Novel Transmission-Blocking Malaria DNA Vaccine Candidate Uses Vical's Adjuvant

Vical Incorporated recently announced researchers at Ehime University in Japan and their collaborators have developed a Vaxfectin-formulated DNA vaccine candidate with the potential to prevent transmission of malaria. Results of the initial testing, recently published in the journal Vaccine, demonstrated that the malaria parasite life cycle was interrupted in mosquitoes fed with malaria-infected human red blood cells incubated with serum from vaccinated mice. Vical provided the DNA vaccine plasmid backbone and the adjuvant used in the research.

The malaria parasite advances through several life cycle stages in humans and through additional life cycle stages in mosquitoes. The transmission-blocking DNA vaccine candidate, formulated with Vical’s Vaxfectin adjuvant, expresses the Plasmodium vivax malaria parasite protein Pvs230, which is present in both human and mosquito stages of the parasite’s life cycle. Anti-Pvs230 antibodies generated by vaccinated mice recognized the Pvs230 protein and interrupted the parasite’s development in mosquitoes. The amino acid sequence of Pvs230 protein is also highly conserved among multiple field isolates of P. vivax, increasing the potential for a single vaccine to provide broad protection.

The mouse-generated Pvs230 antibodies, incubated with P. vivax-infected human red blood cells and then fed to mosquitoes, statistically reduced the number of parasites and the infection rate in mosquitoes. A Vaxfectin-formulated malaria vaccine therefore has the potential to interfere with the transmission of P. vivax to humans through mosquitoes. This novel transmission-blocking approach may thereby protect the broader population from widespread malaria outbreaks.

Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases. Potential applications of the company’s DNA delivery technology include DNA vaccines for infectious diseases or cancer, in which the expressed protein is an immunogen; cancer immunotherapeutics, in which the expressed protein is an immune system stimulant; and cardiovascular therapies, in which the expressed protein is an angiogenic growth factor. The company is developing certain infectious disease vaccines and cancer therapeutics internally.

In addition, the company collaborates with major pharmaceutical companies and biotechnology companies that give it access to complementary technologies or greater resources. These strategic partnerships provide the company with mutually beneficial opportunities to expand its product pipeline and address significant unmet medical needs. Additional information on Vical is available at www.vical.com.