‘Bird flu’ refers to a subtype of Influenza A virus, H5N1 which is a highly pathogenic strain affecting millions of chickens and ducks and preventive measures include large-scale culling of these birds. This virus is yet to achieve human-to-human transmission, but there have been reports of atleast 650 people being infected with H5N1 since 2003, with a 60% mortality rate amongst humans.
A team of scientists from St. Jude Children’s Research Hospital, Stanford University Medical Center and MacoGenics have developed an antibody which gives 100% protection against the virus when tested in two species of animal models. Their work was published in the Journal of Virology.
The H5N1 virus has a high tendency to undergo mutations and hence antivirals have been largely unsuccessful in curbing its spread. Vaccines take atleast six months to develop following a pandemic, and even if its produced, it is not very effective in elderly and immunocompromised individuals.
Hence the investigators designed an antibody, which when bound to the antigens on the viruses as specifically as a key binds to the lock, disables them. However, mutations could render an antibody ineffective too.
“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,” said Richard Webby, a Member in the Infectious Diseases Department at St. Jude Children’s Research Hospital, Memphis, TN, and Director of the World Health Organization (WHO) Collaborating Center for Studies on the Ecology of Influenza Viruses in Lower Animals and Birds.
This new compound called FcDART, for Fc(the type of fusion protein) Dual-Affinity ReTargeting molecule, makes it much harder for resistance to emerge. “This dose could be given one day before infection—for example, to protect healthcare providers—or up to three days after,” said Webby.
“Laboratory models are rough approximations of what might happen in humans,” said first author Mark Zanin, a post-doctoral fellow in Webby’s lab at St. Jude. “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.”
The original publication can be accessed here.