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Baculovirus-Based Nasal Drop Vaccine Confers Complete Protection against Malaria by Natural Boosting of Vaccine-Induced Antibodies in Mice

Yoshida, Shigeto, Araki, Hitomi, Yokomine, Takashi
Infection and immunity 2010 v.78 no.2 pp. 595-602
B-lymphocytes, Plasmodium yoelii, animal models, antibodies, humoral immunity, malaria, merozoites, mice, nose, parasites, surface proteins, vaccination, vaccine development, vaccines, viruses
Blood-stage malaria parasites ablate memory B cells generated by vaccination in mice, resulting in diminishing natural boosting of vaccine-induced antibody responses to infection. Here we show the development of a new vaccine comprising a baculovirus-based Plasmodium yoelii 19-kDa carboxyl terminus of merozoite surface protein 1 (PyMSP1₁₉) capable of circumventing the tactics of parasites in a murine model. The baculovirus-based vaccine displayed PyMSP1₁₉ on the surface of the virus envelope in its native three-dimensional structure. Needle-free intranasal immunization of mice with the baculovirus-based vaccine induced strong systemic humoral immune responses with high titers of PyMSP1₁₉-specific antibodies. Most importantly, this vaccine conferred complete protection by natural boosting of vaccine-induced PyMSP1₁₉-specific antibody responses shortly after challenge. The protective mechanism is a mixed Th1/Th2-type immunity, which is associated with the Toll-like receptor 9 (TLR9)-dependent pathway. The present study offers a novel strategy for the development of malaria blood-stage vaccines capable of naturally boosting vaccine-induced antibody responses to infection.