One Step Closer To An Effective, Long-term Malaria Vaccine?
A Deadly Parasite
New research, as reported in ScienceDaily, aims to bring us one step closer with the discovery of a human antibody that protects mice from infection with Plasmodium falciparum, the deadliest malaria parasite.
This new discovery could pave the way for future testing in humans to find out whether the antibody is able to provide short-term protection against malaria in people, and could prove helpful in the quest to develop an effective, long-term vaccine.
Discovering a Protective Antibody
Investigators at the National Institute of Allergy and Infectious Diseases (part of the National Institutes of Health) led the research, alongside researchers at the Fred Hutchinson Cancer Research Center in Seattle, were able to isolate an antibody called CIS43 from the blood of a volunteer who had been inoculated with an experimental vaccine. The vaccine was created using whole, weakened parasites (PfSPZ Vaccine-Sanaria). Following inoculation, the volunteer was (carefully, and under controlled conditions) exposed to infectious malaria-carrying mosquitos, and did not become infected.
In two different models looking at malaria infection in mice, the isolated CIS43 antibody proved to be highly effective at preventing the mice from becoming infected with malaria.
How it Works and What's Next
Looking at the CIS43 antibody in more detail shows that it works by binding to a specific portion of a key parasite surface protein, one that occurs only once along the length of the protein. Not only that, but the CIS43-binding epitope is conserved across 99.8% of all known strains of P. falciparum.
Because of this, the CIS43 antibody is an attractive target for researching next-generation experimental malaria vaccines, with the goal of producing this "neutralizing" antibody. If the results seen in mice are confirmed via human studies, CIS43 could be developed as a prophylactic measure designed to prevent infection long-term (for several months) following administration. If found to be effective at preventing malaria infection for six months, it could potentially work in combination with antimalarial drugs to help eliminate the disease in regions where malaria is endemic.
Scientists at the NIAID Vaccine Research Center are looking to assess the safety and efficacy of this new antibody in the coming year through controlled human malaria infection challenge trials.
Further Reading & References:
Neville K Kisalu, Azza H Idris, Connor Weidle, Yevel Flores-Garcia, Barbara J Flynn, Brandon K Sack, Sean Murphy, Arne Schon, Ernesto Freire, Joseph R Francica, Alex B Miller, Jason Gregory, Sandra March, Hua-Xin Liao, Barton F Haynes, Kevin Wiehe, Ashley M Trama, Kevin O Saunders, Morgan A Gladden, Anthony Monroe, Mattia Bonsignori, Masaru Kanekiyo, Adam K Wheatley, Adrian B McDermott, S Katie Farney, Gwo-Yu Chuang, Baoshan Zhang, Natasha Kc, Sumana Chakravarty, Peter D Kwong, Photini Sinnis, Sangeeta N Bhatia, Stefan H I Kappe, B Kim Lee Sim, Stephen L Hoffman, Fidel Zavala, Marie Pancera, Robert A Seder. A human monoclonal antibody prevents malaria infection by targeting a new site of vulnerability on the parasite. Nature Medicine, 2018; DOI: 10.1038/nm.4512
NIH/National Institute of Allergy and Infectious Diseases. "Newly described human antibody prevents malaria in mice: Research might help prevent malaria and aid design of next-generation vaccines." ScienceDaily. ScienceDaily, 19 March 2018. www.sciencedaily.com/releases/2018/03/180319215840.htm
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