• Safety and tolerability of intranasal ALN-RSV01 versus placebo, administered in a multiple-dose schedule (once daily for 5 days) to healthy adult volunteers experimentally inoculated with respiratory syncytial virus [ Time Frame: 28 days ]
  

• Determining the impact of ALN-RSV01 on symptoms of RSV infection, RSV infection rate based upon measures of viral load, and understanding the potential antiviral activity of ALN-RSV01 [ Time Frame: 28 days ]
  

Inclusion Criteria:

• Availability for the required study period (including the inpatient phase, ability to comply with study requirements and attend follow-up study visits
• Able to provide written consent for participation after reading the Consent Form and after having adequate opportunity to discuss the study with an investigator or qualified deputy.
• Good general health status as determined by a screening evaluation no greater than 120 days but not less than 14 days prior to enrollment and admission to the research unit
• Low titers of RSV neutralizing antibody measured during screening.

Exclusion Criteria:

• Significant acute or chronic, uncontrolled medical illness

• Presence of household member or close contact to someone who:

  • Is less than three(3) years of age
  • Has a known immunodeficiency
  • Is receiving immunosuppressant drugs
  • Is undergoing or soon to undergo cancer chemotherapy within 28 days of enrollment
  • Has diagnosed emphysema, chronic obstructive pulmonary disease(COPD), or severe lung disease
  • Is elderly and residing in a nursing home, or
  • Has received an organ transplant
• Females are not eligible for this study
• Evidence of or history of drug or alcohol abuse (within the past 6 months) or positive urine drug or alcohol screen

Other protocol-defined inclusion/exclusion criteria may apply.