Phase I and Fast Track proposals will be accepted Direct-to-Phase II proposals will not be accepted Number of anticipated awards: 2-3 Budget (total costs): Phase I: $ 300,000 for up to 2 years Phase II: $ 1 million for up to 3 years. Page 105 Background Globally, an estimated 58 million people have chronic hepatitis C virus (HCV) infection, with about 1.5 million new cases occurring per year. Among people living with human immunodeficiency virus (HIV), morbidity and mortality are increasingly driven by coinfections. For such individuals, the odds of acquiring HCV are six times higher than for their HIV-negative counterparts. In the United States, an estimated 15 to 30% of persons living with HIV have HCV coinfection, but these rates vary significantly based on the individual's risk factor for acquiring HIV. WHO-recommended direct-acting antiviral (DAA) drug combination therapy can cure up to 95% of persons with hepatitis C infection, and treatment duration is usually 8-12 weeks (in the absence of cirrhosis). However, access to HCV diagnosis and treatment, although improving worldwide, remains limited, especially in low-income and lower-middle-income countries. Compliance is also of concern in treatment success, particularly in people co-infected with HIV-HCV who are required to adhere to co-administration of multiple drugs. These challenges may potentially be overcome by the use of long-acting (LA) treatments for HCV to allow intermittent dosing intervals, and, ideally, a one-dose alternative to cure the HCV infection. It is anticipated that LA treatments will be more expensive than standard drug regimens due to increased costs in manufacture, storage, and delivery. However, such LA products, now being highly acceptable by patients and providers, offer notable advantages as (1) they would allow a much-simplified test and treat strategies, (2) reduce the health care infrastructure needs for HCV medicines thereby enabling treatments to be deployed even in very remote settings, and (3) significantly mitigate concern about drug resistance development due to non-compliance. Thus, in the long term, the LA drug products could potentially help to eradicate Hepatitis C.