Vical's Vaxfectin Adjuvant Enhanced Vaccine Antibody Response

Vical has announced that a seasonal influenza vaccine formulated with its Vaxfectin adjuvant generated up to 60-fold higher antibody responses than an unformulated vaccine at the same dose in a recently completed study in mice.

Formulation of sanofi pasteur's Fluzone commercial vaccine with Vaxfectin also allowed a nearly 10-fold reduction in vaccine dose while generating equivalent or better antibody responses compared with unformulated vaccine, even at the lowest doses tested, Vical said.

Vical is developing its own Vaxfectin-formulated DNA vaccine designed to protect against emerging strains of influenza that have the potential to cause a pandemic. The company previously reported study results showing that its lead Vaxfectin-formulated, DNA vaccine candidate provided 100 percent protection in mice and ferrets against lethal challenges with a highly pathogenic strain of H5N1 influenza virus. Initial human testing of Vical's influenza DNA vaccine is expected to begin in the second half of 2007.

Vical said it tested the Vaxfectin adjuvant with Fluzone seasonal influenza vaccine to evaluate its potential to ease a possible shortage of stockpiled pandemic influenza vaccine and the limited global vaccine manufacturing capacity.

The new Fluzone study data confirm and expand on an earlier study in mice, presented last year, which suggested the potential for Vaxfectin to be used as a dose-sparing agent with conventional influenza vaccines. Both studies used the Fluzone 2005-2006 inactivated seasonal influenza vaccine. Mice were vaccinated with 1, 3 or 9 micrograms of Fluzone alone or Fluzone formulated with one of two dose levels of Vaxfectin. Immune responses were evaluated by measuring hemagglutination inhibition antibody titers, the accepted standard correlate of protection for conventional influenza vaccines, against a single influenza strain included in the trivalent inactivated vaccine, as well as total antibody titers against all three of the strains included in the vaccine.