Comparative Circulation Dynamics of the Five Main HIV Types in China

Insights into the molecular network characteristics of major HIV-1 subtypes in developed Eastern China: a study based on comprehensive molecular surveillance data

PURPOSE

This study aimed to conduct a comprehensive molecular epidemiology study of major HIV-1 subtypes in developed Eastern China (Zhejiang Province).

METHODS

Plasma samples and epidemiological information were collected from 4180 newly diagnosed HIV-1 positive patients in Zhejiang Province in 2021. Pol sequences were obtained to determine the subtypes via multiple analytical tools. HIV-1 molecular networks were constructed on the basis of genetic distances to analyze transmission patterns among major subtypes. Furthermore, the birth-death skyline (BDSKY) model was utilized to estimate the transmission risks associated with large clusters (LCs).

RESULTS

In 4180 patients, 3699 (88.49%) pol sequences were successfully obtained and classified into four subtype groups. In the networks under an optimal genetic distance of 0.01 substitutions/site, the majority of links (74.52%, 1383/1856) involved individuals within the same city, highlighting the predominant role of local transmission in driving the HIV-1 epidemic. In the CRF07_BC, CRF01_AE, and others/URFs networks, men who have sex with men (MSM) were the primary sexual transmission population, with the younger MSM group (< 30 years old) exhibiting higher linkage frequencies. Within the CRF08_BC network, 93.98% of individuals were infected primarily through heterosexual contact and had a significantly greater risk of localized clustering than other subtypes did. Moreover, fifteen identified LCs were predominantly transmitted through commercial heterosexual contact (CHC), exhibiting localized clustering and high potential for sustained diffusion.

CONCLUSIONS

Overall, our findings reveal a diverse and heterogeneous distribution of HIV-1 subtypes in Zhejiang Province, with noticeable variations in hotspots across different geographic areas and populations.

Molecular cluster, transmission characteristics, origin and dynamics analysis of HIV-1 CRF59_01B in China: A molecular epidemiology study

PURPOSE

This study investigated for the HIV-1 CRF59_01B epidemic's spatiotemporal dynamics and its transmission networks in China.

METHODS

Between 2007 and 2020, a total of 250 partial pol gene sequences of HIV-1 CRF59_01B were collected from four regions (10 Chinese provinces). Phylogenetic tree construction and cluster identification were then performed. The Bayesian skyline and birth-death susceptible-infected-removed models were employed for the phylodynamic analyses of subtypes and large clusters, respectively. Phylogenetic analyses and trait diffusion of these sequences were performed using Bayesian phylogenetic methods (beast-classic package). Distance-based molecular network analyses were performed to identify putative relationships.

RESULTS

Using a genetic distance threshold of 1.3 %, We identified 45 clusters that included 62.40 % (156/250) of the sequences. Three clusters (6.67 %, 3/45) had 10 or more sequences, and were considered "large clusters". Six clusters (13.33 %) included sequences from different regions (Southeast, Northeast, Southeast, and Central China). Thirteen clusters (28.89 %) included sequences of men who had sex with men only, three clusters (6.67 %) included sequences of heterosexuals only, and 12 clusters (26.67 %) included sequences of both groups. The substitution rate of CRF59_01B was 1.91 × 10-3 substitutions per site per year [95 % highest posterior density (HPD) interval: 1.39 × 10-3-2.49 × 10-3)], the time to the most recent common ancestor of CRF59_01B was to be 1992.83 (95 % HPD: 1977.97-2002.81). A Bayesian skyline plot revealed that the effective population size of CRF59_01B increased from 2000 to 2015 and remained stable after 2015. The large clusters showed continuous growth from 2013 to 2020. Phylogeographic analysis showed that CRF59_01B B most likely originated in Southeast China, with a posterior probability of 97.44 %, and then spread to other regions.

CONCLUSIONS

Our study revealed the temporal and geographical origins of HIV-1 CRF59_01B as well as the process of transmission among various regions and risk groups in China, which can help develop targeted HIV prevention strategies.

The evolutionary and transmission dynamics of HIV-1 CRF08_BC

HIV-1 CRF08_BC is a significant subtype in China, though its origin and spread remain incompletely understood. Previous studies using partial genomic data have provided insights but lack comprehensive analysis. Here, we investigate the early evolutionary and spatiotemporal dynamics of HIV-1 CRF08_BC in China and Myanmar using near-complete genome sequences. We analyzed 28 near-complete HIV-1 CRF08_BC genomes from China and Myanmar (1997-2013). Phylogenetic, molecular clock, and Bayesian discrete trait analyses were performed to infer the virus's origin, spread, and associated risk groups. Based on Bayesian time-scaled inference with the best-fitting combination of models determined by marginal likelihood estimation (MLE), we inferred the time to the most recent common ancestor (TMRCA) and evolutionary rate of HIV-1 CRF08_BC to be at 3 October 1991 (95% HPD: 22 February1989-27 November 1993) and 2.30 × 10-3 substitutions per site per year (95% HPD: 1.96 × 10-3-2.63 × 10-3), respectively. Our analysis suggests that HIV-1 CRF08_BC originated in Yunnan Province, China, among injecting drug users, and subsequently spread to other regions. This study provides valuable insights into the early dynamics of HIV-1 CRF08_BC through combined genomic and epidemiological data, which may inform effective prevention and mitigation efforts. However, the limited genomic data influenced the extent of our findings, and challenges in collecting accurate risk group information during surveillance were evident.

Molecular transmission network analysis reveals the challenge of HIV-1 in ageing patients in China: elderly people play a crucial role in the transmission of subtypes and high pretreatment drug resistance in developed Eastern China, 2019-2023

BACKGROUND

The number and proportion of HIV/AIDS patients among older people are continuously and rapidly increasing in China. We conducted a detailed molecular epidemiological analysis of HIV-1 epidemic strains in a developed city in eastern China and found that elderly people play a crucial role in the transmission of subtypes and high pretreatment drug resistance (PDR).

