Epigenetic regulation is essential to the well-being of developing as well as developed cells by providing tissue-specific gene expression. DNA methylation on cytosine nucleotides is one of the core elements of epigenetic machinery, and stable DNA methylation patterns are maintained by properly regulated DNA methylation and DNA demethylation. DNA methylation has been studied extensively in the past 15 years, while the DNA demethylation process has largely been unknown. In this review, we briefly survey recent advances on DNA methylation/demethylation axis with special emphasis on the aspects of DNA demethylation.

The analysis of the molecular epidemiological characteristics of newly diagnosed HIV-infected patients in Jiaxing City is essential for developing effective HIV prevention. Blood samples were collected from newly diagnosed HIV-infected individuals in Jiaxing City from October 2022 to October 2023, and the HIV-1 pol region gene was amplified and sequenced. These sequences were used to construct a molecular transmission network and analyse transmitted drug resistance mutations. We identified 11 subtypes, of which CRF07_BC and CRF01_AE were the most prevalent. The rate of surveillance drug resistance mutation (SDRM) sites in newly diagnosed cases was 9%. A total of 37 molecular transmission clusters were identified, the largest of which was the CRF07_BC-1 cluster (13 nodes). This cluster has five probable high-risk transmitters. Two additional larger clusters in the molecular network were the heterosexual transmission clusters for middle-aged and older males, CRF08_BC-1 (eight nodes) and CRF85_BC-1 (eight nodes). The mean degree of the two clusters was high, and the patients were high-risk transmitters, indicating a higher risk of HIV transmission. The distribution of HIV-1 subtypes in Jiaxing City was widespread, with moderate levels of transmission resistance. Larger molecule clusters carry a high risk of transmission, indicating that we should strengthen monitoring and intervention.

Background: Since the first recorded HIV-1 infection in 1998, Jiaxing City has seen increasing HIV infections among men who have sex with men (MSM), necessitating targeted research to understand HIV-1 subtypes and drug resistance patterns to improve prevention and treatment strategies. Objectives: The study aimed to assess the variety of HIV-1 subtypes, the pre-treatment drug re-sistance (PDR) among MSM in Jiaxing, China, and transmission dynamics of drug-resistant strains. The findings may contribute to the development of targeted HIV prevention and control strategies for the MSM population. Methods: Plasma samples from all newly reported cases of HIV-1 transmitted through male-to-male sexual contact in Jiaxing City from 2020 to 2022 were retrospectively analyzed. Demo-graphic and epidemiological data were collected. Partial pol gene regions were amplified, se-quenced, and analyzed for drug resistance mutations (DRMs) using the Stanford HIV Drug Re-sistance Database. The Calibrated Population Resistance (CPR) program was utilised to identify Surveillance Drug Resistance Mutation (SDRM). A molecular transmission network was con-structed to investigate the scale of transmitted drug resistance (TDR) strains. Results: We obtained a total of 298 eligible genetic sequences, revealing a diverse distribution of HIV-1 subtypes, with CRF07_BC, CRF01_AE, and CRF55_01B as the most prevalent. Pretreat-ment DRMs were detected in 91 cases (30.5%), yielding an overall PDR prevalence of 11.0%. Resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) was most frequent (5.4% each). TDR prevalence reached 7.0%, showing an increasing trend (2020-2022). The molecular network analysis indicated sporadic dissemination of drug-resistant cases rather than large-scale transmission chains. Conclusion: The convergence of high HIV-1 subtype diversity, elevated PDR prevalence, rising TDR rates, and sporadic resistant strain transmission within MSM networks necessitates the sus-tained resistance surveillance and precision public health interventions.

Human metapneumovirus (hMPV) represents a leading cause of both upper and lower respiratory tract infections among children and adults globally. To investigate the prevalence and evolution of hMPV in the Jiaxing area of China between 2023 and 2025, we screened 3600 pharyngeal swab specimens by real-time PCR, identified 101 positives, and obtained genomic sequences of 48 viral isolates using high-throughput sequencing. Using the sequencing data, we reconstructed a phylogenetic tree and examined amino acid substitutions. The epidemiological analysis revealed an overall hMPV positivity rate of 2.81% (101/3600) in Jiaxing during 2023–2025. Although positive cases were detected across all age groups, they were mainly children, with no significant difference between genders. Regarding seasonal patterns, the peak of hMPV activity occurred predominantly during winter and spring. Over the study period, four genotypes co-circulated, in the order of B2 (41.67%), A2.2.2 (37.50%), A2.2.1 (16.67%), and B1 (4.17%). Further phylogenetic analysis showed that the B1 strains from Jiaxing clustered primarily with those from Beijing, China, while B2, A2.2.1, and A2.2.2 strains were more closely related to strains from the United States and Beijing. Of note, an A2c_111nt-dup variant was identified in Jiaxing in 2023. Starting from November 2024, the prevailing genotype transitioned from A2.2.1/A2.2.2 to B2, and B2 emerged as the absolutely dominant strain by 2025. In comparison with earlier circulating strains, several amino acid substitutions have accumulated in current isolates, such as T223N, D280N, I392T, R396Q, S444N, K450R, and T521A in the F protein of B2 strains. Furthermore, the G, L, P, and SH proteins also displayed temporally patterned amino acid replacements. While the biological significance of these mutations is yet to be determined, these results highlight the public health importance of ongoing hMPV surveillance and dynamic monitoring of its genetic evolution.