A nasal vaccine developed by researchers at Duke University provided protective immunity against West Nile virus in mice after two doses, according to new research presented recently at the American Society for Microbiology Biodefense and Emerging Diseases Research Meeting in Washington, D.C.
The mosquito-borne virus, which causes inflammation of the brain and meningitis, first appeared in the U.S. in 1999 and has since caused a reported 2,374 cases of infection in people, including 114 deaths in 2013 alone, according to the Centers for Disease Control and Prevention. An injectable vaccine based on killed virus is available for horses, but no human vaccine is on the market.
"A nasally administered, needle-free vaccine able to rapidly induce protective immunity with minimal vaccine doses per subject would be beneficial for use during WNV outbreaks," said Herman Staats, a professor of pathology at Duke and a researcher on the study, in a statement released by the American Society for Microbiology.
Staats and his colleagues tried two experimental vaccines, including a three-dose vaccine formulation in which 15 micrograms of the West Nile virus antigen was combined with the peptide and bacterial DNA adjuvants and administered to mice in three doses over a period of three weeks. Researchers also tested a two-dose vaccine of both 45 and 60 micrograms of antigen administered in two doses over two weeks.
Most vaccines that use purified protein antigens such as the hepatitis B virus vaccine or the human papillomavirus vaccine require a total of three immunizations to induce protective immunity.
When mice were infected with West Nile virus at day 60, the two-dose vaccine containing 60 micrograms of antigen combined with adjuvants protected all the infected mice from death. Meanwhile, the two-dose vaccine regimen using 45 micrograms of antigen combined with adjuvant and the three-dose vaccine regimen of 15 micrograms of antigen combined with adjuvants only protected some mice from death or weight loss.
The researchers plan to continue testing their intranasal vaccine in rabbits, whose nasal cavity is close in size to the human nasal cavity.
- here's the press release