Bolstering “Natural Killer” Cells against Flu

“A few years ago, Prof. Ofer Mandelboim, discovered that NK cells are important in fighting flu infection,” Bar-On tells ISRAEL21c. “However, when we infected mice with influenza virus, we found that the virus can manipulate the NK cells and evade getting killed. The NK function is not 100% because the influenza fights back.”

Bar-On and Mandelboim were able to identify the weapon that the virus uses to battle the body’s natural killers: It’s a protein called neuraminidase, and it effectively neutralizes receptors on the NK cells that are responsible for detecting influenza-virus-infected cells. The flu virus uses neuraminidase to cut the function of NK cells to about 50% of their normal effectiveness. “When we inhibited the neuraminidase we noticed the NK worked better, and the mice actually recovered from the flu,” says Bar-On. 

Emergence of new influenza strains lead to severe pandemics across the world. Recently, a deadly avian influenza strain (H7N9) in China caused the death of six people in one month. Medical experts are frustrated that many flu strains have become resistant to existing antiviral drugs. Bar-On and Mandelboim’s discovery sets the tone for developing new treatments to help the immune system’s natural killer cells do their job better.

“Existing drugs work to inhibit a different protein in the flu virus to inhibit the spread of the virus, but their disadvantage is that the virus can mutate and evade the effects of the drug,” Bar-On explains. The Israelis’ idea is to inhibit neuraminidase in order to allow the NK cells to function at full strength. “It will be much harder for the virus to evade this new kind of treatment,” says Bar-On.