Genotype Distribution and Molecular Epidemiology of Hepatitis C Virus in Hubei, Central China

Below: Map highlighting Hubei Province and the 17 provinces and municipalities in China as well as Vietnam where HCV reference sequences were selected.

For easier distinction and comparison, the 16 provinces and municipalities other than Hubei Province were divided into five larger regions according to a previous nation-wide study [5] with slight modification: (i) the north-northeast (Beijing, Shanxi, and Liaoning), (ii) the northwest (Xinjiang, Qinghai, and Shaanxi), (iii) the central south (Hunan, Guangdong, and Hainan), (iv) the southeast (Fujian, Jiangxi, Zhejiang, and Shanghai), (v) the southwest (Sichuan, Yunnan, and Guangxi). Accordingly, five colors, red, yellow, green, cyan, and blue were used to mark these five regions on the map. For Hubei, magenta was used, and this color scheme is indicated above the map.

Below: Circle form of a phylogenetic tree based on the NS5B sequences from 177 study subjects co-analyzed with 5 references for 5 assigned subtypes.

Different subtypes are shown in different colors, as indicated on the left of the tree. All references are shown in magenta with their format as: subtype_isolate ID_GenBank accession number. The bar at the base of the figure shows the scale for nucleotide substitution per site. The pie chart inside the tree indicates the percentages of the different HCV subtypes of the 177 isolates obtained in this study. (B) Topology tree converted from the circular form of the tree shown in panel A. Each branch represents a single subtype and is labeled to the right with the number of isolates in parentheses and at the top with the level of bootstrap support.

A total of 570 patients from Hubei Province in central China were enrolled. These patients were tested positive for HCV antibody prior to blood transfusion. Among them, 177 were characterized by partial NS5B and/or Core-E1 sequences and classified into five subtypes: 1b, 83.0% (147/177); 2a, 13.0% (23/177); 3b, 2.3% (4/177); 6a, 1.1% (2/177); 3a, 0.6% (1/177). Analysis of genotype-associated risk factors revealed that paid blood donation and transfusion before 1997 were strongly associated with subtypes 1b and 2a, while some subtype 2a cases were also found in individuals with high risk sexual behaviors; subtypes 3b, 6a, and 3a were detected only in intravenous drug users. Phylogeographic analyses based on the coalescent datasets demonstrated that 1b, 2a, 3b, and 6a were locally epidemic in Hubei Province. Among them, subtype 1b Hubei strains may have served as the origins of this subtype in China, and 2a and 3b Hubei strains may have descended from the northwest and southwest of China, respectively, while 6a Hubei strains may have been imported from the central south and southwest.

The results suggest that the migration patterns of HCV in Hubei are complex and variable among different subtypes. Implementation of mandatory HCV screening before donation has significantly decreased the incidence of transfusion-associated HCV infection since 1997. More attention should be paid to intravenous drug use and unsafe sexual contact, which may have become new risk factors for HCV infection in Hubei Province.

Read more at: http://goo.gl/NaF6Ur HT https://twitter.com/PLOSONE