Louis Pasteur and Insect Viruses

We told you last time about our trip to the Society for Invertebrate Pathology meeting in Tours, France.  This was another highly enjoyable gathering.  It also proved to be very successful for two of our OET-sponsored PhD students at Oxford Brookes University.  Mine Aksular won second prize for her poster presentation, “Improving baculovirus surface display system”. Leo Graves had a commendation for his talk, “3-Dimensional ultrastructural modelling of Autographa californica multicapsid nucleopolyhedrovirus infection in insect cells to determine the role of P10 during baculovirus infection”  He might have received a higher award had the audio visual equipment been able to show properly his movie depicting the 3D model of the P10 protein.  Abstracts for these talks can still be accessed: Mine’s is on page 125 and Leo’s on page 31 of the abstract book.

Our visit to France also brought to mind some of the history to baculovirus expression vectors and how indirectly, they are linked to one of the greatest of all chemists/microbiologists, Louis Pasteur.  If you don’t know about Pasteur then you need to go to the bottom of the class and take a remedial course in the history of microbiology!  Just think germ theory of diseases, which gave rise to the process of pasteurization (ergo fresh milk on your doorstep!), together with vaccination and immunization and you have some idea of the impact this scientist has had on the world.  He has also had an indirect bearing on the development of insect virus expression vectors.

Back in the mid 19th century the French silk industry was suffering unprecedented losses owing to deaths of silkworms.  Pasteur, his reputation already high owing to his earlier work on germ theory, was invited to Alais (now Alès) to determine the cause of this high mortality.  After several years’ work, Pasteur determined that microbes were responsible for the problem.  Briefly, two parasitic diseases called pébrine and flacherie were killing the silkworms.  Although their precise nature was not recognised until much later, the intellectual reasoning of Pasteur and the way he deduced that silkworms could be reared free of disease was and remains astonishing.  When so much work these days relies in slapping samples through a next generation sequencer and using sophisticated software to characterize the microbial flora of your favourite ecological niche (with some merit, I might add) Pasteur’s results are still outstanding.

Pébrine is now known to be caused by a microsporidian and flacherie by a complex that comprises an iflavirus, a densovirus and a cypovirus.  Other species of iflaviruses also infect bees and are thought be involved in colony collapse in beehives.  Densoviruses can also cause problems in commercial production of insects for food.  Cypoviruses have long been known to cause problems in insectaries dedicated to rearing butterflies and moths.

Another legacy of Pasteur’s work in silkworm production was the establishment of a strong tradition for the study of invertebrate diseases in France.  Much of this work was centred in Montpellier and San Cristol les Alès.  It resulted in many advances in baculovirology, the family of viruses from which we have obtained most of the insect cell expression systems in use today.

So although the work of Pasteur might seem buried in the distant past, his pioneering work resonates down the years and has relevance today.  It is a corny saying that we stand on the shoulders of giants, but for most virologists it really is true.

Enjoy the rest of your summer; we will be back in September with our next blog.