Liaw Yun-Fan, Brunetto Maurizia R, Hadziyannis Stephanos
Liver Research Unit, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan.
Antivir Ther. 2010;15 Suppl 3:25-33. doi: 10.3851/IMP1621.
Although chronic HBV infection is a global health issue, there are geographical differences in the mode of transmission, prevalence and HBV genotype distribution. Chronic HBV infection is a dynamic state of interactions between HBV, hepatocytes and immune cells of the host. Accordingly, the natural history of chronic HBV infection typically starts with an immune tolerant phase, followed by an immune clearance phase and finally an inactive phase. The duration of the immune tolerant phase is usually long in chronic HBV infection acquired perinatally or in early childhood, otherwise the duration is very short. During the inactive phase, spontaneous hepatitis B surface antigen (HBsAg) seroclearance might occur at an annual rate of 1-2%; however, HBV reactivation with hepatitis activity could occur over time in one-quarter to one-third of HBsAg-seropositive patients. This occurs more frequently in males and in patients infected with genotypes D, C and B. The effort of active HBV replication-triggered immune clearance is the driving force of liver injury and subsequent disease progression in patients with hepatitis B e antigen (HBeAg)-positive or HBeAg-negative hepatitis. Clinical studies have shown that chronic HBV infection in western countries is associated with a higher incidence of cirrhosis, but lower incidence of hepatocellular carcinoma, than in Asian countries. The geographical differences in age at the time of infection and predominant HBV genotype could account for the variance in the natural history of chronic HBV infection; however, some of these differences might actually result from comparisons between cohorts with different age, gender distribution or fibrosis stage.
尽管慢性乙型肝炎病毒（HBV）感染是一个全球性的健康问题，但在传播方式、流行率和HBV基因型分布方面存在地域差异。慢性HBV感染是HBV、宿主肝细胞和免疫细胞之间相互作用的动态状态。因此，慢性HBV感染的自然史通常始于免疫耐受期，随后是免疫清除期，最后是静止期。围产期或幼儿期获得的慢性HBV感染，免疫耐受期通常较长，否则该期持续时间很短。在静止期，乙肝表面抗原（HBsAg）血清学清除可能以每年1%-2%的速率自发发生；然而，四分之一至三分之一的HBsAg血清阳性患者随着时间的推移可能会出现伴有肝炎活动的HBV再激活。这在男性以及感染D、C和B基因型的患者中更常见。乙肝e抗原（HBeAg）阳性或HBeAg阴性肝炎患者中，由活跃的HBV复制引发的免疫清除作用是肝损伤及随后疾病进展的驱动力。临床研究表明，与亚洲国家相比，西方国家慢性HBV感染患者肝硬化的发病率较高，但肝细胞癌的发病率较低。感染时的年龄和主要HBV基因型的地域差异可能是慢性HBV感染自然史存在差异的原因；然而，其中一些差异可能实际上是由于不同年龄、性别分布或纤维化阶段的队列之间的比较所致。
