We were sifting through stuff found in a service room the other day, when I found a box of glass slides – undisturbed since about 1979 or so. A very interesting box: double- and triple-width microscope slides, coated with dried agarose gel, and stained with Coomassie Brilliant Blue. With my handwriting on them. With whole virus electropherograms on them….
Backing up a bit: back in a previous research career, I was a plant virologist who had become an expert, during my MSc project, on physical and serological techniques to do with plant viruses, and the multicomponent isometric bromoviruses in particular. This included differential, density gradient and analytical centrifugation; methods for purification of virus, capsid protein and genomic nucleic acid (all ssRNA); double-diffusion gel precipitin (=Ouchterlony’s technique) assays; the then new-fangled enzyme-linked immunosorbent assays (ELISA) – and whole-virus agarose gel electrophoresis, and immunoelectrophoresis.
This is mostly published – in my first-ever paper published in 1981, that I was too naive to know I shouldn’t submit to a good journal, so got it into Virology.
However, there were some bits that only ever made it into my Masters write-up – and then only in monochrome. Here, then, is a little piece of virological and personal history: electropherograms of Brome mosaic bromovirus strains, electrophoresed in 1% agarose on glass slides, then dried down and stained with CBB. Left all alone, in a drawer, undisturbed from then till now.
It is very easy to see how the three strains on the right have a pI between pH 6.0 and pH 7.5, and that the two on the left and the one on the furthest right seem to be mixtures of differently-charged variants.
Interesting technique, this: it’s a very nice way of characterising and in fact separating virus strains that differ only in a couple of charges in their capsid proteins – for future infectivity assays, if need be, or for preparative purposes by sucrose gradient “zone” electrophoresis, as done here. The thing about the slide gels, though, is that it is very cheap, very easy, and very quick – ideal for practicals and demonstrations.
I’m going to make my current MSc student characterise his plant-made virus-like particles this way…B-)
Oh, and while we’re archeologising: here is a 30+ year experiment in sedimentation at one gravity, of Tobacco mosaic virus. Shows why one should stay in one place for a while. Or not…B-)