Department of Medical Laboratory Sciences, Faculty of Health Science, University of Buea, P.O. Box 23, Buea, Southwest Region, Cameroon.
Regional Hospital of Buea, P.O. Box 32, Buea, Southwest Region, Cameroon.
Malar J. 2019 Jan 22;18(1):16. doi: 10.1186/s12936-019-2654-9.
Studies reporting the natural immune responses against malaria in children from different geographical settings in endemic areas are not readily available. This study was aimed at comparing the immune responses against Plasmodium falciparum MSP-1 antigen in children from five contrasting bioecological zones in Cameroon.
In a cross-sectional survey, children between 2 and 15 years, were enrolled from five ecological strata including the south Cameroonian equatorial forest, sudano-sahelian, high inland plateau, high western plateau, and the coastal strata. The children were screened for clinical malaria (defined by malaria parasitaemia ≥ 5000 parasites/µl plus axillary temperature ≥ 37.5 °C). Their antibody responses were measured against P. falciparum MSP-1 antigen using standard ELISA technique.
In all, 415 children comprising 217 (52.3%) males participated. Total IgG and IgG1-IgG4 titres were observed to increase with age in all the strata except in the sudano-sahelian and high inland plateau strata. Total IgG and IgG1-IgG4 titres were significantly higher in the coastal strata and lowest in the high inland plateau (for IgG1 and IgG2) and sudano-sahelian strata (for IgG3 and IgG4). Titres of the cytophilic antibodies (IgG1 and IgG3) were significantly higher than the non-cytophilic antibodies (IgG2 and IgG4) in all the strata except in the sudano-sahelian and high inland plateau strata. Total IgG and IgG subclass titres were significantly higher in children positive for clinical malaria compared to negative children in all study sites except in the high western plateau and coastal (for IgG1 and IgG3), and the sudano-sahelian strata (for all antibodies). Furthermore, a significant positive correlation was observed between parasite density and IgG2 or IgG4 titres in all study sites except in the south Cameroonian equatorial forest and sudano-sahelian strata.
This study showed that antibody responses against MSP-1 vary considerably in children from the different bioecological strata in Cameroon and could be linked to the differential exposure to malaria in the different strata. Furthermore, the rate of antibody acquisition was not observed to increase in an age-dependent manner in low transmission settings.
在疟疾流行地区，来自不同地理位置的儿童对疟疾的天然免疫反应的研究报告并不常见。本研究旨在比较喀麦隆五个截然不同的生物生态区儿童对恶性疟原虫 MSP-1 抗原的免疫反应。
在一项横断面研究中，从五个生态层（包括喀麦隆南部赤道森林、苏丹-萨赫勒、内陆高原、西部高原和沿海地带）招募了 2 至 15 岁的儿童。这些儿童被筛选出患有临床疟疾（定义为疟疾寄生虫血症≥5000 个寄生虫/μl 加上腋温≥37.5°C）。使用标准 ELISA 技术测量他们对恶性疟原虫 MSP-1 抗原的抗体反应。
共有 415 名儿童参与了研究，其中 217 名（52.3%）为男性。除苏丹-萨赫勒和内陆高原层外，所有层的总 IgG 和 IgG1-IgG4 滴度均随年龄增长而增加。沿海地区的总 IgG 和 IgG1-IgG4 滴度显著高于内陆高原（IgG1 和 IgG2）和苏丹-萨赫勒地区（IgG3 和 IgG4）。除苏丹-萨赫勒和内陆高原层外，所有层的细胞亲合力抗体（IgG1 和 IgG3）的滴度均显著高于非细胞亲合力抗体（IgG2 和 IgG4）。除了西部高原和沿海地区（IgG1 和 IgG3）以及苏丹-萨赫勒地区（所有抗体）外，所有研究地点临床疟疾阳性儿童的总 IgG 和 IgG 亚类滴度均显著高于阴性儿童。此外，除喀麦隆南部赤道森林和苏丹-萨赫勒层外，所有研究地点的寄生虫密度与 IgG2 或 IgG4 滴度之间均呈显著正相关。
本研究表明，喀麦隆不同生物生态区儿童对 MSP-1 的抗体反应差异很大，这可能与不同层次的疟疾暴露有关。此外，在低传播环境中，抗体的获得率并未观察到随年龄的增长而增加。