METHODS

A total of 1048 samples were obtained from 1129 (92.8%) newly confirmed HIV-1-positive and treatment-naive patients between 2019 and 2023. The 1316 bp target fragment of the pol gene was amplified by reverse transcription polymerase chain reaction (RT‒PCR) and nested PCR, and Maximum-likelihood (ML) phylogenetic trees and molecular transmission network were constructed to analyse the subtypes and transmission clusters. Molecular transmission network was visualized using Cytoscape with the distance threshold of 0.0075. PDR-associated mutations were determined according to the Stanford University HIV Drug Resistance Database.

RESULTS

A total of 933 pol sequences (89.0%, 933/1048) were successfully obtained, and twelve HIV-1 subtypes were detected. CRF07_BC was the predominant subtype, accounting for 48.1% (449/933) of sequences, followed by CRF01_AE (29.4%, 274/933). A total of 398 individuals (42.7%, 398/933) formed 89 clusters in the network. Multivariable logistic regression analysis revealed that age, nationality, subtype, and PDR were the most significant factors associated with clustering in the transmission network. The prevalence of PDR was 14.6% (136/933).PDR associated with non-nucleoside reverse transcriptase inhibitors (10.0%, 93/933) was much more common than that associated with nucleoside reverse transcriptase inhibitors (1.8%, 17/933) and protease inhibitors (3.2%, 30/933) (χ2 = 77.961, p < 0.001). The most frequent NNRTI mutations were K103N/S/KN/NS (52.2%, 71/136), which led to the highest proportion of high-level resistance to nevirapine and efavirenz (52.2%).

CONCLUSIONS

Our study revealed the important influence of elderly people on CRF07_BC transmission and the high prevalence of PDR. The clustering of drug-resistant cases was significant, which suggested the potential for localized widespread transmission of drug-resistant strains. HIV screening and the determination of PDR are recommended for older patients to improve early detection and reduce treatment failure and second-generation transmission.

Characteristics of Subtype and Molecular Transmission Networks among Newly Diagnosed HIV-1 Infections in Patients Residing in Taiyuan City, Shanxi Province, China, from 2021 to 2023

The HIV-1 pandemic, spanning four decades, presents a significant challenge to global public health. This study aimed to understand the molecular transmission characteristics of newly reported HIV infections in Taiyuan, Shanxi Province, China, to analyze the characteristics of subtypes and the risk factors of the transmission network, providing a scientific basis for precise prevention and intervention measures. A total of 720 samples were collected from newly diagnosed HIV-1 patients residing in Taiyuan between 2021 and 2023. Sequencing of partial genes of the HIV-1 pol gene resulted in multiple sequence acquisitions and was conducted to analyze their subtypes and molecular transmission networks. Out of the samples, 584 pol sequences were obtained, revealing 17 HIV-1 subtypes, with CRF07_BC (48.29%), CRF01_AE (31.34%), and CRF79_0107 (7.19%) being the dominant subtypes. Using a genetic distance threshold of 1.5%, 49 molecular transmission clusters were generated from the 313 pol gene sequences. Univariate analysis showed significant differences in the HIV transmission molecular network in terms of HIV subtype and household registration (p < 0.05). Multivariate logistic regression analysis showed that CRF79_0107 subtype and its migrants were associated with higher proportions of sequences in the HIV transmission network. These findings provide a scientific foundation for the development of localized HIV-specific intervention strategies.

Identification of two novel HIV-1 unique recombinant forms (CRF01_AE/CRF07_BC) and genomic characterization in Tongzhou district of Beijing, China

Continuous recombination and variation during replication could lead to rapid evolution and genetic diversity of HIV-1. Some studies had identified that it was easy to develop new recombinant strains of HIV-1 among the populations of men who have sex with men (MSM). Surveillance of genetic variants of HIV-1 in key populations was crucial for comprehending the development of regional HIV-1 epidemics. The finding was reported the identification of two new unique recombinant forms (URF 20110561 and 21110743) from individuals infected with HIV-1 in Tongzhou, Beijing in 2020-2022. Sequences of near full-length genome (NFLG) were amplified, then identification of amplification products used phylogenetic analyses. The result showed that CRF01_AE was the main backbone of 20110561 and 21110743. In the gag region of the virus, 20110561 was inserted two fragments from CRF07_BC, while in the pol and tat regions of the virus, 21110743 was inserted four fragments from CRF07_BC. The CRF01_AE parental origin in the genomes of the two URFs was derived from the CRF01_AE Cluster 4. In the phylogenetic tree, the CRF07_BC parental origin of 20110561 clustered with 07BC_N and the CRF07_BC parental origin of 21110743 clustered with 07BC_O. In summary, the prevalence of novel second-generation URFs of HIV-1 was monitored in Tongzhou, Beijing. The emergence of the novel CRF01_AE/CRF07_BC recombination demonstrated that there was a great significance of continuous monitoring of new URFs in MSM populations to prevent and control the spreading of new HIV-1 URFs.

Molecular transmission network analysis of newly diagnosed HIV-1 infections in Nanjing from 2019 to 2021

OBJECTIVE

The objective of this study was to conduct a comprehensive analysis of the molecular transmission networks and transmitted drug resistance (TDR) patterns among individuals newly diagnosed with HIV-1 in Nanjing.

METHODS

Plasma samples were collected from newly diagnosed HIV patients in Nanjing between 2019 and 2021. The HIV pol gene was amplified, and the resulting sequences were utilized for determining TDR, identifying viral subtypes, and constructing molecular transmission network. Logistic regression analyses were employed to investigate the epidemiological characteristics associated with molecular transmission clusters.

