Dengue virus DNA vaccine protects macaques only in the short term.

2003 JUN 18 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Short-term protection against the dengue-2 virus in rhesus macaques was conferred by a DNA vaccine containing a plasmid DNA vector with pre-membrane (prM) and envelope (E) genes expressed by a cytomegalovirus promoter.

"The DNA was adsorbed onto gold microspheres for administration by a gene gun," reported Robert Putnak and colleagues at Walter Reed Army Institute of Research, the United States Army Medical Research Institute of Infectious Diseases, and Powderject Vaccines, Inc. "Expression was demonstrated by transfection of mouse cells in culture where the prM and E antigens were detected intracellularly, and the E antigen was detected in the culture supernatant fluid, similar to a natural infection.

"The vaccine elicited neutralizing antibodies to dengue-2 virus and antigen-specific cytotoxic T lymphocyte responses in mice. Several vaccination regimens were evaluated in rhesus macaques for the ability to elicit neutralizing antibodies and protect against viremia after challenge with live dengue-2 virus."

Neutralizing antibodies were produced in 100% (3/3) of the macaques that received four 2-microgram doses, 33% (2/6) that received two 1-microgram doses, and 0% (0/3) that received one 1-microgram dose.

"When dengue virus challenge was performed one month after vaccination, the three animals that received four 2-microgram doses exhibited 0, 0, and 1 day of viremia compared with unimmunized controls which exhibited 4, 4, and 6 days of viremia," said Putnak and his collaborators.

The three animal vaccinated with two 1-microgram doses experienced 0, 0, and 1 day of viremia when challenged one month after vaccination compared to 0, 3, and 5 days for animals that received one ...