Salemi M, Vandamme A M, Gradozzi C, Van Laethem K, Cattaneo E, Taylor G, Casoli C, Goubau P, Desmyter J, Bertazzoni U
Rega Institute for Medical Research and University Hospitals, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
J Mol Evol. 1998 May;46(5):602-11. doi: 10.1007/pl00006340.
Seven new Italian and two new British HTLV-II isolates were obtained from injecting drug users and the entire long terminal repeat (LTR) region was sequenced. Restriction analysis showed that all the Italian isolates are of the IIb subtype, whereas the British isolates are of the IIa subtype. To understand whether the further differentiation of each two principal HTLV-II subtypes in several subgroups could be statistically supported by phylogenetic analysis, the neighbor-joining, parsimony, and maximum likelihood methods were used. The separation between IIa and IIb is very well supported by all three methods. At least two phylogenetic subgroups exist within the HTLV-IIa and at least three within the HTLV-IIb subtype. In the present analysis, no statistical support was obtained for additional phylogroups. Two particular subgroups seem interesting because they include all European and North American injecting drug user strains within the IIa and IIb subtypes, respectively. These data confirm that European HTLV-II infection among drug users is probably derived from North America. They also suggest that though a certain differentiation by restriction analysis in different subgroups is possible, carefully interpreted phylogenetic analyses remain necessary. Using the likelihood ratio test, a molecular clock for the drug user strains was calibrated. A fixation rate between 1.08 x 10(-4) and 2.7 x 10(-5) nucleotide substitutions per site per year was calculated for the IIa and IIb injecting drug user strains. This is the lowest fixation rate so far reported for RNA viruses, including for HIV, which typically range between 10(-2) and 10(-4).
从注射吸毒者中获得了7株新的意大利HTLV-II分离株和2株新的英国HTLV-II分离株，并对整个长末端重复序列（LTR）区域进行了测序。限制性分析表明，所有意大利分离株均为IIb亚型，而英国分离株为IIa亚型。为了了解通过系统发育分析能否从统计学上支持将HTLV-II的两种主要亚型进一步细分为几个亚组，我们使用了邻接法、简约法和最大似然法。这三种方法都很好地支持了IIa和IIb之间的分离。HTLV-IIa亚型内至少存在两个系统发育亚组，HTLV-IIb亚型内至少存在三个亚组。在本分析中，未获得其他系统发育组的统计学支持。有两个特殊的亚组似乎很有意思，因为它们分别包含了IIa和IIb亚型内所有来自欧洲和北美的注射吸毒者毒株。这些数据证实，吸毒者中的欧洲HTLV-II感染可能源自北美。它们还表明，虽然通过限制性分析在不同亚组中进行一定程度的区分是可能的，但仔细解读的系统发育分析仍然是必要的。使用似然比检验，校准了吸毒者毒株的分子钟。计算出IIa和IIb注射吸毒者毒株的固定率为每年每个位点1.08×10^(-4)至2.7×10^(-5)个核苷酸替换。这是迄今为止报道的RNA病毒（包括HIV，其固定率通常在10^(-2)至10^(-4)之间）的最低固定率。
