Setting your virus free

I was reminded, as I walked in my garden in the Cape Town late afternoon sun a short while ago, of a Master’s degree project I had started with a very bright young person.  A young person who didn’t finish, because she abandoned her degree in the interests of finding herself – and subsequently got into computer-based education some 16 years ago, but that’s another story.

I have written about her previously, as it happens: she is the “Dr” Jacobson in this story, written about a year after her Honours essay on Emerging Viruses became the most authoritative source in the world on Ebola virus that was available electronically – and the Kikwit Ebola outbreak that occurred soon afterwards caused the world to go frantically looking for information.

Sadly for her, she could not work on Ebola for her Master’s, so I gave her what I thought was the next best thing: a project on making a replicating DNA vector system out of Abutilon mosaic virus (AbMV), a two-component ssDNA begomovirus.  The project started in the easiest way imaginable: she went to the local plant nursery, and bought a variegated Abutilon striatum in a pot, and planted it in our Departmental plant room.

Abutilon leaves and flower

AbMV in what is now an ornamental abutilon produces very striking symptoms, which accounts for the popularity of the plant, and its spread across much of the world – by cuttings, mainly.  This is fortunate, as in most cases the virus has lost its natural mode of transmission, which is only via whiteflies (Bemisia tabaci).  Thus, by fortuitous accident, a virus that is  effectively crippled is now spread far beyond its point of origin in South America, purely by human intervention.

Be this as it may, our mission was to harness the fact that AbMV maintains itself as an episome for the lifetime of a plant by making it into an expression vector for plant-made vaccines.  Kenneth Palmer in my lab had already done similar work with Maize streak virus; however, maize was not really a usable host because it is an annual and was hard to infect and the vector did not spread.  It was also not usable in dicot hosts, so we settled on AbMV as being available in our and many other back yards.

We did not get far: while Alison was really bright, by this time she had discovered that science really wasn’t for her, and made essentially no progress beyond cloning a B genome and getting some sequence out of it.  She left to find more fulfilling things to do, and her experimental material continued to grow in the plant room – and gather red spider mites.  I still have the badge off her labcoat, incidentally: I couldn’t let it go; it was and is the only Led Zeppelin logo I have ever seen on the standard white coat.

This is where we get to the title of this post. In 1996 or so, I took the by-now largish plant in its pot back home, and set it free: I planted it in my garden.  It eventually developed into a large bush, easily 3 x 2 metres wide and tall – and has just been cut back, after some 16 years, to allow it to redevelop.  I get a little kick out of seeing civilians step nervously away from it, after I have walked them up to it, and say: “And this is the biggest virus you will ever meet”.  Let’s see you do THAT, Ebola virologists!

Oh, it isn’t entirely free: we sampled it again a couple of years ago when the fearsomely efficient geminivirus-hunting crew that grew out of my lab wanted samples to test their then-new phi29 rolling circle amplification chops on.  We could still only get a B genome out of it, and one that was 10% different from any other published AbMV – so maybe there’s still a story there.

But all it has to do now is keep on growing.  And look beautiful.

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One Response to “Setting your virus free”

  1. Ed Rybicki Says:

    Damn thing died B-(

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