Horizontal transmission might be a common route of hepatitis B virus exposure in highly endemic areas.

Hepatitis B virus (HBV) is a common viral pathogen that infects more than a third of the world's population; however, the transmission route remains to be further defined. The 18-year implementation of the free HBV vaccine for children has greatly changed the prevalence of HBV infection in China, which presents a unique real-world model for assessing the pattern of HBV transmission. Cross-sectional data of HBV seromarkers between July 2019 and April 2020 were collected from 53 371 individuals aged 1-60 years in four areas of North to South in Eastern China. Longitudinal data of HBV seromarkers between 2007 and 2020 were collected from 177 adults in an area of South China. The regional- and age-specific changes in HBV seromarkers were analyzed. Overall, positive rates of HBV surface antigen (HBsAg; from 3.44% to 15.1%) and antibody against HBV core antigen (anti-HBc; from 7.6% to 44.0%) significantly increased from North to South. Among persons aged ≤18 years, the positive rates of antibody against HBsAg (anti-HBs) and anti-HBc (+) remained at low levels in the North, while they were increasing among persons aged >12 years in the South, despite higher positive rates of anti-HBs (+). Among persons aged >18 years, the anti-HBs (+) rates remained relatively stable (~60%), while anti-HBc (+) rates increased significantly with age. Up to ~80% of the anti-HBs (+) adults in the South was anti-HBc (+) while it was 13.6% in the North. In the longitudinal cohort, the anti-HBc (+) rate among adults in the South increased by 14.2% during 10 years of follow-up. Horizontal transmission might be a common route in highly endemic areas, and may help to explain the high HBV exposure worldwide. The risk of horizontal transmission among children without seroprotective anti-HBs should be notified in highly endemic areas.

Human cytomegalovirus latent infection alters the expression of cellular and viral microRNA.

BACKGROUND: MicroRNAs (miRNAs) play important roles in regulating gene expression of plants, animals and viruses. Comprehensive characterization of host and viral miRNA will help uncover the molecular mechanisms that underlie the progression of human cytomegalovirus (HCMV) latent infection. To investigate the miRNA expression profile of HCMV and host cells during latent infection, we performed deep-sequencing analysis of the small RNAs isolated from HCMV-infected and mock-infected human monocytic leukemia cell line, THP-1. RESULTS: We established a HCMV latent infection cell model using the THP-1 cells. High-throughput sequencing technology was used to sequence small RNA libraries of the HCMV-infected and mock-infected THP-1 and to investigate their small RNA transcriptomes. We found eight miRNAs including miR-US25-1, miR-US25-2-5p and miR-UL112 that were expressed by HCMV during latent infection. The expressions of the host miRNAs were also affected by HCMV latent infection. At least 49 cellular miRNAs were differentially expressed: 39 were up-regulated and 10 were down-regulated upon HCMV latent infection. The expression of the human miRNA hsa-miR-124-3p was significantly up-regulated in the HCMV latent infection library. In addition, we found 14 cellular novel miRNAs in the HCMV-infected and mock-infected THP-1 libraries. Functional annotation of the target genes of the differentially expressed miRNAs suggested that the majority of the genes are involved in melanogenesis, pathways in cancer, endocytosis and wnt signaling pathway. CONCLUSIONS: The small RNA transcriptomes obtained in this study demonstrate the usefulness of the deep-sequencing combined with bioinformatics approach in understanding of the expression and function of host and viral small RNAs in HCMV latent infection. This approach can also be applied to the study of other kinds of viruses.