Vical develops malaria vaccine that prevents transmission

Vical Incorporated, a biopharmaceutical research and development company, announced on Wednesday that researchers at Ehime University in Japan have developed a malaria vaccine candidate using Vical's DNA plasmid backbone and adjuvant.

The Vaxfectin(R)-formulated DNA vaccine candidate has the potential to prevent malaria transmission. Initial testing showed that the malaria parasite life cycle was halted in mosquitoes fed with malaria-infected human red blood cells that were incubated with serum from mice who were vaccinated.

The malaria parasite goes through multiple life cycle stages in humans and additional life cycle stages in mosquitoes. The vaccine candidate, which was formulated with Vical's Vaxfectin(R) adjuvant, expresses a malaria parasite protein present in Plasmodium vivax called Pvs230. The protein is present in both mosquito and human stages of the parasite's life cycle. The anti-Pvs230 antibodies generated by the vaccinated mice recognized the protein and put a halt to the parasite's development in mosquitoes.

Since the Pvs230 protein's amino acid sequence is highly conserved among multiple P. vivax field isolates, a single vaccine could potentially provide broad protection. The mouse-generated antibodies to Pvs230 statistically reduced the infection rate and number of parasites in mosquitoes. The novel approach of blocking transmissions may protect the population at large from widespread malaria outbreaks.

The authors proposed further study of the vaccine candidate.