Princeton researchers identify unexpected bottleneck in the spread of herpes simplex virus

Nov. 5, 2012 11 a.m.


Unlike most viruses that spread to new cells by bombarding them with millions of particles, herpes simplex virus type 1 (HSV-1) — a virus that causes cold sores and genital lesions — requires just one or two viral particles to infect a skin cell in the first stage of cold sore formation, Princeton University researchers reported in the Proceedings of the National Academy of Sciences.



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This restriction to one or two particles limits the genetic diversity of the virus that spreads to the next individual, Enquist said. This puts the virus at a disadvantage, he said, because having a variety of distinct genomes enhances the overall chances of the virus surviving and spreading. A well-known example of a virus that relies on genetic diversity to thrive is HIV, which involves large numbers of viral particles with distinct genomes.




Model of herpes virus spread from neuron to skin cell Herpes virus particles move via axonal transport inside a neuron. Upon exiting the neuron, only one or two viral particles enter the susceptible skin cell, resulting in a bottleneck that restricts viral spread. (Image courtesy of Matthew Taylor)





Taylor then filmed individual virus particles of pseudorabies virus, a model alpha-herpes virus that infects animals, as the particles exited neurons and entered skin cells. He found that the bottleneck limiting infection to one or two particles exists for pseudorabies virus as well.

As shown in the video of the process (above), viral particles, genetically altered to glow red, travel down long extensions of the neuron cell body called axons. 



The paper, "Alphaherpesvirus axon-to-cell spread involves limited virion transmission," was published Oct. 16 in the Proceedings of the National Academy of Sciences. The work was supported by the National Institutes of Health and the American Cancer Society.