A Study to Evaluate the Safety and Immunogenicity of Ad5-105K in Adults Aged 18 to 49 Years

1 doses of Ad5-105K vaccine (1 x 10\^8 vp)) on Day 0, Nebulized Inhalation (IH) through mouth

1 doses of placebo on Day 0, IH

1 doses of Ad5-105K vaccine (2 x 10\^8 vp)) on Day 0, IH

1 doses of placebo on Day 0, IH