A functioning protein homeostasis network, which includes cellular chaperones and the ubiquitin-proteasome system, is critical to cellular viability and human health. This is evidenced by an ever-growing number of diseases associated with protein folding dysfunction. Viral infection also places a significant burden on the cellular proten homeostasis machinery, due to the large amount of a few structurally complex proteins during infection. We have shown previously that chemical inhibitors of the 90kDa heat-shock protein, Hsp90, potently block infection by numerous enteroviral species by inhibiting the processing of their capsid precursor protein, P1. Notably, in all of the viruses tested, resistant viral variantsdid not emerge, even after long-term passage suggesting that mutations that lead to folding of P1 independent of Hsp90 reduce fitness of the virus. This is supported by the observation that selection has significant effects on the composition of the viral population that persists after selection. The goal of this proposal is (i) to leverage new deep-sequencing technologies and population genetics to quantify the effect of Hsp90 inhibitors on viral population structure, and (ii) to biophysically characterize the mechanism of chaperone independence observed in the selected population. Our working hypothesis is that the inhibition of Hsp90 function will change the viral population structure and viral genome sequence to reflect the altered constraints on viral protein folding.
Virus infection relies heavily on the action of cellular chaperone function and, as such, chaperone inhibitors are currently being evaluated as antiviral therapies. Recent work from the Frydman lab has established that the chemical inhibition of the cellular chaperone Hsp90 potently blocks enterovirus infection. Notably, even after long-term passage, resistance to these inhibitors does not emerge. This proposal outlines an innovative approach to quantify the effect of Hsp90 inhibitors on poliovirus evolution and to characterize the barriers to resistance. The mechanistic details uncovered by this study will have direct implications on the future development of chaperone inhibitors as antiviral compounds.
| Dolan, Patrick T; Whitfield, Zachary J; Andino, Raul (2018) Mapping the Evolutionary Potential of RNA Viruses. Cell Host Microbe 23:435-446 |
| Xiao, Yinghong; Dolan, Patrick Timothy; Goldstein, Elizabeth Faul et al. (2017) Poliovirus intrahost evolution is required to overcome tissue-specific innate immune responses. Nat Commun 8:375 |
| Whitfield, Zachary J; Dolan, Patrick T; Kunitomi, Mark et al. (2017) The Diversity, Structure, and Function of Heritable Adaptive Immunity Sequences in the Aedes aegypti Genome. Curr Biol 27:3511-3519.e7 |
