Researchers found a plant virus in the throats of healthy humans that could alter visual processing and spatial orientation.
The horror movie-like findings suggest viruses deemed noninfectious to humans require a second look, Johns Hopkins reported.
"This is a striking example showing that the 'innocuous' microorganisms we carry can affect behavior and cognition," said lead investigator Dr. Robert Yolken, a virologist and pediatric infectious disease specialist at the Johns Hopkins Children's Center and director of the Stanley Neurovirology Laboratory at Johns Hopkins. "Many physiological differences between person A and person B are encoded in the set of genes each inherits from parents, yet some of these differences are fueled by the various microorganisms we harbor and the way they interact with our genes."
The study also reveals a biological function called "viral jumping" in which a virus is spread from one species to another, such as what occurred in swine flu.
The team made the finding by accident when analyzing the microbes in the throats of healthy patients for a non-related study; they were shocked to find Acanthocystis turfacea Chlorella virus 1 (ATCV-10), which is known to infect green algae.
The team found 40 of the 92 study participants carried the virus and those that did had a lower level of performance on a set of tasks that measured the speed and accuracy of visual processing. They performed an average of nearly nine points lower on a task in which they were asked to draw a line between sequentially numbered circles than those who did not have the virus.
To further back up their findings the researchers infected a group of mice with the virus and found they had similar deficits in recognition memory and spatial orientation.
"The similarity of our findings in mice and humans underscores the common mechanisms that many microbes use to affect cognitive function in both animals and people," said co-investigator Mikhail Pletnikov, director of the Behavioral Neurobiology and Neuroimmunology Laboratory at Johns Hopkins. "This commonality is precisely what allows us to study the pathologies that these microorganisms fuel and do so in a controlled systematic way."
The virus is believed to cause changes in the hippocampus, the region of the brain responsible for cataloguing short term and long term memories as well as spatial orientation.
The findings were published in a recent edition of the Proceedings of the National Academy of Science.
