Sunday, November 11, 2007

HPV and cervical cancer.

HPV, or human papillomavirus has been making the news and been a hot topic of controversy lately. Cervical cancer is the second most common cancer among women world wide and HPV infections are present in 100% of all cervical cancer patients, coincidence? Definitely not!

HPV is the most commonly transmitted infection in the United States and over half of all sexually active American are infected at some time in their lives. There are usually no symptoms so passing it to someone else without even knowing it is fairly easy, it requires only skin on skin contact to be transmitted. I am going to assume that the stats are pretty close for Canadians as well. Not so scary considering that most HPV infections will come and go without ever causing any symptoms, our ever amazing immune systems taking care of the virus before it causes any damage. But (of course there is a but), of the 37 types of HPV that are spread through sexual contact, there are about 19 "high risk"types that can develop into cervical cancer.
(ThinPrep Pap smear with group of normal cervical cells on left and HPV-infected cells on right. The HPV-infected cells show features typical of koilocytes: enlarged (x2 or x3) nuclei and hyperchromasia)

The virus does so by producing the proteins E6 and E7 which effectively inactivates or turns off the P53 gene. Why does this matter so much? The P53 gene is a tumor suppressor gene, a transcription factor that regulate the cycle and cell apoptosis. Without it there is excessive cell division that leads to tumors and cancer.

But alas, unlike other forms of cancer there is a vaccine. Gardasil and Cervarix are two types of vaccines that work against type 16 and 18 of the virus by getting the body to produce virus-neutralizing antibodies that will prevent initial infections. That's right, just like the flu shot! Hallow virus-like particles are produces from recombinant HVP coat proteins. What? Well, DNA from the viral protein coat are inserted into another organisms genome, such as the plasmids of bacteria. This DNA is expressed and a virus-like particle is assembled that has no viral DNA and therefore cannot cause infection. This initial vaccines is expected to last for 4.5 years with repeated inoculations later.

So we have a preventative measure, but what if you already have cervical cancer or cannot get the vaccines? Like any other form of cancer early detection is the key. Regular Pap smears and visits to your doctor are a must. Edward Yeung an Iowa State University professor has developed a method of detecting a single HPV molecule. The current test being used requires 10 to 50 viral molecules. This new technology, which is not in use yet, creates chemical reagents that recognize the genetic sequence of HPV. The reagents label the genome by florescence, which are lite when passed through a laser. "Yeung said single molecule detection of the virus could help women and families decide to get vaccinated. He said vaccines administered after such early detection could still have time to stop the virus."

Preventative measures and early detection, is cervical cancer going the way of Polio and the dinosaurs? Hopefully with education and common sense we can see a decline in the women who suffer from what now seem to be a preventable disease.


Image from


Polly Pocket said...

Where did you get your information from that says that the vaccine will last for 4-5 years? I am curious because all my sources have said that there was no definiate time frame as to how long the vaccine lasts for.

lotus flower said...

If you go to the wikipedia link it says there that the vaccine is expectd to last 4.5 years. So it's not a definite time frame, I'm assuming more of an educated quess.

Dominic B. said...

Prevention is always, and has always been important. With prevention and regular visit to the doctor's office for an uncomfortable pap test you decrease the risk of an undetected infection and cancer

Anonymous said...

I've heard some people have had cervical cancer because of the constant use of generic viagra I don't know if that's true, so I use to take it and now I'll be careful with that situation.