American scientists have located a virus that attacks human DNA, which may cause those infected to be less intelligent, impairing brain activity, learning and memory.

Researchers from Johns Hopkins School of Medicine and the University of Nebraska have identified traces of an algal virus, known as ATCV-1, in throat swabs drawn from healthy volunteers which appeared to lessen their mental capacity.

The researchers had originally been working on an unrelated study into throat microbes when they unexpectedly located traces of ATCV-1 in human DNA samples. At first the research team, led by Dr Robert Yolken of Johns Hopkins, didn’t know what ATCV-1 was, and had to carry out a database search to find out more about the unknown virus.