Hepatitis B virus (HBV) infection is a global health problem. HBV has been classified into eight genotypes (A-H) based on genome sequence diver-gence. Worldwide, approximately 350 million indivi-duals are afflicted with HBV (9).The distribution of the genotypes shows significant regional or ethnic differences. However, 75% of infections occur in Asia. Genomic have many differences in different countries or different parts of the same country (2, 4). The major points are as follows: genotype A is mainly distributed in North Europe, Western Europe, America, and Africa; B and C genotypes are mainly distributed in Eastern Asia (6); the D genotype is distributed all over the world, but mainly in Middle East, North Africa and Southern Europe; genotype E is only found in Africa; genotype F is distributed throughout America; genotype G has been found in America and France; genotype H is distributed in Northern Latin America, Mexico, Middle American and other areas (1, 8). Thus, the HBV genotypes have distinct geographical distributions. Up to now, four genotypes (A, B, C and D) have been reported in China: of which genotype B and C are highly prevalent while genotype A and D play minor roles. Genotype C accounts for a major proportion of cases in the northern areas of Mainland China and genotype B cases increase gradually from north to south where it represents the main genotype (7). In addition to these isolates mixed genotypes have also been found; the majority of these are B+C, with fewer cases of C+D and B+C+D. In this experiment, a total of 101 serum specimens were obtained from chronically HBV-infected patients of Dai nationality who visited the Xishuangbanna Dai Autonomous District Hospital; all patients were not HCV infected. The study comprised 63 males and 38 females aged from 0.5-67 years (average: 37.2years). HBV various infection modes detection results are summarized in Table 1. Table. 2 summarizes information regarding the 101 serum specimens.
Table 1. HBV various infection modes detection results
Table 2. 101 serum specimens information
The standard HBV markers, including HBsAg, HBsAb, HBeAg, HBe Ab and HBcAb, were tested with commercial kits (ELISA; Kehua Bio-engineering Co. Ltd, Shanghai, China). Genotype-specific primers-PCR were used for identification of HBV genotypes (3). If bands required further clarification, we repeated the PCR using only the specific primers (Fig. 1).
Figure 1. The electrophoresis pattern of HBV genotypes by genotype-specific primers amplification. M, DNA Marker; 1, Negative control; 2/3, Genotype B (281bp); 4/5, Genotype C (122bp); 6/7: Mixed genotype B+C (281bp and 122bp); 8/9, Genotype E (167bp).
The study indicated that among the 101 serum specimens amplified by Genotype-specific primers-PCR, the proportions of the positive specimens were 43 cases. Meanwhile, we found two cases of HBV E genotypes (the combination model of HBV serologic markers respectively were HBsAg+; HBeAg+; HBcAb+ and HBsAb+; HBeAb+; HBcAb+). These products were further analysed by sequencing. This the first time the E or B+E genotype has been discovered outside Africa. We will follow-up these two cases by exa-mining the virus infection history and clinical symptoms.
The HBV E Genotype Discover in Dai Nationality in Xishuangbanna, Yunnan Province *
- Received Date: 15 August 2008
- Accepted Date: 05 December 2008
Abstract: To investigate the distribution of Hepatitis B virus (HBV) genotypes among the population of Dai nationality in Xishuangbanna, Yunnan Province HBV genotypes of the Serum samples were tested by PCR-RFLP. This is the first time to discover the B+E genotypes in China. This finding provides new information for understanding the distribution of HBV genotype in China and a provides a basis for establishing a Chinese gene bank.