RESULTS

A total of 1161 HIV pol sequences were successfully extracted from newly diagnosed individuals, each accompanied by reliable epidemiologic information. The analysis revealed the presence of multiple HIV-1 subtypes, with CRF 07_BC (40.57%) and CRF01_AE (38.42%) being the most prevalent. Additionally, six other subtypes and unique recombinant forms (URFs) were identified. The prevalence of TDR among the newly diagnosed cases was 7.84% during the study period. Employing a genetic distance threshold of 1.50%, the construction of the molecular transmission network resulted in the identification of 137 clusters, encompassing 613 nodes, which accounted for approximately 52.80% of the cases. Multivariate analysis indicated that individuals within these clusters were more likely to be aged ≥ 60, unemployed, baseline CD4 cell count ≥ 200 cells/mm3, and infected with the CRF119_0107 (P < 0.05). Furthermore, the analysis of larger clusters revealed that individuals aged ≥ 60, peasants, those without TDR, and individuals infected with the CRF119_0107 were more likely to be part of these clusters.

CONCLUSIONS

This study revealed the high risk of local HIV transmission and high TDR prevalence in Nanjing, especially the rapid spread of CRF119_0107. It is crucial to implement targeted interventions for the molecular transmission clusters identified in this study to effectively control the HIV epidemic.

Analysis of the immunological response to antiviral therapy in patients with different subtypes of HIV/AIDS: a retrospective cohort study

OBJECTIVE

To evaluate the effectiveness of standardised antiretroviral therapy (ART) among different HIV subtypes in people living with HIV/AIDS (PLWHA), and to screen the best ART regimen for this patient population.

DESIGN

A retrospective cohort study was performed, and PLWHA residing in Huzhou, China, between 2018 and 2020, were enrolled.

SETTING AND PARTICIPANTS

Data from 625 patients, who were newly diagnosed with HIV/AIDS in the AIDS Prevention and Control Information System in Huzhou between 2018 and 2020, were reviewed.

ANALYSIS AND OUTCOME MEASURES

Data regarding demographic characteristics and laboratory investigation results were collected. Immune system recovery was used to assess the effectiveness of ART, and an increased percentage of CD4+ T lymphocyte counts >30% after receiving ART for >1 year was determined as immunopositive. A multiple logistic regression model was used to comprehensively quantify the association between PLWHA immunological response status and virus subtype. In addition, the joint association between different subtypes and treatment regimens on immunological response status was investigated.

RESULTS

Among 326 enrolled PLWHA with circulating recombinant forms (CRFs) CRF01_AE, CRF07_BC and other HIV/AIDS subtypes, the percentages of immunopositivity were 74.0%, 65.6% and 69.6%, respectively. According to multivariate logistic regression models, there was no difference in the immunological response between patients with CRF01_AE, CRF07_BC and other subtypes of HIV/AIDS who underwent ART (CRF07_BC: adjusted OR (aOR) (95% CI) = 0.8 (0.4 to 1.4); other subtypes: aOR (95% CI) = 1.2 (0.6 to 2.3)). There was no evidence of an obvious joint association between HIV subtypes and ART regimens on immunological response.

CONCLUSIONS

Standardised ART was beneficial to all PLWHA, regardless of HIV subtypes, although it was more effective, to some extent, in PLWHA with CRF01_AE.

Molecular genetic characterization analysis of a novel HIV-1 circulating recombinant form (CRF156_0755) in Guangdong, China

Introduction

The characteristic of human immunodeficiency virus type 1 (HIV-1) is its susceptibility to erroneous replication and recombination, which plays a crucial role in the diverse and dynamic variation of HIV-1. The spread of different subtypes in the same population often leads to the emergence of circulating recombination forms (CRFs). At present, the main recombinant subtypes of HIV-1 in China are CRF07_BC, CRF01_AE, CRF08_BC and B' subtypes, while CRF55_01B has become the fifth major epidemic strain in China after rapid growth in recent years since it was first reported in 2013. In this study, we obtained five nearly full-length genomes (NFLGs) and one half-length genome from five different cities in Guangdong. Here, we focused on analyzing their characteristics, parental origin and drug resistance.

Methods

Plasma samples were collected from six HIV-1 infected patients in Guangdong Province who had no epidemiological association with each other. The NFLGs of HIV-1 were amplified in two overlapping segments by the near-terminal dilution method. The positive products were sequenced directly to obtain genomic sequences. The recombinant patterns and breakpoints of the NFLGs were determined using the Simplot software and confirmed by the maximum likelihood trees for segments using the IQ-TREE and BEAST software. The genotypic resistance profiles of the protease reverse transcriptase and integrase were resolved by the Stanford HIV drug resistance database.

Results

The six genomes shared highly similar recombinant pattern, with the CRF55_01B backbone substituted by CRF07_BC segments, therefore assigned as CRF156_0755. The evolutionary analysis of the segments showed that CRF07_BC segments were not clustered with the Chinese MSM variants in the CRF07_BC lineage. All the five NFLGs were identified with the non-nucleoside reverse-transcription inhibitors (NNRTIs) resistance mutation V179E.

Discussion

With the accumulation and evolution of recombination between CRF55_01B and CRF 07_BC, the prevalence of more recombinant strains of CRF55_01B and CRF 07_BC may occur. Therefore, it is necessary to strengthen the identification and monitoring of the recombination of CRF55_01B and CRF 07_BC.

The origin, dissemination, and molecular networks of HIV-1 CRF65_cpx strain in Hainan Island, China

BACKGROUND

HIV-1 CRF65_cpx strain carries drug-resistant mutations, which raises concerns about its potential for causing virologic failure. The CRF65_cpx ranks as the fourth most prevalent on Hainan Island, China. However, the origin and molecular epidemiology of CRF65_cpx strains in this area remain unclear. This study aims to estimate the spatial origins and dissemination patterns of HIV-1 CRF65_cpx in this specific region.

