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Genotypic distribution of hepatitis C virus in Thailand and Southeast Asia
Rujipat Wasitthankasem1, Sompong Vongpunsawad1, Nipaporn Siripon1
1Center of Excellence in Clinical Virology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Insights
Hepatitis C virus (HCV) genotype distribution varies across Southeast Asia. Genotype 3a is most common in Thailand, while genotype 6 is prevalent in northern Southeast Asia and genotype 1 in island nations.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Hepatitis C virus (HCV) infection frequently leads to chronic liver disease, cirrhosis, and hepatocellular carcinoma.
- An estimated 150 million people worldwide are infected with HCV, representing 3% of the global population.
- HCV genotype distribution exhibits significant geographical variation.
Purpose of the Study:
- To assess the distribution of hepatitis C virus (HCV) genotypes in Thailand and compare it with regional data from Southeast Asia.
- To provide crucial epidemiological data for public health policy and tracking HCV spread.
Main Methods:
- Characterization of HCV 5' untranslated region, Core, and NS5B regions from 588 HCV-positive Thai samples using nested PCR.
- Phylogenetic analysis of nucleotide sequences to assign genotypes based on published references.
- Comparison of Thai HCV genotype data with epidemiological findings across Southeast Asia.
Main Results:
- Subtype 3a was the predominant HCV subtype in Thailand (36.4%), followed by 1a (19.9%) and 1b (12.6%).
- Genotype 1 was prevalent across Thailand (27-36%), with genotype 3 more common in the south.
- Genotype 6 (20.9%) showed significantly lower prevalence in southern Thailand compared to the north and northeast (p = 0.027 and p = 0.030).
- Regional analysis revealed genotype 6 prevalence in northern Southeast Asia (Myanmar, Laos, Vietnam), genotype 3 in Thailand and Malaysia, and genotype 1 in island nations (Singapore, Indonesia, Philippines).
Conclusions:
- HCV genotype distribution in Thailand shows regional variations, with genotype 3a being most common.
- Distinct geographical patterns of HCV genotypes exist across Southeast Asia, with genotype 6 in the north, genotype 3 in Thailand/Malaysia, and genotype 1 in island nations.
- This study provides valuable regional HCV genotype data to inform public health strategies and monitor future viral spread.
Abstract:
The majority of hepatitis C virus (HCV) infection results in chronic infection, which can lead to liver cirrhosis and hepatocellular carcinoma. Global burden of hepatitis C virus (HCV) is estimated at 150 million individuals, or 3% of the world's population. The distribution of the seven major genotypes of HCV varies with geographical regions. Since Asia has a high incidence of HCV, we assessed the distribution of HCV genotypes in Thailand and Southeast Asia. From 588 HCV-positive samples obtained throughout Thailand, we characterized the HCV 5' untranslated region, Core, and NS5B regions by nested PCR. Nucleotide sequences obtained from both the Core and NS5B of these isolates were subjected to phylogenetic analysis, and genotypes were assigned using published reference genotypes. Results were compared to the epidemiological data of HCV genotypes identified within Southeast Asian. Among the HCV subtypes characterized in the Thai samples, subtype 3a was the most predominant (36.4%), followed by 1a (19.9%), 1b (12.6%), 3b (9.7%) and 2a (0.5%). While genotype 1 was prevalent throughout Thailand (27-36%), genotype 3 was more common in the south. Genotype 6 (20.9%) constituted subtype 6f (7.8%), 6n (7.7%), 6i (3.4%), 6j and 6m (0.7% each), 6c (0.3%), 6v and 6xa (0.2% each) and its prevalence was significantly lower in southern Thailand compared to the north and northeast (p = 0.027 and p = 0.030, respectively). Within Southeast Asia, high prevalence of genotype 6 occurred in northern countries such as Myanmar, Laos, and Vietnam, while genotype 3 was prevalent in Thailand and Malaysia. Island nations of Singapore, Indonesia and Philippines demonstrated prevalence of genotype 1. This study further provides regional HCV genotype information that may be useful in fostering sound public health policy and tracking future patterns of HCV spread.
