Australian immunologists believe they've made a key discovery about the human body's immune response to bird flu that could significantly reduce the death toll of the next pandemic.
Researchers at Melbourne's Peter Doherty Institute for Infection and Immunity, working with the Shanghai Public Health Clinical Centre, Fudan University analysed blood samples taken from a group of 11 patients infected with the A/H7N9 virus.
Eight of the patients recovered, while three had died as a result of the infection.
Survival was found to be strongly correlated with a specific type of immune cell circulating in the patient's blood - known as CD8 T cells.
Published in journal Nature Communications, the researchers detected an early temporary presence of these CD8 T cells was found in those who survived, while a "prolonged" presence of these highly active cells was consistently observed in the patients that died.
Co-lead author, University of Melbourne Professor Katherine Kedzierska says by monitoring white blood cells for these biomarkers they may be able to predict "life or death outcomes" for severe infections.
"The study provides a novel and fundamental contribution to our understanding of mechanisms underlying dysfunctional immunity in flu, and it may be generalisable to other severe viral infections," said Professor Kedzierska.
Avian influenza, also called bird flu, is a severe illness spread from birds to humans through close contact and has a 40 per cent mortality rate.
The official name for the most commonly seen and most deadly form of the virus is called Influenza A (H5N1), or the "H5N1 virus."
A strain of bird flu previously not seen in humans - H7N9 - was detected in China in 2013.
Just since October 2013, its "fifth wave" has been responsible for 713 known human cases, including 205 deaths globally, according to the Doherty Institute.
"Overall, this work points to the possibility of limiting the severity of emerging, and perhaps very severe and widespread disease or pandemic," said study co-author, Dr Zhongfang Wang.
The next step for the researchers is to identify precisely how the ebb and flow of these specific immune cells mediate recovery in some individuals and not others.
