Although a few stops short of a zombie apocalypse, and a bit more exciting than toxoplasmosis (which may affect 1/3 of humans), a newly found algae virus appears to be negatively impacting the cognitive abilities of at least those living in cities on the ocean.

This is actually pretty revolutionary, primarily because it is the first known example of a virus completely jumping kingdoms and moving between plants and animals.

The virus, called ATCV-1, which first showed up assays of human brain tissue several years ago, was initially assumed to have entered the tissue after the death of the patients. This post-mortem hypothesis was quickly defeated when the virus started showing up in the throats of people with psychiatric diseases.

Infectious disease expert Robert Yolken from Johns Hopkins University School of Medicine in Baltimore, Maryland, and his colleagues were investigating what pathogens play a role in these psychiatric conditions. At first, they didn’t know what ATCV-1 was, but a database search exposed its identity as a virus that typically infects a species of freshwater green algae.

A follow-up study of 92 healthy people found that 43% of them had the virus, and that was associated with a reduction in cognitive functioning by approximately 10%.

To see if this was really more likely simply a correlation, and not a causation, the cognitive experiments were repeated with mice (further reducing the number of complex variables and genetic differences when dealing with humans). Surprisingly, the 10% reduction in cognitive ability  was exactly replicated in the mice (10% longer to escape a maze, and 20% less time investigating a new object), as well as revealing that infection with ACTV-1 changed the expression levels of 1300 genes found in brain tissue!

Before you stop eating sea food, no one has figured out how this virus infects people or how many people actually have it (the preliminary studies were carried out in Baltimore).

Although it seems likely at this point, there is not even any guarantee that it is actually slowing down those who are infected. More follow-up studies are going to be needed before we can really characterize exactly how this virus infects and affects humans, and through what channels so many could become infected: by the ocean breeze, sushi, or something else entirely?

Michael Thomas

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