changes from GPGQ to GPGR along with the progression of disease.