Science In The Pub Adelaide

Viruses​

Viruses are small parasites that need a host to reproduce. On their own, they barely exist and may not even be capable of surviving for a long time, but once they find a host which is a susceptible cell, they can use the cell machinery to reproduce and create more viruses. In most cases, a virus has either DNA or RNA as its genetic material, and the nucleic acid can be double or single-stranded. The infectious particle in the virus, which is virion, is made of nucleic acid with an outer protein shell.  In the simplest viruses, the DNA or RNA is just enough for four proteins, but there are complex ones that can encode up to two hundred proteins.

Studying plant viruses was one of the first experiments performed in molecular biology, and as early as 1935, tobacco mosaic virus has been partly crystallised and purified. Soon after that, many other plant viruses were also crystallised. This opened the floodgates for research into animal viruses and bacterial viruses. The result has been a better understanding of the viral structure and cell biology through the study of virus-infected cells.

Generally, DNA viruses make use of cellular enzymes to synthesise their mRNAs and DNA genomes. All viruses make use of the cellular ribosome, translation factors, and tRNAs to synthesise their proteins. One the virus infects the cell, it generally takes control of the cell machinery for its macromolecular synthesis; it directs it to synthesise viral proteins and mRNAs instead of the normal cellular macromolecules. An example is where animal cells with influenza infection are only capable of synthesising one or two kinds of glycoproteins which have viral genes as compared to a regular uninfected cell that can produce many glycoproteins.

Host Ranges

There are also wide host ranges which are features of some animal viruses that can grow some mammalian and insect cells. However, most animal viruses are restricted to phyla and only infect related species, and they are further restricted in the types of cell they can attack which has to be cells that have the right receptors for the virions.