Study of Bemnifosbuvir/Ruzasvir as a Fixed-dose Combination in Subjects With Normal or Severely Impaired Renal or Hepatic Function

Inclusion Criteria: * Must agree to use two methods of birth control from Screening through 90 days after administration of the last dose of study drug * Females must have a negative pregnancy test at Screening and prior to dosing * BMI of 18.5 to 43.0 kg/m2 * Willing to comply with the study requirements and to provide written informed consent Renal Impaired Subjects (Group 1): * Considered stable in the judgement of an Investigator * Presence of severe renal impairment or kidney failure (as defined by eGFR\< 30 mL/ min) Hepatic Impaired Subjects (Group 2): * Considered stable for at least 1 month prior to Screening, as per the judgement of an Investigator * Presence of severe hepatic impairment (Child-Pugh Class C: score of 10 to 15). Subjects with Normal Hepatic and Renal Function (Group 3): * Medically healthy, in the opinion of an Investigator * Must match by gender, age (± 10 years), and BMI (within 20%) to the pooled mean values of subjects with severe renal and hepatic impairment Exclusion Criteria: * Pregnant or breastfeeding * Infected with hepatitis B virus, hepatitis C virus or HIV * Abuse of alcohol or drugs * Use of other investigational drugs within 28 days of dosing * Other clinically significant medical conditions or laboratory abnormalities Renal and Hepatic Impaired Subjects (Group 1 and 2): * Presence of poorly controlled Type 1 or Type 2 diabetes as defined by Hemoglobin A1c \> 10% * Undergoing any method of dialysis * Subjects requiring treatment for hepatic impairment or other chronic disease must be on a stable treatment plan Renal Impaired Subjects (Group 1): * History of renal transplant * Concurrent use of medications known to affect the elimination of serum creatinine Hepatic Impaired Subjects (Group 2): * History of liver transplant * Evidence of hepatic carcinoma presence at Screening