A team of investigators from St. Jude Children’s Research Hospital, Stanford University Medical Center, and MacroGenics has developed an antibody that proved to be 100% protective against the H5N1 influenza virus in two species of animal models.

According to a news release from the American Society for Microbiology (ASM), the H5N1 influenza virus, also known as the bird flu, has caused the deaths of millions of ducks and chickens and has infected more than 650 people. The virus has yet to achieve human-to-human transmission, but a small number of mutations could change that.

Antivirals have been possible sources of protection but are hampered by the tendency of the viruses to rapidly mutate, often resulting in resistance, as indicated on the ASM news release. In addition, Richard Webby, PhD, corresponding author of the study, explains that vaccines must be developed to match each flu virus, which may take at least 6 months following the emergence of a pandemic. As such, the investigators turned to antibodies that target antigens on viruses and therefore disables them. However, mutations can render antibodies ineffective.

Webby states, “Our solution was to make a ‘dual-specific’ antibody by combining two different antibodies that attach strongly to H5N1 viruses into a single antibody-like molecule.” Webby explains that this should make it harder for resistance to emerge.

The new compound developed is called FcDART, and a single low dose of the compound provided complete protection against lethal H5N1 viruses in laboratory models of influenza. Webby says, “This dose could be given one day before infection—for example, to protect healthcare providers—or up to three days after.”

First author of the study Mark Zanin explains, “Laboratory models are rough approximations of what might happen in humans. We did see complete protection against H5N1 in ferrets, which have long been used as a model for human flu, so we are confident in our results.”

Source: ASM Society