Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana.
Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana.
Malar J. 2023 Apr 15;22(1):126. doi: 10.1186/s12936-023-04557-8.
The human host elicits specific immune responses after exposure to various life stages of the malaria parasite as well as components of mosquito saliva injected into the host during a mosquito bite. This study describes differences in IgG responses against antigens derived from the sporozoite (PfCSP), asexual stage parasite (PfEBA175) and the gametocyte (Pfs230), in addition to an Anopheles gambiae salivary gland antigen (gSG6-P1), in two communities in Ghana with similar blood stage malaria parasite prevalence.
This study used archived plasma samples collected from an earlier cross-sectional study that enrolled volunteers aged from 6 months to 70 years from Simiw, peri-urban community (N = 347) and Obom, rural community (N = 291). An archived thick and thin blood smear for microscopy was used for the estimation of Plasmodium parasite density and species and DNA extraction from blood spots and P. falciparum confirmation was performed using PCR. This study used the stored plasma samples to determine IgG antibody levels to P. falciparum and Anopheles salivary antigens using indirect ELISA.
Individuals from Simiw had significantly higher levels of IgG against mosquito gSG6-P1 [median (95%CI)] [2.590 (2.452-2.783) ng/mL] compared to those from Obom [2.119 (1.957-2.345) ng/mL], p < 0.0001. Both IgG responses against Pfs230proC (p = 0.0006), and PfCSP (p = 0.002) were significantly lower in volunteers from Simiw compared to the participants from Obom. The seroprevalence of PfEBA-175.5R (p = 0.8613), gSG6-P1 (p = 0.0704), PfCSP (p = 0.7798) IgG were all similar in Obom and Simiw. However, Pfs230 seroprevalence was significantly higher at Obom compared to Simiw (p = 0.0006). Spearman correlation analysis showed no significant association between IgG responses against gSG6-P1, PfCSP, Pfs230proC and PfEBA-175.5R and parasite density at both Obom and Simiw (p > 0.05).
In conclusion, the study showed that participants from Simiw had higher concentrations of circulating gSG6-P1 IgG antibodies but lower concentrations of P. falciparum antibodies, PfCSP IgG and Pfs230proC IgG compared to participants from Obom.
人类宿主在暴露于疟原虫的各种生活阶段以及蚊子叮咬时注入宿主的蚊子唾液成分后，会产生特异性免疫反应。本研究描述了在加纳两个社区中，针对来自孢子体（PfCSP）、无性阶段寄生虫（PfEBA175）和配子体（Pfs230）的抗原以及按蚊唾液腺抗原（gSG6-P1）的 IgG 反应的差异，这两个社区的血阶段疟原虫流行率相似。
本研究使用了先前一项横断面研究中保存的血浆样本，该研究招募了来自西米（Simiw）的 6 个月至 70 岁的志愿者（N=347）和奥比姆（Obom）的志愿者（N=291）。使用存档的厚血涂片和薄血涂片进行显微镜检查，以估计疟原虫寄生虫密度和种类，并从血斑中提取 DNA，然后使用 PCR 进行确认。本研究使用储存的血浆样本，通过间接 ELISA 法测定针对 Pf 疟原虫和按蚊唾液抗原的 IgG 抗体水平。
与奥比姆的参与者相比，西米的参与者对蚊子 gSG6-P1 的 IgG 水平明显更高[中位数（95%CI）] [2.590（2.452-2.783）ng/mL]，p<0.0001。与奥比姆的参与者相比，西米的志愿者针对 Pfs230proC（p=0.0006）和 PfCSP（p=0.002）的 IgG 反应均明显较低。PfEBA-175.5R（p=0.8613）、gSG6-P1（p=0.0704）和 PfCSP（p=0.7798）的 IgG 血清阳性率在奥比姆和西米均相似。然而，与西米相比，奥比姆的 Pfs230 血清阳性率明显更高（p=0.0006）。Spearman 相关分析显示，在奥比姆和西米，gSG6-P1、PfCSP、Pfs230proC 和 PfEBA-175.5R 与寄生虫密度之间均无显著相关性（p>0.05）。
总之，该研究表明，与奥比姆的参与者相比，西米的参与者具有更高浓度的循环 gSG6-P1 IgG 抗体，但 Pf 疟原虫抗体、PfCSP IgG 和 Pfs230proC IgG 的浓度较低。
