Development and longevity of naturally acquired antibody and memory B cell responses against Plasmodium vivax infection.

Plasmodium vivax malaria causes significant public health problems in endemic regions. Considering the rapid spread of drug-resistant parasite strains and the development of hypnozoites in the liver with potential for relapse, development of a safe and effective vaccine for preventing, controlling, and eliminating the infection is critical. Immunity to malaria is mediated by antibodies that inhibit sporozoite or merozoite invasion into host cells and protect against clinical disease. Epidemiologic data from malaria endemic regions show the presence of naturally acquired antibodies to P. vivax antigens during and following infection. But data on the persistence of these antibodies, development of P. vivax-specific memory B cells (MBCs), and their relation to reduction of malaria severity and risk is limited. This review provides an overview of the acquisition and persistence of naturally acquired humoral immunity to P. vivax infection. Also, we summarize and discuss current progress in assessment of immune responses to candidate vaccine antigens in P. vivax patients from different transmission settings. Longitudinal studies of MBC and antibody responses to these antigens will open new avenues for developing vaccines against malaria infection and its transmission. Author summary: Despite the Plasmodium vivax parasite causing a large proportion of the global malaria burden, it has been neglected by much of the research world. Vaccines that can effectively induce strong and long-lasting antibody and memory B cell (MBC) responses are necessary for disease control and elimination, as they are crucial for blocking subsequent infection. The development and longevity of antibodies and MBC responses against different stages of P. vivax have been studied in various transmission settings. Some candidate antigens have been investigated in clinical trials with promising results. Previous reports have provided evidence of antibody acquisition to representative candidate P. vivax antigens from pre-erythrocytic, blood and transmission stages. However, evidence of durable antibody responses and development of P. vivax-specific MBCs is still lacking. Recently, expansion of atypical MBCs along with up-regulation of inhibitory receptors and reduced BCR signaling has been demonstrated and associated with short-lived antibody responses, culminating in impaired humoral immunity. Collectively, the capacity of P. vivax antigens to induce naturally acquired humoral immunity has been addressed. The results allow optimization of vaccine design to enhance immune responses to the parasite and protect against disease. [ABSTRACT FROM AUTHOR]