Institute of Evolutionary Biology, University of Edinburgh, London, United Kingdom.
J Infect Dis. 2011 Nov;204(9):1463-9. doi: 10.1093/infdis/jir550. Epub 2011 Sep 15.
Many studies of sexual behavior have shown that individuals vary greatly in their number of sexual partners over time, but it has proved difficult to obtain parameter estimates relating to the dynamics of human immunodeficiency virus (HIV) transmission except in small-scale contact tracing studies. Recent developments in molecular phylodynamics have provided new routes to obtain these parameter estimates, and current clinical practice provides suitable data for entire infected populations.
A phylodynamic analysis was performed on partial pol gene sequences obtained for routine clinical care from 14,560 individuals, representing approximately 60% of the HIV-positive men who have sex with men (MSM) under care in the United Kingdom.
Among individuals linked to others in the data set, 29% are linked to only 1 individual, 41% are linked to 2-10 individuals, and 29% are linked to ≥10 individuals. The right-skewed degree distribution can be approximated by a power law, but the data are best fitted by a Waring distribution for all time depths. For time depths of 5-7 years, the distribution parameter ρ lies within the range that indicates infinite variance.
The transmission network among UK MSM is characterized by preferential association such that a randomly distributed intervention would not be expected to stop the epidemic.
许多关于性行为的研究表明，个体在不同时间的性伴侣数量存在很大差异，但除了小规模的接触追踪研究外，很难获得与人类免疫缺陷病毒（HIV）传播动力学相关的参数估计。分子系统发育动力学的最新发展为获得这些参数估计提供了新的途径，而当前的临床实践为整个感染人群提供了合适的数据。
对从 14560 名个体中获得的常规临床护理中的部分 pol 基因序列进行了系统发育分析，这些个体代表了在英国接受护理的男男性行为（MSM）艾滋病毒阳性者中的约 60%。
在与数据集内其他人相关联的个体中，29%的个体仅与 1 个人相关联，41%的个体与 2-10 个人相关联，29%的个体与≥10 个人相关联。偏态分布可以用幂律来近似，但对于所有时间深度，数据最好用 Warin 分布来拟合。对于 5-7 年的时间深度，分布参数ρ位于表明无限方差的范围内。
英国 MSM 之间的传播网络的特征是优先关联，因此随机分布的干预措施预计不会阻止疫情的传播。
