非洲输入中国卵形疟原虫裂殖子表面蛋白 1 羧基端 19kDa 片段的遗传多样性和免疫原性。

Genetic diversity and immunogenicity of the merozoite surface protein 1 C-terminal 19-kDa fragment of Plasmodium ovale imported from Africa into China.

机构信息

Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, People's Republic of China.

Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasite Diseases, Wuxi, 214064, Jiangsu, People's Republic of China.

出版信息

Parasit Vectors. 2021 Nov 24;14(1):583. doi: 10.1186/s13071-021-05086-6.

DOI:10.1186/s13071-021-05086-6

PMID:34819151

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8611641/

Abstract

BACKGROUND

Merozoite surface protein 1 (MSP1) plays an essential role in erythrocyte invasion by malaria parasites. The C-terminal 19-kDa region of MSP1 has long been considered one of the major candidate antigens for a malaria blood-stage vaccine against Plasmodium falciparum. However, there is limited information on the C-terminal 19-kDa region of Plasmodium ovale MSP1 (PoMSP1). This study aims to analyze the genetic diversity and immunogenicity of PoMSP1.

METHODS

A total of 37 clinical Plasmodium ovale isolates including Plasmodium ovale curtisi and Plasmodium ovale wallikeri imported from Africa into China and collected during the period 2012-2016 were used. Genomic DNA was used to amplify P. ovale curtisi (poc) msp1 (pocmsp1) and P. ovale wallikeri (pow) msp1 (powmsp1) genes by polymerase chain reaction. The genetic diversity of pomsp1 was analyzed using the GeneDoc version 6 programs. Recombinant PoMSP1 (rPoMSP1)-glutathione S-transferase (GST) proteins were expressed in an Escherichia coli expression system and analyzed by western blot. Immune responses in BALB/c mice immunized with rPoMSP1-GST were determined using enzyme-linked immunosorbent assay. In addition, antigen-specific T cell responses were assessed by lymphocyte proliferation assays. A total of 49 serum samples from healthy individuals and individuals infected with P. ovale were used for the evaluation of natural immune responses by using protein microarrays.

RESULTS

Sequences of pomsp1 were found to be thoroughly conserved in all the clinical isolates. rPoMSP1 proteins were efficiently expressed and purified as ~ 37-kDa proteins. High antibody responses in mice immunized with rPoMSP1-GST were observed. rPoMSP1-GST induced high avidity indexes, with an average of 92.57% and 85.32% for rPocMSP1 and rPowMSP1, respectively. Cross-reactivity between rPocMSP1 and rPowMSP1 was observed. Cellular immune responses to rPocMSP1 (69.51%) and rPowMSP1 (52.17%) induced in rPocMSP1- and rPowMSP1-immunized mice were found in the splenocyte proliferation assays. The sensitivity and specificity of rPoMSP1-GST proteins for the detection of natural immune responses in patients infected with P. ovale were 89.96% and 75%, respectively.

CONCLUSIONS

This study revealed highly conserved gene sequences of pomsp1. In addition, naturally acquired humoral immune responses against rPoMSP1 were observed in P. ovale infections, and high immunogenicity of rPoMSP1 in mice was also identified. These instructive findings should encourage further testing of PoMSP1 for rational vaccine design.

摘要

背景

裂殖子表面蛋白 1（MSP1）在疟原虫入侵红细胞中起着重要作用。MSP1 的 C 端 19kDa 区域长期以来一直被认为是恶性疟原虫血阶段疫苗的主要候选抗原之一。然而，关于卵形疟原虫 MSP1（PoMSP1）的 C 端 19kDa 区域的信息有限。本研究旨在分析 PoMSP1 的遗传多样性和免疫原性。

方法

使用了 37 株临床卵形疟原虫分离株，包括从非洲输入中国的卵形疟原虫 curtisi 和卵形疟原虫 wallikeri，以及 2012-2016 年期间采集的分离株。使用聚合酶链反应从基因组 DNA 扩增卵形疟原虫 curtisi（poc）msp1（pocmsp1）和卵形疟原虫 wallikeri（pow）msp1（powmsp1）基因。使用 GeneDoc 版本 6 程序分析 pomsp1 的遗传多样性。在大肠杆菌表达系统中表达重组 PoMSP1（rPoMSP1）-谷胱甘肽 S-转移酶（GST）蛋白，并通过 Western blot 进行分析。用酶联免疫吸附试验检测用 rPoMSP1-GST 免疫的 BALB/c 小鼠的免疫反应。此外，通过淋巴细胞增殖试验评估抗原特异性 T 细胞反应。使用蛋白质微阵列评估来自健康个体和感染卵形疟原虫个体的 49 份血清样本的天然免疫反应。

结果

发现所有临床分离株的 pomsp1 序列都非常保守。rPoMSP1 蛋白作为~37kDa 蛋白高效表达和纯化。用 rPoMSP1-GST 免疫的小鼠产生了高抗体反应。rPoMSP1-GST 诱导了高亲和力指数，rPocMSP1 和 rPowMSP1 的平均亲和力指数分别为 92.57%和 85.32%。在 rPocMSP1 和 rPowMSP1 免疫的小鼠中观察到 rPocMSP1 和 rPowMSP1 之间的交叉反应性。rPocMSP1（69.51%）和 rPowMSP1（52.17%）诱导的细胞免疫反应在 rPocMSP1 和 rPowMSP1 免疫的小鼠脾细胞增殖试验中被发现。rPoMSP1-GST 蛋白对检测感染卵形疟原虫患者天然免疫反应的敏感性和特异性分别为 89.96%和 75%。