Inovio Pharmaceuticals, Inc. recently announced that in a preclinical study of its influenza DNA vaccine against the newly emergent, virulent H7N9 flu virus it achieved immune response levels exceeding what are considered protective levels in other common influenza subtypes.
Interim results from a study in mice in a collaboration with researchers from the University of Pennsylvania and Canada’s National Microbiology Laboratory in Winnipeg demonstrated that Inovio’s H7N9 influenza DNA vaccine achieved greater than 1:40 hemagglutination inhibition (HAI) in 100% of tested animals (n=10), with a geometric mean HAI titer of 1:130 against the A/Anhui/1/13 strain of H7N9 virus. HAI titers at or above 1:40 are considered to denote protection against the influenza virus in humans. These mice received just two vaccinations three weeks apart and the samples tested were from week 5.
Since the first-ever infection of a human with this new influenza subtype in early 2013, the very rapid spread of H7N9 reached a total of 131 confirmed human infections in Asia, with 39 deaths. Experts remain fearful of the possibility of the virus mutating into a form easily transmissible between humans, with the potential to trigger a pandemic.
Laboratory tests showed that in some patients the H7N9 virus was resistant to treatment drugs, researchers in China wrote in the medical journal The Lancet last month, adding that their findings were “concerning.”
Dr. J. Joseph Kim, Inovio’s President and CEO said, “These results show the advantages of Inovio’s DNA vaccines versus traditional approaches in two significant ways: how our DNA vaccines can mount a robust defense against emerging potent viral threats with pandemic potential; and, how rapidly we can create a DNA vaccine construct to address a new global threat.”
In the preclinical study Inovio researchers constructed a consensus DNA vaccine targeting the HA influenza antigen from sequences collected from several infected H7N9 patients to be broadly protective against all H7N9 viruses. The vaccine was designed, optimized, and manufactured within two weeks, and mice were immunized intramuscularly with two doses followed by electroporation three weeks apart. In an interim analysis, researchers tested sera from the animals against an unmatched H7N9 influenza strain, A/Anhui/1/13. The researchers observed levels of HAI titers, or functional antibodies, that predict protection against the H7N9 virus as well as robust levels of binding antibodies which can block virus entry into host cells as well as inhibit other viral functions.
Generating these very strong immune responses against an unmatched influenza strain adds further to the growing data set indicating the universal protective capability that Inovio’s SynCon DNA vaccines are able to achieve within targeted subtypes. While this study demonstrates that Inovio can respond to an urgent need to address a new subtype of influenza, it also provides further validation of its approach to address the more important need of providing truly preemptive and broad long-term protection against the constant strain mutations that occur within influenza subtypes. The ideal outcome would be to achieve a universal influenza vaccine capable of broad protection against existing and newly emergent unmatched strains across subtypes known to threaten humans.
Source: Inovio Pharmaceuticals Inc.