Novavax, Inc. has announced positive preclinical results with Novavax's 2009 novel H1N1 influenza virus-like particle (VLP) vaccine. The study, conducted by scientists from Novavax and the Centers for Disease Control and Prevention (CDC) based in Atlanta, GA, under a collaborative agreement, represents the first efficacy report of a 2009 novel H1N1 vaccine in ferrets. The ferret model is widely accepted to be the most appropriate animal model for evaluating influenza disease and vaccines. Novavax scientists designed the vaccine using recombinant virus like particles (VLP) technology against an H1N1 virus strain (A/California/04/2009) isolated in the beginning of the 2009 H1N1 outbreak.
Novavax produced the candidate vaccine and delivered it to the CDC in less than four (4) weeks from the day the genetic sequences of the virus strain became available. The speed at which this was accomplished is a testament to the fast response afforded by Novavax's proprietary, recombinant cell-based VLP technology which is not dependent on growing influenza virus in eggs and the development of virus seed stocks.
The Novavax VLP vaccine candidate protected ferrets against the 2009 novel H1N1 virus. The ferrets received a 3.75, 7.5, or 15.0 mcg dose of the 2009 H1N1 VLP vaccine or a placebo and were boosted with a second dose after three (3) weeks. All of the H1N1 VLP vaccinated animals, even in the lowest 3.75 mcg dose group, developed hemagglutination inhibition (HI) antibody titers of 1:40 or higher, considered a protective level of immunity, against the H1N1 virus. Remarkably, even after receiving a single dose of 7.5 or 15 mcg 2009 H1N1 VLPs, the animals developed an HI titer of 1:40 or higher against the H1N1 virus.
Vaccinated animals were challenged with nasal exposure of live H1N1 A/Mexico/4482/2009 (MX/4482) influenza virus strain that was distinct from the H1N1 A/California/04/2009 strain against which the vaccine was derived. The MX/4482 challenge strain was isolated in Mexico from a female patient with severe respiratory disease and was described in a study published on July 24, 2009 in the journal Science by the CDC and Harvard-MIT Division of Health Science and Technology. In that study, this virus strain was demonstrated to replicate efficiently in the respiratory tract and cause significant disease in ferrets. After three (3) days post challenge, animals immunized with the 15 mcg dose of the H1N1 VLP vaccine had no detectable virus recovered in nasal washes and showed no signs of disease. By day five (5) after challenge, immunized ferrets at all vaccine dose levels had cleared the H1N1 virus and showed no sign of disease. In contrast, control animals that received no vaccine displayed lethargy, elevated body temperatures and shed infectious virus for up to six (6) days post infection.
"Demonstrating that our influenza VLP vaccine candidate protects against the pandemic H1N1 virus in an animal model is another important milestone for us to have met," said Dr. Gale Smith, Vice President of Vaccine Development. "An even broader significance of this study is that these data, for the first time, indicate that a vaccine against H1N1 A/California/04/2009 influenza strain has the potential to protect against the 2009 pandemic H1N1 virus."