Tuesday, March 8, 2016

Vaccines and my Daughters

Vaccines have revolutionized medicine since their inception by Edward Jenner in 1798. Diseases such as small pox or polio which used to kill millions have almost been eradicated using vaccines.   These two along with a litany of other diseases are prevented through a series of childhood vaccinations. With three kids, my wife and I (mostly my wife) made numerous trips to the pediatrician's office in order for one or more of my kids to get their "shots".

One of the more recent advancements in vaccine therapies has been the development of vaccines towards human papillomavirus (HPV).  HPV is one of the most common viruses on the planet -- most people don't even know they have it and it is often sexually transmitted. In some women, however, it can have concerning consequences as the virus causes abnormal cells in the cervix and can lead to cervical cancer if left untreated. Currently HPV is the etiologic agent in 5% of all cancers worldwide [1]. These vaccines, marketed under the names Gardasil and Cervarix, provide immunity from about 75% of HPV strains. Most importantly is that it protects against those strains that are known to cause cervical cancer. Unfortunately this vaccine does not help those already infected with HPV and that's the problem.


High Grade Squamous intraepithelial lesion Pap Test.
High Grade Squamous intraepithelial lesion Pap Test. Courtesy of Michael Bonert  [2].

The inventor of the vaccine, Ian Frazer, explains this "It's quite simple really, most viruses kill the cells they infect, which is a nasty danger signal for the body so it turns on its defenses pretty quickly to kill it and then kill the cells making more of the virus. This process saves us from flu and a whole range of different infections." Human papillomavirus doesn't kill the cells it infects -- rather it makes them grow more. There's no danger signal to body -- all the body sees is tissue repairing itself." [3].  Because of this, Professor Ian Frazer and others are working on a vaccine that uses viral proteins that are normally on the surface of the infected cell as immunogens rather than the coat proteins of the intact virus.  It turns out that a new type of vaccine seems to work best in animal models, namely DNA vaccines.

DNA vaccines are considered to be the third generation of vaccine technology, and contain DNA coding specific proteins (antigens) from a pathogen. The vaccine DNA is injected into the cells of the body, where the "inner machinery" of the host cells "reads" the DNA and uses it to synthesize the pathogen's proteins. Because these proteins are recognized as foreign, when they are processed by the host cells and displayed on their surface, the immune system is alerted, which then triggers a range of immune responses.

While both of my daughters received the HPV vaccine as children and are most likely protected, these new vaccine technologies have the potential to save millions of lives. This technology is being used primarily in animals and currently there are no DNA vaccines approved in the US, but the few experimental trials offer substantial promise. If this can be made to work it might be a viable therapy for a number of other diseases including some cancers.


References
  1. Parkin et. al. (2005) Global Cancer Statistics, 2002 CA Cancer J. Clin. 55:74-108.
  2. By Nephron - Own work, CC BY-SA 3.0,  (2010)  https://commons.wikimedia.org/w/index.php?curid=9084518
  3. Cayla Dengate, (2016)  “Gardasil Creator Is Testing A DNA Vaccine To Wipe Out Cervical Cancer-Causing HPV Virus” Huffington Post Australia, http://www.huffingtonpost.com.au/2016/03/01/cervical-cancer-dna-vaccine-hpv_n_9350280.html.

By: BioTek Instruments, Paul Held, PhD., Laboratory Manager

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