An antibody that can bind to many different types of influenza virus prevented macaques from getting seriously sick, and dying, from a highly pathogenic strain of H5N1 bird flu.
The findings could help in the development of a universal flu vaccine, the authors wrote in their Jan. 30 Science paper sharing the results.
“This antibody is targeting a region that does not vary across different influenza viruses,” lead researcher Simon Barratt-Boyes, Ph.D., a microbiologist at the University of Pittsburgh, said in a Jan. 30 release. “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.”
All nine macaques given the control developed severe disease when exposed to bird flu, as did all given the smallest dose of protective antibody. When macaques were given 10 milligrams or 30 milligrams of the antibody per kilogram of body weight, however, none of them developed severe disease.
University of Pittsburgh scientists teamed up with researchers from the National Institutes of Health’s Vaccine Research Center and AstraZeneca, among others, to perform the study.
The antibody, MEDI8852, had previously been shown to bind to all subtypes of the influenza A virus, which includes bird flu as well as seasonal flu. In that earlier study, the molecule also improved survival in mice infected with three strains of seasonal flu and ferrets infected with bird flu.
In the new study, researchers took a dose de-escalation strategy in order to find the smallest concentration of antibody necessary to protect the primates.
Protective levels of MEDI8852 lingered in the blood for about eight weeks after a single 30-mg/kg injection, the authors wrote in the paper, “providing a realistic preventative window in the face of an H5N1 outbreak.”
If such an outbreak did occur, the antibody could be used to protect medical professionals and first responders tending to patients, the researchers suggested in the release.
“In our testing, the antibody performed beautifully," study author Douglas Reed, Ph.D., an immunologist at Pitt’s School of Medicine and the Center for Vaccine Research, said in the release. "The antibody could be useful as a prophylactic of severe disease in vulnerable populations, and it also helped us establish the testing threshold for antibody levels in blood, which would be useful for judging the immune protection generated by a universal flu vaccine.”