Vical Incorporated announced that the company's DNA vaccine against A/H1N1 pandemic influenza (swine flu) has demonstrated robust immune responses in 100 per cent of vaccinated animals against virus strains isolated from recent outbreaks in three distinct geographic locations -- California, Texas and Mexico.

Vical's plasmid DNA vaccine contains the H1 hemagglutinin gene sequence provided by the US Centers for Disease Control and Prevention (CDC) for the swine-origin A/California/04/09 pandemic influenza virus, and after two doses produced immune responses well above the accepted protection threshold in 100 per cent of vaccinated mice and rabbits using HI assays against the swine-origin A/California/07/09 x-179a, A/Texas/15/09 and A/Mexico/4108/09 influenza viruses. Hemagglutination inhibition (HI) titers were well above the protection threshold of 40, ranging from 320 to 2,560 in mice, and from 640 to 2,560 in rabbits against the California strain. Results against the Texas and Mexico strains were essentially equivalent, ranging from 640 to 2,560 in both mice and rabbits. Vical's vaccine would also be expected to provide similar robust immune responses against other swine-origin A/H1N1 influenza virus subtypes, supporting selection of a single A/H1N1 virus strain as the basis for the vaccine.

"Cross-reactivity is consistent with previous CDC reports that circulating strains of swine-origin A/H1N1 pandemic influenza have remained antigenically homogeneous," said Vijay B Samant, president and chief executive officer of Vical, "but future viral changes are unpredictable and could be far more substantial. The inherent speed of our DNA vaccine platform both in initial development and manufacturing could be extremely important in addressing the potential shortfalls of conventional vaccine approaches."

Vical has entered into a Cooperative Research and Development Agreement (CRADA) with the US Naval Medical Research Center (NMRC), a biomedical research organization within the U.S. Navy, to develop a vaccine against H1N1 influenza.

"We are working with the US Navy to secure funding to advance our H1 vaccine into human clinical testing," added Samant. "Based on the sustained threat from the ongoing H1N1 pandemic, we have initiated critical-path manufacturing activities to allow initiation of a phase 1 trial in as little as four to six weeks after funding is secured."

Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases.