Pharmacokinetic Study in Cerebral Spinal Fluid After a Single Dose of AVI-4020

Inclusion Criteria: * Adult males 18 years to 64 years of age; * Good general health (as evidenced by no chronic conditions, normal physical exam, vital signs within normal limits; laboratory evaluations within normal range) * Signed and dated written informed consent form; and * Willing to participate in all study activities and all requirements, including effective contraception (viz., a double-barrier method) during the 7-day study surveillance period. Exclusion Criteria: * Hematology, serum chemistry (exclusive of electrolytes), and urinalysis laboratory test values \>2 times upper limits of normal or anemia (hemoglobulin \<11 g/dL), leukopenia (total white blood count \<3,000/µL or total neutrophils \<1,500/ µL) or thrombocytopenia (platelets \<100,000/µL). Electrolytes and coagulation values exceeding normal ranges are to be excluded. * Body Mass Index (BMI) \>35. * Calculated creatinine clearance (by the Cockroft and Gault Formula) \<70 mL/min, based on age and gender. * Positive HIV-1 or HIV-2 serology. * Positive HCV serology and/or positive plasma HCV-RNA status. * Positive Hepatitis B status. * Solid or hematopoetic organ transplant recipient. * Active illness or recent illness within 30 days of the first dose of study drug. * History of any of the following: brain injury, neoplasm, chronic or migraine headaches, cancer, meningitis or hydrocephalus. * Usage of any prescribed, over-the-counter or illicit drug(s) within 30 days of study drug administration. Use of herbal remedies and/or supplements at the discretion of the Investigator. * Unwilling to practice effective contraception during the study period. * Participation in any clinical interventional trial within the previous 6 months. * Positive drug urine screen.