A complex hepatitis B virus (X/C) recombinant is common in Long An county, Guangxi and may have originated in southern China.
Recently, a complex (X/C) hepatitis B virus (HBV) recombinant, first reported in 2000, was proposed as a new genotype; although this was refuted immediately because the strains differ by less than 8 % in nucleotide distance from genotype C. Over 13.5 % (38/281) of HBV isolates from the Long An cohort in China were not assigned to a specific genotype, using current genotyping tools to analyse surface ORF sequences, and these have about 98 % similarity to the X/C recombinants. To determine whether this close identity extends to the full-length sequences and to investigate the evolutionary history of the Long An X/C recombinants, 17 complete genome sequences were determined. They are highly similar (96-99 %) to the Vietnamese strains and, although some reach or exceed 8 % nucleotide sequence difference from all known genotypes, they cluster together in the same clade, separating in a phylogenetic tree from the genotype C branch. Analysis of recombination reveals that all but one of the Long An isolates resembles the Vietnamese isolates in that they result from apparent recombination between genotype C and a parent of unknown genotype (X), which shows similarity in part to genotype G. The exception, isolate QL523, has a greater proportion of genotype C parent. Phylogeographic analysis reveals that these recombinants probably arose in southern China and spread later to Vietnam and Laos.
Division of Medicine, UCL Medical School, London, UK.
Zhong-Liao
ZL
Fang
Stéphane
S
Hué
Caroline A
CA
Sabin
Guo-Jian
GJ
Li
Jin-Ye
JY
Yang
Qin-Yan
QY
Chen
Kong-Xiong
KX
Fang
Jian
J
Huang
Xue-Yan
XY
Wang
Tim J
TJ
Harrison
D006528:Carcinoma, Hepatocellular / Q000453:epidemiology / Q000821:virology; D002681:China / Q000453:epidemiology; D016679:Genome, Viral; D006509:Hepatitis B / Q000453:epidemiology* / Q000821:virology*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000453:epidemiology / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D016865:Reassortant Viruses / Q000235:genetics*