Department of Epidemiology, Infectious Disease Control and Prevention, Hiroshima University Graduate School of Biomedical and Health Sciences, Japan; 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
National Immunization Programme, Ministry of Health, 151-152 Kampuchea Krom Avenue, Phonm Penh, Cambodia.
BMC Infect Dis. 2020 Apr 25;20(1):305. doi: 10.1186/s12879-020-05025-3.
This study aimed to detect Hepatitis B virus (HBV) genome sequences and their variants as of nationwide scale using dried blood spot (DBS) samples and to provide up-to-date reference data for infection control and surveillance in Cambodia.
Among 2518 children age 5-7 years and their 2023 mothers participated in 2017 Cambodia nationwide sero-survey on hepatitis B surface antigen (HBsAg) prevalence using multistage random sampling strategy, 95 mothers and 13 children positive to HBsAg were included in this study. HBV DNA was extracted from DBS, then performed polymerase chain reaction. HBV genotypes and potential variants were examined by partial and full length genomic analysis.
HBsAg positive rate was 4.7% (95/2023) in mothers and 0.52% (13/2518) in their children. Genotype C (80.49%) was abundantly found throughout the whole Cambodia whilst genotype B (19.51%) was exclusively found in regions bordering Vietnam. S gene mutants of HBV were found in 24.29% of mothers and 16.67% of children with HBV DNA positive sera. Full-length genome analysis revealed the homology of 99.62-100% in each mother-child pair. Genotype B was clarified to recombinant genotype B4/C2 and B2/C2. Double (48.39%) and combination mutation (32.26%) were observed in core promoter region of HBV C1 strains.
This study showed the capable of DBS for large-scale molecular epidemiological study of HBV in resource limited countries. Full-genome sequences yield the better understanding of sub-genotypes, their variants and the degree of homology between strains isolated from mother-child pairs calls for effective strategies on prevention, control and surveillance of mother-to-child HBV transmission in Cambodia.
本研究旨在通过采集干血斑（DBS）样本，从全国范围内检测乙型肝炎病毒（HBV）基因组序列及其变异体，为柬埔寨的感染控制和监测提供最新的参考数据。
在 2017 年采用多阶段随机抽样策略对柬埔寨全国范围内的乙型肝炎表面抗原（HBsAg）流行率进行血清学调查的 2518 名 5-7 岁儿童及其 2023 名母亲中，有 95 名母亲和 13 名儿童 HBsAg 阳性，纳入本研究。从 DBS 中提取 HBV DNA，然后进行聚合酶链反应。通过部分和全长基因组分析检测 HBV 基因型和潜在变异体。
母亲 HBsAg 阳性率为 4.7%（95/2023），儿童为 0.52%（13/2518）。整个柬埔寨都广泛存在基因型 C（80.49%），而基因型 B（19.51%）仅在与越南接壤的地区发现。24.29%的 HBV DNA 阳性母亲和 16.67%的 HBV DNA 阳性儿童的 HBV S 基因发生突变。全长基因组分析显示，每对母婴的同源性为 99.62%-100%。基因型 B 被确定为重组基因型 B4/C2 和 B2/C2。HBV C1 株核心启动子区观察到双重（48.39%）和组合突变（32.26%）。
本研究表明，DBS 可用于资源有限国家的 HBV 大规模分子流行病学研究。全基因组序列更好地了解了亚基因型、其变异体以及从母婴对分离的菌株之间的同源性程度，这就需要在柬埔寨采取有效的预防、控制和监测母婴传播 HBV 的策略。
