The highly adaptable nature of viruses is one of their most dangerous strengths. They are programmed to survive at all costs, mutating into different forms that often make the leap between different species. The infamous Ebola virus, which has infected almost 15,000 people in Africa this year, first evolved in monkeys and then evolved into a form which could be transmitted to humans.

Mammal to mammal transmission is not a huge leap to make, however, as the physiology involved is similar in each species. But could viruses that affect totally different life forms, such as algae, possibly evolve into a variety that could threaten humans?

Research from the Johns Hopkins University School of Medicine in Baltimore, Maryland suggests that humans could in fact fall prey to the ATCV-1 virus, a bug that has, until now, been content to reside in very basic organisms such as algae.

The team of researchers, led by pediatric infectious disease expert Robert Yolken, initially identified the presence of the virus in the brain tissue of deceased subjects, but it was not clear at that time whether the virus had entered the body pre or post-mortem. Sometime later, however, during a random survey of the pathogenic bacteria and micro-organisms existing in the throats of live subjects, ATCV-1 was detected again. Its origins were then unknown, but its usual habitat was eventually traced back to the green algae that is normally found in lakes and rivers.

But what harm, if any, did ATCV-1 have upon its hosts?

When tested on mice, the virus did not make them ill but did appear to slow down cognitive function. Infected animals took ten per cent longer to find their way out of mazes and were twenty per cent less likely to investigate new objects. The results were small, but significant.

To determine its physiological effects in humans, researchers tested 92 healthy subjects for the virus and found it living in 43% of them. In cognitive ability tests, the afflicted subjects were shown to mimic the results of their rodent counterparts: they were ten per cent less proficient than unaffected subjects as their responses were slower, had shortened attention spans and were less able to make numerical connections.

The findings of the study, which was published online in the Proceedings of the National Academy of Sciences, indicated that the cognitive impairment due to ATCV-1 was not linked to gender, socio-economic status, cultural or ethnic origins, or even whether subjects were smokers. But neither did they indicate that the reduction in brain function was solely due to ATCV-1, or whether it was merely present because it was feeding on some other potential cause of cognitive decline, such as pollutants or other infectious agents.

Tests were also done on the hippocampus in the brains of infected mice, the area associated with memory and general comprehension, and found that ATCV-1 appeared to have changed the activity of almost 1,300 genes, particularly those that were involved in reactions with the neurotransmitter dopamine and others that were vital for immune function.Yolken believes that it is via the immune system that ATCV-1 begins to influence brain activity, prompting immune responses that affect gene expression.

Should we be worried about yet another viral predator in our midst?

So far, there have been limited studies on the virus so its true potential for harm is not yet apparent, but based on the results so far the scientific community are not convinced that it poses much of a threat to the human race.

“If you ask me if I am worried about the existence of this virus, I am not,” commented Joram Feldon, a neuroscientist emeritus at the Swiss Federal Institute of Technology in Zurich who was not involved with the work.

Yet other scientists in the field were not so complacent, and believe that the study should pave the way for more research in this area. Allan Kalueff, the director of the ZENEREI Institute in Slidell, Louisiana, is concerned that ATCV-1 is just one of many other similar algae-derived viruses that could affect human cognition. If so, then those who work in close daily contact with these micro-organisms, such as those in the seafood industry, could potentially be at risk.

"We clearly need more studies, including both animal and plant/algal studies," he said.

Other research into viral diseases affecting the seafood industry has indentified a role for probiotics in the fight against the harmful pathogens that may develop there. Probiotics, defined as microorganisms that are beneficial for the human host, being selected as the best alternatives to artificial antimicrobial agents as they have been shown to have anti-viral properties, and also act as natural immune enhancers which help to increase disease resistance in seafood,

For those worried about being infected by such insidious viral predators as ATCV-1, the same protective effects can be obtained in humans. Studies have indicated that, as our intestines act as "mission control" for two-thirds of the body’s immune system , it may be important to keep one’s probiotic levels high by taking probiotic supplements. These so-called "friendly bacteria" live in the mucus lining our intestinal wall, and act as a barrier against numerous pathogenic substances.

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