Current research in & Retrovirology 2021, Vol.4, Issue 3 Editorial

Bahman Khalilidehkordi Shahrekord University of Medical Sciences, Iran

mobile genetic elements of cells (such as transposons, Editorial or ) that became encapsulated in , acquired the power to “break free” from Virology is that the study of – submicroscopic, the host and infect other cells. Of particular interest parasitic particles of genetic material contained during a here is , a huge that infects amoebae and protein coat – and virus-like agents. It focuses on the sub- encodes much of the molecular machinery traditionally sequent aspects of viruses: their structure, classification associated with . Two possibilities are that it’s a and evolution, their ways to infect and exploit host cells for simplified version of a parasitic or it originated copy , their interaction with host physiology and as an easier virus that acquired from its host. The immunity, the diseases they cause, the techniques to iso- evolution of viruses, which frequently occurs together with late and culture them, and their use in research and ther- the evolution of their hosts, is studied within the field of apy. Virology is a subfield of microbiology.Structure and . While viruses reproduce and evolve, they’re classification of Virus: A major branch of virology is virus doing not engage in metabolism, don’t move, and depend classification. Viruses are often classified consistent with on variety cell for copy . The often-debated question of the host cell they infect: viruses, viruses, fun- whether or not they’re alive or not could also be a matter gal viruses, and (viruses infecting bacte- of definition that does not affect the biological reality of vi- ria, which include the foremost complex viruses). Another ruses. Molecular biology research and viral therapy: Bacte- classification uses the geometrical shape of their riophages, the viruses which infect bacteria, are often rel- (often a helix or an icosahedron) or the virus’s structure atively easily grown as viral plaques on bacterial cultures. (e.g. presence or absence of a lipid envelope). Viruses Bacteriophages occasionally move genetic material from home in size from about 30 nm to about 450 nm, which one bacterial cell to a different during a process referred suggests that the majority of them can’t be seen with light to as , and this horizontal transfer is one microscopes. The shape and structure of viruses has been reason why they served as a major research tool within the studied by microscopy, NMR spectroscopy, and X-ray crys- early development of biology . The ordering , the function tallography. The most useful and most generally used ar- of , the primary recombinant deoxyribonucleic rangement distinguishes viruses consistent with the sort acid and early genetic libraries were all received using bac- of macromolecule they use as genetic material and there- teriophages. Certain genetic elements derived from virus- fore the method they employ to coax host es, like highly effective promoters, are commonly utilized cells into producing more viruses: in biology research today. Growing animal viruses outside DNA viruses (divided into double-stranded DNA viruses of the living host animal is harder . Classically, fertilized and single-stranded DNA viruses), RNA viruses (divided chicken eggs have often been used, but cell cultures are into positive-sense single-stranded RNA viruses, nega- increasingly employed for this purpose today. Since some tive-sense single-stranded RNA viruses and thus the much viruses that infect got to transport their genet- less common double-stranded RNA viruses), reverse tran- ic material into the host cell’s nucleus, they’re attractive scribing viruses (double-stranded reverse-transcribing tools for introducing new genes into the host (known as DNA viruses and single-stranded reverse-transcribing RNA transformation or ). Modified are viruses including retroviruses). often used for this purpose, as they integrate their genes into the host’s . Virologists also study subviral particles, infectious entities notably smaller and simpler than viruses: (naked DNA viruses circular RNA molecules infecting ), satellites (nu- Viruses with a DNA , except for the DNA reverse cleic acid molecules with or without a capsid that require transcribing viruses, are members of three of the four rec- a helper virus for infection and reproduction), and ognized viral realms: Duplodnaviria, Monodnaviria, and ( which will exist during a pathological conforma- Varidnaviria. But the , tion that induces other molecules to assume that and many other incertae sedis families and genera, are very same conformation). Taxa in virology aren’t necessar- also used to classify DNA viruses. The domains Duplodna- ily monophyletic, because the evolutionary relationships viria and Varidnaviria consist of double-stranded DNA vi- of the varied virus groups remain unclear. Three hypothe- ruses; other double-stranded DNA viruses are incertae se- ses regarding their origin exist: Viruses arose from non-liv- dis. The Monodnaviria consists of single-stranded ing matter, separately from yet in parallel to cells, perhaps DNA viruses that generally encode a HUH endonuclease; within the type of self-replicating RNA ribozymes almost other single-stranded DNA viruses are incertae sedis. like viroids. Viruses arose by genome reduction from ear- lier, more competent cellular forms that became par- RNA viruses: asites to host cells and subsequently lost most of their All viruses that have an RNA genome, and that encode an functionality; samples of such tiny parasitic RNA-dependent RNA polymerase (RdRp), are members of are Mycoplasma and Nanoarchaea. Viruses arose from the , within the .