Malaria is known to be one of the most critical health crises in developing countries. It affects almost a quarter of billion people each year and kills a child every 30 seconds and in spite of this there is no vaccine available for the disease. That however could be a thing of the past as researchers from The Rockefeller University claim to have genetically modified the yellow fever vaccine to protect the immune system from mosquito borne parasites that may bring about malaria.
Researchers identified that the modified vaccine coupled with a booster provide mice the immunity required to combat malaria. It has been known since 1960s that one form of the sporozoites is capable of reviving the immune system and protects against future infection. The only way to attain sporozoites is to pluck them one-by-one from salivary glands of irradiated and malaria ridden mosquitoes. In order to provide immunity the undermined parasite must be injected in high doses. It can also be delivered by hundred bites of mosquitoes; however this is labor intensive and not viable for extensive use.
Charles M. Rice, head of the Laboratory of Virology and Infectious Disease says that they desired to come up with another way in order to attain benefits of sporozoite immunization. Researchers analyzed that fighting the infection with another infection may be a good approach. They started experimenting with the mitigate yellow fever strain used in the yellow fever vaccine which was known as YF17D. Since 1937.this vaccine was used successfully to vaccinate more than 400 million people. Prior work in the Rice laboratory and by others revealed that this vaccine strain could be tailored to include short sequences from other pathogens, including malaria.
Researchers inserted almost the complete sequence of a malaria gene into the YF17D vaccine. It was identified that the gene could produce its proteins in cultured cells. This protein called CSP covers the surface of the malaria sporozoite and it is in the form of a parasite that provokes the immune system effectively.
Immunization of mice with the YF17D-CSP vaccine led to a considerable leap in immune activity fighting the malaria protein. It was observed though a single shot was not enough to protect the animals from the mouse form of the malaria parasite.
“These results are exciting because they show the YF17D-CSP vaccine can prime the immune response against a malaria parasite,” says lead author Cristina Stoyanov. Although the utility of this approach for human immunization is not yet clear, the team hopes that further studies in other animal models might eventually lead to an effective vaccine.
The group further added a booster shot to the vaccination. Animals vaccinated with YF17D-CSP or with saline solution control were injected with a low dose of sporozoites. The saline sporozoite group was partly defended from this challenge due to feasible parasites. It was observed that immunization with YF17D-CSP and the sporozoites saved almost 100 percent of the animals from being affected by the infection.
This research was published last month in Vaccine.