METHODS

Between 2018 and 2021, a total of 58 pol sequences of the CRF65_cpx were collected from HIV-positive patients on Hainan Island. The available CRF65_cpx pol sequences from public databases were compiled. The HIV-TRACE tool was used to construct transmission networks. The evolutionary history of the introduction and dissemination of HIV-1 CRF65_cpx on Hainan Island were analyzed using phylogenetic analysis and the Bayesian coalescent-based approach.

RESULTS

Among the 58 participants, 89.66% were men who have sex with men (MSM). The median age was 25 years, and 43.10% of the individuals had a college degree or above. The results indicated that 39 (67.24%) sequences were interconnected within a single transmission network. A consistent expansion was evident from 2019 to 2021, with an incremental annual addition of four sequences into the networks. Phylodynamic analyses showed that the CRF65_cpx on Hainan Island originated from Beijing (Bayes factor, BF = 17.4), with transmission among MSM on Hainan Island in 2013.2 (95%HPD: 2012.4, 2019.5), subsequently leading to an outbreak. Haikou was the local center of the CRF65_cpx epidemic. This strain propagated from Haikou to other locations, including Sanya (BF > 1000), Danzhou (BF = 299.3), Chengmai (BF = 27.0) and Tunchang (BF = 16.3). The analyses of the viral migration patterns between age subgroups and risk subgroups revealed that the viral migration directions were from "25-40 years old" to "17-24 years old" (BF = 14.6) and to "over 40 years old" (BF = 17.6), and from MSM to heterosexuals (BF > 1000) on Hainan Island.

CONCLUSION

Our analyses elucidate the transmission dynamics of CRF65_cpx strain on Hainan Island. Haikou is identified as the potential hotspot for CRF65_cpx transmission, with middle-aged MSM identified as the key population. These findings suggest that targeted interventions in hotspots and key populations may be more effective in controlling the HIV epidemic.

Uncovering the endemic circulation of rabies in Cambodia

In epidemiology, endemicity characterizes sustained pathogen circulation in a geographical area, which involves a circulation that is not being maintained by external introductions. Because it could potentially shape the design of public health interventions, there is an interest in fully uncovering the endemic pattern of a disease. Here, we use a phylogeographic approach to investigate the endemic signature of rabies virus (RABV) circulation in Cambodia. Cambodia is located in one of the most affected regions by rabies in the world, but RABV circulation between and within Southeast Asian countries remains understudied. Our analyses are based on a new comprehensive data set of 199 RABV genomes collected between 2014 and 2017 as well as previously published Southeast Asian RABV sequences. We show that most Cambodian sequences belong to a distinct clade that has been circulating almost exclusively in Cambodia. Our results thus point towards rabies circulation in Cambodia that does not rely on external introductions. We further characterize within-Cambodia RABV circulation by estimating lineage dispersal metrics that appear to be similar to other settings, and by performing landscape phylogeographic analyses to investigate environmental factors impacting the dispersal dynamic of viral lineages. The latter analyses do not lead to the identification of environmental variables that would be associated with the heterogeneity of viral lineage dispersal velocities, which calls for a better understanding of local dog ecology and further investigations of the potential drivers of RABV spread in the region. Overall, our study illustrates how phylogeographic investigations can be performed to assess and characterize viral endemicity in a context of relatively limited data.

Impact and mitigation of sampling bias to determine viral spread: Evaluating discrete phylogeography through CTMC modeling and structured coalescent model approximations

Bayesian phylogeographic inference is a powerful tool in molecular epidemiological studies, which enables reconstruction of the origin and subsequent geographic spread of pathogens. Such inference is, however, potentially affected by geographic sampling bias. Here, we investigated the impact of sampling bias on the spatiotemporal reconstruction of viral epidemics using Bayesian discrete phylogeographic models and explored different operational strategies to mitigate this impact. We considered the continuous-time Markov chain (CTMC) model and two structured coalescent approximations (Bayesian structured coalescent approximation [BASTA] and marginal approximation of the structured coalescent [MASCOT]). For each approach, we compared the estimated and simulated spatiotemporal histories in biased and unbiased conditions based on the simulated epidemics of rabies virus (RABV) in dogs in Morocco. While the reconstructed spatiotemporal histories were impacted by sampling bias for the three approaches, BASTA and MASCOT reconstructions were also biased when employing unbiased samples. Increasing the number of analyzed genomes led to more robust estimates at low sampling bias for the CTMC model. Alternative sampling strategies that maximize the spatiotemporal coverage greatly improved the inference at intermediate sampling bias for the CTMC model, and to a lesser extent, for BASTA and MASCOT. In contrast, allowing for time-varying population sizes in MASCOT resulted in robust inference. We further applied these approaches to two empirical datasets: a RABV dataset from the Philippines and a SARS-CoV-2 dataset describing its early spread across the world. In conclusion, sampling biases are ubiquitous in phylogeographic analyses but may be accommodated by increasing the sample size, balancing spatial and temporal composition in the samples, and informing structured coalescent models with reliable case count data.

Identification and genomic characterization of a novel HIV-1 unique recombinant form (CRF01_AE/CRF07_BC) in Zhejiang Province, China

Mutation and recombination are important mechanisms leading to the frequent evolution and genetic diversity of viruses as HIV-1. In this study, we identified the near full-length genomic characterization of a novel HIV-1 unique recombinant form (URF) strain (Sample ID: ZJ20202195/ZJ/CHN/2020, hereafter referred to as ZJ20202195) isolated during the HIV-1 molecular surveillance in 2020 in Zhejiang Province, China, through different recombination analysis tools and phylogenetic analysis. Our results amply proved that the near full-length genome (NFLG) sequence of ZJ20202195 was a novel HIV-1 unique recombinant form (URF) consisting of CRF01_AE and CRF07_BC subtype, and delimited three recombinant segments, of which the Segment I (HXB2:776-5559 nucleotide (nt)) and Segment III (HXB2:6224-9412 nt) were mainly originated from CRF01_AE cluster g4a strains prevalent in China and Segment II (HXB2:5560-6223 nt) was from CRF07_BC subtype. Overall, our findings provide insight and a scientific basis in the genetic diversity and accurate determination of HIV-1 recombinant strains in China.

