UNASSIGNED: HIV molecular network based on genetic distance (GD) has been extensively utilized. However, the GD threshold for the non-B subtype differs from that of subtype B. This study aimed to optimize the GD threshold for inferring the CRF01_AE molecular network.
UNASSIGNED: Next-generation sequencing data of partial CRF01_AE pol sequences were obtained for 59 samples from 12 transmission pairs enrolled from a high-risk cohort during 2009 and 2014. The paired GD was calculated using the Tamura-Nei 93 model to infer a GD threshold range for HIV molecular networks.
UNASSIGNED: 2,019 CRF01_AE pol sequences and information on recent HIV infection (RHI) from newly diagnosed individuals in Shenyang from 2016 to 2019 were collected to construct molecular networks to assess the ability of the inferred GD thresholds to predict recent transmission events. When HIV transmission occurs within a span of 1-4 years, the mean paired GD between the sequences of the donor and recipient within the same transmission pair were as follow: 0.008, 0.011, 0.013, and 0.023 substitutions/site. Using these four GD thresholds, it was found that 98.9%, 96.0%, 88.2%, and 40.4% of all randomly paired GD values from 12 transmission pairs were correctly identified as originating from the same transmission pairs. In the real world, as the GD threshold increased from 0.001 to 0.02 substitutions/site, the proportion of RHI within the molecular network gradually increased from 16.6% to 92.3%. Meanwhile, the proportion of links with RHI gradually decreased from 87.0% to 48.2%. The two curves intersected at a GD of 0.008 substitutions/site.
UNASSIGNED: A suitable range of GD thresholds, 0.008-0.013 substitutions/site, was identified to infer the CRF01_AE molecular transmission network and identify HIV transmission events that occurred within the past three years. This finding provides valuable data for selecting an appropriate GD thresholds in constructing molecular networks for non-B subtypes.

Human immunodeficiency virus type 1 (HIV-1) remains a serious health threat in Indonesia. In particular, the CRF01_AE viruses were the predominant HIV-1 strains in various cities in Indonesia. However, information on the dynamic transmission characteristics and spatial-temporal transmission of HIV-1 CRF01_AE in Indonesia is limited. Therefore, the present study examined the spatial-temporal transmission networks and evolutionary characteristics of HIV-1 CRF01_AE in Indonesia. To clarify the epidemiological connection between CRF01_AE outbreaks in Indonesia and the rest of the world, we performed phylogenetic studies on nearly full genomes of CRF01_AE viruses isolated in Indonesia. Our results showed that five epidemic clades, namely, IDN clades 1-5, of CRF01_AE were found in Indonesia. To determine the potential source and mode of transmission of CRF01_AE, we performed Bayesian analysis and built maximum clade credibility trees for each clade. Our study revealed that CRF01_AE viruses were commonly introduced into Indonesia from Southeast Asia, particularly Thailand. The CRF01_AE viruses might have spread through major pandemics in Asian countries, such as China, Vietnam, and Laos, rather than being introduced directly from Africa in the early 1980s. This study has major implications for public health practice and policy development in Indonesia. The contributions of this study include understanding the dynamics of HIV-1 transmission that is important for the implementation of HIV disease control and prevention strategies in Indonesia.

The Philippines has had a rapidly growing human immunodeficiency virus (HIV) epidemic with a shift in the prevalent subtype from B to CRF01_AE. However, the phylodynamic history of CRF01_AE in the Philippines has yet to be reconstructed. We conducted a descriptive retrospective study reconstructing the history of HIV-1 CRF01_AE transmissions in the Philippines through molecular epidemiology. Partial polymerase sequences (n = 1144) collected between 2008 and 2018 from three island groups were collated from the Research Institute for Tropical Medicine drug resistance genotyping database. Estimation of the time to the most recent common ancestor (tMRCA), effective reproductive number (Re), effective viral population size (Ne), relative migration rates, and geographic spread of CRF01_AE was performed with BEAST. Re and Ne were compared between CRF01_AE and B. Most CRF01_AE sequences formed a single clade with a tMRCA of June 1996 [95 per cent highest posterior density (HPD): December 1991, October 1999]. An increasing CRF01_AE Ne was observed from the tMRCA to 2013. The CRF01_AE Re reached peaks of 2.46 [95 per cent HPD: 1.76, 3.27] in 2007 and 2.52 [95 per cent HPD: 1.83, 3.34] in 2015. A decrease of CRF01_AE Re occurred in the intervening years of 2007 to 2011, reaching as low as 1.43 [95 per cent HPD: 1.06, 1.90] in 2011, followed by a rebound. The CRF01_AE epidemic most likely started in Luzon and then spread to the other island groups of the country. Both CRF01_AE and Subtype B exhibited similar patterns of Re fluctuation over time. These results characterize the subtype-specific phylodynamic history of the largest CRF01_AE cluster in the Philippines, which contextualizes and may inform past, present, and future public health measures toward controlling the HIV epidemic in the Philippines.

