A new study on human immune cells gives scientists new hope to develop a universal flu vaccine that can kill all strains of the influenza virus.

Flu virus is one of the most complex viruses that plague both humans and animals. Health complications can become serious like extreme fatigue, diarrhea, dehydration, and death.

Smart Flu

Typically, the immune system should be able to fight off the virus by making a memory of the strain; hence, stopping the infection. However, there are each of the three influenza strains - A, B, and C - mutate each season, making it more difficult for the white blood cells to detect danger ahead of time.

Previous studies have shown that the so-called killer cells or CD8+T cells can only execute repeated attacks against the influenza strain A.

Katherine Kedzierska, a professor at the University of Melbourne and the lead author of the study conducted at Peter Doherty Institute for Infection and Immunity, followed through her initial research on 2013 influenza H7N9 outbreak in China.

She concluded that who survived the avian flu virus have robust killer cell responses compared to those who died from the illness.

"After spending the past 40 years working on the virus-specific 'killer' T cells, this is the first study from our group that shows their role in protecting people against a new human influenza virus," said Nobel Laureate Professor Peter Doherty from the University of Melbourne.

The Making Of Universal Flu Shot

The challenge now is to analyze a total of 67,000 viral epitopes of strains A, B, and C and identify which ones are common amongst them.

"Our first experiments were like finding a needle in a haystack," said Maria Koutsakos, a PhD candidate at the Doherty Institute.

Samples of the flu epitopes were extracted through blood from healthy individuals and flu-stricken adults and children. Researchers then performed vaccination on mice containing the peptides responsible for activating the killer cells.

Kedzierska's team proved that killer T cells have "unprecedented immunity" across all strains of influenza, which is a major criterion in the development of a universal vaccine.

The study was published Feb. 18 in the journal Nature Immunology.