Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411 008, India.
J Biosci. 2020;45(1). doi: 10.1007/s12038-020-0025-x.
In host-parasite co-evolution, parasites are assumed to have an advantage owing to their shorter generation time. Evolution of pathogens within the lifetime of a host individual is implicated as a strong selective force in the evolution of sex and aging in the host. However, this assumption or its testable predictions have not been examined empirically. We classified infectious bacteria and viruses into those that can have continued longterm existence on the host body (group 1) versus those that have only a short-term interaction during an active infection (group 2). We surveyed the literature for age-specific incidence data about infections from both the groups. The age trends of the two groups show contrasting patterns. The incidence of infections by all group 1 pathogens showed a 2.28- to 28-fold increase in older ages. In group 2, 6 out of the 9 pathogens showed a significant declining trend in incidence with age. In both groups, there was greater mortality or morbidity among the infected in the old-age classes. These patterns are better explained by pathogen evolution than by age-related decline in immunity.
在宿主-寄生虫共同进化中，寄生虫由于其较短的世代时间而被认为具有优势。在宿主个体的生命周期内，病原体的进化被认为是宿主性别和衰老进化的一个强大的选择力量。然而，这种假设或其可检验的预测尚未被经验性地检验。我们将传染性细菌和病毒分为可以在宿主身体上持续长期存在的（第 1 组）和在活跃感染期间只有短期相互作用的（第 2 组）。我们查阅了文献中关于这两组感染的年龄特异性发病率数据。这两组的年龄趋势表现出相反的模式。所有第 1 组病原体的感染发病率在老年时增加了 2.28 到 28 倍。在第 2 组中，9 种病原体中有 6 种的发病率随着年龄的增长呈显著下降趋势。在这两组中，老年感染者的死亡率或发病率更高。这些模式可以通过病原体进化来更好地解释，而不是通过与年龄相关的免疫下降来解释。
