Gut bacteria may be able to help hosts fend off viral infections, according to a paper appearing in Science from Georgia State University's Andrew Gewirtz and colleagues.
In mice, Gewirtz and his colleagues found that treatment with bacterial flagella could prevent rotavirus infection in mice as well as clear chronic infections. For this effect to occur, they say that both the flagellin receptors Toll-like receptor 5 (TLR5) and NOD-like receptor C4 (NLRC4) were needed. The flagella seemed to set off TLR5 activation in dendritic cells that then induced cytokine interleukin-22 (IL-22), which, in turn, led to changes in gene expression in intestinal epithelial cells.
"We were very, very surprised that a bacteria component offered powerful protection against a viral infection," Gewirtz tells NPR's Goats and Soda blog. "The basic thinking before was that bacteria have certain components on their surface that activate the immune system to fight bacteria, not viruses."
He adds that he hopes that these proteins will someday help treat rotavirus infections in developing countries where vaccines like the ones used in the US are less effective.