Virus: ‘A piece of bad news wrapped in a protein’
-Sir Peter Medawar
Diagram of the HIV virus. US National Institute of Health (redrawn by en:User:Carl Henderson)
It is no secret that viruses are a bane of modern life—prior to the Bird Flu, Ebola, and HIV most individuals did not put much worry in catching a cold nor the influenza. However, the arrival of HIV in the late 1970s opened the eyes of many people—(and HIV’s source seemingly came from ‘monkey meat.’) While all along, the question as to whether viruses were a form of life was hotly debated and still remains partly solved (with the mainstream regarding viruses as non-life). Truth be told, the definition of life is a thorny issue to the majority of biologists.
The lack of understanding of viruses plagues the field of astrobiology as well. Googling the terms—viral life and astrobiology will nearly turn up an empty cache. One other remarkable fact is the number of viruses are said to outnumber bacteria by one order of magnitude. (Estimates put the number of viruses at 1031and the number of bacteria at 1030. That is the number 10 with 31 zeros behind it.) Any place there is humanity, you may well find a virus feeding as a parasite. In fact, there are viruses that feed on other viruses.
The discipline of astrobiology is studying viruses, and it may help discern the puzzle of fossilized life on the side (see note at end of post). However more to point, I will speak of ‘virus fundamentals.’ Viruses trick their host into ‘believing’ that their chemistry is a part of host’s biochemistry. The virus will attach itself to the ‘wall of its host’ and insert its DNA (or RNA) to make more copies of itself. It is correctly pointed out that viruses play a prominent role in life’s present and past evolution. (Viruses have been a part of the Earth’s biology since near the beginning of life.) And, it is pointed out that by finding ET-viruses it will help us to understand how life may have arisen elsewhere. That argument is put forth because viruses are now found in archaea, the bacterial communities that survive under extreme conditions. It has also has been reported that archaeal viruses may survive for extended periods by coating their exteriors with a glassy silica (related to sand).
The likelihood of finding ET-viruses is one which intrigues the astrobiology community. However, scenarios posed show a murky picture at best. If viral entities are found everywhere, it may be nearly impossible to discern ‘infected-life’ from ‘non-infected-life.’ Further clouding the scenario is the mainstream view that viruses are not alive but collections of chemical bags that bear little similarity to conventional life.
REFERENCES for READING and STUDY:
Matti Jalasvuori, Anni-Maria Örmälä and Jaana K.H. Bamford (2009). On the astrobiological relevance of viruses in extraterrestrial ecosystems. International Journal of Astrobiology, 8, pp 95-100. doi:10.1017/S1473550409004479.
Griffin D.W. (2013). The quest for extraterrestrial life: what about the viruses? Astrobiology. 2013 Aug;13(8):774-83. doi: 10.1089/ast.2012.0959.
REFERENCE related to fossils and biosignatures:
Laidler, J., Shugart, J., Cady, S., Bahjat, K., Stedman, K. “Reversible Inactivation and Desiccation Tolerance of Silicified Viruses.” J. Virol. 10.1128/JVL.02825-13. http://jvi.asm.org/content/early/2013/10/03/JVI.02825-13.full.pdf+html?sid=affa42aa-f145-4284-b6db-e12bdd34b1ed