Browsing by Author "Tachibana, Mayumi."

Now showing 1 - 3 of 3
  • No Thumbnail Available
    PublicationMetadata only
    Identification of Novel Malaria Transmission-Blocking Vaccine Candidates
    (Frontiers, 2021-11-30) Takashima, Eizo.; Tachibana, Mayumi.; Morita, Masayuki.; Nagaoka, Hikaru.; Kanoi, Bernard N.; Tsuboi, Takafumi.
    Control measures have significantly reduced malaria morbidity and mortality in the last two decades; however, the downward trends have stalled and have become complicated by the emergence of COVID-19. Significant efforts have been made to develop malaria vaccines, but currently only the RTS,S/AS01 vaccine against Plasmodium falciparum has been recommended by the WHO, for widespread use among children in sub-Saharan Africa. The efficacy of RTS,S/AS01 is modest, and therefore the development of more efficacious vaccines is still needed. In addition, the development of transmission-blocking vaccines (TBVs) to reduce the parasite transmission from humans to mosquitoes is required toward the goal of malaria elimination. Few TBVs have reached clinical development, and challenges include low immunogenicity or high reactogenicity in humans. Therefore, novel approaches to accelerate TBV research and development are urgently needed, especially novel TBV candidate discovery. In this mini review we summarize the progress in TBV research and development, novel TBV candidate discovery, and discuss how to accelerate novel TBV candidate discovery.
  • No Thumbnail Available
    PublicationMetadata only
    Identification of target proteins of clinical immunity to Plasmodium falciparum in a region of low malaria transmission
    (Parasitology International, 2018-01-04) Sakamoto, Hirokazu.; Takeo, Satoru.; Takashima, Eizo.; Miura, Kazutoyo.; Kanoi, Bernard N.; Kaneko, Takamasa.; Han, Eun-Taek.; Tachibana, Mayumi.; Matsuoka, Kazuhiro.; Sattabongkot, Jetsumon.; Udomsangpetch, Rachanee.
    The target molecules of antibodies against falciparum malaria remain largely unknown. Recently we have identified multiple proteins as targets of immunity against Plasmodium falciparum using African serum samples. To investigate whether potential targets of clinical immunity differ with transmission intensity, we assessed immune responses in residents of low malaria transmission region in Thailand. Malaria asymptomatic volunteers (Asy: n = 19) and symptomatic patients (Sym: n = 21) were enrolled into the study. Serum immunoreactivity to 186 wheat germ cell-free system (WGCFS)-synthesized recombinant P. falciparum asexual-blood stage proteins were determined by AlphaScreen, and subsequently compared between the study groups. Forty proteins were determined as immunoreactive with antibody responses to 35 proteins being higher in Asy group than in Sym group. Among the 35 proteins, antibodies to MSP3, MSPDBL1, RH2b, and MSP7 were significantly higher in Asy than Sym (unadjusted p < 0.005) suggesting these antigens may have a protective role in clinical malaria. MSP3 reactivity remained significantly different between Asy and Sym groups even after multiple comparison adjustments (adjusted p = 0.033). Interestingly, while our two preceding studies using African sera were conducted differently (e.g., cross-sectional vs. longitudinal design, observed clinical manifestation vs. functional activity), those studies similarly identified MSP3 and MSPDBL1 as potential targets of protective immunity. This study further provides a strong rationale for the application of WGCFS-based immunoprofiling to malaria vaccine candidate and biomarker discovery even in low or reduced malaria transmission settings.
  • No Thumbnail Available
    PublicationMetadata only
    Malaria transmission-blocking vaccines: wheat germ cell-free technology can accelerate vaccine development
    (Expert Review of Vaccines, 2019-10-10) Miura, Kazutoyo.; Tachibana, Mayumi.; Takashima, Eizo.; Morita, Masayuki.; Kanoi, Bernard N.; Nagaoka, Hikaru.; Baba, Minami.; Torii, Motomi.; Ishino, Tomoko.; Tsuboi, Takafumi.
    Introduction: Highly effective malaria vaccines are essential component toward malaria elimination. Although the leading malaria vaccine, RTS,S/AS01, with modest efficacy is being evaluated in a pilot feasibility trial, development of a malaria transmission-blocking vaccine (TBV) could make a major contribution toward malaria elimination. Only a few TBV antigens have reached pre-clinical or clinical development but with several challenges including difficulties in the expression of malaria recombinant proteins and low immunogenicity in humans. Therefore, novel approaches to accelerate TBV research to preclinical development are critical to generate an efficacious TBV. Areas covered: PubMed was searched to review the progress and future prospects of malaria TBV research and development. We also reviewed registered trials at ClinicalTrials.gov as well as post-genome TBV candidate discovery research including our efforts. Expert opinion: Wheat germ cell-free protein synthesis technology can accelerate TBV development by overcoming some current challenges of TBV research.