Today’s Diary Entry is sponsored by Pets Bureau
Today we started looking at Virology, which is the study of viruses. Within the veterinary field this is extremely important as there are significant zoonotic diseases (diseases that pass between humans and animals) that are viral. Some of the best known of these is Rabies (Rhabdoviridae), Yellow Fever (Flaviviridae), Rotavirus, and Poxiviridae which is the case of chicken pox/small pox etc.
Now the significant thing with viruses is that they are extremely small, which is because they lack the common features associated with other bacteria to allow replication and respiration. Instead viruses inject themselves into other cells which they then simply hijack to turn them into a virus replicating machine! This is because viruses are composed solely of either DNA or RNA, and depending on the family either 1 or two strands of this. Once a virus particle enters a cell, this genetic material enters the nucleus and the viral replication starts.
This leaves us with two problems when working with viruses, first of all we have the extremely small size – in some cases 100’s of times smaller than bacteria – which means to have a chance of seeing a virus we need to use an electron microscope. The second problem is actually cultivating or growing the virus, as the virus particle does not contain replication or respiration organs we cannot simply feed it like we do with bacteria. Instead when working with viruses we need to provide it with cells to use to replicate and grow in.
Now there are several different possible solutions here (some more distasteful than others) however the most common method is to use kidney cells. These are prepared using sterile technique from kidneys from various dead animals. The kidney is first cut up (or pulped) into extremely small pieces, which are then washed with trypsin (a digestion enzyme) and the cells from this collected in the liquid and centrifuged. This cell solution is then spread in a single layer onto a glass culture plate and the virus particles applied for growth.
At the moment I am still unsure as to how replication occurs in these cells after the death of the body that contains them and the removal of the blood supply that feeds them… However I will find out soon as my curiosity is now raised!