Following on from yesterday’s post about the Tasmanian Devils, this is all about HPV – a highly infectious virus that can cause cancer (well, sort of. Read on.)
The Human Papillomavirus is crazy infectious – around three out of four women will have it at some time in their lives. That’s a LOT of people considering it’s transmitted sexually – ‘specially when you consider people who get married before sex and nuns and what not. It’s spread by skin to skin contact in the genital region, so a condom won’t completely protect you. Cling wrap all around the nether regions is what you need to stop this ninja virus. The stealthy, sneaky sonbich could be anywhere, including in your cells right now.
HPV infects the epidermis and can cause nothing, warts, or cancer. Most HPV just loiters around and is eventually cast out by your hard-core immune system, making you a lucky carrier! Some forms of HPV cause genital warts, an unpleasant and unattractive affliction which is nevertheless treatable. Other types are associated with cervical (and anal, vaginal and penile) cancers. Cervical cancer is the second most frequent cancer in women worldwide. 🙁
How does a virus cause cancer? Well, to put it simply, it messes with the cell cycle. Before your cell divides, it checks that things are okay – it checks the DNA for any mistakes (p53 is a protein involved in this) and it makes sure it has enough proteins to go ahead without making more mistakes (pRB is the man for this.) The virus produces two proteins – E6 and E7 that bind to p53 and pRB respectively, and inactivates them. This means your cell can replicate without the proper checks (good for the virus), leading to more cancerous changes. p53 in particular is a famous tumor suppressant, and messing with it can lead to out of control replication and chromosomal instability. In some cases, the virus DNA can insert itself into your normal DNA – then there’s no getting rid of it.
The journey to cancer takes around 10 years and a number of other cell mutations. Very different to the Tasmanian Devil face tumors in which the cancer is directly infectious. When I say “HPV causes cancer” I actually mean certain types of HPV can cause pre-cancerous changes in a cell which could one day lead to cancer. Think of it as the first mutation…
Freaked out? Well good news! There is a vaccine! Two actually, Cervarix and Gardasil protect against HPV types 16 and 18, which cause 70% of cervical cancers. Gardasil also protects against most genital warts by coinkidink. That doesn’t mean you can stop getting pap smears ladies. Still gotta do that. Sucks to be us.
This is a very cool vaccine though – in one generation of women (in the developed world they immunised at the age of 12, hope it’s available to developing countries as well), we could eliminate 70% of cervical cancer cases. That’s freaking fantastic! Oh, and HPV isn’t the only virus that can lead to cancer. Hepatitis can cause liver cancer, and Epstein-Barr Virus, lymphoma. We’ve got vaccines against Hepatitis viruses too!
A parting tip, swanky statistics available from WHO. And don’t type HPV into google images. Not cool guys… not cool.