Experimental vaccine elicits strong antibody response in primates.

2003 NOV 12 - (NewsRx.com & NewsRx.net) -- For the first time, scientists have demonstrated that an experimental vaccine for hantavirus pulmonary syndrome (HPS), a highly lethal disease, elicits a strong neutralizing antibody response in laboratory animals - a response that is key to preventing the virus from causing infection.

In addition, the antibodies, produced in nonhuman primates that received the vaccine, protected hamsters from disease even when administered 5 days after exposure.

These findings provide proof of concept in nonhuman primates for a vaccine against HPS, as well as for postexposure prophylactic treatment of HPS and a related disease known as hemorrhagic fever with renal syndrome (HFRS).

In an article published in the Journal of Virology, investigators at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) described using a naked DNA approach to develop a hantavirus vaccine. The technique involves vaccination with plasmid DNA that encodes a specific hantavirus gene. When the plasmid DNA is introduced into the cells of a vaccine recipient, using a harmless device called a "gene gun," the cloned gene is expressed and presented to the immune system.

According to senior author Jay W. Hooper, PhD, the USAMRIID team constructed an expression plasmid containing the full-length M genome segment of Andes virus, a South American hantavirus. Vaccination with the plasmid elicited a potent neutralizing antibody response in rhesus macaques that were vaccinated a total of four times at 3-week intervals.

To look at the duration of that response, the team collected serum samples for about 6 months. The monkeys who received the Andes vaccine displayed robust antibody levels as long as 25 weeks after the last vaccination.

Hantaviruses are carried by rodents and have caused epidemics in Europe, Asia, and the Americas. Some cause HPS, while others are responsible for the more common HFRS. The viruses are pathogens of known military importance in endemic areas.