Dose cohorts may be dosed with one of up to 4 possible total weekly doses (0.3 mg, 1 mg, 2 mg, 4 mg). Dose escalation or repetition will be governed by pre-specified safety and activity rules. Subjects will be confined on either days 1-3 and/or days 8-10. Follow-up visits are also required periodically through day 43. Study procedures involve taking blood samples for pharmacokinetic, pharmacodynamic, virologic, and safety assessments.