Structure-Based Discovery and Characterization of a Preclinical Drug Candidate for the Treatment of HIV-1 Infection

HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) area key component of the current HIV-1 combination drug regimens. Although they exhibit potent anti-HIV-1 activity and modest toxicity, the emergence of mutant strains limits their application in clinical. Our previous research efforts contributed to the identification of compound K-5a2, which exhibits nanomolar activity in HIV-1-infected MT-4 cells. In this study, K-5a2 was shown to have a high level of anti-HIV-1 activity against various lab-adapted strains and clinical isolate strains, being comparable to ETR. Moreover, we showed the feasibility of K-5a2 as a preclinical anti-HIV-1 candidate by establishing its synergistic or additive anti-HIV-1 activity in combination with other representative anti-HIV-1 drugs and candidates. In addition, K-5a2 exhibited no inhibitory activity to the primary CYP isoforms and favorable pharmacokinetics. Taken together, its robust anti-HIV-1 potency, synergistic or additive effects with other anti-HIV drugs, and favorable pharmacokinetic and safety profiles make K-5a2 a potent alternative drug for HIV/AIDS treatment.

The Emergence, Diversification, and Transmission of Subgroup J Avian Leukosis Virus Reveals that the Live Chicken Trade Plays a Critical Role in the Adaption and Endemicity of Viruses to the Yellow-Chickens

The geographical spread and inter-host transmission of the subgroup J avian leukosis virus (ALV-J) may be the most important issues for epidemiology. An integrated analysis, including phylogenetic trees, homology modeling, evolutionary dynamics, selection analysis and viral transmission, based on the gp85 gene sequences of the 665 worldwide ALV-J isolates during 1988-2020, was performed. A new Clade 3 has been emerging and was evolved from the dominating Clade 1.3 of the Chinese Yellow-chicken, and the loss of a α-helix or β-sheet of the gp85 protein monomer was found by the homology modeling. The rapid evolution found in Clades 1.3 and 3 may be closely associated with the adaption and endemicity of viruses to the Yellow-chickens. The early U.S. strains from Clade 1.1 acted as an important source for the global spread of ALV-J and the earliest introduction into China was closely associated with the imported chicken breeders in the 1990s. The dominant outward migrations of Clades 1.1 and 1.2, respectively, from the Chinese northern White-chickens and layers to the Chinese southern Yellow-chickens, and the dominating migration of Clade 1.3 from the Chinese southern Yellow-chickens to other regions and hosts, indicated that the long-distance movement of these viruses between regions in China was associated with the live chicken trade. Furthermore, Yellow-chickens have been facing the risk of infections of the emerging Clades 2 and 3. Our findings provide new insights for the epidemiology and help to understand the critical factors involved in ALV-J dissemination. IMPORTANCE Although the general epidemiology of ALV-J is well studied, the ongoing evolutionary and transmission dynamics of the virus remain poorly investigated. The phylogenetic differences and relationship of the clades and subclades were characterized, and the epidemics and factors driving the geographical spread and inter-host transmission of different ALV-J clades were explored for the first time. The results indicated that the earliest ALV-J (Clade 1.1) from the United States, acted as the source for global spreads, and Clades 1.2, 1.3 and 3 were all subsequently evolved. Also the epidemiological investigation showed that the early imported breeders and the inter-region movements of live chickens facilitated the ALV-J dispersal throughout China and highlighted the needs to implement more effective containment measures.

The Molecular Epidemiological and Immunological Characteristics of HIV-1 CRF01_AE/B Recombinants in Nanjing, China

Human immunodeficiency virus-type 1 (HIV-1) CRF01_AE/B recombinants are newly emerging strains that are spreading rapidly in Southern and Eastern China. This study aimed to elucidate the molecular epidemiological characteristics of HIV-1 CRF01_AE/B recombinants in Nanjing and to explore the impact of these novel strains on the immunological status. A total of 1,013 blood samples from newly diagnosed HIV-1-infected patients were collected in Nanjing from 2015 to 2019, among which 958 partial Pol sequences were sequenced successfully. We depicted the molecular epidemiological characteristics of CRF01_AE/B recombinants by the molecular evolutionary analysis, Bayesian system evolution analysis, and transmission network analysis. The generalized additive mixed model was applied to evaluate the CD4+ T-cell count change of CRF01_AE/B recombinants. The Kaplan–Meier analysis was performed to assess the time from combined antiretroviral therapy (cART) initiation to immune reconstruction. We have identified 102 CRF01_AE/B recombinants (102/958, 10.65%) in Nanjing, including CRF67_01B (45/102, 44.12%), CRF68_01B (35/102, 34.31%), and CRF55_01B (22/102, 12.57%). According to the Bayesian phylogenetic inference, CRF55_01B had a rapid decline stage during 2017–2019, while CRF67_01B and CRF68_01B have experienced a fast growth phase during 2014–2015 and then remained stable. We have constructed 83 transmission networks, in which three larger clusters were composed of CRF67_01B and CRF68_01B. CRF01_AE/B recombinants manifested a faster decrease rate of CD4+ T-cell count than CRF_07BC but similar to CRF01_AE. The probability of achieving immune reconstruction in CRF01_AE/B recombinants was lower than CRF07_BC in the subgroup of baseline CD4+ T-cell count at cART initiation &lt;300 cells/μl. In summary, CRF67_01B and CRF68_01B were the major strains of CRF01_AE/B recombinants in Nanjing, which have formed large transmission clusters between Nanjing and other provinces. CRF01_AE/B recombinants might be associated with rapid disease progression and poor immune reconstruction. The continuous epidemiological monitoring of CRF01_AE/B recombinants should be highly emphasized.

