Zombie Viruses – Baculoviruses

The true nature of the author, especially after too many snow days!

The other day I dragged Spouse to see the new zombie movie, Warm Bodies.  By now, he is used to my bad eclectic taste in tv and movies.

The movie is about a world in which most people are zombies due to some kind of infectious process.  After being zombies for a while, zombies become bonies, a skeletal version of zombies that are much more powerful and vicious.  It turns out that zombies (but not bonies) can be turned back into humans again through the power of love.  Yup, love makes their hearts start to beat again and their bodies heal.  In fact the main character turns back into a good-looking guy if you consider he was rotting and eating brains only a few weeks earlier.

It is a fun story if you can get past the medical improbability of a dead body regenerating itself.

A lot of zombie stories are based on some type of infectious agent.  I was wondering whether this had any real basis, and remembered a friend of mine telling me about zombie insects.  It turns out, insects can be infected with a few things that can turn them into “zombies”.  One of these is a virus called baculovirus.

Baculoviruses are found all over plants.  Baculoviruses are found everywhere, even all over our food.  One study in 1973 showed that a single serving of cabbage has over 100 million baculoviruses.  Aren’t you glad you ate your corned beef and cabbage for St. Patrick’s Day ?

Baculoviruses are only harmful to insects.  Even though you probably ate your share of baculoviruses this week, you have nothing to fear.  Baculoviruses infect insects, particularly caterpillars.  When caterpillars eat a virus-coated leaf, the virus begins to multiply in the caterpillar making millions of copies of itself.

Baculoviruses make a single protein that turns the caterpillars into zombies.  In a really elegant study (reviewed here), a group of scientists showed that a single protein made by the virus allows the virus to take over the caterpillar turning it into a zombie.

Zombie caterpillars are brainwashed.  Normal, every day caterpillar behavior involves climbing to the tops of trees at night to feed and climbing back down during the day to hide.  Infected zombie caterpillars however climb to the tops of trees, and stay up there, eating ravenously.  They also stop molting.

Zombie caterpillars face a grisly end.  Brainwashed caterpillars stay in the tops of trees until they die.  Within hours of dying, the caterpillars’ bodies turn into liquid and rain down millions of viruses onto the leaves below.

I thought we faced some pretty nasty viruses, but I am glad I am not a caterpillar!

PS.  The kids and I had a lot of fun making ourselves into zombies during the snow day yesterday using The Walking Dead’s Zombie App.