Currently there are no vaccines or antiviral drugs to protect against or treat HPS. The disease affects previously healthy individuals in all age groups, disease progression is rapid, and the case fatality rate is one of the highest for any acute viral disease known. In addition, there have been reports of person-to-person transmission of Andes virus in southern Argentina and Chile.
Having successfully vaccinated rhesus macaques with a hantavirus vaccine candidate, the USAMRIID scientists next asked whether the neutralizing antibody response elicited by the vaccine could protect hamsters from lethal hantavirus infection. The team had already developed a lethal-disease model of Andes virus in Syrian hamsters. To further explore this question, they tested serum from a monkey that had received the Andes vaccine for protective efficacy when administered to hamsters following challenge with the virus.
In these post-challenge experiments, 15 of 16 animals that received the antibody on day 3, 4, or 5 after challenge survived. The level of protection dropped significantly when the antibody was administered on day 6 or later. While all but one of the post-challenge survivors were infected with Andes virus, no deaths were observed.
"Aside from the immunogenicity of the vaccine in nonhuman primates, the most exciting thing about this was the indication that post-exposure prophylaxis might work--even five days out from exposure," Hooper commented. "When we administered antibody after challenge, we got nearly complete protection."
While the immediate need is for a vaccine against HFRS, the USAMRIID team believes the DNA vaccine approach could one day be used to develop a multivalent vaccine for hantaviruses that would be broadly protective against HPS and other forms of the disease.
"This work is an example of the many medical products that USAMRIID offers the Nation
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Contact: Caree Vander Linden
Caree.Vander-Linden@amedd.army.mil
301-619-2285
US Army Medical Research Institute of Infectious Diseases
23-Oct-2003