Antivirals – Medicinal Chemistry – D5

The topic of antivirals is taught specifically in the medicinal chemistry option, section D5.  Given the current global situation with COVID-19, this is a perfect opportunity for a blog post on the subject. I will try to keep to the syllabus but I think, it is inevitable that I may wander off topic a bit.

COVID-19 is caused by a virus. Viruses are very interesting organisms. I can always remember being told in school that viruses were not alive as they fail on one of the conditions needed for life – their ability to reproduce. You see viruses can reproduce, but they can only do so by invading a cell and hijacking the cells reproductive ability. I’m not sure how many biology teachers would agree with what I was taught but it does illustrate a point. A virus does not have the tools to reproduce itself. It needs another organism to do so.

Viruses are very simple organisms. This is why they cannot reproduce by themselves. They are typically composed of two or three things. Genetic material (DNA or RNA), a protein coat and sometimes a lipid envelope encasing the protein. The DNA / RNA will typically only have a few genes (although some can have up to 200) – compare this with the number of genes in a human (20 – 25,000) and you get an idea of how simple they really are.

Covid-19 gets its name from the disease it causes, in other words, the name of the disease is ‘coronavirus disease’ or COVID-19 but the name of the virus is actually severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This may seem a little confusing, but think of HIV (the virus) and AIDS (the disease) and it begins to make more sense.

One way of fighting the virus is by developing an antiviral drug. But what is an antiviral and what makes it different to an antibiotic?

An antiviral is a drug that treats viral infections. Its mode of action works by inhibiting the development (reproduction) of the virus. There are specific antivirals (for example, the developmental anti viral drug Radalbuvir (https://en.wikipedia.org/wiki/Radalbuvir ) and broad spectrum antivirals.

Antibiotics on the other hand work by disrupting or breaking down the bacterial cell wall.

This is not be confused with a vaccination. A vaccination will stop people getting a disease whereas an antiviral treats people who have the disease. For obvious reasons, a vaccination is much more preferred to an antiviral.

By CDC/ Alissa Eckert, MS; Dan Higgins, MAM – This media comes from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL), with identification number #23312.Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers., Public Domain, https://commons.wikimedia.org/w/index.php?curid=86444014

You may or may not be aware but all IB courses are reviewed and ‘relaunched’ every 7 years (although for one reason or another, the group 4 subject reviews are taking 8 years this time around). The ‘new’ chemistry course is due to be released in 2022. With that knowledge, I am fairly confident that we will see this particular part of the course updated to reflect COVID-19 and the search for an antiviral. Who said chemistry was an old subject?!