A research team from Purdue University and Texas Biomedical Research Institute is in pursuit of important new approaches to validate the host V-ATPase. The project goal to define antiviral drug leads for diseases caused by Ebola and Marburg filoviruses. Many viral pathogens bind to specific factors of host cells to penetrate the plasma member inside vesicles called endosomes. However, entry of the virus to the host cells requires escape from these vesicles. A majority of these viruses utilize the low pH of late endosomes to trigger the final steps in viral entry. Since the acidification of endosomes depends on vacuolar H(+)-ATPases (V-ATPases), inhibiting this pump interferes with entry of a wide range of viruses. Thus, the host V-ATPase represents a truly broad-spectrum target for antiviral drugs. While feasible, there are challenges for developing antiviral drugs that targets host factors like V-ATPase because of the potential risk of toxicity to non-infected cells and tissues. The approach used in this project directly addresses this challenge which will apply discovery and pharmaceutical technologies to achieve selectivity of drug action. The project team brings significant expertise to the challenges for discovery and development of host-targeted antiviral therapeutics. Efforts will integrate chemistry and biochemistry of natural-product V-ATPase inhibitors, viral-host entry pathways, Ebola and Marburg animal disease models in BSL4 facility, in vitro and in vivo ADME-pharmacokinetics, and toxicology. Currently, there is a lack of suitable in vivo chemical probes available to test safety and efficacy of pharmaceutical interventions targeting V-ATPase. The objectives for this five-year project are to: a) qualify a class of selective chemical inhibitors for V-ATPase suitable for in vivo antiviral efficacy testing, and b) identify a new drug lead candidate targeting V-ATPase function during the viral entry process for Ebola and Marburg filoviruses. These complementary objectives will impact the prospects and precise strategy for developing antiviral therapies to treat unmet needs.