Last year, US scientists reported the presence of an algae virus in the throat of healthy people and linked it to impaired cognitive function. Now, researchers from Denmark refute the controversial finding, indicating it was the result of contamination in the laboratory.
At the end of October 2014, a paper in the scientific journal Proceedings of the National Academy of Sciences (PNAS) drew a considerable amount of public interest. Headlines in mainstream media included claims along the lines of ‘scientists discover stupidity virus’, although the scientists themselves didn’t actually use the word ‘stupid’.
The researchers from Johns Hopkins School of Medicine and University of Nebraska reported that they had found DNA from a virus, ATCV-1, in throat samples from healthy people participating in a study on cognition. This virus is usually associated with freshwater algae and is not known to infect other species.
After subjecting the 92 study participants to various cognitive tests, the researchers found that the 40 people who were (allegedly) infected with the virus performed slightly worse on some tests. For instance, they appeared to be slower at processing visual information. Next, the scientists injected algae with and without the ATCV-1 virus into the mouths of mice. The mice that received the virus were slower to solve certain puzzles than the virus-free mice.
No scientific evidence
The controversial results are now rebutted by scientists in Denmark, as reported recently in PNAS. Based on their findings from an unrelated DNA sequencing experiment, the scientists conclude that there’s currently no scientific evidence of the algae virus being linked to impaired cognitive function.
“We screened 289 human specimens and detected DNA originating from ATCV-1 in 16 samples from 7 different types of cancer,” says Anders Hansen from the University of Copenhagen, senior author of the new study.
What really alerted them was that they also detected the virus in a control sample where no human DNA was added. This made the researchers confident that the viral DNA came from laboratory reagents, rather than being in any way connected to the cancers.
“We were able to correlate the presence of ATCV-1 in our samples with two laboratory reagents that are used together in the protocols. Furthermore, we found other algae viruses in our samples. Thus, we could conclude that ATCV-1 originates from laboratory component contamination,” Hansen explains.
Jose Izarzugaza from Technical University of Denmark (DTU), co-author of the new study, highlights the importance of exercising extreme caution when interpreting data from high-throughput DNA sequencing experiments.
“Reflective and [self-]critical assessment of the experimental observations is mandatory to avoid erroneous conclusions. It will turn out as a well invested effort, as a number of examples of the contrary in the recent literature [has] lead to withdrawal of the papers after criticism by the scientific community,” he says.
Adapted from DTU News