HPV and Gardasil

HPV, and the vaccine Gardasil, have been in the news a lot lately.  A few weeks ago (yeah, I’m bad about getting to these), I received the following question:
Disclaimer:  I’m not asking you to practice medicine.  
What are your thoughts about Gardasil?  In your opinion, has it been thoroughly tested?  Are there side effects besides making you an incurable slut, according to the 700 club or whoever?  I’m going in for a GYN appointment soonish (a few months) and I plan to ask about it then too but I want a second (zeroth?) opinion too.  And I trust you and I know you and all that jazz.  🙂

You know, it’s good that you are not asking me to practice medicine, because I am not a doctor and I’d probably screw you up more than otherwise.  All I can pretty much tell you is what I know about HPV and Gardasil.  From there, you gotta make your own decision.


First thing first.  I know most people know this already, but I still get this question ALL this time.  So.  You cannot cure a virus with an antibiotic.  Antibiotics are for bacterial infections only.  Similarly, you do not use a viral vaccine to protect you from a bacterial infection.  For the record:
Bacteria: Single cells which get in your body, replicate, and give off toxins that make you ill. 

 (bacteria)
Viruses: NOT cells.  Most people aren’t even sure whether they are actually alive.  Viruses are little (very little) packets of DNA or RNA, surrounded by a protein coat.  When this gets in you, the protein coat binds to one of your cells, and inserts its genetic material.  That DNA or RNA will then hijack your own cell’s genetic material, using it to make more viruses, and sometimes killing the cell in the process.  When your immune system recognizes that a cell is under attack, it mounts a massive defense, and it is the immune response (and your cells dying) that makes you sick.

 (the cold virus)
 
Now, on to HPV.
HPV is the acronym for the human papillomavirus.  This is not just one virus, there’s a whole family of these, right now people think there are at least 130 types.  Estimates right now are that up to 80% of the population may already be infected with some form of HPV (keep in mind, though, not all of them are harmful).  When most people think of HPV, they think of connections with cervical cancer and genital warts.  However, HPVs can also cause:
regular skin warts: that’s HPV type 2 and 7
genital warts (which includes anal): types 6, 11, 42, 43, 44, and 55
plantar warts: the ones on your feet: types 1,2, and 4
subungual warts: the particular kind that that occurs around your fingers: types 2 and 7

flat warts: these usually happen on your arms and legs and sometimes your head, types 3 and 10.
Respiratory papillomatosis: this is when you get recurring warts on your larynx, it’s pretty rare, types 6 and 11.
Epidermodysplasia verruciformis: this is VERY rare, but it involves the growth of scaly stuff on your hands and feet (more than 15 types can cause this, but they are really rare)
Oral papillomas: warts (they are usually mucus filled sacs) in your mouth, types 6,7,11,16, and 32
And finally: genital cancers: 16, 18, 31, 33, 35, 39, 45, and 51
When you read the list, it’s pretty clear that HPV types that cause genital warts are NOT the same as those that cause genital cancers.  But a person can be infected with several kinds of HPV at once.
Many people associate HPV with cervical cancer in particular.  High-risk HPV variants are present in more than 99% of cervical cancers (Walboomers et al 1999).  It’s estimated right now that 15.2% of women between the ages of 14 and 59 are infected with a high risk HPV (see Dunne et al 2007). 
But HPV doesn’t just cause cervical cancer.  It can also cause anal cancer, vulvar cancer, and penile cancer, and some types of HPV can cause head and neck cancers (see Parkin 2006 and D’Souza 2007). 

