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The HPV Vaccine: Part 2

Within the human papilloma viruses as a group, there is a lot of variation based on their DNA sequence. DNA is the Master Plan for the cell, and it is also the Master Plan for the virus. DNA contains the plans for cell-specific proteins, which are what make things and do things within the cell, and all cells and viruses have their own DNA.

Remember: Different strains of HPV=different DNA=different proteins.

Because of these differences in DNA sequence, some strains produce specific proteins which in true, terrible-at-naming-things Scientist fashion, have been called E6 and E7.

E6 and E7 run around the host cell and interact with some very important host cellular proteins, which, in the same scientific naming tradition, have been dubbed p53 and Rb.

p53 and Rb play vital roles in making sure that a cell does not divide when it shouldn’t.  For instance, a cell could have damaged DNA.  Under normal circumstances, the p53 and Rb proteins are guardians that survey the cell and assess its readiness to divide.  They have the power to say, “Stop!  We are not ready to divide!  Halt at once, and repair our Master Plan!” and the cell will listen, repair DNA, and not divide until p53 and Rb are cool with it.  E6 and E7 find p53 and Rb and physically prevent them from sounding the alarm, so suddenly, a cell that probably shouldn’t be dividing at all is instead dividing like crazy.

So we have cells dividing like crazy, creating masses that aren’t useful to us where they shouldn’t be…Sounds like cancer, right?

That’s because it is cancer!  See?  I knew we could Science this together!

Luckily, not all HPV viruses have E6, E7, or similar proteins.  And most humans with an intact immune system will either completely fight off most HPV infections, or the immune system will beat the HPV into dormancy.

At the same time, though, it is very rare for cervical cancer cells to not be infected with HPV, which rather strongly suggests that most cases of cervical cancer can be attributed to HPV.  Why wasn’t the HPV infection defeated by the immune system?  That may be because the human picked up a particularly nasty strain, but there’s also the fact that some humans don’t have an intact immune system—they could have an inherited immune disorder, or diabetes, or be on systemic steroids to treat a whole bunch of things, or have AIDS…I could literally make a blog entry on reasons why folks may be immunosuppressed.

The particularly nasty, common, high-risk strains of HPV with proteins E6 and E7 are called types 16 and 18.

Due to producing proteins E6 and E7, these strains are much more likely to cause cancer.

There are also two very common HPV strains, strains 6 and 11, and they usually cause anogenital warts.  However, these strains can also potentially cause cancer, and since so many people are infected by them, types 6 and 11 statistically give at least some people cancer.  It’s sort of like how, even though it is extremely unlikely, people manage to get struck by lightning.  There’s just a lot of lightning and a lot of people.  Statistically, someone will get struck.

So that’s the HPV virus in a nutshell. We’ve Scienced the heck out of it!  With that information in mind, let’s discuss the diseases caused by these cellular shenanigans!

Tell Me Why I Care:  The Effects of HPV Infections

Most commonly, HPV can cause cervical cancer.  These same strains can also cause anal cancer, oropharyngeal cancer, and something called respiratory papillomatosis which is a disease that occurs rarely when an HPV infection is transmitted to an infant’s respiratory tract from their mother during vaginal birth.  This means that masses will grow in the infant’s airway that will suffocate them if  not removed by surgery or lasers.

All of these are terrible.  All of these could potentially be a blog entry all by themselves.

However, given that this is the Sheroes blog and Sheroes has a lot of cervix-having members, I’m going to give you a relatively brief, generalized overview of cervical cancer.

Luckily for women of North America and most industrialized countries, we have access to something called a pap smear.

For readers who haven’t experienced this not-especially-fun-but-also-generally-not-too-painful procedure, a pap smear is when a doctor takes a sterile, specialized brush on a stick and swabs it lightly over your cervix. The brush picks up a layer of epithelial cells, the very cells HPV infects.  The doc then sends the sample to a lab.

A technician can put infected cells on a slide, stick the slide under a microscope, take a peek, and say, “Huh, this is not how a cervical cell should look!”

And then they will send the report to your doctor, who will tell you there is something called a dysplastic change.

Dysplastic change is a fancy phrase for “your cells look weird”.  However, in a woman who has had proper screening at regular intervals throughout her adult life, this is probably not a cause to panic right away since the change has probably been caught early. Depending on the individual patient, doctors tend to opt for either “watchful waiting” or something called a colposcopy and biopsy, in which case they’ll coat your cervix with a very dilute acid that makes the HPV infected cells turn white.  They will then take a small sample of your cervical tissue called a biopsy, and send that to the lab for analysis.

If the biopsy does show evidence of cancer, then the doctors can treat it with the usual suspects: surgery, radiation, chemo.

While a treatment plans are highly individual, in general, cancers which are caught early and confined to the surface of the cervix can be treated with a simple outpatient surgical procedure with nearly 100% success, as long as all of the cancer is cut out.

However, cervical cancer has a tendency to spread locally. It can move to the uterus, fallopian tubes, or ovaries.  This development may also necessitate a hysterectomy.  That can be really hard for women to go through emotionally, but again, survival rates at this stage are around 85%.

Even worse, the cancer can also invade nearby structures, like the anal canal, or ureters. One cause of death in cases like these is kidney failure, because the cancer literally blocks urine from getting out, which damages the kidneys irreparably.

In cases this advanced, patients may be offered a procedure that goes by several names, one of them being “hemicorporectomy.”

Dust off your Latin and Greek; we’re going to break this word down:

Hemi=half

Corp=body

Ectomy=surgical removal

…Yeah.

It’s intense.

Let’s take a moment to think about that word and what it might mean for a patient.

