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

Structures and immune recognition of Env trimers from two Asia prevalent HIV-1 CRFs

Structure-guided immunofocusing HIV-1 vaccine design entails a comprehensive understanding of Envs from diverse HIV-1 subtypes, including circulating recombinant forms (CRFs). Here, we present the cryo-EM structures of Envs from two Asia prevalent CRFs (CRF01_AE and CRF07_BC) at 3.0 and 3.5 Å. We compare the structures and glycosylation patterns of Envs from different subtypes and perform cross-clade statistical analyses to reveal the unique features of CRF01_AE V1 region, which are associated with the resistance to certain bNAbs. We also solve a 4.1 Å cryo-EM structure of CRF01_AE Env in complex with F6, the first bNAb from CRF01_AE-infected individuals. F6 recognizes a gp120-gp41 spanning epitope to allosterically destabilize the Env trimer apex and weaken inter-protomer packing, which in turn hinders the receptor binding and induces Env trimer disassembly, demonstrating a dual mechanism of neutralization. These findings broaden our understanding of CRF Envs and shed lights on immunofocusing HIV-1 vaccine design.

Inferring the multiplicity of founder variants initiating HIV-1 infection: a systematic review and individual patient data meta-analysis

BACKGROUND

HIV-1 infections initiated by multiple founder variants are characterised by a higher viral load and a worse clinical prognosis than those initiated with single founder variants, yet little is known about the routes of exposure through which transmission of multiple founder variants is most probable. Here we used individual patient data to calculate the probability of multiple founders stratified by route of HIV exposure and study methodology.

METHODS

We conducted a systematic review and meta-analysis of studies that estimated founder variant multiplicity in HIV-1 infection, searching MEDLINE, Embase, and Global Health databases for papers published between Jan 1, 1990, and Sept 14, 2020. Eligible studies must have reported original estimates of founder variant multiplicity in people with acute or early HIV-1 infections, have clearly detailed the methods used, and reported the route of exposure. Studies were excluded if they reported data concerning people living with HIV-1 who had known or suspected superinfection, who were documented as having received pre-exposure prophylaxis, or if the transmitting partner was known to be receiving antiretroviral treatment. Individual patient data were collated from all studies, with authors contacted if these data were not publicly available. We applied logistic meta-regression to these data to estimate the probability that an HIV infection is initiated by multiple founder variants. We calculated a pooled estimate using a random effects model, subsequently stratifying this estimate across exposure routes in a univariable analysis. We then extended our model to adjust for different study methods in a multivariable analysis, recalculating estimates across the exposure routes. This study is registered with PROSPERO, CRD42020202672.

FINDINGS

We included 70 publications in our analysis, comprising 1657 individual patients. Our pooled estimate of the probability that an infection is initiated by multiple founder variants was 0·25 (95% CI 0·21-0·29), with moderate heterogeneity (Q=132·3, p<0·0001, I²=64·2%). Our multivariable analysis uncovered differences in the probability of multiple variant infection by exposure route. Relative to a baseline of male-to-female transmission, the predicted probability for female-to-male multiple variant transmission was significantly lower at 0·13 (95% CI 0·08-0·20), and the probabilities were significantly higher for transmissions in people who inject drugs (0·37 [0·24-0·53]) and men who have sex with men (0·30 [0·33-0·40]). There was no significant difference in the probability of multiple variant transmission between male-to-female transmission (0·21 [0·14-0·31]), post-partum transmission (0·18 [0·03-0·57]), pre-partum transmission (0·17 [0·08-0·33]), and intra-partum transmission (0·27 [0·14-0·45]).

INTERPRETATION

We identified that transmissions in people who inject drugs and men who have sex with men are significantly more likely to result in an infection initiated by multiple founder variants, and female-to-male infections are significantly less probable. Quantifying how the routes of HIV infection affect the transmission of multiple variants allows us to better understand how the evolution and epidemiology of HIV-1 determine clinical outcomes.

FUNDING

Medical Research Council Precision Medicine Doctoral Training Programme and a European Research Council Starting Grant.

