Respiratory Tract Immunization May Protect Against Ebola Virus

Ebola virus is a highly contagious form of severe hemorrhagic fever with a mortality rate of up to 88% in humans. Because it can be transmitted by contact and aerosol route, it is also considered to be high risk for use as a biological weapon. With the respiratory route as the common portal of pathogen entry, intranasal vaccines may prove vital in preventative therapies.

In the study researchers developed a vaccine incorporating the human parainfluenza virus type 3 (HPIV3), a common pediatric respiratory pathogen, and administered it by respiratory route to rhesus monkeys. Some monkeys were immunized once and others twice, then all were challenged with a highly lethal dose of the Ebola virus. Results showed that a single immunization protected 88% of the animals against severe hemorrhagic fever and death, while all those receiving two doses not only survived but were symptom free and no detectable Ebola virus was found in the bloodstream.

"These data illustrate the feasibility of immunization via the respiratory tract against the hemorrhagic fever caused by Ebola virus," say the researchers. "To our knowledge, this is the first study in which topical immunization through respiratory tract achieved prevention of a viral hemorrhagic fever infection in a primate model."

Researchers from the National Institutes of Health, Bethesda, MD and the Centers for Disease Control, Atlanta, GA report their findings in the June 2007 issue of the Journal of Virology. (A. Bukreyev, P.E. Rollin, M.K. Tate, L. Yang, S.R. Zaki, W.J. Shieh, B.R. Murphy, P.L. Collins, A. Sanchez. 2007. Successful topical respiratory tract immunization of primates against Ebola virus. Journal of Virology, 81. 12: 6379-6388).