Search for novel vaccine candidate antigens using plasma of patients with vivax malaria inhibition

P. vivax, which is prevalent mainly in Asia, has a low mortality rate and the difficulty of obtaining protozoa, so countermeasures have been delayed despite the large impact on public health and economic activities. Development of a transmission-blocking vaccine that stops the development of malaria parasites in the body of vector mosquitoes is expected, but none has been put into practical use yet. Focusing on the fact that the plasma of residents of endemic areas has a transmission-blocking effect, this study clarified which protozoan protein induced the transmission-blocking antibody acquired by natural infection, and was able to develop an effective vaccine. Aiming to search for antigens, joint research will be conduted in collaboration with researchers in the Kingdom of Thailand. In this project, protein arrays are used to screen for proteins commonly recognized by patient plasma that have propagation-blocking effects. In creating the protein array, in addition to proteome analysis, the information of the gametocyte protein array targeting Plasmodium falciparum was referred to to identify proteins that are expected to be expressed in the gametocyte and gametophyte and to be surfaced or secreted. 301 types were selected. In addition, in consideration of the situation in which they could not go out into the field, a genetically modified murine malaria parasite was created in which only the target protein was replaced with the vivax plasmodium type. Although the efficiency is lower than that of the wild type, oocyst formation was observed in mosquitoes. Using this as a model, it became possible to check the specificity of the antibody and measure its propagation-blocking effect in the laboratory. . In order to further increase the number of candidate antigens, antibodies were prepared for the two proteins, and their effects on propagation using murine malaria parasites were investigated, but no inhibitory effect was observed.

Project details

P. vivax
Vaccines

Oct 2019 — Mar 2023

$159,474

Japan

Towards a vaccine for Plasmodium vivax