Characterization of molecular transmission network and drug resistance in newly diagnosed HIV-1 population aged 50 years and above in Huzhou City， Zhejiang Province

ObjectiveTo analyze the characteristics of HIV-1 molecular network and pretreatment drug resistance genes in the middle-aged and elderly people aged ≥50 years in Huzhou City, Zhejiang Province, and to provide an evidence for the prevention and control of AIDS epidemic.MethodsA total of 332 samples from the newly reported and untreated AIDS patients aged ≥50 years in Huzhou City from January 2020 to December 2023 were collected, pol genes were amplified by reverse transcription polymerase chain reaction (RT-PCR) and nested polymerase chain reaction (nest⁃PCR). Phylogenetic trees analyzing the subtypes were constructed, and a molecular network with a gene distance threshold of 1.0% were constructed at the same time. Mutation sites of drug resistance-related genes were identified through the Data Analysis and Detection System of HIV-1 Resistance Gene Detection of Stanford University, USA.ResultsSequence samples of 308 patients were obtained, and 9 genotypes were identified, including CRF07_BC in 172 cases (55.8%), CRF01_AE in 61 cases (19.8%), CRF08_BC in 43 cases (14.0%), CRF85_BC in 9 cases (2.9%), and CRF55_01B in 8 cases (2.6%), subtype B in 5 cases (1.6%), subtype C in 4 cases (1.3%), CRF67_01B in 3 cases (1.0%), and unique recombination URF01_AE/07_BC in 3 cases (1.0%). When the gene distance threshold was 1.0%, 28 molecular clusters were formed, and 139 cases were connected to the network, with an access rate of 45.0%. The largest transmission cluster C1 contained 44 cases infected with CRF07_BC subtype, all of whom were heterosexually transmitted, and predominantly by males. A total of 30 patients were found to have low-grade or higher drug resistance mutations, and the pretreatment drug resistance rate was 9.7% (30/308). Among them, there were 5 cases (16.7%) of protease inhibitor (PI) related drug resistance mutations, and 26 cases (86.7%) of non-nucleoside reverse transcriptase inhibitors (NNRTI) related drug resistance mutations.ConclusionCRF07_BC is the subtype with the most clusters among the middle-aged and elderly infected patients aged ≥50 years in Huzhou City. Middle-aged and elderly transmission clusters are formed within the three counties of WX, NX and CX through related activities. Molecular network monitoring on newly reported cases aged ≥50 years in Huzhou City should be strengthened so that the new characteristics of epidemic changes can be detected in time, providing a scientific basis for adjusting AIDS prevention and control measures for the elderly.