Unique profile of predominant CCR5-tropic in CRF07_BC HIV-1 infections and discovery of an unusual CXCR4-tropic strain

CRF07_BC is one of the most prevalent HIV-1 strains in China, which contributes over one-third of the virus transmissions in the country. In general, CRF07_BC is associated with slower disease progression, while the underlying mechanisms remain unclear. Our study focused on envelope proteins (Env) and its V3 loop which determine viral binding to co-receptors during infection of cells. We studied a large dataset of 3,937 env sequences in China and found that CRF07_BC had a unique profile of predominantly single CCR5 tropism compared with CCR5 and CXCR4 dual tropisms in other HIV-1 subtypes. The percentages of the CXCR4-tropic virus in B (3.7%) and CRF01_AE (10.4%) infection are much higher than that of CRF07_BC (0.1%), which is supported by median false-positive rates (FPRs) of 69.8%, 25.5%, and 13.4% for CRF07_BC, B, and CRF01_AE respectively, with a cutoff FPR for CXCR4-tropic at 2%. In this study, we identified the first pure CXCR4-tropic virus from one CRF07_BC-infected patient with an extremely low CD4⁺T cell count (7 cells/mm³). Structural analysis found that the V3 region of this virus has the characteristic 7T and 25R and a substitution of conserved “GPGQ” crown motif for “GPGH”. This study provided compelling evidence that CRF07_BC has the ability to evolve into CXCR4 strains. Our study also lay down the groundwork for studies on tropism switch, which were commonly done for other HIV-1 subtypes, for the long-delayed CRF07_BC.

Schlafen 5 suppresses human immunodeficiency virus type 1 transcription by commandeering cellular epigenetic machinery

Schlafen-5 (SLFN5) is an interferon-induced protein of the Schlafen family, which are involved in immune responses and oncogenesis. To date, little is known regarding its anti-HIV-1 function. Here, the authors report that overexpression of SLFN5 inhibits HIV-1 replication and reduces viral mRNA levels, whereas depletion of endogenous SLFN5 promotes HIV-1 replication. Moreover, they show that SLFN5 markedly decreases the transcriptional activity of HIV-1 long terminal repeat (LTR) via binding to two sequences in the U5-R region, which consequently represses the recruitment of RNA polymerase II to the transcription initiation site. Mutagenesis studies show the importance of nuclear localization and the N-terminal 1-570 amino acids fragment in the inhibition of HIV-1. Further mechanistic studies demonstrate that SLFN5 interacts with components of the PRC2 complex, G9a and Histone H3, thereby promoting H3K27me2 and H3K27me3 modification leading to silencing HIV-1 transcription. In concert with this, they find that SLFN5 blocks the activation of latent HIV-1. Altogether, their findings demonstrate that SLFN5 is a transcriptional repressor of HIV-1 through epigenetic modulation and a potential determinant of HIV-1 latency.

Increased predominance of HIV-1 CRF01_AE and its recombinants in the Philippines

The growth rate of new HIV infections in the Philippines was the fastest of any countries in the Asia-Pacific region between 2010 and 2016. To date, HIV-1 subtyping results in the Philippines have been determined by characterizing only partial viral genome sequences. It is not known whether recombination occurs in the majority of unsequenced genome regions. Near-full-length genome (NFLG) sequences were obtained by amplifying two overlapping half genomes from plasma samples collected between 2015 and 2017 from 23 newly diagnosed infected individuals in the Philippines. Phylogenetic analysis showed that the newly characterized sequences were CRF01_AE (14), subtype B (3), CRF01/B recombinants (5) and a CRF01/CRF07/B recombinant (1). All 14 CRF01_AE formed a tight cluster, suggesting that they were derived from a single introduction. The time to the most recent common ancestor (tMRCA) for CRF01_AE in the Philippines was 1995 (1992-1998), about 10-15 years later than that of CRF01_AE in China and Thailand. All five CRF01/B recombinants showed distinct recombination patterns, suggesting ongoing recombination between the two predominant circulating viruses. The identification of partial CRF07_BC sequences in one CRF01/CRF07/B recombinant, not reported previously in the Philippines, indicated that CRF07_BC may have been recently introduced into that country from China, where CRF07_BC is prevalent. Our results show that the major epidemic strains may have shifted to an increased predominance of CRF01_AE and its recombinants, and that other genotypes such as CRF07_BC may have been introduced into the Philippines.

