Malaria affects almost one-half of the world's population and causes more than one million deaths annually. Young children in malaria endemic areas of Africa have the highest mortality because of their immature immune systems. Global efforts to control the disease have had limited success and no vaccine has yet been approved for clinical use. Therefore, there is an urgent unmet need to discover new vaccine candidates using novel approaches, especially for mothers and infants who represent key target groups. Dr. Michelow's research goal for the proposed Mentored Career Development Award is to discover new anti-malarial vaccines for women of childbearing age in order to protect their highly vulnerable offspring from severe or fatal malaria in early infancy. Under the mentorship of Drs. Kurtis and Friedman from Brown University, and Drs. Duffy and Fried from the NIH/NIAID Laboratory of Malaria Immunology and Vaccinology, who are internationally renowned investigators, he plans to test the hypothesis that novel vaccine targets can be discovered by identifying transplacentally acquired malarial antibodies that mediate infants'resistance to severe or fatal malaria. The objective of this proposal is to identify conserved Plasmodium falciparum antigens that are uniquely recognized by IgG antibodies in venous blood obtained at delivery from mothers whose infants survived their first year of life with mild or no clinical malaria, but that are not recognized by IgG antibodies from mothers whose infants suffered severe disease or death due to malaria. Dr. Michelow's team will capitalize on plasma samples and epidemiological data that they already collected from a large well-characterized longitudinal cohort in Muheza, Tanzania (n=739). In order to achieve these objectives, they propose three Specific Aims that are directed at 1) discovering, 2) validating and 3) downselecting P. falciparum candidate vaccine antigens. The strength of this patient-oriented translational strategy derives from the fact that they will use plasma of mothers and infants with naturally acquired malarial antibodies at the earliest stage of vaccine epitope discovery. Based on the successful approach pioneered by Dr. Kurtis, they will perform a differential high throughput whole proteome screen on select groups of pooled plasma from mothers of infants with severe malaria vs. mothers of infants with mild or no malaria. They will use a newly produced P. falciparum (3D7) malaria genomic DNA T7 phage display library as well as a wild type blood-stage complementary DNA T7 phage library for this purpose. Candidate vaccine antigens will then be validated by testing a large independent cohort of mothers and infants from the same population to determine which specific malarial antibodies most reliably predict better malaria outcomes. They will employ mixed effects logistic regression modeling to account for repeated measures and confounding variables as well as the Cox proportional hazards survival model to compare time to predefined endpoints. Lead candidate antigens will then be downselected using bioinformatics and surface localization studies, as well as functional evaluations, using invasion and growth inhibition assays for blood stage candidates. Dr. Michelow's previous clinical training in Pediatric Infectious Diseases and Tropical Medicine, his research on diagnostic tests for children with pneumonia or congenital syphilis, and his laboratory work on production of novel immunotherapeutics for glycosylated virus infections, have laid a solid foundation for his proposed research project. Under the guidance of his mentors, he will bridge the gap between basic science and patient-oriented research by applying rigorous, mechanistic and creative methods of enquiry to translate basic science concepts into relevant human interventions and therapies. He plans to accomplish his goals by acquiring critical new skills in the following three key areas: 1) vaccine immunology, 2) advanced molecular methods, and 3) applied biostatistics, epidemiology and human population research. Specifically, he will be trained in methods to implement innovative phage-based molecular screening strategies, select and test optimal malaria vaccine epitopes, cultivate and genetically manipulate malaria parasites, perform cell-based infection assays, interrogate the malaria genome/proteome databases, use sophisticated cell imaging technologies, model complex data using advanced statistical methods to account for confounding variables and repeated measures, and reinforce importance of bioethical issues. The proposed research experiences will prepare Dr. Michelow to achieve his long-term career goal of becoming a skilled investigator in hypothesis-driven translational research in the field of malaria vaccine discovery. One or more rationally identified lead candidate vaccine epitopes from the current proposal will form the basis of his R01 application. His objectives will be to 1) confirm the relevance of the antigen/s derived from native P. falciparum strains from Tanzania, 2) conduct animal studies to study effectiveness and mechanisms of action of new vaccines, and 3) establish a Phase I healthy human volunteer vaccine study. Dr. Michelow and his team of highly accomplished investigators are committed to the mission of developing new effective malaria vaccines using creative strategies. PROJECT NARRATIVE: Malaria affects almost one-half of the world's population and causes the highest mortality in African children.
This research aims to develop an effective new malaria vaccine to protect infants by taking advantage of maternal antibodies that cross the placenta. Candidate vaccine proteins will be screened, confirmed and selected for clinical trials using pioneering molecular tools and blood samples from pregnant African women and their infants.
Malaria affects almost one-half of the world's population and causes the highest mortality in African children. This research aims to develop an effective new malaria vaccine to protect infants by taking advantage of maternal antibodies that cross the placenta. Candidate vaccine proteins will be screened, confirmed and selected for clinical trials using pioneering molecular tools and blood samples from pregnant African women and their infants.
|Raj, Dipak K; Nixon, Christian P; Nixon, Christina E et al. (2014) Antibodies to PfSEA-1 block parasite egress from RBCs and protect against malaria infection. Science 344:871-7|