肝炎.检验方法.ppt

* * * HBV侵入人体后，与肝细胞膜上的受体结合，脱去包膜，穿入肝细胞质内，然后脱去衣壳，部分双链环状HBV DNA进入肝细胞核内，在宿主酶的作用下，以负链DNA为模板延长正链，修补正链中的裂隙区，形成共价闭合环状DNA (cccDNA)，然后以cccDNA为模板，在宿主RNA聚合酶II的作用下，转录成几种不同长短的mRNA，其中3.5kb的mRNA含有HBV DNA序列上全部遗传信息，称为前基因组RNA。后者进入肝细胞质作为模板，在HBV 逆转录酶作用下，合成负链DNA；再以负链DNA为模板，在HBV DNA聚合酶作用下，合成正链DNA，形成子代的部分双链环状DNA，它与在内质网内生成的含有s抗原的囊膜成分最后装配成完整的HBV，释放至肝细胞外。胞质中的子代部分双链环状DNA也可进入肝细胞核内，再形成cccDNA并继续复制。 * HBV 含４个部分重叠的开放读码框 (ORF)，即前 S／S 区、前 C／C 区、P 区和 X 区。S基因编码S抗原、前S1抗原、前S2抗原,S抗原是病毒感染的标志，前S1抗原诱导特异性保护性抗体（抗-HBs），根据前S2抗原核苷酸序列异源性分为不同基因型；前C和C基因编码核心抗原和HBeAg，其中核心抗原是病毒复制的标志，基因变异与HBeAg阴性慢性乙型肝炎有关；P基因编码聚合酶，基因区变异株在核苷（酸）类似物治疗中受药物选择而成为优势株；X基因编码X蛋白。 * * * * * * * * * * * * * 31 * * * 具有(1)并有(2) 或 (3) 的患者应进行抗病毒治疗；对达不到上述治疗标准者，应监测病情变化，如持续HBV DNA阳性，且ALT异常，也应考虑抗病毒治疗 * 具有(1)并有(2) 或 (3) 的患者应进行抗病毒治疗；对达不到上述治疗标准者，应监测病情变化，如持续HBV DNA阳性，且ALT异常，也应考虑抗病毒治疗 五、预防策略与措施 主要防制措施与乙肝相同 接种乙肝疫苗 加强献血管理 防止HBV携带者和HDV携带者密切接触 第四节 丁型肝炎 谢谢 * * * 2 Before the discovery of hepatitis A virus (HAV) and hepatitis B virus (HBV) during the 1960s and 1970s, patients with viral hepatitis were classified based on epidemiological studies as having either infectious (transmitted person to person by the fecal-oral route) or serum (transmitted by transfusion of blood products) hepatitis. When diagnostic tests for HAV and HBV infections were developed, HAV was found to be the major cause of infectious hepatitis and HBV was found to be the major cause of serum hepatitis. Hepatitis delta virus (HDV), discovered in 1977, is a defective virus requiring the presence of HBV in order to replicate. However, some patients with typical signs and symptoms of viral hepatitis did not have serologic markers of HAV, HBV, or HDV infection and were categorized based on epidemiological characteristics as having either parenterally transmitted non-A, non-B (NANB) hepatitis or enterically transmitted NANB hepatitis. Subsequently, two additional viruses were discovered: hepatitis C virus (HCV) and hepatitis E virus (HEV). HCV is the major cause of parenterally transmitted NA