Nousbaum J B
Service d'hépato-gastroentérologie, CHU de la Cavale blanche, Brest.
Bull Soc Pathol Exot. 1998;91(1):29-33.
Hepatitis C virus demonstrates a high degree of variability HCV isolates have been classified into at least six genotypes, according to the percentage of nucleotide sequence homology. Geographical differences in the distribution of virus genotypes are well documented. Types 1, 2 and 3 are the major types observed in Japan, Western Europe and North America; type 4 has been found in Central and Northern Africa and in the Middle East; type 5 has been described in South Africa, type 6 in South-East Asia. The relative prevalence of these genotypes varies between different regions. In the Indian subcontinent, subtype 1b seems to be the most prevalent type, but many isolates have been described, related to genotype 3, in Northern and Southern India, Pakistan and Nepal. HCV genotypes may have potential clinical implications: a) the association with the severity of liver disease is still controversial; b) the association between some genotypes, particularly 1b, and a poor response to interferon alpha therapy has been well established; c) genotyping may be useful for identifying some unusual modes of transmission of the virus. Finally, the variability of HCV virus has major implications for the design of new vaccines strategies since there is no cross-protection between different HCV types.
丙型肝炎病毒具有高度变异性。根据核苷酸序列同源性百分比，丙型肝炎病毒分离株已被分为至少六种基因型。病毒基因型分布的地理差异已有充分记录。1型、2型和3型是在日本、西欧和北美观察到的主要类型；4型在中非、北非和中东被发现；5型在南非被描述；6型在东南亚被发现。这些基因型的相对流行率在不同地区有所不同。在印度次大陆，1b亚型似乎是最流行的类型，但在印度北部和南部、巴基斯坦和尼泊尔，已描述了许多与3型基因型相关的分离株。丙型肝炎病毒基因型可能具有潜在的临床意义：a）与肝病严重程度的关联仍存在争议；b）某些基因型，特别是1b型，与对α干扰素治疗反应不佳之间的关联已得到充分证实；c）基因分型可能有助于识别病毒的一些不寻常传播方式。最后，丙型肝炎病毒的变异性对新疫苗策略的设计具有重要意义，因为不同的丙型肝炎病毒类型之间不存在交叉保护。