Epidemiology and Clinical Outcomes of HIV Infection in South-Central China: A Retrospective Study From 2003 to 2018

Objective

HIV epidemiology in South-Central China is rarely reported. This study aims to characterize epidemiological and clinical features of HIV-infected patients in Hunan Province, located in South-Central China, for better management of HIV infections.

Methods

This retrospective study retrieved multi-center records of laboratory-confirmed HIV-infected patients in Hunan province. Information on HIV-associated mortality and antiretroviral therapies was also collected.

Results

Among 34,297 patients diagnosed with HIV infections from 2003 to 2018, 73.9% were males, 41.3% were older adults (≥50 years), and 71.2% were infected by heterosexual transmission. Despite a slow growth of new HIV infections in the overall population, annual percentages of HIV infections increased in older males (85.3% through heterosexual transmission) and young patients <30 years (39.9% through homosexual transmission). At baseline, serum levels of CD4+ T-cell counts were lower in older adults (191.0 cells/μl) than in young patients (294.6 cells/μl, p-value < 0.0001). A large proportion (47.2%, N = 16,165) of HIV-infected patients had advanced HIV disease (CD4+ T-cell counts < 200 cells/μl) from 2003 to 2018. All-cause mortality (57.0% due to AIDS-related illnesses) was reported among 4411 HIV-infected patients, including 2619 older adults. The 10-year survival rate was significantly lower in elderly males than in other patients (59.0 vs. 78.4%, p-value < 0.05).

Conclusions

Elderly males are prone to HIV infections with a high risk of HIV-associated fatality. Our findings support early prevention and critical care for elderly populations to control HIV infections.

HIV incidence and risk factors among transgender women and cisgender men who have sex with men in two cities of China: a prospective cohort study

Background

HIV epidemic among men who have sex with men (MSM) remains a major public health concern in China. Despite a growing body of research on transgender women worldwide, little is known about Chinese transgender women within MSM. We sought to estimate HIV incidence and distinguish risk factors of HIV acquisition among them from that among cisgener (non-transgender) MSM (cis-MSM).

Methods

We conducted an open cohort study among Chinese MSM, including those who were identified as transgender in Shanghai and Tianjin. Participants were initially recruited by local community-based organizations from January to June, 2016, and were followed up approximately every 6 months until June 2018. At each visit, a structured questionnaire was used to gather information on demographics, sexual risk behaviors, and HIV status. HIV incidence was calculated as the number of seroconversions divided by total number of person-years of follow-up among HIV-negatives at baseline. Risk factors of HIV acquisition were assessed by univariate and multivariate Cox regression models with time-dependent variables.

Results

A total of 1056 participants contributed 1260.53 person-years (PYs) of follow-up, 33 HIV seroconversions occurred during the follow-up period, yielding an estimated HIV incidence of 2.62 (95% CI 1.80–3.68) per 100 PYs. HIV incidence among transgender women was 4.42 per 100 PYs, which was significantly higher than that of 1.35 per 100 PYs among cis-MSM, demonstrating a threefold higher odds of HIV infection than cis-MSM. For transgender women, those lived locally ≤ 2 years (adjusted hazard ratio [aHR] = 1.76, 95% CI 1.13–2.76) and unprotected anal sex last time (aHR = 4.22, 95% CI 1.82–9.79) were more likely to acquire HIV. For cis-MSM, factors associated with HIV acquisition were frequency of anal sex ≥ 3 times in past one month (aHR = 4.19, 95% CI 1.06–16.47) and unprotected anal sex last time (aHR = 5.33, 95% CI 1.52–18.73).

Conclusions

Compared to cis-MSM, transgender women were at higher risk of HIV acquisition, highlighting an urgent need of tailored prevention. Future HIV program should consider to include them to ensure that this population in China are not left behind.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-00947-3.

The Emergence and Transmission Dynamics of HIV-1 CRF07_BC in Mainland China

A total of 1155 partial pol gene sequences of human immunodeficiency virus (HIV)-1 CRF07_BC were sampled between 1997 and 2015, spanning 13 provinces in Mainland China and risk groups [heterosexual, injecting drug users (IDU), and men who have sex with men (MSM)] to investigate the evolution, adaptation, spatiotemporal and risk group dynamics, migration patterns, and protein structure of HIV-1 CRF07_BC. Due to the unequal distribution of sequences across time, location, and risk group in the complete dataset (‘full1155’), subsampling methods were used. Maximum-likelihood and Bayesian phylogenetic analysis as well as discrete trait analysis of geographical location and risk group were carried out. To study mutations of a cluster of HIV-1 CRF07_BC (CRF07-1), we performed a comparative analysis of this cluster to the other CRF07_BC sequences (‘backbone_295’) and mapped the mutations observed in the respective protein structure. Our findings showed that HIV-1 CRF07_BC most likely originated among IDU in Yunnan Province between October 1992 to July 1993 [95 per cent hightest posterior density (HPD): May 1989–August 1995] and that IDU in Yunnan Province and MSM in Guangdong Province likely served as the viral sources during the early and more recent spread in Mainland China. We also revealed that HIV-1 CRF07-1 has been spreading for roughly 20 years and continues to cause local transmission in Mainland China and worldwide. Overall, our study sheds light on the dynamics of HIV-1 CRF07_BC distribution patterns in Mainland China. Our research may also be useful in formulating public health policies aimed at controlling acquired immune deficiency syndrome in Mainland China and globally.

