Inovio says H7N9 bird flu vaccine effective in mice

Another vaccine has shown promise in preclinical studies against the virulent H7N9 avian influenza strain, which has so far infected more than 130 people and caused 39 deaths.

The deadly flu strain, which originated in China early this year, has world health experts and scientists on edge because of its potential to mutate into a strain that's fully transmissible among humans and possibly cause a pandemic.

Blue Bell, PA-based Inovio Pharmaceuticals ($INO) Friday revealed positive preclinical data on the company's H7N9 vaccine candidate. In a mouse study conducted in a collaboration with researchers from the University of Pennsylvania and Canada's National Microbiology Laboratory in Winnipeg, the vaccine achieved immune response levels exceeding what are considered protective levels in other common influenza subtypes.

Humans who've caught the virus have reported a history of exposure to animals, especially chickens, according to the World Health Organization, and while studies have shown that the disease can pass between ferrets under certain conditions, scientists are still unsure whether it can be passed among people.

Laboratory tests showed that in some patients the H7N9 virus was resistant to treatment drugs, according to a recent study in The Lancet, and scientists have predicted low immunogenicity for H7N9 vaccines--that is, new vaccines are likely to be limited in their ability to provoke an immune response in humans.

Using sequences collected from several infected H7N9 patients, Inovio researchers constructed a DNA vaccine to target the HA influenza antigen. The mice were given the vaccine intramuscularly with two doses followed by electroporation three weeks apart. The researchers observed levels of HAI titers, or functional antibodies, to guard against H7N9 as well as high levels of binding antibodies, which can block viruses from invading host cells plus inhibit other viral functions.

Inovio is not the only vaccinemaker in the H7N9 race. Earlier in June, Canada's Medicago also revealed positive preclinical results for its H7N9 vaccine.

- here's the press release