A total of 20 healthy subjects will be enrolled into one of two dosing cohorts. Each dosing cohort will consist of 10 subjects. Within each cohort, subjects will be randomized to clinical trial material (CTM) (PRTX-100 or placebo) such that 8 subjects receive PRTX-100 and 2 subjects receive placebo. The PRTX-100 doses to be assessed in an ascending fashion are: 0.30 mcg/kg and 0.45 mcg/kg. Dosing of Cohort 2 will occur after the Investigator reviews Day 0-14 safety data and confers with the Sponsor Medical Monitor.