Molecular Network Analysis Reveals Transmission of HIV-1 Drug-Resistant Strains Among Newly Diagnosed HIV-1 Infections in a Moderately HIV Endemic City in China

Since the implementation of the "treat all" policy in China in 2016, there have been few data on the prevalence of transmitted drug resistance (TDR) in China. In this study, we describe TDR in patients newly diagnosed with human immunodeficiency virus (HIV) infection between 2016 and 2019 in Shenyang city, China. Demographic information and plasma samples from all newly reported HIV-infected individuals in Shenyang from 2016 to 2019 were collected. The HIV pol gene was amplified and sequenced for subtyping and TDR. The spread of TDR was analyzed by inferring an HIV molecular network based on pairwise genetic distance. In total, 2,882 sequences including CRF01_AE (2019/2,882, 70.0%), CRF07_BC (526/2,882, 18.3%), subtype B (132/2,882, 4.6%), and other subtypes (205/2,882, 7.1%) were obtained. The overall prevalence of TDR was 9.1% [95% confidence interval (CI): 8.1-10.2%]; the prevalence of TDR in each subtype in descending order was CRF07_BC [14.6% (95% CI: 11.7-18.0%)], subtype B [9.1% (95% CI: 4.8-15.3%)], CRF01_AE [7.9% (95% CI: 6.7-9.1%)], and other sequences [7.3% (95% CI: 4.2-11.8%)]. TDR mutations detected in more than 10 cases were Q58E (n = 51), M46ILV (n = 46), K103N (n = 26), E138AGKQ (n = 25), K103R/V179D (n = 20), and A98G (n = 12). Molecular network analysis revealed three CRF07_BC clusters with TDR [two with Q58E (29/29) and one with K103N (10/19)]; and five CRF01_AE clusters with TDR [two with M46L (6/6), one with A98G (4/4), one with E138A (3/3), and one with K103R/V179D (3/3)]. In the TDR clusters, 96.4% (53/55) of individuals were men who have sex with men (MSM). These results indicate that TDR is moderately prevalent in Shenyang (5-15%) and that TDR strains are mainly transmitted among MSM, providing precise targets for interventions in China.

The Viral Founder Effect and Economic-Driven Human Mobility Shaped the Distinct Epidemic Pattern of HIV-1 CRF01_AE in Northeast China

Background: In China, two distinct lineages shaped the epidemic of HIV-1 CRF01_AE among men who have sex with men (MSM), of which the uneven distributions were observed geographically. One lineage spread across China, while another dominated in Northeast China. Understanding the drivers of viral diffusion would provide guidelines for identifying the source and hotspots of HIV transmission among MSM to target interventions in China.

Methods: We collected the pol sequences between 2002–2017 to reconstruct the spatiotemporal history of CRF01_AE lineages in Shenyang, one economic center of Northeast China, using the Bayesian phylogeographic and phylodynamic approaches. Importantly, for the datasets with the high sample density, we did the down-sampling to avoid the sampling bias.

Results: Two lineages accounted for 97%, including 426 and 1516 sequences, and homosexuals and bisexuals were above 80%. One lineage appeared earlier 7 years than another (1993 vs. 2002) among homosexuals and bisexuals, whereas among heterosexuals, both lineages were observed firstly in 2002. 96% viral migrations within one lineage were from homosexuals toward bisexuals (49%) and male-heterosexuals (46%). Within another, except for homosexuals (72%), bisexuals (23%) served as the top second source, and female-heterosexuals (11%) were the third recipients following bisexuals (44%) and male-heterosexuals (39%). Although the basic reproduction number (R₀) of two lineages were similar and both of the effective production number (R_e) fell below 1 at the most recent sampling time, the starts of the R_e declining varied.

Conclusions: Our findings revealed that throughout the viral national spread chain, Shenyang is the source for the initial expanding of one lineage, where is only a sink of another, proving that the viral founder effect and regional human mobility contributed to the uneven distribution of two lineages, and emphasizing the important roles of the area where the virus originated and economy-driven migrants in HIV transmission.

Long-Term Changes of HIV/AIDS Incidence Rate in China and the U.S. Population From 1994 to 2019: A Join-Point and Age-Period-Cohort Analysis

Although HIV caused one of the worst epidemics since the late twentieth century, China and the U.S. has made substantial progress to control the spread of HIV/AIDS. However, the trends of HIV/AIDS incidence remain unclear in both countries. Therefore, this study aimed to highlight the long-term trends of HIV/AIDS incidence by gender in China and the U.S. population. The data were retrieved from the Global Burden of Disease (GBD) database since it would be helpful to assess the impact/role of designed policies in the control of HIV/AIDS incidence in both countries. The age-period-cohort (APC) model and join-point regression analysis were employed to estimate the age-period-cohort effect and the average annual percentage change (AAPC) on HIV incidence. Between 1994 and 2019, we observed an oscillating trend of the age-standardized incidence rate (ASIR) in China and an increasing ASIR trend in the U.S. Despite the period effect in China declined for both genders after peaked in 2004, the age effect in China grew among the young (from 15–19 to 25–29) and the old age groups (from 65–69 to 75–79). Similarly, the cohort effect increased among those born in the early (from 1924–1928 to 1934–1938) and the latest birth groups (from 1979–1983 to 2004–2009). In the case of the U.S., the age effect declined after it peaked in the 25–29 age group. People born in recent birth groups had a higher cohort effect than those born in early groups. In both countries, women were less infected by HIV than men. Therefore, besides effective strategies and awareness essential to protect the young age groups from HIV risk factors, the Chinese government should pay attention to the elderly who lacked family support and were exposed to HIV risk factors.

