Targeting intramolecular proteinase NS2B/3 cleavages for trans -dominant inhibition of dengue virus

Significance Inhibitors of dengue virus, a mosquito-borne pathogen, are urgently needed. Virally encoded NS2B/3, a two-subunit serine proteinase, is responsible for many cleavages within the viral polyprotein. We demonstrate that two cleavage sites flanking NS3 and one that is internal are self-processing. This strict intramolecular cleavage dictates that, if uncleaved precursors can inhibit viral growth, this phenotype will be trans -dominant. Indeed, a mutation that abrogates one of the self-processing sites caused trans -dominant inhibition of wild-type virus. This site is also the most susceptible to a dengue proteinase inhibitor, providing a compelling rationale for its efficacy. We suggest that explicit targeting of specific intramolecular cleavage sites will be an effective antiviral strategy that can suppress multiple variants in an intracellular quasispecies.