Disparate impact on CD4 T cell count by two distinct HIV-1 phylogenetic clusters from the same clade

HIV-1 evolved into various genetic subtypes and circulating recombinant forms (CRFs) in the global epidemic. The same subtype or CRF is usually considered to have similar phenotype. Being one of the world's major CRFs, CRF01_AE infection was reported to associate with higher prevalence of CXCR4 (X4) viruses and faster CD4 decline. However, the underlying mechanisms remain unclear. We identified eight phylogenetic clusters of CRF01_AE in China and hypothesized that they may have different phenotypes. In the National HIV Molecular Epidemiology Survey, we discovered that people infected by CRF01_AE cluster 4 had significantly lower CD4 counts (391 vs. 470, P < 0.0001) and higher prevalence of X4-using viruses (17.1% vs. 4.4%, P < 0.0001) compared with those infected by cluster 5. In an MSM cohort, X4-using viruses were only isolated from seroconvertors in cluster 4, which was associated with low a CD4 count within the first year of infection (141 vs. 440, P = 0.003). Using a coreceptor binding model, we identified unique V3 signatures in cluster 4 that favor CXCR4 use. We demonstrate that the HIV-1 phenotype and pathogenicity can be determined at the phylogenetic cluster level in the same subtype. Since its initial spread to humans from chimpanzees, estimated to be the first half of the 20th century, HIV-1 continues to undergo rapid evolution in larger and more diverse populations. The divergent phenotype evolution of two major CRF01_AE clusters highlights the importance of monitoring the genetic evolution and phenotypic shift of HIV-1 to provide early warning of the appearance of more pathogenic strains.

Correlates of recent HIV infection among men who have sex with men recruited through the internet in Huzhou City, Eastern China

OBJECTIVE

To identify factors associated with recent HIV infection among men who have sex with men (MSM) in Huzhou City, Eastern China, who seek sexual partners via the internet.

METHODS

Adult members of Tencent QQ instant messaging software, who completed a face-to-face interview questionnaire and serological HIV testing at baseline, were enrolled into this prospective cohort study. Questionnaires and serological testing were also completed at 6 and 12 months. Cox proportional hazards was used for initial bivariate analyses of differences between participants with or without recent HIV infection, and for subsequent forward stepwise multiple regression of statistically significant variables.

RESULTS

Out of 415 baseline participants, 283 completed the 12-month follow-up (25 with recent HIV infection and 258 without; recent HIV infection rate, 8.20 per 100 person-years). Recent HIV infection was shown to be significantly associated with ≤ high school education (versus college/university), registered residence outside Huzhou City (versus within Huzhou City), having ≥ two male sexual partners, and syphilis infection.

CONCLUSIONS

Improving education levels, treating syphilis promptly, and reducing the number of male sexual partners may reduce HIV transmission among MSM in Eastern China.

Tandem bispecific neutralizing antibody eliminates HIV-1 infection in humanized mice

The discovery of an HIV-1 cure remains a medical challenge because the virus rebounds quickly after the cessation of combination antiretroviral therapy (cART). Here, we investigate the potential of an engineered tandem bispecific broadly neutralizing antibody (bs-bnAb) as an innovative product for HIV-1 prophylactic and therapeutic interventions. We discovered that by preserving 2 single-chain variable fragment (scFv) binding domains of each parental bnAb, a single gene-encoded tandem bs-bnAb, BiIA-SG, displayed substantially improved breadth and potency. BiIA-SG neutralized all 124 HIV-1-pseudotyped viruses tested, including global subtypes/recombinant forms, transmitted/founder viruses, variants not susceptible to parental bnAbs and to many other bnAbs with an average IC50 value of 0.073 μg/ml (range < 0.001-1.03 μg/ml). In humanized mice, an injection of BiIA-SG conferred sterile protection when administered prior to challenges with diverse live HIV-1 stains. Moreover, whereas BiIA-SG delayed viral rebound in a short-term therapeutic setting when combined with cART, a single injection of adeno-associated virus-transferred (AAV-transferred) BiIA-SG gene resulted dose-dependently in prolonged in vivo expression of BiIA-SG, which was associated with complete viremia control and subsequent elimination of infected cells in humanized mice. These results warrant the clinical development of BiIA-SG as a promising bs-bnAb-based biomedical intervention for the prevention and treatment of HIV-1 infection.

Infant transmitted/founder HIV-1 viruses from peripartum transmission are neutralization resistant to paired maternal plasma

