A constant search for new viruses

Dec ,13 2016

Viruses are the most diverse group of organisms that have ever been on earth. They are present in all the ecosystems and virtually every part of the world. This is why there are more and more researchers devoted to find new viruses with as yet unknown characteristics that we could take advantage of, or maybe viruses with potential danger to the human race that we do not know of their existence. Here I summarize briefly three important discoveries in the field in 2015.

A new avian influenza (AI) virus has been discovered in China


Chinese researchers have recently reported the discovery of a new strain of AI virus of type H5N9 that represents a hybrid of the highly pathogenic H5N1 and the human H7N9. It was isolated from samples taken in 2013 from different types of birds taken from live-bird markets. They found distinct strains of influenza and when they analysed the H5N9 strains encountered, they found that the hemagglutinin (H) protein matched that of H5N1 isolated from Vietnam (the highly pathogenic H5N1) whereas the neuraminidase (N) protein derived from a human H7N9 isolate.

Many will remember the news that filled the journals several years ago, when a highly pathogenic strain of influenza (H5N1) caused an epidemic in South Asia. Fortunately, and I say this not taking into account the poultry industry that had to slaughter thousands of birds, this strain did not present natural spread between humans. Obviously, testing pathogenicity of the new virus in mammals was obligated. Researchers concluded that the new strain prefers avian-type cell receptors, known as alpha-2,3 sialic acid receptors, rather than the human-type receptors, called alpha-2,6. Lucky for humans, but for birds…

This is a highly pathogenic new strain of avian influenza virus originating from H5N1, H7N9 and also H9N2 subtypes. Live-bird markets, mainly those gigantic in South Asia, represent a potential transmission risk to public health and the poultry industry and this is due to the capacity of generating reassortant viruses (see picture below).





Different strains of influenza virus that infect the same host
can combine genetic segments, a process called reassortment,
to generate a new virus whose genetic material will be a mixture
of segments from the ‘parent’ viruses. Picture taken from
http://afludiary.blogspot.co.uk/2014/11/bird-flu-reports-from-india-japan-korea.html



Two new groups of bunyaviruses have been discovered

The bunyavirus family comprises five different groups of viruses, many of them causing severe illnesses both in human and animals, and also plants. Most bunyaviruses are spread through blood-feeding insects. This group includes the Rift Valley Fever virus that causes febrile episodes in humans with severe bleeding, and the Schmallenberg virus that is transmitted by mosquitoes and causes serious foetal malformations in ruminant animals.

Researchers at the University of Bonn and the German Center for Infection Research (DZIF) have been searching for new viruses in the African tropical forest of the Ivory Coast for more than ten years. They have captured more than 7500 mosquitoes all over the research with the aim of discovering new viruses within the bunyaviridae family. Instead of isolating the whole viral particle itself, the researchers obtained fragments of the viral genetic material and joined them to obtain the entire genome sequences. Once the genome sequences were compared to those in databases they concluded that two independent bunyavirus lineages, that they named Jonchet and Ferak viruses, were existing at least in that geographical part of Africa.

Now they need to address the crucial question: are they dangerous? And also, can they be easily transmitted to humans and animals? The first results show that it is very unlikely that the new viruses can infect humans and other vertebrates. To obtain such results they have used specific biological techniques that they are also applying to other viruses to know their risk of vertebrate infection, something that has been in the front line of research since the epidemics of SARS and Ebola.

Kansas suffers from the new deadly Bourbon virus

The Centre for Disease Control (CDC) in USA announced the discovery of a new virus isolated from an infected patient in early 2015. It was called Bourbon virus after the county where the patient used to live. The fifty-year-old patient had suffered from multiple tick bites in the spring of 2014 while he was working outside on his property. The man fell ill with fever and vomiting and was hospitalized. After testing for multiple infectious diseases with negative results, doctors could do nothing for his life and the man died of a heart attack eleven days after becoming sick. Results from a blood sample sent to the CDC determined that he had been infected with an unknown virus.

We now know that Bourbon virus belongs to the family of thogotoviruses. This family of viruses is known to be present in Europe, Asia and Africa and to infect through tick bites, but it was the first time that a virus from such family causes illness in the United States. Although this is the only case reported so far, it is very likely that the virus can spread through tick bites. There is now a great concern about this, so Kansas health authorities are currently sending continuous warnings to the population to protect themselves against ticks.

The oceans contain the main reserve of viruses

Archaea involves single-celled microorganisms that live in many distinct environments. Some of the most hard environments can be found thousands of kilometres below the water surface, in the ocean depths. Scientists are continuously exploring the deep seas in search of new viruses that can provide answers to questions about evolution and interaction of viruses and living organisms. This time, scientists have found a virus that lives beneath the ocean floor and infects archaea.

This recent discovery sheds light of how viruses and archaea can adapt in this hostile environment. Such viral type is suggested to be distributed around the globe, and investigations have shown that it has a high capacity of mutation. It seems that the virus is able to modify parts of its own genome as a mechanism of defence against the cell’s own defences. Interestingly, they observed that some members of archaea also mutate their genome and this can be the key to survive in the hostile environment that lies beneath the earth’s surface.

The capacity to modify certain proteins according to the environment is of great importance in biology. Maybe in the near future, when we know more about the mechanisms that lead to such mutations, we can apply them to combat certain genetic disorders causing disease in humans.


References
http://www.worldpoultry.net/Broilers/Health/2015/6/Novel-AI-virus-discovered-in-China-1782785W/
http://phys.org/news/2015-03-intraterrestrials-viruses-ocean-depths.html
http://edition.cnn.com/2015/02/20/health/new-virus-discovered/
http://afludiary.blogspot.co.uk/2014/11/bird-flu-reports-from-india-japan-korea.html