Stewart Lindsay B, Escolar Elena Lantero, Philpott James, Cox-Singh Janet, Singh Balbir, Conway David J
Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK.
Malaria Research Centre, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia.
Int J Parasitol. 2025 Jun;55(7):387-393. doi: 10.1016/j.ijpara.2025.02.003. Epub 2025 Mar 4.
Replication rates and virulence of pathogens are hypothesised to evolve in response to varying intensity of transmission and competition among genotypes. Under exponential growth conditions in culture, clinical isolates of the malaria parasite Plasmodium falciparum have variable intrinsic multiplication rates, but comparisons of samples from different areas are needed. To analyse parasites from an area of low endemicity, Malaysian clinical isolates cryopreserved prior to malaria elimination were studied. The mean and range of P. falciparum multiplication rates in Malaysian isolates were no less than that seen among isolates from more highly endemic populations in Africa, which does not support a hypothesis of adaptation to prevailing levels of infection endemicity. Moreover, the distribution of multiplication rates was similar between isolates with single parasite genotypes and those containing multiple genotypes, which does not support a hypothesis of facultative adjustment to competing parasites. Based solely on clinical isolates, the findings indicate that parasites may not evolve lower multiplication rates under conditions of reduced transmission, and that the virulence potential is likely to be undiminished in pre-elimination settings. This encourages efforts to eliminate endemic infection completely, as has been achieved at the national level in Malaysia.
据推测，病原体的复制率和毒力会随着不同基因型之间传播强度和竞争的变化而演变。在培养的指数增长条件下，恶性疟原虫的临床分离株具有可变的内在增殖率，但需要对来自不同地区的样本进行比较。为了分析来自低流行地区的疟原虫，研究了马来西亚在疟疾消除之前冷冻保存的临床分离株。马来西亚分离株中恶性疟原虫增殖率的平均值和范围不低于非洲高流行人群分离株中的水平，这并不支持适应流行感染程度的假设。此外，单一寄生虫基因型的分离株和包含多种基因型的分离株之间的增殖率分布相似，这并不支持对竞争性寄生虫进行兼性调整的假设。仅基于临床分离株，研究结果表明，在传播减少的情况下，疟原虫可能不会进化出更低的增殖率，并且在消除前的环境中毒力潜力可能不会减弱。这鼓励人们努力彻底消除地方性感染，马来西亚已在国家层面实现了这一目标。
