Participant: PROMISE AGEP Research Symposium
Lampouguin Yenkoidiok Douti
Institution: University of Maryland, College Park (UMD)
Malaria vaccine: finding the Achilles heel in the mosquito.
To be successfully transmitted, malaria parasite, Plasmodium,must survive and complete its life cycle inside the mosquito vector. Thus, interfering with the ability of mosquitoes to support the parasite could help control and ultimately eradicate malaria. Transmission-blocking vaccines are based on the insight that antibodies can bind and block parasites development in the mosquito. Recently, we have shown that Pfs47 could be a potent transmission-blocking target and have identified the key epitope for vaccine development. However, for Pfs47 vaccine to be clinically relevant, it is necessary to generate long-lasting and high-affinity antibodies so that the vaccine remains effective as antibody levels decrease over time. To achieve this goal, we need to optimize the immunogenicity of Pfs47 vaccine. Here, we compared the efficacy of Pfs47 vaccine in two leading antigen delivery systems that have been recently shown to enable strong immune responses to poorly immunogenic antigens. In one platform, Pfs47 was conjugated to a non-toxic Pseudomonas aeruginosa ExoProtein A (EPA) while in the second, Pfs47 was conjugated to a virus-like-particle. In both cases, group of Balb/c mice were immunized with the same amount of vaccine. Antibody levels were quantified throughout the immunization regimen using ELISA. Antibody functionality were assessed via standard membrane feeding assays. Results indicate that the presence of anti-Pfs47 antibodies in Plasmodium-infected blood reduces parasite density in mosquitoes, up to 99%.
Assessing the Potential of Plasmodium P47 as a Malaria Transmission Blocking Vaccine
Malaria is a life-threatening disease caused by Plasmodium falciparum parasites and transmitted by anopheline mosquitoes. One key step to control/eradicate malaria is to reduce the rate of disease transmission. Transmission-blocking vaccines rely on functional antibodies interacting with the sexual/sporogonic stages parasite surface proteins to reduce parasite survival in the mosquito. Recently, Pfs47, a three-domain surface protein, has been shown to mediate Plasmodium parasite evasion of the mosquito immune system. Studies testing the potential of P47 as a transmission blocking target showed a moderate transmission blocking activity. Interestingly, monoclonal antibodies obtained after immunization could only recognize domains 1 and 3 of P47. We hypothesized that the ability to target the domain 2 of P47 could improve the potential of the vaccine to generate an effective transmission blocking response. Using the murine model of malaria, P. berghei, the recombinant P47 domain 2 protein was expressed, used to immunize mice following a prime/boost regimen and tested by ELISA. Immunized and control mice were infected using a green fluorescence protein transgenic parasite and used to feed Anopheles gambiae mosquitoes. Immunization with Pb47-D2 tuned a significant proportion of the immune response toward a critical epitope of the parasite surface protein. This effective priming of the immune response translated into lower oocysts count in mosquitoes fed with immunized mice indicating effective transmission blocking activity. These studies suggest that improved P47 targeting may lead to the development of a novel malaria transmission blocking vaccine.
Lampouguin graduated from the University of Maryland, College Park in 2015 with a B.S. in Bioengineering. While an undergraduate, he gained strong research experiences when he participated in summer research programs at NIH and NIST. These research opportunities encouraged him to pursue higher education, so in the Fall of 2015, he enrolled as a doctoral student at the University of Maryland in the Robert E. Fischell Department of Bioengineering. Lampouguin is currently a second year PhD student and was awarded the 2015 – 2017 National Science Foundation funded Bridge-to-the Doctorate Fellowship plus an additional institutional fellowship toward his graduate education. Lampouguin’s doctoral research is focused on developing novel Malaria vaccines and is also working to integrate novel biomaterials into improved Malaria research. He is supervised by Dr. Carolina Barillas-Mury at the NIH Malaria Branch and co-advised by Dr. Jewell at UMD.
GENERAL SUMMARY OF GRADUATE RESEARCH
It is currently agreed that malaria eradication could only be achieved via the combination of multiples strategies. One emerging approach to complement current therapies is to develop a vaccine capable of inhibiting the development of the malaria parasite within the mosquito, thus preventing the spread of the disease. Several candidate antigens have been tested and shown compelling blocking activity. However, it is not well understood whether the transmission blocking response is only mediated by antibodies, as argued by current studies, or a concerted humoral and cell mediated immune response. Since cell mediated immunity has been shown to play an important role in the resolution of blood-stage malaria, shedding light on this unknown question could have significant implications on vaccine design. My first goal is to optimize the heterologous expression and purification of a novel transmission blocking vaccine candidate, P47, and evaluate its blocking potential. Secondly, I plan to assess the role of cell-mediated versus humoral immunity in the transmission blocking response elicited following mice immunization with P47 protein using different immune cells deficient mice models. I also plan to compare standard injection techniques with immunization via the skin using microneedles as they possess the added advantage of improving patient compliance by eliminating injection-associated pain. Together, these objectives could help improve current malaria vaccine design and immunization strategies and yield rationales for novel knowledge applicable to other diseases.
SELECTED LIST OF PRESENTATIONS AND PUBLICATIONS
- Gaspar E. Canepa, Alvaro Molina-Cruz, Lampouguin Yenkoidiok Douti al. “Antibody targeting of a specific region of Pfs47 blocks Plasmodium falciparummalaria transmission” NPJ Vaccine 2018
- Tek N. Lamichhane, Christopher A. Leung, Lampouguin Yenkoidiok Douti, Steven M. Jay. “Ethanol Induces Enhanced Vascularization Bioactivity of Endothelial Cell-Derived Extracellular Vesicles via Regulation of MicroRNAs and Long Non-Coding RNAs” Scientific Reports 2017
- “Development and Optimization of PlasmodiumPfs47 Vaccine to Block Malaria Transmission” Lampouguin Y. Douti, NIH-NIAID seminar series, NIAID TWIII, Rockville, Maryland, September 09th2018. (Podium)
- “Advances in the Assessment of Plasmodium Falciparum Pfs47 as a Transmission Blocking Target” Gaspar Canepa, Alvaro Molina-Cruz, Lampouguin Y. Douti, Carolina Barillas-Mury, ASTMH 66thAnnual Meeting, Baltimore, MD, November 5 – 9 2017. (Poster)
- “Novel Malaria Vaccine to Recruit Mosquito Immunity Toward a Robust Transmission Blocking Activity” Lampouguin Y. Douti, Gaspar Canepa, Carolina Barillas-Mury, BMES Annual Meeting, Phoenix, Arizona, October 11 – 15 2017. (Poster)
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