Delatorre Edson, Mir Daiana, Bello Gonzalo
Laboratório de AIDS & Imunologia Molecular, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.
PLoS One. 2014 Jun 11;9(2):e98908. doi: 10.1371/journal.pone.0098908. eCollection 2014.
The human immunodeficiency virus type 1 (HIV-1) subtype G is the second most prevalent HIV-1 clade in West Africa, accounting for nearly 30% of infections in the region. There is no information about the spatiotemporal dynamics of dissemination of this HIV-1 clade in Africa. To this end, we analyzed a total of 305 HIV-1 subtype G pol sequences isolated from 11 different countries from West and Central Africa over a period of 20 years (1992 to 2011). Evolutionary, phylogeographic and demographic parameters were jointly estimated from sequence data using a Bayesian coalescent-based method. Our analyses indicate that subtype G most probably emerged in Central Africa in 1968 (1956-1976). From Central Africa, the virus was disseminated to West and West Central Africa at multiple times from the middle 1970s onwards. Two subtype G strains probably introduced into Nigeria and Togo between the middle and the late 1970s were disseminated locally and to neighboring countries, leading to the origin of two major western African clades (G WA-I and G WA-II). Subtype G clades circulating in western and central African regions displayed an initial phase of exponential growth followed by a decline in growth rate since the early/middle 1990 s; but the mean epidemic growth rate of G WA-I (0.75 year-1) and G WA-II (0.95 year-1) clades was about two times higher than that estimated for central African lineages (0.47 year-1). Notably, the overall evolutionary and demographic history of G WA-I and G WA-II clades was very similar to that estimated for the CRF06_cpx clade circulating in the same region. These results support the notion that the spatiotemporal dissemination dynamics of major HIV-1 clades circulating in western Africa have probably been shaped by the same ecological factors.
人类免疫缺陷病毒1型（HIV-1）G亚型是西非第二大流行的HIV-1进化枝，占该地区感染病例的近30%。目前尚无关于该HIV-1进化枝在非洲传播的时空动态信息。为此，我们分析了从1992年至2011年这20年间从西非和中非11个不同国家分离出的总共305个HIV-1 G亚型pol序列。使用基于贝叶斯合并的方法从序列数据中联合估计进化、系统地理学和人口统计学参数。我们的分析表明，G亚型最有可能于1968年（1956 - 1976年）在中非出现。从那时起，该病毒于20世纪70年代中期开始多次从中非传播到西非和中西非。20世纪70年代中期至后期可能传入尼日利亚和多哥的两个G亚型毒株在当地以及邻国传播，导致了两个主要的西非进化枝（G WA-I和G WA-II）的起源。在西非和中非地区传播的G亚型进化枝在20世纪90年代初/中期之后显示出指数增长的初始阶段，随后增长率下降；但是G WA-I（0.75年-1）和G WA-II（0.95年-1）进化枝的平均流行增长率大约是中非谱系估计值（0.47年-1）的两倍。值得注意的是，G WA-I和G WA-II进化枝的总体进化和人口统计学历史与在同一地区传播的CRF06_cpx进化枝的估计情况非常相似。这些结果支持了这样一种观点，即西非主要HIV-1进化枝的时空传播动态可能受到相同生态因素的影响。