Hebei, a province with a low Human Immunodeficiency Virus (HIV) prevalence, is also a region with the most abundant HIV-1 genetic diversity. HIV-1 recombinant forms have been the key factor influencing the effectiveness of HIV-1 control and therapy.
We aimed to study inter-subtype recombinant structures of new HIV-1-second generation recombinant forms.
Monitoring the HIV-1 subtype by phylogenetic and recombinant breakpoint analyses are the two most frequent methods among men who have sex with men (MSM). Here, three near full-length genomes (NFLGs) were obtained from HIV-1 seropositive MSM in Shijiazhuang City, China, who have never received antiretroviral therapy in 2021.
Phylogenetic analysis indicated that three NFLGs were novel inter-subtype recombinant forms between CRF07_BC and CRF01_AE. For the NFLG 21S009, four CRF07_BC gene fragments were inserted into the pol, vif-vpr, vpu-env, and nef-3` LTR gene regions within a CRF01_ AE backbone, respectively. For the NFLG 21S095, four breakpoints were identified in HIV-1 pol and vpu regions. The NFLG 21S370 contained four gene recombinant breakpoints within HIV-1 pol and vpu-env gene regions. Of these three NFLGs, the NFLG 21S009 contained the most breakpoints, distributed in the pol, vif, vpr, vpu, env, and nef regions, respectively. In the gag-pol regions, three NFLGs had only one CRF07_BC gene fragment inserted into gene points between 4250 and 4792.
Our findings provide strong evidence that the surveillance of novel recombinant forms is necessary for the increase in better control of HIV.

During HIV genotypic drug resistance testing of patient samples in Baoding, Hebei Province, China, in 2022, a recombinant fragment was detected in the pol region of an HIV-1 strain.
The objective of the study was to analyze the near full-length genome of a novel HIV-1 CRF01_AE/CRF07_BC recombinant with a complex genomic structure.
Viral RNA was extracted from the blood of the infected individual and reverse transcribed to cDNA. Two overlapping segments of the HIV-1 genome were amplified using a nearendpoint dilution method and sequenced. Recombinant breakpoints were determined using RIP, jpHMM, and SimPlot 3.5.1 software. MEGA 6.0 software was used to construct a neighbor-joining phylogenetic tree.
We obtained the near full-length genome sequence (8680 bp) of a novel HIV-1 CRF01_AE/CRF07_BC recombinant. Recombination analysis showed that the genome comprised at least 12 overlapping segments, including six CRF07_BC and six CRF01_AE segments, with CRF07_BC as the backbone. The emergence of CRF01_AE/CRF07_BC recombinant strains indicated that HIV-1 co-infection is common. However, the increasing genetic complexity of the HIV-1 epidemic in China warrants continued investigation.
The increase in CRF01_AE/CRF07_BC recombinant viruses suggests that HIV-1 has a high genetic mutation rate in Hebei, China. This highlights the need for close monitoring of HIV-1 molecular epidemiologic changes to provide accurate, up-to-date information for effective disease control.

