● ERVs - Endogenous RetroViruses

In this section, we begin with a simple introduction, explaining what a virus is, what a retrovirus is, what a provirus is, and what an endogenous retrovirus is.

There then follows a section explaining how ERVs prove common ancestry among species and series of answers, in depth, to frequently asked questions (FAQs) about them. 

We then look at a series of blog articles written by “creation scientists” and unidentifiable intelligent designer spotting enthusiasts, attempting to refute the irrefutable evidence from ERVs.

● So, what is a virus?

A virus is a particle in the form of a special package that contains a genome in the form of RNA or DNA. It reproduces by invading the cells of host organisms and induces them to create new viral particles. Some people question whether viruses exist. See ● How were viruses discovered, below.

● and a retrovirus?

A retrovirus is a particularly fiendish type of virus that stores its genome in RNA form. It enters a host cell, makes a DNA version of its genome and does a cut and paste, inserting the DNA version, (integrating it with the host DNA, in the jargon), into the host’s own DNA, leaving telltale, duplicate snippets of original host DNA at either end of the integration site or locus. The cell then unwittingly reads the integrated viral DNA and processes it, resulting in the production of new viruses. The integrated viral DNA is called a provirus. The best known example of a retrovirus is HIV, (Human Immunodeficiency Virus), a virus that causes AIDS (AutoImmune Deficiency Syndrome). How do we know that proviruses are caused by retroviruses? Go here to see.

● and an endogenous retrovirus (an ERV)?

Some retroviruses have integrated their DNA with the DNA of gametes - sex cells - egg or sperm cells. In this way, they become heritable. They are passed from parent to offspring in just the same way as DNA for other inherited characteristics such as hair or eye colour. They have become just another part of the organism’s genome, hence the word endogenous - within the genome. An exogenous virus on the other hand is a virus outside, in the environment.

● OK, what’s so special about ERVs?

The most significant fact about retroviral integration by an exogenous retrovirus is that it cannot target any specific locus (position or location) within the host’s DNA.  Proviruses are to be found in infected cells in almost any locus, which varies from cell to cell. Not all cells of the body are infected. These are the two signs of infection by an exogenous virus.

In contrast to the above, all the cells of an individual, even if they have not been exposed to an exogenous retrovirus, also have thousands of remains of proviral integrations, each example in exactly the same DNA locus as one another, going from cell to cell. This proves that each of these viral remains are the remains of an exogenous retroviral integration, not with the cells of the individual, but with the DNA of a gamete of an ancestor, and the individual inherited it from that ancestor.

Direct infection will not place the same retroviral DNA in every cell of an individual in exactly the same DNA locus, going from cell to cell. Inheritance will.

● How were viruses discovered?

With the invention of microscopes, a whole new world of microscopic organisms was discovered, and it was found that some of these could cause disease. However, there were still diseases that were thought to be caused by agents that were too small to be seen, even through the most powerful microscopes available at the time. Filtering fluids that were known to cause infections through ceramic filters that would retain bacteria showed that something smaller was indeed responsible. Those somethings were named viruses. For an interesting account, see the History of virology @ Wikipedia.

Tobacco mosaic virus