Recombinant P. vivax MSP-1 (a.a. 108) [MBP]

Malaria, which seriously affects people's health and quality of life, is caused by Plasmodium spp. and is transmitted through mosquito bites. Plasmodium falciparum and Plasmodium vivax are among the most important pathogenic parasites, with P. falciparum being the most lethal and P. vivax being the most widely distributed. The development of a malaria vaccine is the best way to prevent, control, and eliminate malaria, but many obstacles have arisen in the development of a vaccine for P. vivax, with the greatest challenge being the difficulty in finding the optimal immunogen for inducing a protective effect. On the other hand, the long-term in vitro culture of P. vivax cannot be established in the laboratory, which also makes antigen discovery more challenging. Therefore, some researchers have attempted to use computers to identify parasite proteins, assess characteristics such as antigenicity and immunogenicity, and test antigens against different stages of the parasite's life cycle with different adjuvants and immunization combinations.

After an infected mosquito bites a human, the sporozoites are inoculated into the skin, and upon entering the skin the sporozoites gain motility, penetrate blood vessels and begin to stimulate an immune response in the host. Then the sporozoites reach the liver through the blood system and invades the hepatocytes. In the hepatocytes the sporozoites undergo a series of morphological changes, after which the merozoites are released into the bloodstream. In Plasmodium vivax infection the parasites selectively invade reticulocytes and thus develop low parasitemia. In this case, blood-stage vaccines attempt to prevent symptoms by stopping the invasion of merozoites into blood cells or preventing them from developing into erythrocytes.

Figure 1. Plasmodium vivax life cycle and targets of malaria vaccines
(Source: da Veiga GTS, et al. 2023)

Merozoite surface protein 1 (MSP 1), the most studied molecule on the surface of asexual blood-stage Plasmodium vivax, induces high levels of cellular and humoral immune responses and is considered a malaria vaccine candidate. In early vaccine studies using purified proteins MSP 1 was shown to protect rodent parasite models against Plasmodium infection. MSP 1 is involved in erythrocyte invasion, during which it is split by proteolytic hydrolysis into distinct MSP 1 fragments, where the C-terminal MSP-1₄₂ fragment remains on the surface of the merozoites and attaches via GPI anchors. After treatment, two fragments are produced, MSP-1₃₃ corresponding to the N-terminal region and MSP-1₁₉ corresponding to the C-terminal region. MSP-1₃₃ also cleaves into two other fragments, MSP-1₁₄ and MSP-1₂₀. All these fragments can be used in vaccine formulations and have shown protective effects in different animal models by inducing highly specific antibody and cytokine responses as well as reducing parasitemia.

Plasmodium vivax MSP 1
Plasmodium vivax merozoite surface protein 1
P. vivax merozoite surface protein 1