Despite extensive genetic diversity of HIV-1 in chronic infection, a single or few maternal virus variants become the founders of an infant’s infection. These transmitted/founder (T/F) variants are of particular interest, as a maternal or infant HIV vaccine should raise envelope (Env) specific IgG responses capable of blocking this group of viruses. However, the maternal or infant factors that contribute to selection of infant T/F viruses are not well understood. In this study, we amplified HIV-1 env genes by single genome amplification from 16 mother-infant transmitting pairs from the U.S. pre-antiretroviral era Women Infant Transmission Study (WITS). Infant T/F and representative maternal non-transmitted Env variants from plasma were identified and used to generate pseudoviruses for paired maternal plasma neutralization sensitivity analysis. Eighteen out of 21 (85%) infant T/F Env pseudoviruses were neutralization resistant to paired maternal plasma. Yet, all infant T/F viruses were neutralization sensitive to a panel of HIV-1 broadly neutralizing antibodies and variably sensitive to heterologous plasma neutralizing antibodies. Also, these infant T/F pseudoviruses were overall more neutralization resistant to paired maternal plasma in comparison to pseudoviruses from maternal non-transmitted variants (p = 0.012). Altogether, our findings suggest that autologous neutralization of circulating viruses by maternal plasma antibodies select for neutralization-resistant viruses that initiate peripartum transmission, raising the speculation that enhancement of this response at the end of pregnancy could further reduce infant HIV-1 infection risk.

Mother to child transmission (MTCT) of HIV-1 can occur during pregnancy (in utero), at the time of delivery (peripartum) or by breastfeeding (postpartum). With the availability of anti-retroviral therapy (ART), rate of MTCT of HIV-1 have been significantly lowered. However, significant implementation challenges remain in resource-poor areas, making it difficult to eliminate pediatric HIV. An improved understanding of the viral population (escape variants from autologous neutralizing antibodies) that lead to infection of infants at time of transmission will help in designing immune interventions to reduce perinatal HIV-1 transmission. Here, we selected 16 HIV-1-infected mother-infant pairs from WITS cohort (from pre anti-retroviral era), where infants became infected peripartum. HIV-1 env gene sequences were obtained by the single genome amplification (SGA) method. The sensitivity of these infant Env pseudoviruses against paired maternal plasma and a panel of broadly neutralizing monoclonal antibodies (bNAbs) was analyzed. We demonstrated that the infant T/F viruses were more resistant against maternal plasma than non-transmitted maternal variants, but sensitive to most (bNAbs). Signature sequence analysis of infant T/F and non-transmitted maternal variants revealed the potential importance of V3 and MPER region for resistance against paired maternal plasma. These findings provide insights for the design of maternal immunization strategies to enhance neutralizing antibodies that target V3 region of autologous virus populations, which could work synergistically with maternal ARVs to further reduce the rate of peripartum HIV-1 transmission.

Naturally Occurring Mutations in HIV-1 CRF01_AE Capsid Affect Viral Sensitivity to Restriction Factors

TRIM5α and MxB are known as restriction factors that inhibit the early step of intracellular HIV-1 replication cycle. Both factors are believed to interact with the incoming virus core to suppress HIV-1 infection. The extreme diversity of HIV-1 is thought to be a consequence of its propensity to mutate to escape immune responses and host restriction factors. We recently determined the capsid sequences for 144 HIV-1 CRF01_AE viruses obtained in Thailand from 2005 to 2011. In this study, we further analyzed the amino acid variations among the capsid sequences of 204 HIV-1 CRF01_AE obtained in Thailand and China, including 84 of the aforementioned 144 viruses, to detect mutations permitting escape from restriction by host factors. We found a characteristic combination of E79D, V83T, and H87Q in sequences from Chinese viruses and subsequently showed that this combination conferred partial resistance to MxB. Interestingly, this combination conferred resistance to human TRIM5α as well. The H87Q mutation alone conferred resistance to MxB in the CRF01_AE background, but not in subtype B virus. In contrast, the H87Q mutation alone conferred resistance to human TRIM5α in both the CFR01_AE and subtype B backgrounds. BLAST analysis revealed the presence of the E79D, V83T, and H87Q combination in CRF01_AE viruses isolated not only in China but also in many other countries. Although the mechanistic details as well as precise role of MxB antiviral activity in infected individuals remain to be clarified, our data suggest an interaction between MxB and the HIV-1 capsid in vivo.

Surging HIV-1 CRF07_BC epidemic among recently infected men who have sex with men in Fujian, China

