RNA viruses are prominent members of NIAID's Category A, B, and C lists of biodefense and emerginginfectious disease agents. In this proposal therapeutics are being identified, characterized and developed.As our target we have chosen to focus on receptor interaction and entry. This is the first step in establishingan infection, and disruption has proved effective at preventing infection and virus spread. We havedeveloped and published a series of assays that have become a platform technology for identifying suchdrugs and, importantly, for mechanism of action analysis. Our systems are now developed to the point wherewe can perform very high-density screens. To begin, we will use a library of 200,000 compounds incollaboration with the NIH Chemical Genomics Center. Active compounds will be prioritized based oncomparative analyses of structure-activity relationships across the panel of assays determined from multipledosages. Our UTMB team will work to develop hits into useful drugs. We will systematically compare twomembers each of three classes of virus, the filoviruses, Ebola and Marburg; arenaviruses, Lassa and Junin;and the alphaviruses, Venezuelan equine encephalitis and chikungunya viruses. Comparing each virus inone screen will be an effective means to identify potential drugs active against 1) specific virus types, 2) virusfamilies, or 3) those of broad spectrum activity. All drugs will be tested against wild-type viruses. Next, wewill follow up on our Ebola virus study, in which we identified FDA-approved drugs effective at blocking Ebolavirus infection. In preliminary screens with small drug libraries and siRNA, we discovered that drugs thatblock calcium flux into cells are effective at inhibiting Ebola virus infection and cell entry, thereby preventingcytopathic effect. We will characterize each drug's mechanism of action. First, we will identify the mostpotent calcium channel blocking drugs via our specialized virus entry assays and use of wild-type virus.Second, we will address mechanism of action by identifying downstream signaling targets (e.g., CALM andCAM kinases) that may, in turn, be useful targets for anti-viral therapy. Third, we will examine the role ofvirus envelope protein in triggering this cascade by biochemically analyzing envelope protein-cellinteractions. Finally, we will test the candidate drugs in animal disease models. We will also test otherfiloviruses, including Marburg virus. Our findings will aid in developing a robust filovirus therapy and anunderstanding of how calcium signaling functions in virus infection and potentially pathogenesis.
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