Most viruses, whether they infect bacteria, plants or animals, have fairly similar structures. They consist of an outer shell called a capsid that contains the viral genome — either DNA or RNA. In many DNA viruses the long strands of nucleic acid are tightly wound in a crystalline structure. The repulsive forces formed by the layered strands of genetic material exert a large amount of pressure on the capsid, and according to previous research done by Evilevitch, this pressure is ultimately what propels DNA out of a small porthole in the virus's capsid and into a host cell. That hole is no larger than the width of a DNA chain.

Both research studies are about the same discovery made for two different viruses, namely that viruses can convert their DNA to liquid form at the moment of infection. Thanks to this conversion, the virus can more easily transfer its DNA into the cells of its victim, which thus become infected. One of the studies investigated the herpes virus, which infects humans.

This discovery was very surprising, because no one was previously aware of the 'phase transition' from solid to fluid form in virus DNA. The phase transition for the studied herpes virus is temperature-dependent and takes place at 37°C, which is a direct adaptation to human body temperature.

Researchers hopes that the research findings will lead to a new type of medicine that targets the phase transition for virus DNA, which could then reduce the infection capability and limit the spread of the virus. This drug affects the physical properties of the virus’s DNA, which means that the drug could resist the virus’s mutation and more importantly this kind of therapy is not linked to the gene or protein of virus that may represent great advantage in overcoming drug resistance.

The second study that researcher colleagues have published recently is about bacteriophages, i.e. viruses that infect bacteria, in this case E coli bacteria in the human gastrointestinal tract. The results show that this virus also has the ability to convert its DNA from solid to fluid form. As with the herpes virus, the phase transition takes place at 37°C, i.e. adapted to human body temperature.

These two virus types, bacteriophages and the herpes virus, separated at an early stage in evolution, several billion years ago. The fact that they both demonstrate the same ability to convert their DNA in order to facilitate infection indicates that this could be a general mechanism found in many types of virus and maybe in other noninfectious diseases.

In previous studies, these group of researchers have succeeded in measuring the DNA pressure inside the virus that provides the driving force for infection. The pressure is five times higher than in an unopened champagne bottle. This high pressure is generated by very tightly packed DNA inside the virus. The pressure serves as a trigger that enables the virus to eject its DNA into a cell in the host organism.

This mean that there is positive pressure in DNA of virus and negative pressure in  DNA of host’s cell ,as logically a nucleus of host cell should make a space to unwillingly accept a genetic material of virus by doing some steric changes in the layered strands of genetic material .

Also a gas(or frozen ) phase of DNA surprisingly is possible in vitro conditions  ,as it is found that vaporization of DNA, even at high temperatures, does not lead to a total disruption of the double helix. Rather, the DNA duplex preserves gross structural, energetic, and dynamic features of the conformation of the double helix in aqueous solution. Thus, the two strands remain bound, the global structure has a slight helicity, and the total number of DNA-DNA interactions is not dramatically different from that found in solution.

References:

  • http://www.futurity.org/dna-viruses-phase-transition-775052/,
  • http://www.nature.com/nchembio/journal/v10/n10/nchembio.1628/metrics/news
  • http://www.designntrend.com/articles/21011/20141008/liquid-dna-enables-viral-attacks.htm
  • http://www.cmu.edu/news/stories/archives/2014/september/september29_evilevitchdnadiscovery.html
  • http://www.lunduniversity.lu.se/article/liquid-dna-behind-virus-attacks
  • http://www.sciencedaily.com/releases/2014/10/141006084917.htm
  • http://www.ncbi.nlm.nih.gov/pubmed/12823023

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