sciencehabit writes: In a new study, researchers led by Edward Chuong, a computational biologist at the University of Utah in Salt Lake City, explored whether endogenous retroviruses (ERVs) help us fend off invaders. The scientists scanned three different human cell lines for ERVs in their DNA that could bind to innate immunity transcription factors, which turn on genes to ramp up the immune system's attack against pathogens. They found thousands of ERVs. The researchers predicted that if they remove this viral DNA from the cell, the transcription factors would not function properly, potentially disrupting genes involved in the innate immune response. Using the gene-editing tool CRISPR, they snipped out several endogenous viruses from the cell's DNA. When researchers infected these ERV-depleted cells with the vaccinia virus, they found a much weaker innate immune response that unedited normal cells, the team reports online today in Science. A key immune protein wasn't produced and thus was not fighting the virus. When researchers later added the genes back into the cells experimentally, immune function was restored. This new research provides evidence that "an ancient viral element is assisting us against an infection," Chuong says.