A rapidly increasing number of HIV-1 infections have been identified among men who have sex with men (MSM) in Fujian province of China since 2010. We aimed to investigate the causative factors underlying this surging epidemic. Using immunoassays for HIV-1 diagnosis and phylogenetic analysis for viral genotyping, we found that the number of MSM infections doubled from 171 in 2011 to 340 in 2013 with a significantly increased prevalent rate from 4.1% to 5.2%. Majority of these increased infections took place in Fuzhou, Xiamen, and Quanzhou, three large cities in Fujian, mainly among youth, unemployed, business, and well-educated MSMs. Phylogenetic analysis revealed three major HIV-1 genotypes including CRF01_AE, CRF07_BC, and B/B' yet the surging MSM infections were primarily associated with the rapid sexual spread of CRF07_BC in addition to CRF01_AE. In particular, there was a significant proportional expansion of CRF07_BC infections among recently infected MSMs from 19% in 2012 to 41.9% in 2013. This increase was accompanied by emergence of complex patterns of viral recombination including multiple hybrid variants derived from CRF01_AE and CRF07_BC. Full-genome analysis indicated that CRF07_BC in Fujian was likely originated from similar strains previously found among IDUs in Yunnan province but with unique recombination break points. Our findings indicated that HIV-1 CRF07_BC has adapted for rapid sexual transmission, resulting in the surging HIV-1 epidemic and the emergence of new recombinant strains among MSMs in Fujian. Our findings have implications to vaccine and passive immunization trials in Fujian with emphasis on the induction of cross-subtype protective immunity.

α4β7+ CD4+ Effector/Effector Memory T Cells Differentiate into Productively and Latently Infected Central Memory T Cells by Transforming Growth Factor β1 during HIV-1 Infection

HIV-1 transmission occurs mainly through mucosal tissues. During mucosal transmission, HIV-1 preferentially infects α₄β₇⁺ gut-homing CCR7^- CD4⁺ effector/effector memory T cells (T_EM) and results in massive depletion of these cells and other subsets of T_EM in gut-associated lymphoid tissues. However, besides being eliminated by HIV-1, the role of T_EM during the early stage of infection remains inconclusive. Here, using in vitro-induced α₄β₇⁺ gut-homing T_EM (α₄β₇⁺ T_EM), we found that α₄β₇⁺ T_EM differentiated into CCR7⁺ CD4⁺ central memory T cells (T_CM). This differentiation was HIV-1 independent but was inhibited by SB431542, a specific transforming growth factor β (TGF-β) receptor I kinase inhibitor. Consistently, T_EM-to-T_CM differentiation was observed in α₄β₇⁺ T_EM stimulated with TGF-β1 (TGF-β). The T_CM properties of the TGF-β-induced T_EM-derived T_CM (α₄β₇⁺ T_CM) were confirmed by their enhanced CCL19 chemotaxis and the downregulation of surface CCR7 upon T cell activation in vitro Importantly, the effect of TGF-β on T_CM differentiation also held in T_EM directly isolated from peripheral blood. To investigate the significance of the TGF-β-dependent T_EM-to-T_CM differentiation in HIV/AIDS pathogenesis, we observed that both productively and latently infected α₄β₇⁺ T_CM could differentiate from α₄β₇⁺ T_EM in the presence of TGF-β during HIV-1 infection. Collectively, this study not only provides a new insight for the plasticity of T_EM but also suggests that the TGF-β-dependent T_EM-to-T_CM differentiation is a previously unrecognized mechanism for the formation of latently infected T_CM after HIV-1 infection.IMPORTANCE HIV-1 is the causative agent of HIV/AIDS, which has led to millions of deaths in the past 30 years. Although the implementation of highly active antiretroviral therapy has remarkably reduced the HIV-1-related morbidity and mortality, HIV-1 is not eradicated in treated patients due to the presence of latent reservoirs. Besides, the pathogenesis in CD4 T cells early after infection still remains elusive. Immediately after HIV-1 mucosal infection, CD4 T cells are preferentially infected and depleted. However, in addition to being depleted, the other roles of the CD4 T cells, especially the effector/effector memory T cells (T_EM), in disease progression are not completely understood. The significance of this study is in revealing a novel mechanism for the formation of latently HIV-1-infected central memory CD4 T cells, a major latent reservoir from CD4 T_EM after infection. Our findings suggest previously unrecognized roles of CD4 T_EM in HIV-1 pathogenesis.

The HIV Genomic Incidence Assay Meets False Recency Rate and Mean Duration of Recency Infection Performance Standards

HIV incidence is a primary metric for epidemic surveillance and prevention efficacy assessment. HIV incidence assay performance is evaluated via false recency rate (FRR) and mean duration of recent infection (MDRI). We conducted a meta-analysis of 438 incident and 305 chronic specimens' HIV envelope genes from a diverse global cohort. The genome similarity index (GSI) accurately characterized infection stage across diverse host and viral factors. All except one chronic specimen had GSIs below 0.67, yielding a FRR of 0.33 [0-0.98] %. We modeled the incidence assay biomarker dynamics with a logistic link function assuming individual variabilities in a Beta distribution. The GSI probability density function peaked close to 1 in early infection and 0 around two years post infection, yielding MDRI of 420 [361, 467] days. We tested the assay by newly sequencing 744 envelope genes from 59 specimens of 21 subjects who followed from HIV negative status. Both standardized residuals and Anderson-Darling tests showed that the test dataset was statistically consistent with the model biomarker dynamics. This is the first reported incidence assay meeting the optimal FRR and MDRI performance standards. Signatures of HIV gene diversification can allow precise cross-sectional surveillance with a desirable temporal range of incidence detection.