 (hypothesized structure of HPV)
So how does HPV infect your cells?  HPV is a DNA type virus (as opposed to an RNA type), which 8000 base pairs that can be divided in two sets of genes; early and late (Hausen 2002).  The Early type genes (which are noted by an ‘E’), stimulate the proliferation of the infected cell, and so it is these types of genes that are thought to stimulate formation of cancer.  In particular, there is an E gene called E6, which suppresses the protein p53 (there is also another gene, E7, which has a similar function in the retinoblastoma family of proteins).
P53 is something known as a ‘tumor-suppressor’ protein.  It is basically the bodyguard of your DNA.  As I’m sure most people know from high school biology, when a cell replicates, the DNA replicates, too.  And in this process, mistakes can be made.  When the cell finds a mistake, it produces high levels of p53.  These high levels of p53 prevent the cell from dividing again until the mistake in the DNA can be found and repaired. 
The HPV E6 gene suppresses p53, which makes the cell think that it’s ok to divide, regardless of whether there are DNA mistake or not.  When the cell proliferates like this, without stopping to check if DNA mistakes are being made, proliferation can become uncontrolled, and a tumor can develop.  Tumors are even more likely to occur if the HPV DNA is incorporated into the host cell genome, leading to really high levels of E6, which is what happens with the most high-risk types of HPV. 
The gential and cancer causing types of HPV are spread through sexual contact, and while using a condom can help, it doesn’t stop all infections (college girls using condoms had a 37% infection rate, while those not had an 89% infection rate, see Cottler 2006).
Most people who get infected with various types of HPV will be able to fight it off, but those that do not develop a risk of cervical cancer, most without ever knowing they were infected in the first place.  Right now it is estimated that 0.69% of women will be diagnosed with cervical cancers during their lifetime, and 4,800 women will die per year from cervical cancer.  It’s the 5th most deadly cancer in women.
The good thing is that scientists can induce your body to fight off a virus using a vaccine.  The vaccines contain a “dead” virus (one that cannot replicate), a piece of viral DNA or protein coat that your immune system can recognize, or a small dose of a live virus, but not enough to give you symptoms of sickness.  Your body is able to easily fight these off, but also remembers the virus, so that you are protected against the real virus that could make you sick. 
In the case of HPV, we cannot grow it in the laboratory to make a “live” virus.  This is because infection with HPV requires tissue that is actively growing.  So the HPV vaccine uses a subunit of the viral protein coat, a part that your immune system can recognize and react to (Ault 2006).  This is actually a very good thing, because the vaccine uses the protein coat instead of DNA, it is non-infectious and cannot cause cancer. 
Unfortunately, because the HPV family has so many different types of HPV, the vaccine cannot protect you from all types out there.  So the goal of HPV vaccines is to protect you from the most common high-risk cancer causing types.  Gardasil is what is called a multivalent vaccine, and is designed to prevent HPV 16, 18, 6, and 11.  HPV 16 and 18 together cause about 70% of HPV related cervical cancers (and may cause some throat cancers), and HPV 6 and 11 are the main cause of genital warts, though they do not cause cancer.  Gardasil is considered by the National Cancer Institute to be 100% efficacious for those HPV types that it covers.  You COULD still get cervical cancer from other type listed above, but those are considered far less common.  Probably other vaccines will come out in the future that provide for those as well. 
Gardasil may cause some side effects, like most vaccines do.  Soreness at the injection site is common, and very rarely, something like an allergic reaction or fainting.  But those last two are very rare.   As far as testing, the vaccine has already been tested in over 11,000 women, with reported adverse effects in 1, 637 of those tested (D’Souza 2007). 
As far as I can tell, there is no evidence for it turning anyone into an incurable slut, and that argument is one of those things that just makes me seethe, because it implies that if you get cervical cancer from HPV, it must be because you slept around and you deserve it.   For all they know, you could get it from your husband!   Interestingly, though, scientists originally found that HPVs can cause cervical cancer because they found more cervical cancer in prostitutes than in nuns
So that’s about what I know.  I’m looking into getting it myself, whether that influences your decision or not.  I hope this helps!
And now I should get to the stuff that I should really be writing.  Like papers instead of posts, you know, those things that are supposed to help me graduate.

2 Responses

  1. You mentioned a few male-oriented (or at least not female-only) cancers that HPV can cause, and think even that gardasil targets the appropriate types of HPV for those. has anyone considered this drug for men? or a men’s version? from the post, there certainly seems to be a point for them.

  2. A good question. There is no reason that the vaccine couldn’t be given to men as well. I think most of the reason it hasn’t been discussed is because penile cancer is not in the public eye the way cervical cancer is.

    Right now, there is some talk about vaccinating everyone, especially when it was found that HPV could cause oral and throat cancers. Right now the major opponents of the vaccine don’t like it because they are afraid that it will somehow make girls have random sex. But there is no indication that that is the case, and even with an HPV vaccine, there should be plenty of other STDs out there to scare our little ones with.

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