Human immunodeficiency virus (HIV)-1 CRF01_AE is one of the most important genotypes in China, especially in the population of men who have sex with men (MSM). It has become the most prevalent strain among them. Describing the variant characterization of CRF01_AE will help to reveal the reason behind its predominance in MSM. In this study, the complete DNA sequences (CDSs) for gp120 from the envelope protein (env) gene of CRF01_AE in China and Thailand were retrieved from the Los Alamos HIV database. The CDSs for gp120 were divided into three subgroups according to the risk factors for HIV-1 transmission in a variety of populations, such as intravenous drug users (IDU), heterosexual contacts (HC), and MSM. The N-linked CDS glycosylation sites for gp120 in CRF01_AE were analyzed. The results showed a unique hyperglycosylation site N-339 (refer to Hxb2) in the gp120 of CRF01_AE in MSM compared with the IDU and HC groups from China. The result was the same in the MSM group from Thailand, which suggests that the hyperglycosylation site N-339 may explain the widespread CRF01_AE genotype in MSM.

UNASSIGNED: Since only a few studies have been conducted on the factors associated with different HIV-1 tropisms in low-level viral load HIV-1 infections in China, we investigated the sequences of HIV-1 V3 loop in prevalent HIV-1 subtypes and factors related to HIV-1 tropism and immune recovery in HIV-1 infections after 6 months of highly active antiretroviral therapy (HAART) in Guangdong, China.
UNASSIGNED: Plasma samples with HIV-1 RNA of 400-999 copies/mL were collected. We analyzed the amino acid sequence of the V3 loop by in silico prediction algorithms. Mann-Whitney and Chi-square tests were used for statistical comparison. Furthermore, logistic regression and multiple linear regression were used, respectively, for factors associated with 351 HIV-1 tropism and immune recovery of 67 cases with continued CD4+ T cell count during HAART.
UNASSIGNED: There was a lower percentage of HIV-1 R5-tropic virus in CRF01_AE (66.3%) (p < 0.0001) and CRF55_01B (52.6%) (p < 0.0001) compared with both CRF07_BC (96.1%) and CRF08_BC (97.4%), respectively. Compared with the R5-tropic virus, higher proportions of IIe8/Val8, Arg11/Lys11, and Arg18/His18/Lys18 were observed in the X4-tropic virus of CRF01_AE and CRF07_BC (p < 0.0001). The baseline CD4+ T cell count (p < 0.0001) and baseline CD4+ T/CD8+ T ratio (p = 0.0006) of all R5-tropic infections were higher than those in the X4-tropic infection. The baseline CD4+ T cell count (odds ratio [OR] 0.9963, p = 0.0097), CRF07_BC (OR 0.1283, p = 0.0002), and CRF08_BC (OR 0.1124, p = 0.0381) were associated with less HIV-1 X4-tropism. The baseline CD4+ T cell count was a positive factor (p < 0.0001) in the recovery of CD4+ T cell count during HAART.
UNASSIGNED: R5-tropism represented the majority in low-level viral load HIV-1 infections receiving HAART for more than 6 months in Guangdong, China. The baseline immune level in the HIV-1 R5-tropic infections was higher than that in the X4-tropic infections. The amino acids of the 8th, 11th, and 18th of the HIV-1 V3 loop were more variable in the X4-tropic HIV-1. CRF01_AE, CRF55_01B, and lower baseline CD4+ T cell count were associated with more HIV-1 X4-tropism. The immune recovery during HAART was positively related to baseline CD4+ T cell count.

Subtypes circulating recombinant form (CRF)01_AE and C are two human immunodeficiency virus (HIV)-1 strains that are prevalent in different key populations such as men who have sex with men (MSM) in China. Co-circulating of different HIV-1 subtypes is easy to result in the generation of second-generation recombinants. In this study, three new HIV-1 CRF01_AE/C recombinants from three MSMs were detected in Hebei province, China. Phylogenetic tree and recombination analysis showed that the near-full-length genomic of S114 had seven recombination breakpoints, including four C fragments inserted into the CRF01_AE backbone; M363 had six recombination breakpoints, including three C fragments inserted into the CRF01_AE backbone; M162 had eight recombination breakpoints, including four C fragments inserted into the CRF01_AE backbone. Furthermore, phylogenetic tree analysis based on subregion gene fragments also identified this kind of CRF01_AE/C recombinant structure. This study suggests a more complex HIV-1 epidemiological trend in Hebei province, China and the urgency of continuous HIV-1 recombinant strain registry in sexually transmitted populations.

