Researchers have mapped the genetic diversity, drug resistance patterns, and molecular transmission networks of HIV-1 in Zunyi, a prefecture-level city in Guizhou Province, southwestern China, in a study published in BMC Infectious Diseases. The work offers a detailed local picture of an epidemic that health authorities have found difficult to characterize at the prefecture level.
The study was motivated by the scale of new infections in the region. Zunyi reported 1,335 new HIV cases in 2023 and 1,317 in 2024, a total of 2,652 newly reported cases during the study period, with more than 10,000 people living with HIV/AIDS in the area. Southwestern China is known to have a heterogeneous HIV epidemic, and the authors note that molecular transmission characteristics at the prefecture level have remained insufficiently characterized.
To investigate, the team enrolled 231 newly diagnosed individuals and attempted amplification and sequencing of the HIV-1 pol gene, successfully obtaining 208 sequences.
Phylogenetic trees were reconstructed using three complementary approaches: neighbor-joining and maximum likelihood methods implemented in MEGA, and Bayesian inference using MrBayes. The three methods yielded highly concordant tree topologies, which the researchers say provides strong support for the robustness of their genotype classification and clustering patterns.
Two circulating recombinant forms dominated the local epidemic. CRF07_BC accounted for 56.3 percent of the typed sequences and CRF01_AE for 29.3 percent. This mix of recombinant lineages reflects the high genetic diversity that characterizes HIV-1 in parts of China and complicates efforts to trace transmission chains.
Pretreatment drug resistance, meaning resistance detected in people before they begin antiretroviral therapy, was found in 21.2 percent of participants. The prevalence varied significantly across genotypes, with higher levels observed in CRF08_BC and other recombinant forms.
Molecular transmission networks were inferred based on pairwise genetic distances under the TN93 model together with branch support. The analysis initially identified 31 transmission clusters. After excluding 8 clusters whose bootstrap support values fell below 70, the researchers retained 23 well-supported clusters involving 55 sequences, or 26.4 percent of the dataset, for downstream association analyses.
Most of the retained clusters were small, and the network contained both densely connected subgraphs and simple linear chains, a pattern the authors describe as indicating heterogeneous transmission dynamics. In other words, some transmission occurs within tightly linked groups of infections, while other chains spread through longer, sequential links between individuals.
The team also used logistic regression to identify factors associated with pretreatment drug resistance and molecular clustering. In univariate analysis, marital status, transmission route, and education level were each associated with clustering. However, after multivariate adjustment, only marital status remained independently associated: compared with married participants, divorced or widowed participants were less likely to be included in molecular clusters.
The authors conclude that the HIV epidemic in Zunyi is characterized by high genetic diversity, fragmented molecular transmission networks, and genotype-specific clustering patterns. They suggest that integrating molecular network analysis with routine drug resistance surveillance can improve understanding of local transmission dynamics and support precision HIV prevention strategies in southwestern China. As an observational study of newly diagnosed individuals in a single prefecture, the findings describe local transmission patterns rather than outcomes of any intervention, and the authors position the work as a contribution to surveillance-informed prevention planning in the region.
Subject of Research: HIV-1 genetic diversity, drug resistance, and molecular transmission networks in Zunyi, China
Article Title: Genetic diversity, drug resistance, and molecular transmission networks of HIV-1 in Zunyi: implications for precision prevention
Article References: Wang, Y., Ma, Y., He, M., Wan, Y., Liu, Y., Ma, L., Zhang, Y., Zheng, M., Yuan, Z., Gao, Z., & Zhang, X. (2026). Genetic diversity, drug resistance, and molecular transmission networks of HIV-1 in Zunyi: implications for precision prevention. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14360-w
Image Credits: AI Generated
DOI: 10.1186/s12879-026-14360-w
Keywords: HIV-1, Zunyi, Guizhou, pretreatment drug resistance, molecular transmission networks, phylogenetics, CRF07_BC, CRF01_AE, pol gene, public health surveillance, China, infectious diseases
News Source: Kristina Jarvis. (October 28, 2026). HIV-1 in Zunyi shows high genetic diversity and pretreatment drug resistance. Scienmag.