Transmission of Multiple HIV-1 Subtype C Transmitted/founder Viruses into the Same Recipients Was not Determined by Modest Phenotypic Differences

A severe bottleneck exists during HIV-1 mucosal transmission. However, viral properties that determine HIV-1 transmissibility are not fully elucidated. We identified multiple transmitted/founder (T/F) viruses in six HIV-1-infected subjects by analyzing whole genome sequences. Comparison of biological phenotypes of different T/F viruses from the same individual allowed us to more precisely identify critical determinants for viral transmissibility since they were transmitted under similar conditions. All T/F viruses used coreceptor CCR5, while no T/F viruses used CXCR4 or GPR15. However, the efficiency for different T/F viruses from the same individual to use CCR5 was significantly variable, and the differences were even more significant for usage of coreceptors FPRL1, CCR3 and APJ. Resistance to IFN-α was also different between T/F viruses in 2 of 3 individuals. The relative fitness between T/F viruses from the same subject was highly variable (2-6%). Importantly, the levels of coreceptor usage efficiency, resistance to IFN-α and viral fitness were not associated with proportions of T/F viruses in each individual during acute infection. Our results show that the modest but significant differences in coreceptor usage efficiency, IFN-α sensitivity and viral fitness each alone may not play a critical role in HIV-1 transmission.

Brain Invasion by CD4(+) T Cells Infected with a Transmitted/Founder HIV-1BJZS7 During Acute Stage in Humanized Mice

Human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) is one of the common causes of cognitive dysfunction and morbidity among infected patients. However, to date, it remains unknown if a transmitted/founder (T/F) HIV-1 leads to neurological disorders during acute phase of infection. Since it is impossible to answer this question in humans, we studied NOD.Cg-Prkdc scid Il2rgtm1Wjl/SzJ mice (NSG) reconstituted with human PBMC (NSG-HuPBL), followed by the peritoneal challenge with the chronic HIV-1JR-FL and the T/F HIV-1BJZS7, respectively. By measuring viral load, P24 antigenemia and P24(+) cells in peripheral blood and various tissue compartments, we found that systemic infections were rapidly established in NSG-HuPBL mice by both HIV-1 strains. Although comparable peripheral viral loads were detected during acute infection, the T/F virus appeared to cause less CD4(+) T cell loss and less numbers of infected cells in different organs and tissue compartments. Both viruses, however, invaded brains with P24(+)/CD3(+) T cells detected primarily in meninges, cerebral cortex and perivascular areas. Critically, brain infections with HIV-1JR-FL but not with HIV-1BJZS7 resulted in damaged neurons together with activated microgliosis and astrocytosis as determined by significantly increased numbers of Iba1(+) microglial cells and GFAP(+) astrocytes, respectively. The increased Iba1(+) microglia was correlated positively with levels of P24 antigenemia and negatively with numbers of NeuN(+) neurons in brains of infected animals. Our findings, therefore, indicate the establishment of two useful NSG-HuPBL models, which may facilitate future investigation of mechanisms underlying HIV-1-induced microgliosis and astrocytosis.

Short Communication: The Distribution of Potential N-Linked Glycosylation Sites in Gp120 Differs Among Major HIV-1 Subtypes Circulating in China

CRF01_AE shows an obvious sexual transmission advantage over other major HIV-1 subtypes circulating in China. Previous studies showed that the presence or absence of potential N-linked glycosylation sites (PNGSs) in variable loops might affect HIV-1 transmission; it is therefore of interest to compare the distribution of potential PNGSs on envelopes of different subtypes circulating in China. Compared to CRF07_BC, CRF08_BC, B, and B' subtypes isolated in China, CRF01_AE subtypes isolated from both China and outside China had significantly fewer PNGSs in total and in V2/V4, while they had significantly more PNGSs in V5. HIV-1 subtype CRF01_AE has a unique PNGS distribution pattern in Gp120, which may contribute to its advantage in sexual transmission in China.