PITTSBURGH, June 22 - Two new approaches could form the basis for the first-ever human vaccine for Rift Valley Fever (RVF), an infectious disease that threatens both farm animals and people, say researchers at the University of Pittsburgh Center for Vaccine Research. Reported in this week's PLoS Neglected Tropical Diseases, experimental vaccines developed with these approaches produced strong immune responses in mice and may be safer than the only available RVF vaccine, which is limited to animal use.
Although RVF mainly affects farm animals, the virus has spread to human populations causing serious illness and death in several regions in Africa and the Middle East. Additionally, it has been classified as a select agent by the U.S. federal government because of its potential use in biowarfare, prompting vaccine development research.
"RVF is a veterinary and public health threat that continues to spread," said Ted M. Ross, Ph.D., lead author of the study and associate professor, University of Pittsburgh Center for Vaccine Research. "At the same time, vaccine development has been challenging because of adverse side effects from live virus vaccines and uncertainty about whether the virus could revert to a more dangerous form during vaccine manufacturing."
Unlike other potential vaccines for RVF, which are derived from live viruses, the vaccines tested by Pitt and University of North Carolina researchers were developed using two approaches―DNA and alphavirus replicon-based―that use only a modified portion of an inactivated virus. Mice immunized with either strategy were protected from disease and death when directly exposed to the pathogenic virus. When the strategies were combined, researchers noted both increased concentrations of antibodies that neutralize infectious agents and heightened cell-based immune responses.
"These vaccine strategies may be advantageous to controlling RVF because they provide a safer alternative and appear to work as well as live virus vaccines," said Dr. Ross.
The study was funded by the National Institutes of Health. Co-authors include Nitin Bhardwaj, D.V.M., M.S., University of Pittsburgh, and Mark T. Heise, Ph.D., University of North Carolina.
The Center for Vaccine Research (CVR) at the University of Pittsburgh houses both the Regional Biocontainment Laboratory and the Vaccine Research Laboratory. Researchers at the CVR, directed by Donald S. Burke, M.D., dean of the University of Pittsburgh Graduate School of Public Health and UPMC Jonas Salk Professor of Global Health, develop new methods and strategies to prevent and treat infectious diseases, potentially improving and protecting global health.