The Molecular Epidemiology Of HCV Genotypes Detected By Nucleic Acid Sequencing Method

Objectives:Hepatitis C virus (HCV) infection is the worldwild disease. It is one of the main causes of chronic liver disease, cirrhosis and hepatocellular carcinoma (HCC). HCV genotypes play an important role of HCV infection, transmission and prognosis. At the same time, it can provide important evidences for epidemiology studying. HCV genome has a high variability and six genotypes based on the difference of genome nucleotide sequence. Recently, the local studys of HCV genotypes spreading are increased, but the samples came from different regions and were tested by different genotyping methods. Therefore, we detected HCV genotype of307samples using nucleic acid sequencing assay in order to better understand the molecular epidemiological characteristics of HCV in China. We discussed the geographical distribution and the molecular epidemiological characteristics of HCV genotypes and subtypes deeply and provided valuable information of HCV infectionMethods:All the307samples of HCV infection were collected from different regions in China. We extracted HCV RNA with the HCV nucleic acid quantitation assay and the HCV RNA loading was detected by real-time PCR. At the same time, we extracted HCV RNA with the RNA extracted reagents. Then the gene segments of HCV Core/E1regions were amplified by the reverse transcription PCR (RT-PCR) and the products were sequenced. The subtypes of HCV were performed by NCBI genotyping tool. The molecular epidemiological characteristics of HCV infection were analyzed with regarding to HCV genotypes.Results:1. Among the307samples, six subtypes were identified, including genotype1b.156cases (50.8%,156/307); genotype2a,61cases (19.9%,61/307); genotype3a,33cases (10.7%,33/307); genotype3b,6a,25cases (8.1%,25/307), respectively: genotype1a,7cases (2.3%,7/307). The genotypes3a,3b,6a and la consist of29.3%(90/307) in total.2. Load distributions were296cases which had explicit load information. High HCV RNA load group (>106IU/mL) occupied80.7%(239/296) in all samples. The genotype1b had higher detection rate in all load groups. The genotype2a was mainly found in the middle HCV RNA load group (500-106IU/mL), and occupied58.5%(24/41).3. The HCV genotypes’ distribution of area, gender and age(1)Geographical distribution The distribution of HCV genotypes showed a regional difference. There were different detetion rate of HCV genotypes in all provinces. Genotype lb occupying50%(97/194) and52%(59/113) respectively was dominant genotype in Southern and Northern, followed by3a occupying16.0%(31/194) in Southern2a occupying42.5%(48/113) in Northern. There was a significant difference between genotypes and regions (p<0.01).(2)Sexdistribution There were286samples which had explicit gender information. There was no significant difference in genotypes and genders overall (x2=7.102, p>0.05). But there was a significant difference between genotype6a and genders (x2=8.741, p<0.01).(3)Age distribution There were274samples which had clear age information. There were significant differences between genotypes and ages (x2=62.322, p<0.05). Genotype1b and2a were detected higher in all age groups, mainly in patients with≥31years old. The genotype distribution tended to be balanced in21-30years and31-40yeaes age groups. Genotype1b and2a occupying44%,50%. respectively and the genotypes occupying50%in total in two age groups except genotype1b and2a.Conclusions:The study indicated that genotype1b was the main genotype of HCV infection in China, followed by genotype2a. Genotype1b and3a were dominating in south, lb and2a in north. The geographical distribution characteristics were obvious. The detection rate of genotype except1b and2a was increased clearly. The conclusion implied that the geographical distribution characteristics of HCV genotype infection had been changing. There were some relationships between genotypes and gender, age and viral load. Our study attained valuable data of molecular epidemiology of HCV infection in China and strongly suggested the necessity to conduct HCV genotyping for clinical purpose.