Molecular epidemiology of Hepatitis delta virus infection in Minas Gerais state from Brazil, an area outside the hyperendemic region of the Amazon Basin

BACKGROUND Hepatitis delta virus (HDV) infections in hepatitis B virus (HBV) carriers are the most severe form of viral hepatitis. HDV prevalence is high in the Brazilian Amazon, but studies in other regions of the country are still scarce and often underestimated its prevalence by including a small numbers of individuals. OBJECTIVE This study aimed to determine the serological prevalence of hepatitis D, the genotypes circulating and to evaluate the associated risk factors for acquisition of HDV in Minas Gerais state, Brazil. METHODS We screened plasma samples (n = 498) from HBV chronic carriers for anti-HD antibodies using a commercial enzyme-linked immunosorbent assay (ELISA) kit. For those samples that were positive for anti-HD antibodies, we performed a reverse transcriptase (RT) nested-polymerase chain reaction (nested-PCR) in order to detect the viral genome and identify the viral genotypes circulating in the state. FINDINGS The prevalence was 6.22% (31/498). Blood transfusion was the only risk factor associated with HDV infection [risk ratio: 3.73; 95% confidence interval (CI): 1.44 to 9.65]. For 26 anti-HD positive patients, HDAg gene sequences were determined and in all patients HDV genotype 1 was found. CONCLUSIONS This study confirmed the circulation of HDV in Minas Gerais, an area previously considered non-endemic for hepatitis D in Brazil. The prevalence found in this study is much higher when compared to other studies performed in Brazil, probably because the population in our study was selected with minimal bias. Furthermore, in 26 anti-HD positive plasma samples, we were also able to detect the viral genome, indicating that these patients were experienced an active infection at the time of sample collection. These findings emphasise the importance of anti-HD testing in HBV infected individuals, which may contribute to this disease control in Brazil.背景：乙型肝炎病毒（Hepatitis B virus, HBV）携带者合并感染丁型肝炎病毒（Hepatitis delta virus, HDV）是最为严重的病毒性肝炎类型。巴西亚马逊地区的HDV流行率较高，但该国其他区域的相关研究仍较为匮乏，且常因纳入研究对象数量过少而低估了实际流行水平。 目的：本研究旨在明确巴西米纳斯吉拉斯州丁型肝炎的血清流行率、当前流行的病毒基因型，并评估HDV感染的相关危险因素。 方法：我们采用商用酶联免疫吸附试验（enzyme-linked immunosorbent assay, ELISA）试剂盒，对498份慢性HBV感染者的血浆样本开展抗HD抗体筛查。对于抗HD抗体检测呈阳性的样本，通过逆转录（reverse transcriptase, RT）嵌套聚合酶链反应（nested-polymerase chain reaction, nested-PCR）检测病毒基因组，并鉴定该地区流行的病毒基因型。 结果：本研究中HDV的血清流行率为6.22%（31/498）。输血是与HDV感染相关的唯一危险因素[风险比：3.73；95%置信区间（confidence interval, CI）：1.44~9.65]。在26份抗HD抗体阳性的患者样本中，我们完成了HDAg基因序列测定，所有受试对象均检出HDV 1型基因型。 结论：本研究证实了HDV在米纳斯吉拉斯州的流行，该区域此前被认为是巴西丁型肝炎的非流行区。本次研究检出的流行率远高于巴西其他同类研究，这可能得益于本研究人群的选择偏倚极小。此外，我们在26份抗HD抗体阳性的血浆样本中成功检出病毒基因组，表明样本采集时这些患者正处于活动性感染阶段。上述研究结果强调了对HBV感染者进行抗HD检测的重要性，该举措或有助于推动巴西该疾病的防控工作。