Human immunodeficiency virus 1 (HIV-1) is a fast-evolving, genetically diverse virus. The HIV-1 evolution rate is also significantly influenced by the frequency of HIV-1 spread in a population. Transmission via homosexual contact has become the predominant transmission route, leading to an increase in the HIV-1 epidemic in Hebei province, China. In this study, we report three novel HIV-1 CRF01_AE/CRF07_BC recombinant forms isolated from three men who have sex with men (MSM) in the cities of Shijiazhuang (20747) and Langfang (20809 and 20820). Phylogenetic analysis based on HIV-1 near-full-length genome (NFLG) sequences indicated that the three novel recombinant forms formed a distinct monophyletic branch that was separate from all known HIV-1 subtypes and circulating recombinant forms (CRFs). Breakpoint analysis showed that the three NFLGs displayed different recombinant patterns. NFLGs 20747 and 20809 had a recombinant pattern with subtype CRF01_AE gene fragments inserted into a CRF07_BC backbone, spanning from the gag to env gene regions, whereas NFLG 20820 had a recombinant pattern with subtype CRF07_BC gene fragments inserted into a CRF01_AE backbone. Subregion phylogenetic analysis confirmed that these three NFLGs comprised CRF01_AE and CRF07_BC. Our findings confirm the emergence of novel recombinant forms and highlight the need for continuous monitoring of the diversity of HIV-1 among sexually active populations, especially MSM, to better control the HIV-1 epidemic.

Understanding the dynamics of early immune responses to HIV-1 infection, including the evolution of initial neutralizing and antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies, will inform HIV vaccine design. In this study, we assess the development of autologous neutralizing antibodies (ANAbs) against founder envelopes (Envs) from 18 participants with HIV-1 CRF01_AE acute infection. The timing of ANAb development directly associated with the magnitude of the longitudinal ANAb response. Participants that developed ANAbs within 6 months of infection had significantly higher ANAb responses at 1 year (50% inhibitory concentration [IC50] geometric mean titer [GMT] = 2,010 versus 184; P = 0.001) and 2 years (GMT = 3,479 versus 340; P = 0.015), compared to participants that developed ANAb responses after 6 months. Participants with later development of ANAb tended to develop an earlier, potent heterologous tier 1 (92TH023) neutralizing antibody (NAb) response (P = 0.049). CRF01_AE founder Env V1V2 loop lengths correlated indirectly with the timing (P = 0.002, r = -0.675) and directly with magnitude (P = 0.005, r = 0.635) of ANAb responses; Envs with longer V1V2 loop lengths elicited earlier and more potent ANAb responses. While ANAb responses did not associate with viral load, the viral load set point correlated directly with neutralization of the heterologous 92TH023 strain (P = 0.007, r = 0.638). In contrast, a striking inverse correlation was observed between viral load set point and peak ADCC against heterologous 92TH023 Env strain (P = 0.0005, r = -0.738). These data indicate that specific antibody functions can be differentially related to viral load set point and may affect HIV-1 pathogenesis. Exploiting Env properties, such as V1V2 length, could facilitate development of subtype-specific vaccines that elicit more effective immune responses and improved protection. IMPORTANCE Development of an effective HIV-1 vaccine will be facilitated by better understanding the dynamics between the founder virus and the early humoral responses. Variations between subtypes may influence the evolution of immune responses and should be considered as we strive to understand these dynamics. In this study, autologous founder envelope neutralization and heterologous functional humoral responses were evaluated after acute infection by HIV-1 CRF01_AE, a subtype that has not been thoroughly characterized. The evolution of these humoral responses was assessed in relation to envelope characteristics, magnitude of elicited immune responses, and viral load. Understanding immune parameters in natural infection will improve our understanding of protective responses and aid in the development of immunogens that elicit protective functional antibodies. Advancing our knowledge of correlates of positive clinical outcomes should lead to the design of more efficacious vaccines.