To determine the Safety and Tolerability of a single and multiple intranasal doses of REVTx-99 when administered to healthy adults as assessed by the collection of safety data; such as adverse events; clinical laboratory tests; vital signs; 12-lead ECGs and Physical Exams. The clinical laboratory tests to assess safety are as follows: Haematology: Haematocrit; Haemoglobin; Platelet count; White blood cell count and Red blood cell count. Clinical Chemistry: Serum creatinine; Uric Acid; Calcium; Total Protein; Alkaline phosphatase; Urea; Total Bilirubin; Chloride; Bicarbonate; Albumin; Sodium; Potassium; Plasma Glucose; ALT; AST and LDH.[Single Dose: Continuously from Day 1/Predose through to Day 8/Hour 168 - End-of-Study (EOS) Multiple Dose: Continuously from Day 1/Predose through to Day 12 - End-of-Study (EOS) ];To determine the pharmacodynamic (PD) effect of REVTx-99 in healthy adult volunteers as measured by nasal cytokine levels.Nasal cytokines that will be measured include: IP-10; IL-6; IFN-alpha; IFN-beta; IFN-gamma[Single Dose: Nasal mucosa cytokine levels will be measured at Day 1/Predose and postdose at Hours 10-12; Day 2/Hours 20-24; Day 3/Hours 40-50 and Day 8 (EOS)Multiple Dose: Nasal mucosa cytokine levels will be measured at Day 1-5/Predose and Day 12 (EOS)]

To determine the Safety and Tolerability of a single and multiple intranasal doses of REVTx-99 when administered to healthy adults as assessed by the collection of safety data; such as adverse events; clinical laboratory tests; vital signs; 12-lead ECGs and Physical Exams. The clinical laboratory tests to assess safety are as follows: Haematology: Haematocrit; Haemoglobin; Platelet count; White blood cell count and Red blood cell count. Clinical Chemistry: Serum creatinine; Uric Acid; Calcium; Total Protein; Alkaline phosphatase; Urea; Total Bilirubin; Chloride; Bicarbonate; Albumin; Sodium; Potassium; Plasma Glucose; ALT; AST and LDH.[Single Dose: Continuously from Day 1/Predose through to Day 8/Hour 168 - End-of-Study (EOS) Multiple Dose: Continuously from Day 1/Predose through to Day 12 - End-of-Study (EOS) ];To determine the pharmacodynamic (PD) effect of REVTx-99 in healthy adult volunteers as measured by nasal cytokine levels.Nasal cytokines that will be measured include: IP-10; IL-6; IFN-alpha; IFN-beta; IFN-gamma[Single Dose: Nasal mucosa cytokine levels will be measured at Day 1/Predose and postdose at Hours 10-12; Day 2/Hours 20-24; Day 3/Hours 40-50 and Day 8 (EOS)Multiple Dose: Nasal mucosa cytokine levels will be measured at Day 1-5/Predose and Day 12 (EOS)]

To determine the Safety and Tolerability of a single intranasal dose REVTx-99 when administered to healthy adults as assessed by the collection of safety data; such as adverse events; clinical laboratory tests; vital signs; 12-lead ECGs and Physical Exams.The clinical laboratory tests to assess safety are as follows: Haematology: Haematocrit; Haemoglobin; Platelet count; White blood cell count and Red blood cell count. Clinical Chemistry: Serum creatinine; Uric Acid; Calcium; Total Protein; Alkaline phosphatase; Urea; Total Bilirubin; Chloride; Bicarbonate; Albumin; Sodium; Potassium; Plasma Glucose; ALT; AST and LDH.[Continuously from Day 1/Predose through to Day 8/Hour 168 - End-of-Study (EOS)];To determine the pharmacodynamic (PD) effect of REVTx-99 in healthy adult volunteers as measured by nasal cytokine levels.Nasal cytokines that will be measured include: IP-10; IL-6; IFN-alpha; IFN-beta; IFN-gamma[For Cohorts 1-3 Nasal mucosa cytokine levels from anterior nares will be measured at the following timepoints: Day 1/Predose; 30 minutes post-dose and hours 1; 2; 4; 6; 8; 12; Day 2/Hour 24; Day 3/Hour 48 and Day 8/Hour 168 (EOS). For Cohort 4 Nasal Mucosa cytokine levels from anterior nares will be measured at the following timepoints: Day 1/30 minutes post-dose and hours 1; 2; 4; 6; 8; Day 3/Hour 48 and Day 8/Hour 168 (EOS). Nasopharyngeal Nasal cytokine specimens will be collected at Predose; Day 1/Hour 12 and Day 2/Hour 24.]

To determine the Safety and Tolerability of a single intranasal dose REVTx-99 when administered to healthy adults as assessed by the collection of safety data; such as adverse events; clinical laboratory tests; vital signs; 12-lead ECGs and Physical Exams.The clinical laboratory tests to assess safety are as follows: Haematology: Haematocrit; Haemoglobin; Platelet count; White blood cell count and Red blood cell count. Clinical Chemistry: Serum creatinine; Uric Acid; Calcium; Total Protein; Alkaline phosphatase; Urea; Total Bilirubin; Chloride; Bicarbonate; Albumin; Sodium; Potassium; Plasma Glucose; ALT; AST and LDH.[Continuously from Day 1/Predose through to Day 8/Hour 168 - End-of-Study (EOS)];To determine the pharmacodynamic (PD) effect of REVTx-99 in healthy adult volunteers as measured by nasal cytokine levels.Nasal cytokines that will be measured include: IP-10; IL-6; IFN-alpha; IFN-beta; IFN-gamma[For Cohorts 1-3 Nasal mucosa cytokine levels from anterior nares will be measured at the following timepoints: Day 1/Predose; 30 minutes post-dose and hours 1; 2; 4; 6; 8; 12; Day 2/Hour 24; Day 3/Hour 48 and Day 8/Hour 168 (EOS). For Cohort 4 Nasal Mucosa cytokine levels from anterior nares will be measured at the following timepoints: Day 1/30 minutes post-dose and hours 1; 2; 4; 6; 8; Day 3/Hour 48 and Day 8/Hour 168 (EOS). Nasopharyngeal Nasal cytokine specimens will be collected at Predose; Day 1/Hour 12 and Day 2/Hour 24.]