PNAS：HIV病毒浓度中等者传播艾滋病能力最强

生物谷

   发表在10月23日的《美国国家科学院院刊》（Proceedings  of  the  National  Academy  of  Sciences，PNAS）上的文章表示，血液中HIV病毒浓度中等的人是造成病毒传播的主要原因。

    伦敦帝国学院的科学家分析了欧洲、美国和南部非洲的数个HIV阳性人群。结果发现虽然病毒浓度很高的群体感染力最强，但他们传染时间有限，很快就会发展为艾滋病。病毒量——人血内病毒颗粒的多少——在个人之间变化很大。病毒含量越高，病人传染力越强，但寿命也越短，结果这些病毒含量高者并不是造成HIV传播的主要原因。

    病毒量中等的人传染力也较温和，但他们在发展为AIDS前有6-8年的无症状期。这意味着他们有相当长的HIV传播时间，能传染给数个性伙伴，从而造成大范围感染。传染病学系的Deirdre  Hollingsworth博士是文章作者之一，他说：“传染力强并不够，患者需要有足够长的传播时间。这一发现应该引起公共健康部门的注意。”

    目前对于南部非洲的感染者还缺少有效的治疗手段，其中一个想法是首先治疗传染力最强患者以减少传播。但新研究显示这不是最有效的方案，因为病毒含量中等者是主要传染源。中度病毒携带者大部分没有接受治疗，其中一个原因在于病毒已经进化得能在传染力和毒性之间保持平衡，以实现最大的传播效果。作者之一William  Hanage说：“令人惊讶的是自然界中最普遍的病毒含量能保证在杀死宿主前实现最大效率的传染，这应该是进化的结果。”

    文章第一作者Christophe  Fraser博士说：“我们希望能分析病毒是否已经变得适合传染更多人，这对公共健康政策有着重要影响，因为结果一旦成立，那么目前预防传染的一些政策就需要作出调整。我们还需要更多相关实验来验证该理论，这也是科学家目前致力于研究的领域。”（援引教育部科技发展中心）

    原文链接：http://www.physorg.com/news112366618.html

原始出处:

Published online before print October 22, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0708559104
OPEN ACCESS ARTICLE

Variation in HIV-1 set-point viral load: Epidemiological analysis and an evolutionary hypothesis

Christophe Fraser ${dagger}$ , ${ddagger}$ , T. Déirdre Hollingsworth ${dagger}$ , Ruth Chapman ${dagger}$ , $§$ , Frank de Wolf ${dagger}$ ,¶, and William P. Hanage ${dagger}$

${dagger}$ Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London W2 1PG, United Kingdom; $§$ Infectious Diseases Epidemiology Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom; and ¶HIV Monitoring Foundation, Academic Medical Centre of the University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands

Communicated by Stanley Falkow, Stanford University, Stanford, CA, September 10, 2007 (received for review February 9, 2007)

Abstract

The natural course of HIV-1 infection is characterized by a high degree of heterogeneity in viral load, not just within patients over time, but also between patients, especially during the asymptomatic stage of infection. Asymptomatic, or set-point, viral load has been shown to correlate with both decreased time to AIDS and increased infectiousness. The aim of this study is to characterize the epidemiological impact of heterogeneity in set-point viral load. By analyzing two cohorts of untreated patients, we quantify the relationships between both viral load and infectiousness and the duration of the asymptomatic infectious period. We find that, because both the duration of infection and infectiousness determine the opportunities for the virus to be transmitted, this suggests a trade-off between these contributions to the overall transmission potential. Some public health implications of variation in set-point viral load are discussed. We observe that set-point viral loads are clustered around those that maximize the transmission potential, and this leads us to hypothesize that HIV-1 could have evolved to optimize its transmissibility, a form of adaptation to the human host population. We discuss how this evolutionary hypothesis can be tested, review the evidence available to date, and highlight directions for future research.

cohort studies | life-history | mathematical model | trade-off | virulence

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