My daughter, who is only 4 and has been stung twice, would probably be happy to see all bees disappear. But bees are important pollinators and we depend on them for many crops. A very puzzling disorder has been causing bee colonies to collapse in North America: hives that still have abundant resources become abandoned. The bees disappear and die. This is odd because, if there were some infectious disease killing the bees you might expect to find lots of dead bees in the hive. But they seem to just disappear.
Many studies have been done to try to identify the culprit. Israeli accute paralysis virus, Varoa destructor virus -1, and the fungus Nosema ceranae have all been implicated but eventually ruled out because their presence was not strongly correlated with colony collapse disorder. A new culprit has been proposed now: a co-infection by the fungus Nosema and a large DNA virus of the family Iridoviridae called Invertebrate Iridescent Virus (IIV).
In a recent post I described the use of metagenomics to sequence all the nucleic acids present in a sample to find the cause of acute flaccid paralysis in South Asia. Metagenomics had been tried here and failed to identify the true culprit. In this study they used a different approach called proteomics. They sequenced protein fragments, rather than nucleic acids, from both healthy and collapsing bee colonies to try to find specific proteins associated with CCD. What was found were proteins from Nosema and IIV.
There is a strong correlation between the co-infection and CCD, and they went on t show that the co-infection does indeed kill bees. There are still many unknowns, however. What is it about the interaction between these two pathogens that results in this odd disorder? What makes the bees fly away and die rather than die in the hive? Are they getting lost and confused? How is it spread and how can we stop it?
(You can also check out the article in the NY TImes).
TWiV: This Week in Virology. I love listening to this podcast. When people see me listening to my iPod, they may think I’m cool and listening to the hip music all the kids are listening to these days, but no, I’m being nerdy and listening to a bunch of scientists talk about viruses. Its a great resource for learning about virology and just listening in on discussions among scientists gives you a good sense of how science proceeds – lots of questions and curiosity about the world around you.
You can go to the website or download podcasts from iTunes.
One of the things that I find most interesting about viruses is the diversity in their replication cycles. It seems that for every barrier that viruses encounter during replication it is overcome in a myriad of ways.
Imagine you are a warrior invading a castle. How many different ways can you penetrate the defenses, cross the moat, get through the walls, and then access and use all the stuff inside for your own benefit? Will you knock down the gate? Will you sneak through the windows? Catapult yourself over the wall?
A Virus must enter a host cell, take over the machinery to make lots of copies of itself, then get out and transmit to the next host. While the viral replication cycle of all viruses follows the same general patterns, the subtle differences are fascinating. Its like an evolutionary brainstorm that resulted in thousands of different ways to solve the same basic problem.
Ive asked my Biol 105 class to read Ch 19 of Campbell’s Biology and post a comment about an interesting thing about viruses that caught their attention. DId you learn something new and surprising? What is it about it that is interesting to you?
An ongoing question in virology is whether viruses are to be considered living creatures. Its easy to tell that a groundhog is alive but a book is not. But what properties does a groundhog have that a book does not? We can look up basic properties of living things in a biology textbook, and yet it remains difficult to define life in a simple sentence.
I would argue that a virus is not alive. Viruses are completely dependent on host cells to replicate. That said, in absence of the host cell the virus clearly lacks most of the properties of a living thing. (Does stealing those properties from a living thing count towards being alive?) Life seems to emerge from a collection of parts where the whole is greater than the sum of the parts. This emergent property, life, is present in animals, plants, bacteria etc, but in a virus infected cell, that property remains a part of the cell, not the virus.
Alive or not, viruses are an integral part of biology. They help us understand life and they certainly have an effect on living things.