A discovery of how the body’s immune system protects against malaria may hold promise for a vaccine against the disease, which kills as many as 600,000 people each year, mostly children. Currently, no effective vaccine exists for the mosquito-borne disease, which infects the bloodstream and red blood cells, leading to fatigue, headaches, and in severe cases, death.
Antibodies play major roles in immunity to malaria, but a limited understanding of mechanisms mediating protection long has been a barrier to vaccine development. Researchers have known antibodies alone were mostly ineffective at targeting the malaria organism, leading them to believe the antibodies in people resistant to malaria must be getting help from other parts of the immune system.
Professor James Beeson, who heads Burnet’s Centre for Biomedical Research in Melbourne, Australia, said he and his research team discovered that antibodies “needed to recruit other proteins in the blood” in order to block malaria infection. This mechanism, known as a complement,” helps the antibodies coat the malaria organism, according to Beeson. “By working together,” he adds, “these two things are a double-hit that stops malaria from infecting red blood cells.”
The findings represent a major advance in understanding immunity to malaria and provide a much-needed strategy for the development and evaluation of vaccines.
Beeson says Burnet’s researchers will now apply this new knowledge to their strategies to create new and more effective malaria vaccines.
“Exploiting this malaria-blocking activity is a new approach in developing a vaccine. We have shown that it is possible to effectively generate this protective immune response by immunizing humans with a candidate vaccine,” Beeson says.
Historically, vaccines were developed to protect against bacterial and viral diseases that plagued the world population through the 1950s and 1960s. Diphtheria, tetanus, pertussis, polio, smallpox and malaria, among others, were produced in mass quantities to treat large populations.
The advances in immunology, biochemistry, microbiology and biotechnology during the past four decades have opened up the possibilities of creating vaccines for a variety of diseases, including Alzheimer’s, certain cancers, HIV, multiple sclerosis, various tropical diseases, and autoimmune disorders such as diabetes, lupus erythematosus and arthritis.
Vaccines are also being developed against new targets, including Japanese encephalitis, meningitis, certain pollen allergies, metastatic melanoma, Type I diabetes, oral rotavirus, hypertension, and enterotoxigenic Escherichia coli infection.
Currently, researchers are conducting more than 640 clinical trials around the world on a wide variety of vaccines. The World Health Organization estimates there are 120 new vaccines in pharmaceutical/biopharmaceutical company pipelines.
In the United States, the FDA will approve a vaccine if there exist an adequate immunological response, patient safety and established effectiveness of the vaccine at controlling the disease. Vaccine development, approval and production are a costly and long-term venture for any pharmaceutical company. It demands separate, dedicated facilities, equipment and staff. This requires that there be potential revenue and large, diverse patient populations to allow a company to enter into a vaccine venture.
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