Imma Perfetto
Cosmos science journalist
As the highly pathogenic avian influenza H5N1 virus continues to devastate populations of birds and mammals around the world, new research on antibody immune therapy is helping to bridge the gap from animal studies to humans.
Researchers have now discovered that one antibody known to be broadly protective against influenza A viruses in mice and ferrets also protects cynomolgus macaques, which are a much closer match to human physiology, against severe disease caused by H5N1.
“In our testing, the antibody performed beautifully,” says Douglas Reed, an associate professor of immunology at the University of Pittsburgh in the US.
“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.”
MEDI8852 is a “broadly neutralising antibody” which recognises a relatively stable region of the avian influenza virus.
“This antibody is targeting a region that does not vary across different influenza viruses,” says Simon Barratt-Boyes, professor of infectious diseases and microbiology at the University of Pittsburgh.
“[It] is therefore less prone to losing its efficacy than those targeting more mutation-prone structures.
This type of prevention, according to Reed, can be very useful in controlling infection outbreaks and containing a pandemic.
While the H5N1 strain has been jumping to humans in close contact with infected animals, so far, no instances of human-to-human transmission have been reported. However, recent genetic analysis of human samples suggested that the virus is adapting and getting better at causing disease and spreading in mammals.
In the new study, monkeys pre-treated with a moderate dose of a broadly neutralizing MEDI8852 antibody were universally protected against severe disease and death. Antibody levels in the blood also remained at levels sufficient for protection for 8-12 weeks.
This suggests that, if found to be similarly protective in humans, it could protect people caring for patients at the beginning of a human outbreak or pandemic scenario.
However, the researchers point out the difficulty of studying the protective efficacy of antibody treatments against influenza in humans and that “…a derivative of MEDI8852 has recently failed to meet its efficacy endpoint in a phase 2 clinical trial as a prophylaxis.”
“Our macaque model reflects and recapitulates many aspects of human H5N1 influenza virus infection, although there are inevitable differences in our model compared with human cases, including the varying inhaled virus dose, preexisting influenza immunity, supportive treatment, and use of antivirals,” they write.
“These factors may contribute to the disease outcome and could be addressed in future studies.”
The research is published in the journal Science.
