Lago Bárbara V, Mello Francisco C, Kramvis Anna, Niel Christian, Gomes Selma A
Laboratory of Molecular Virology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Hepatitis Virus Diversity Research Programme, Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
PLoS One. 2014 Aug 14;9(8):e105317. doi: 10.1371/journal.pone.0105317. eCollection 2014.
Brazil is a country of low hepatitis B virus (HBV) endemicity in which the genotype A of HBV (HBV/A) is the most prevalent. The complete nucleotide sequences of 26 HBV/A isolates, originating from eight Brazilian states, were determined. All were adw2. Twenty-three belonged to subgenotype A1 and three to A2. By phylogenetic analysis, it was shown that all the 23 HBV/A1 isolates clustered together with isolates from Bangladesh, India, Japan, Nepal, the Philippines and United Arab Emirates, but not with those of Congo, Kenya, Malawi, Rwanda, South Africa, Tanzania, Uganda and Zimbabwe. Four amino acid residues in the polymerase (His138 in the terminal protein domain, Pro18 and His90 in the spacer, and Ser109 in the reverse transcriptase), and one (Phe17) in the precore region, predominated in Latin American and Asian HBV/A1 isolates, but were rarely encountered in African isolates, with the exception of those from Somalia. Specific variations of two adjacent amino acids in the C-terminal domain of the HBx protein, namely Ala146 and Pro147, were found in all the Brazilian, but rarely in the other HBV/A1 isolates. By Bayesian analysis, the existence of an 'Asian-American' clade within subgenotype A1 was supported by a posterior probability value of 0.996. The close relatedness of the Brazilian, Asian and Somalian isolates suggests that the HBV/A1 strains predominant in Brazil did not originate from the five million slaves who were imported from Central and Western Africa from 1551 to 1840, but rather from the 300-400,000 captives forcibly removed from southeast Africa at the middle of the 19th century.
巴西是乙型肝炎病毒（HBV）低流行率国家，其中HBV A基因型（HBV/A）最为普遍。测定了来自巴西八个州的26株HBV/A分离株的完整核苷酸序列。所有分离株均为adw2型。23株属于A1亚基因型，3株属于A2亚基因型。系统发育分析表明，所有23株HBV/A1分离株与来自孟加拉国、印度、日本、尼泊尔、菲律宾和阿拉伯联合酋长国的分离株聚集在一起，但与刚果、肯尼亚、马拉维、卢旺达、南非、坦桑尼亚、乌干达和津巴布韦的分离株不同。聚合酶中的四个氨基酸残基（末端蛋白结构域中的His138、间隔区中的Pro18和His90以及逆转录酶中的Ser109）和前核心区中的一个氨基酸残基（Phe17）在拉丁美洲和亚洲的HBV/A1分离株中占主导地位，但在非洲分离株中很少见，索马里分离株除外。在HBx蛋白C末端结构域中发现了两个相邻氨基酸的特定变异，即Ala146和Pro147，所有巴西分离株中均有此变异，但在其他HBV/A1分离株中很少见。通过贝叶斯分析，A1亚基因型内“亚洲-美洲”分支的存在得到了后验概率值0.996的支持。巴西、亚洲和索马里分离株的密切相关性表明，巴西占主导地位的HBV/A1毒株并非源自1551年至1840年从中部和西部非洲进口的500万奴隶，而是源自19世纪中叶从非洲东南部强行带走的30万至40万俘虏。