Epidemiology and Molecular Transmission Characteristics of HIV in the Capital City of Anhui Province in China

Hefei, Anhui province, is one of the cities in the Yangtze River Delta, where many people migrate to Jiangsu, Zhejiang and Shanghai. High migration also contributes to the HIV epidemic. This study explored the HIV prevalence in Hefei to provide a reference for other provinces and assist in the prevention and control of HIV in China. A total of 816 newly reported people with HIV in Hefei from 2017 to 2020 were recruited as subjects. HIV subtypes were identified by a phylogenetic tree. The most prevalent subtypes were CRF07_BC (41.4%), CRF01_AE (38.1%) and CRF55_01B (6.3%). Molecular networks were inferred using HIV-TRACE. The largest and most active transmission cluster was CRF55_01B in Hefei’s network. A Chinese national database (50,798 sequences) was also subjected to molecular network analysis to study the relationship between patients in Hefei and other provinces. CRF55_01B and CRF07_BC-N had higher clustered and interprovincial transmission rates in the national molecular network. People with HIV in Hefei mainly transmitted the disease within the province. Finally, we displayed the epidemic trend of HIV in Hefei in recent years with the dynamic change of effective reproductive number (Re). The weighted overall Re increased rapidly from 2012 to 2015, with a peak value of 3.20 (95% BCI, 2.18–3.85). After 2015, Re began to decline and remained stable at around 1.80. In addition, the Re of CRF55_01B was calculated to be between 2.0 and 4.0 in 2018 and 2019. More attention needs to be paid to the rapid spread of CRF55_01B and CRF07_BC-N strains among people with HIV and the high Re in Hefei. These data provide necessary support to guide the targeted prevention and control of HIV.

Independent epidemic patterns of HIV-1 CRF01_AE lineages driven by mobile population in Shenzhen, an immigrant city of China

Shenzhen, a city with &gt;12 million migrant population, may play a key role in the spread of human immunodeficiency virus (HIV)-1 in China. The transmission dynamics of CRF01_AE, a predominant subtype in Shenzhen, is a good model to characterize the impact of human mobility on HIV-1 epidemic locally and nationally. We used phylodynamic and phylogeographic methods to estimate the viral transmission dynamics and migration trajectory of variable lineages based on 1,423 CRF01_AE sequences in Shenzhen sampled between 2006 and 2015. Eleven lineages of CRF01_AE were detected in Shenzhen. Of those, four main lineages originated during the 1990s. Their basic viral reproduction number (R0) ranged 1.96–3.92. The effective viral reproduction number (Re) of two lineages prevalent among heterosexuals/people who inject drugs had reduced &lt;1 at the end of sampling, and the main sources were the intra-provincial immigrants (72 per cent) for one and local residents of Shenzhen (91 per cent) for another. Within two lineages among men who have sex with men (MSM), Re had been above or close to 1 at the end of sampling, and the immigrants from Jiangxi/Shaanxi and Hubei as sources accounted for 93 per cent and 68 per cent of all viral migration events, respectively. Moreover, no obvious recipients were found throughout the viral migration history for any lineage. Our findings demonstrate that HIV epidemic is declining in Shenzhen, which coincided with the initiation of the interventions during the 2000s. However, the obvious differences of the epidemic patterns between lineages emphasize the importance of further targeting interventions and continued molecular tracing, focusing on high-risk transmission sources among MSM.

The prevalence of CRF55_01B among HIV-1 strain and its connection with traffic development in China

CRF55_01B is a relatively “young” HIV strain. At present, we do not know much about its transmission characteristics in China. So, to describe the transmission characteristics of CRF55_01B strain among provinces and HIV infected people, and to analyze the reasons for its rapid epidemic in China, a total of 1237 subjects infected with CRF55_01B from 31 provinces spanning a period of 12 years from 2007 to 2018 were enrolled in this study. By constructing a molecular network and Bayesian correlation analysis, we found that CRF55_01B increased exponentially from 2005 to 2009 after its origin in Shenzhen, and increased rapidly after 2010. CRF55_01B began to spread to other provinces in 2007. After 2010, the strain showed a trend of rapid spread and epidemic from Guangdong-Shenzhen to other provinces in China. Guangdong, Shenzhen, Hunan, Beijing, Guangxi, Hubei, Jiangxi, Guizhou, Hebei, Anhui, Shanghai, Shandong, Henan, and Yunnan were the key provinces of CRF55_01B transmission. CRF55_01B, although originating from men who sex with men (MSM), was transmitted among heterosexuals in 2010. Males in heterosexuals played a crucial role in the transmission and diffusion of this strain. We also revealed that CRF55_01B might spread rapidly along with the rapid development of the Beijing-Guangzhou and Beijing-Kowloon railways. This study suggests that if we detect the spread of MSMs in time through molecular monitoring in the early stage of the epidemic, it can help us control the epidemic early and prevent its spread, which is of great significance to China's national prevention and control of HIV-1.

Phylogenetic analyses of SARS-CoV-2 B.1.1.7 lineage suggest a single origin followed by multiple exportation events versus convergent evolution

The emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) herald a new phase of the pandemic. This study used state-of-the-art phylodynamic methods to ascertain that the rapid rise of B.1.1.7 “Variant of Concern” most likely occurred by global dispersal rather than convergent evolution from multiple sources.

Immunological considerations for COVID-19 vaccine strategies

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the most formidable challenge to humanity in a century. It is widely believed that prepandemic normalcy will never return until a safe and effective vaccine strategy becomes available and a global vaccination programme is implemented successfully. Here, we discuss the immunological principles that need to be taken into consideration in the development of COVID-19 vaccine strategies. On the basis of these principles, we examine the current COVID-19 vaccine candidates, their strengths and potential shortfalls, and make inferences about their chances of success. Finally, we discuss the scientific and practical challenges that will be faced in the process of developing a successful vaccine and the ways in which COVID-19 vaccine strategies may evolve over the next few years.