[Comparison of genotypes of hepatitis C virus between Chinese and Burmese drug users living in Dehong Prefecture, Yunnan Province].

Objective: To analyze the distribution of hepatitis C virus (HCV) genotypes among Chinese and Burmese drug users in Dehong Prefecture, Yunnan Province. Methods: Plasma specimens and relevant epidemiological data were collected from 7 545 drug users attending rehabilitation centers and methadone clinics in Dehong Prefecture from January to September in 2015, of which 752 were positive for HCV antibodies. HCV RNA was then extracted from 139 random specimens (64 Burmese and 75 Chinese) and the CE1 and NS5B regions were amplified by nested PCR. The sequences of these HCV genes were aligned, a phylogenetic tree was constructed using MEGA 6.0.6 and the average genetic discrete rate of each subtype group was calculated. We used Fisher's exact test to compare distribution of HCV subtypes from different people, using analysis of variance to compare the discrete rates of different CE1 and NS5B subtypes. Results: While we successfully amplified RNA from 43 specimens provided by Burmese patients (67%), including 31 with CE1 region and 38 with NS5B region, 52 from Chinese patients (69%) were successfully amplified including 43 with CE1 region and 45 with NS5B region. We found that 3b and 6n were the predominant subtypes and were found in 27% (n=14) and 37% (n=19) of Chinese and 28% (n=12) and 33%(n=14) of Burmese specimens. Subtypes 6u, 3a, 1a and 1b were present in 14%(n=7), 19%(n=10), 2% (n=1) and 2%(n=1) of Chinese specimens and 16%(n=7), 5%(n=2), 16%(n=7) and 2%(n=1) of Burmese specimens respectively. While the prevalence of subtype 1a was higher among samples from Burmese patients than Chinese patients (P=0.015), the presence of subtype 3a was higher among the latter (P=0.031). The discrete rates of CE1 region subtypes 1a, 1b, 3a, 3b, 6n and 6u were 0.048±0.007, 0.091±0.013, 0.074± 0.008, 0.061 ± 0.006, 0.136 ± 0.009 and 0.031 ± 0.005 (F=516.26, P<0.001). The discrete rates for NS5B region subtypes 1a, 1b, 3a, 3b, 6n and 6u, meanwhile, were 0.032±0.006, 0.065±0.012, 0.058±0.008, 0.041± 0.005, 0.059 ± 0.008, 0.045 ± 0.006 (F=45.11, P<0.001). Conclusion: Six HCV subtypes were identified among drug users in Dehong Prefecture, of which 6n and 3b were predominant. There were statistically significant differences in the distribution of subtypes 1a and 3b, which have been circulating for a long time in this population, between samples from Chinese and Burmese participants.