Pittsburgh researchers have announced breakthrough findings that could lead to a bird flu vaccine just days after Pennsylvania confirmed a new positive case of Highly Pathogenic Avian Influenza (HPAI) at a poultry farm in Lehigh County.
Researchers at the University of Pittsburgh were able to successfully shield macaque monkeys from severe bird flu infections with a monoclonal antibody treatment, according to findings published in "Science" last week.
“In our testing, the antibody performed beautifully,” said Douglas Reed, a professor of immunology and researcher at Pitt’s Center for Vaccine Research. “This type of prevention can be very useful in controlling infection outbreaks and containing the bird flu pandemic.”
Pennsylvania has so far not reported any human cases of bird flu. But in the last year, there have been 66 confirmed human cases of the current H5N1 strain, including one fatal case in an elderly Louisiana patient.
Notably, those cases have been spread from animals; there has not been any human-to-human transmission of the virus. And federal health officials have said the risk of the virus to the general public remains low. But some people — specifically farmers, animal care workers or those who consume raw or unpasteurized milk and eggs — are at higher risk of exposure.
But the virus has proven to be deadly in the past: of the more than 950 human cases of H5N1 reported globally since 1997, half of them were fatal, according to the World Health Organization.
Reed said the macaque monkey model provides something of a testing ground for human vaccine development, since both experience similar symptoms, including life-threatening acute respiratory distress syndrome. Researchers used an aerosol chamber where the monkeys inhaled infectious particles.
“What this shows is that in an outbreak scenario, [where] the virus did start spreading rapidly, that we could potentially inoculate first responders, patients [and their] contacts and protect them against infection,” he said.
Researchers not only found that the antibody protected the monkeys from severe disease and death, but they also pinpointed the amount of serum needed to provide protection. That means MEDI8852 antibody could be used in the development of a bird flu vaccine for agriculture workers and other vulnerable populations.
“This antibody wouldn't just simply keep you from dying. It would keep you from getting sick at high enough doses,” he said. “And now we have a good idea of what that dose is.”
And the antibody would likely remain effective against the virus even as it mutates: MEDI8852 attaches to a stable region of the virus rather than its more mutation-prone structures. That stable region of the viral structure is shared among different types of influenza, which suggests the antibody could be used to develop a universal influenza vaccine.
Reed’s co-author, Pitt professor of infectious diseases and microbiology Simon Barratt-Boyes, compared the viral structure to a tree: most antibodies attack the leaves, while the MEDI8852 attacks the trunk.
“Different [tree] species have different leaves and crowns, but tree trunks look very much the same,” Barratt-Boyes said. “Similarly, the stalk region of the bird flu virus closely resembles the same structure of seasonal influenza, which makes it possible for stalk-targeting antibodies to provide universal protection.”
Current flu vaccines are developed each year by analyzing data about dominant strains from the previous flu season. A universal flu shot could offer more protection against illness than current vaccines and may not need to be given as often, researchers hope.
The research sets the stage for vaccines or other countermeasures against future influenza virus pandemics. The antibody is owned by global biopharmaceutical giant AstraZeneca, which did not respond to WESA’s request for comment.
Now that their initial study is completed, Reed and Barratt-Boyes plan to next test MEDI8852 against newer strains of H5N1 more closely related to the virus currently circulating in wild bird populations as well as poultry and cattle farms. The duo also plans to test other monoclonal antibodies to determine their efficacy against the virus and what protection they could offer either alone or in combination with MEDI8852.
