Students taking my virology course at the University of Leicester get a weekly newsletter containing extra links relevant to the lectures. This week we have been looking at virus genomes and the class notes are from Principles of Molecular Virology, chapter 6.
A virological view of innate immune recognition
The innate immune system uses multiple strategies to detect viral infections. Because all viruses rely on host cells for their synthesis and propagation, the molecular features used to detect viral infections must be unique to viruses and absent from host cells. Research in the past decade has advanced our understanding of various cell-intrinsic and cell-extrinsic modes of virus recognition. This review examines the innate recognition from the point of view of virus invasion and replication strategies, and places innate sensors in the context of detecting viral genome, replication intermediate, transcriptional by-product, and other viral invasion strategies. On the basis of other unique features common to viral infections, undiscovered areas of virus detection are discussed.
A virological view of innate immune recognition. (2012) Annu Rev Microbiol. 66: 177-196
This relates back to defective virus genomes, which we covered earlier in the course:
Defective viruses are viral particles with genetic mutations or deletions that eliminate essential functions, so that they cannot complete their life cycles independently. They can reproduce only by co-infecting host cells with functional viruses and ‘borrowing’ their functional elements. Defective viruses have been observed for many human pathogens, but they have not been thought to impact epidemiological outcomes. Recently it was reported that a lineage of defective dengue virus spread through humans and mosquitoes in Myanmar for at least 18 months in 2001–2002. This study investigates the emergence and epidemiological impact of this defective lineage by combining genetic sequence analyses with mathematical models. It shows that the defective lineage emerged from circulating dengue viruses between June 1998 and February 2001, and that it spreads because its presence causes functional dengue viruses to transmit more efficiently. This study demonstrates the potential for defective viruses to affect the epidemiology of infectious diseases.
Phylodynamic Analysis of the Emergence and Epidemiological Impact of Transmissible Defective Dengue Viruses. (2013) PLoS Pathog 9(2): e1003193. doi:10.1371/journal.ppat.1003193