Karen Wynbergs Seminar: Coral reefs go viral

Karen Wynberg works at the Australian institute of Marine Science in Townsville Australia, studying the role of viruses on coral reefs. I had the pleasure of getting to know Karen and her co-worker Elisha Wood-Charlson at AIMS, and honestly these two worked regularly around the clock in a specialised lab with their own flow cytometer, to isolate, sequence and portray the virome of a coral reef.  Some of results of this work was published last year, see reference below.

Karen’s seminar was based upon work she conducted when she started at AIMS, regarding what part viruses played in coral bleaching (if any)? But first she presented some fun facts on the importance of viruses on the reef 1) they can play a role in preventing disease, for example bacteriophages that infect pathogenic bacteria. 2) They are crucial in nutrients cycling (the viral shunt) in oligotrophic water and 3) are a key part in horizontal gene transfer, one possible mechanisms which allowed corals to become resistant to V. shilloi in the Red Sea,  as we discussed in the lecture.

Why corals expel their zooxanthellae is still under debate (heated debate between coral biologist) if you then ask a virologist, they’ll put this spin on it:
It’s a virus infecting the zooxanthellae, causing the corals to bleach.

What Karen hypothesised was that the symbiodinium harboured a lysogenic virus that under stress, such as elevated temperature or UV, entered the lytic cycle. She tested her hypothesis using cultured symbiodinium (looking at them with transmission electron microscope) and found filamentous virus like (VLP) particles within the nucleus and cytoplasm. The size and morphology of the VLP were similar to plant viruses, maybe it was a viruses causing bleaching? Unfortunately, no nature paper here.  When she looked at fresh symbiodinium from thin sections of corals, the VLP were never present. The virus must only infect the symbiodinium when it is without the protection of the coral.

She also talked about the possibility of using viruses as biological control in cases of serious disease outbreak, which is something her PhD student is currently working on. They are currently looking into phages that infect cyanobacteria, to use a remedy in the initial stages of black band disease (which starts as a cyanobacteria lesion – see previous post on BBD).

Crown of thorns starfish (COTS) are listed, as one of the largest threats to the Great Barrier Reef, so another biological controls they are looking into is a virus that specifically infects the Ancanthaster planci. If they could isolate such a virus, it could be used instead of the current method, which is injecting a nasty cocktail of chemicals into the COTS and leaving it to die.

This was a great seminar from Karen, and an eye opener into the role of viruses on the reef, where my focus had previously only got as far as bacteria. Virology is a fascinating subject, with a lot to still learn, making it that bit more intriguing. I always admired the two virologists in their lab at the end of the corridor and it was great to be presented with some of Karen’s’ previous ideas, and those to come. I highly recommend keeping an eye on this author if you are interested in reef virology.

Karen's paper mentioned:

Weynberg, K. D., Wood-Charlson, E. M., Suttle, C. A., & van Oppen, M. J. (2014). Generating viral metagenomes from the coral holobiont. Frontiers in microbiology, 5.