The patient’s legs, colon, reproductive system, and lower urinary tract are removed, because the cancer has spread that far.  Doctors recreate what structures they can, but they’re surgeons, not magicians.  It is a radical surgery with radical consequences. It is not done lightly—it is done because the patient will die without it.  Once cervical cancer reaches a certain stage, there is no radiation or chemotherapy that has been shown to increase survival rates.

And some patients still die, either because the cancer has spread too far, or because it recurs.  It is a horrible disease, and while it can be screened for, screening does not help women who without access to regular screening.  Since cervical cancer generally does not become symptomatic until relatively late, cases in unscreened women can be quite advanced, and the consequences can be devastating.  It is estimated that over 4,000 women will die of cervical cancer in 2014.

That’s terrible. The vast majority of these cancers are due to HPV infections and, thus, can be prevented. Luckily, there are two HPV vaccines on the market: Gardasil and Cervarix. Gardasil protects against HPV strains 6, 11, 16, and 18.  Cervarix only protects against strains 16 and 18.

These two vaccines are made from viral proteins produced in bacterial, yeast, or insect cells.  They cannot cause HPV infections because there is no viral DNA in the vaccine. Instead, they stimulate the immune system to respond to the viral proteins, so if the recipient is ever exposed to that strain of HPV, the immune system will be ready to kill the virus and prevent an infection.

How awesome is that?  Get vaccinated!  Get your kids vaccinated!  Vaccines for everyone, less cancer and anogenital warts and respiratory papillomatosis for all!  Heck yes!

Still not convinced? In the next installment, I’ll answer common questions about the HPV vaccine.

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Fancci is a US osteopathic medical school student in her clinical years.  She hopes to one day open a rural family practice clinic, but first needs to survive the rest of med school and a residency.

Please join us over on the forums to discuss this post!

The HPV Vaccine: Part 1

I’m here today to talk about the HPV vaccine.

I know that’s the blandest introductory sentence ever.  I’m sorry, Freshman Comp professor, but I do have a purpose behind it: most blog entries I’ve read about the HPV vaccine frame it as a controversial vaccine starting from the introductory sentence, and it really shouldn’t be controversial.  I’ve chosen to start out with an innocuous topic sentence to convey how boring and routine and non-controversial this vaccine should be.

Getting yourself or your kids the HPV vaccine should be a no-brainer, and I’m here to convince you of that fact.

First, a caveat:  There are folks who will want to turn any discussion about vaccinations into a “controversy”, because they believe Vaccines are Evil.  There are plenty of other articles debunking them and their thinking, so I’m just going to address Anti-Vaxers with this video:

https://www.youtube.com/watch?v=WrjwaqZfjIY

Now shoo, Anti-Vaxers!  We have nothing to discuss, here!

Understanding the Human Papilloma Virus (HPV)

The discussion of the virus is going to involve Science.  Trust me, even if you are Science-adverse, you are smart, and you can handle this!  Just hang with me and we’ll get through the Science together!

Okay, onward!  To the Science!

The human papilloma virus is, as the name implies, a virus.  It’s a pretty hardy little guy that can survive heat, drying, and some kinds of disinfectants, so if it gets on a surface,  it will probably stick around for a while and remain infective.  Most viruses are transmitted by skin-to-skin contact, but the fact that HPV is so resilient does make it difficult to prevent transmission.  For instance, scratching a wart and then touching a cut on a different part of your skin can transmit HPV from the wart to your fingernail to the cells at the cut.  Similarly, if someone gets HPV on their hands and it gets on the outside of a condom while the human is applying a condom during safe sex, the HPV can be transmitted to their sexual partner from the condom.  Fortunately transmission of the virus via an inanimate object (whether a condom, fingernail, or table)does not appear to be super common, but it is possible. So condoms (and other safe-sex barrier methods) have some use in reducing the spread of HPV, but they don’t completely eliminate the risk.

I mean, condoms are totally awesome in preventing all sorts of other STDs, like AIDS, or chlamydia, or gonorrhea, or pregnancy.  Absolutely practice safe sex and use condoms.  Just know that there are limits to safe sex, and unfortunately, this is one of them.

So moving on, how does the virus actually get into your body and infect you? Normal human skin is really resistant to viral entry, so HPV has to get in by a break in the skin—a scratch, a nick, or a microtear, which is a scratch so tiny you probably don’t even know you have it.  Also, mucous membranes – which cover the penis, vulva, vagina, cervix, GI tract, and anus, among other places –are particularly susceptible to microtears and don’t have as strong defenses as regular skin.  Unsurprisingly, this makes mucous membranes an easy target for HPV viruses.

Once the HPV gets past the top layer of cells in your skin or mucous membrane, the virus enters the basal cells.  Basal cells are constantly dividing and producing new cells that will become your skin cells or the cells of your mucous membrane,  so that you don’t run out of skin and walk around skinless (assuming you managed to not die of a massive infection long enough to walk around).

However, if you have HPV, then during the growth and maturation of these new cells the virus will hijack the cell’s growth process to reproduce itself – even as the cell continues to mature.  Once that virus-laden cell reaches the surface of the skin, the virus is shed off into the environment with its host cell, ready to infect more cells and repeat the cycle.

In fact, a lot of viruses reproduce and spread this way, and sometimes this can be pretty benign– including some HPV viruses.  For instance, warts are maybe kind of unsightly, but they are not going to kill you. Unfortunately, HPV can also cause cancer sometimes, which can kill you.

So, what’s the deal with HPV and cancer? Since when does a virus cause cancer, anyway? I’ll answer those questions in the next installment.

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Fancci is a US osteopathic medical school student in her clinical years.  She hopes to one day open a rural family practice clinic, but first needs to survive the rest of med school and a residency.

Please join us over on the forums to discuss this post!