PINNIPERPES: SEA LION CANCER

Tavishi

 I unfortunately have been swallowed by the doing-things-and-schoolwork-black-hole. I am back!! Kradigan will never be abandoned. Even when I am under control of the Big E (employment :o ) I am now back from Wales! Last weekend I was lucky enough to go on the RVC Mountaineering Society's trip to Eryri National Park in northern Wales. It was a lovely, but stormy weekend. Nevertheless, the views were incredible:

shout out to Cecelia [cecelia we love u (I swear she wants to be here, she's just really not photogenic)]

When I came back, I hosted an event with RVC pathology society where we painted histopathology slides. This was largely inspired by the fun that I had making histopathology cookies this winter break.

I decided to paint a slide of otarine herpesvirus 1.

Fun fact- pinnipeds get a lot of herpes.

Herpes is caused by a variety of herpesviruses, all of which have double-stranded DNA. The different herpesviruses can be classified into three groups: alpha, beta, and gamma viruses. The majority of herpes infections in pinnipeds are gammaviruses, with a few alphaviruses thrown in the mix. There are several species known to infect pinnipeds, with up to 22 known viruses so far.

Most prominently among these viruses are phocid- herpesvirus 1 (PhHV-1), which is in alpha virus, and otarine-herpesvirus 1.

PhHV-1 is the first marine mammal herpesvirus ever discovered. In 1986, the virus was found in harbor seals in one of my favorite marine mammal hospitals in the world: Zeehondencentrum Pieterburen.

PhHV-1 has been found in gray and harbor seals. Seals are exposed via bodily fluids like oronasal secretions. After exposure, it takes about four days for the virus to be detected in the body. Young pups are most severely affected by PhHV-1. Between affected species, gray seals have less severe symptoms than harbor seals.

Pacific harbor seals typically have issues of the adrenal glands, whereas Atlantic harbor seals have liver necrosis. I find the regionalization of this pathology quite fascinating.

Next, Otarine herpesvirus one, or OtHV-1. OtHV-1 is known for causing cervical cancer in sea lions. This is one of the most prevalent cancers detected in a wild, free-ranging population.

It's fairly common for viruses to cause cancer and tumor formation. The first ever virus known to cause cancer was Marek's disease, which is also a herpesvirus! It causes paralysis in chickens. Anyways, urogenital carcinoma caused by OtHV-1 is super prominent in California sea lions.

california sea lion copper!

OtHV-1 is thought to be sexually transmitted. The infection is primarily found in adults who are sexually mature, and is more frequently found in males than females.

Not all cases of urogenital carcinoma are caused by OtHV-1. However, OtHV-1 is one of the greatest contributing factors to this cancer, with patients having about 43.57 times the chance of developing urogenital carcinoma when infected with OtHV-1. Urogenital carcinoma begins with neoplasia (cancerous cells) within genital tissues, including the cervix, penis, and vagina. Patients develop dysplasia characteristic of cancer in genital epithelia first. Cancer ultimately ends up metastasizing to the lungs and lymph nodes, often causing high mortality rates. Over the past few decades, prevalence of urogenital carcinoma has increased in California sea lion populations by about 15%. This is thought to be, in part, due to environmental pollutants.

A few factors are considered key towards the development of urogenital carcinoma in California sea lions:

1. OtHV-1: widely considered the greatest cause of urogenital carcinoma

2. Loss of estrogen receptor function: similar stuff has been found in cases of cervical cancer in humans! This is super cool and also a sign that you should go get a pap smear.

3. Environmental contaminants: especially in industrial chemicals and DDT

I think this is a really cool example of one health... I am so sleepy. This is where I call the post for the day.

A more complete Kradigan is coming next week! Happy November!!