Quote:The virus, called ATCV-1, showed up in human brain tissue several years ago, but at the time researchers could not be sure whether it had entered the tissue before or after the people died. Then, it showed up again in a survey of microbes and viruses in the throats of people with psychiatric disease. Pediatric infectious disease expert Robert Yolken from Johns Hopkins University School of Medicine in Baltimore, Maryland, and his colleagues were trying to see if pathogens play a role in these conditions. At first, they didn't know what ATCV-1 was, but a database search revealed its identity as a virus that typically infects a species of green algae found in lakes and rivers.
The researchers wanted to find out if the virus was in healthy people as well as sick people. They checked for it in 92 healthy people participating in a study of cognitive function and found it in 43% of them. What’s more, those infected with the virus performed 10% worse than uninfected people on tests requiring visual processing. They were slower in drawing a line connecting a sequence of numbers randomly placed on a page, for example. And they seemed to have shorter attention spans, the researchers report online today in the Proceedings of the National Academy of Sciences. The effects were modest, but significant.
The researchers also studied gene activity in the animals' hippocampus, a part of the brain important for memory and understanding one's whereabouts. They found changes in the activity of almost 1300 genes in the infected animals. Some of those genes affect how the brain reacts to a key chemical messenger called dopamine, and others are important in immune function. Yolken has not yet found the virus in the brain but suspects it may affect the brain through its influence on the immune system, stimulating certain immune responses that might in turn affect gene expression in the brain.