Since its first outbreak occurred in 1976, Zaire Ebola virus have been associated with 14 outbreaks reported up to 2014. The Zaire Ebola virus in 2014 causing the most serious outbreak was considered to be a new epidemic strain, with GP homology of the gene was only 97.6%, compared to the GP gene of the strain in 1976. This investigational Ad5-EBOV vaccine was developed according to the 2014 epidemic Zaire strain and formulated as freeze-dry products which could be stored at 4℃.

This is a single center, double-blind, placebo control, dose-escalation phase 1 clinical trial. This study will determine the safety and side-effect profile, and immunogenicity of an investigational Ad5-EBOV vaccine.

Inclusion Criteria:

• Aged between 18 and 60 years.
• Able to understand the content of informed consent and willing to sign the informed consent
• Able and willing to complete all the secluded study process during the whole study follow-up period (about 6 months).
• A body mass index (BMI) <35
• Hemoglobin 110-150g/L for female, and 120-160g/L for male.
• White blood cells (WBC) 4.0-10.0×109 cells/L
• Total lymphocyte Count 0.8-4.5×109 cells/L
• Platelets 100-300×109 cells/L
• Alanine aminotransferase (ALT) 0-40U/L
• Serum creatinine 44-106μmol/L
• Partial thromboplastin time (PTT) 20-40 seconds
• Prothrombin time (PT) 10-14 seconds
• Negative in HIV diagnostic blood test
• Axillary temperature ≤37.0°C on the day of enrollment
• General good health as established by medical history and physical examination.

Exclusion Criteria:

• Family history of seizure, epilepsy, brain or mental disease
• Subject that has a medical history of any of the following: allergic history of any vaccination or drugs, or allergic to any ingredient of the Ad5-EBOV vaccine, such as mannitol
• Woman who is pregnant, breast-feeding or positive in β-HCG (human chorionic gonadotropin) pregnancy test (urine) on day of enrollment, or become pregnant during the next 6 months
• Any acute fever disease or infections in last 7 days
• Major congenital defects or not well-controlled chronic illness, such as asthma, diabetes, or thyroid disease
• Hereditary angioneurotic edema or acquired angioneurotic edema
• Urticaria in last one year
• Asplenia or functional asplenia
• Platelet disorder or other bleeding disorder may cause injection contraindication
• Faint at the sight of blood or needles.
• Prior administration of immunodepressant or corticosteroids, antianaphylaxis treatment, cytotoxic treatment in last 6 months
• Prior administration of blood products in last 4 months
• Prior administration of other research medicines in last 1 month
• Prior administration of attenuated vaccine in last 1 month
• Prior administration of inactivated vaccine in last 14 days
• Current anti-tuberculosis prophylaxis or therapy
• Any condition that in the opinion of the investigators may interfere with the evaluation of study objectives