Concept explainers
In 2005 a reconstructed influenza virus containing eight genes from the 1918 Spanish influenza virus was introduced into human lung epithelial cells and mice. This virus was able to rapidly reproduce and cause sudden illness and death in mice. In 2008 these genes were replaced on an individual basis with homologues from a contemporary H1N1 influenza virus and tested for virulence. Substitution of the 1918 gene with the H1N1 hemagglutinin (HA), neuraminidase (NA), or polymerase PB1 subunit severely diminished the virulence of the 1918 virus.
Explain why each of these genes is so critical for infection and virulence.
Do you think there would be an additive effect in loss of virulence if more than one gene were replaced? Explain your answer and discuss what this implies with regard to the emergence of another highly virulent influenza virus capable of causing a pandemic.
Read the original paper: Pappas, C., et al. 2008. Single gene reassortments identify a critical role for PB1, HA, and NA in the high virulence of the 1918 pandemic influenza virus. Proc. Natl. Acad. Sci. USA 105:3064–69.
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Prescott's Microbiology
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