A molecular mechanism for probabilistic bet hedging and its role in viral latency

Proc Natl Acad Sci U S A. 2020 Jul 21;117(29):17240-17248. doi: 10.1073/pnas.1914430117. Epub 2020 Jul 6.


Probabilistic bet hedging, a strategy to maximize fitness in unpredictable environments by matching phenotypic variability to environmental variability, is theorized to account for the evolution of various fate-specification decisions, including viral latency. However, the molecular mechanisms underlying bet hedging remain unclear. Here, we report that large variability in protein abundance within individual herpesvirus virion particles enables probabilistic bet hedging between viral replication and latency. Superresolution imaging of individual virions of the human herpesvirus cytomegalovirus (CMV) showed that virion-to-virion levels of pp71 tegument protein-the major viral transactivator protein-exhibit extreme variability. This super-Poissonian tegument variability promoted alternate replicative strategies: high virion pp71 levels enhance viral replicative fitness but, strikingly, impede silencing, whereas low virion pp71 levels reduce fitness but promote silencing. Overall, the results indicate that stochastic tegument packaging provides a mechanism enabling probabilistic bet hedging between viral replication and latency.

Keywords: fate selection; herpesvirus; latency; stochastic variability; tegument.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Evolution
  • Cytomegalovirus / genetics*
  • Cytomegalovirus / physiology*
  • Cytomegalovirus Infections
  • Gene Expression Regulation, Viral
  • Humans
  • Monocytes
  • Viral Proteins / metabolism*
  • Virion / metabolism
  • Virus Latency / genetics*
  • Virus Latency / physiology*
  • Virus Replication


  • Viral Proteins
  • cytomegalovirus phosphoprotein 71kDa