Protocol AH-105 is a single center, randomized, double-blind, placebo-controlled, sequential, dose escalation study. It will evaluate the safety and PK of single IV doses of ETI-204 administered to approximately 108 healthy male and female subjects. At each dose level, 30 healthy subjects, including at least 4 females, will be randomly assigned to active drug, and at least 6 healthy subjects of both genders will be randomly assigned to matching placebo.