Pseudotyped viral protein particles provide improved efficacy.(Brief Article)

2002 AUG 7 - (NewsRx.com & NewsRx.net) -- by Michael Greer, senior medical writer - HIV protein particles can trigger extensive HIV-specific immune responses when wrapped in the shell of a different virus, researchers in France report.

"In vivo priming of cytotoxic T lymphocytes (CTL) by DNA injection predominantly occurs by antigen transfer from DNA-transfected cells to antigen-presenting cells," explained Delphine Marsac and colleagues working at the Pasteur Institute in Paris. "A rational strategy for increasing DNA vaccine potency would be to use a delivery system that facilitates antigen uptake by antigen-presenting cells."

A DNA vaccine coding for pseudotyped HIV Gag induced a higher degree of virus-specific activity than vectors coding for naked protein, due to the fact that virus-cell interactions enhance cellular antigen uptake, Marsac and coauthors said.

The researchers evaluated the efficacy of DNA plasmids coding for HIV Gag particles pseudotyped with vesicular stomatitis virus glycoprotein (VSV-G). Gag-specific cytotoxic T lymphocyte (CTL) responses in mice inoculated with this vaccine candidate were compared with those seen after immunization with DNA coding for nonpseudotyped Gag particles, according to the report.

Cytotoxic responses directed against viral Gag were both more frequent and more powerful in mice exposed to pseudotyped Gag particles, study data showed. Cultured antigen-presenting cells taken from these mice were able to present pseudotyped Gag epitopes much more efficiently than antigens from the uncoated form of the protein.

Moreover, ...