The Phase I bridging clinical trial is to evaluate on the safety, pharmacokinetics (PK), pharmacodynamics (PD) and ADA of a single intramuscular injection of recombinant anti-rabies human monoclonal antibody injection (SYN023) alone or combined with rabies vaccine in healthy subjects. The study primary purpose was to compare the pharmacokinetics (PK) between U.S and China subjects, therefore to lay a foundation for the follow-up clinical trials. The secondary purpose was to evaluate the PK, PD, Safety and ADA of SYN023 in Chinese Healthy subjects and compare with that of U.S. subjects.

In this bridging study. the Pharmacodynamic, Pharmacokinetic, Safety and ADA(Anti-Drug Antibodies) were evaluated and compared between U.S. and China subjects.

Inclusion Criteria:

1. Sign the informed consent before the trial, fully understand the trial contents, process and possible adverse reactions, and cooperate to observe the adverse events;
2. Could participate the entire study according to the protocol;
3. Subjects including partners are willing to voluntarily take effective contraceptive measures from screening to 6 months after the last study drug administration.
4. Male and female healthy subjects aged 18-50 (including 18 and 50 years old)
5. The weight of male subjects shall not be less than 50 kg, and that of female subjects shall not be less than 45 kg and shall not be more than 90 kg. Body mass index (BMI) = body weight (kg) / height^2 (m^2), body mass index should be in the range of 18-30 kg/m2 (including);
6. Physical examination and vital signs are in normal range or the abnormality without clinical significance, and the body temperature is ≤ 37.6 °C.

Exclusion Criteria:

1. Smoked over 5 cigarettes per day for 3 months before the trial;

2. History of allergy (multi drugs and food allergy); history of severe allergic disease or allergic reaction; including allergy to any component of this drug;

3. History of alcohol addiction (14 units of alcohol per week: 1 unit = 285 mL beer, or 25 mL spirits, or 100 mL wine);

4. Blood donation or massive blood loss (> 450 mL) occurred within 3 months before screening;

5. History of autoimmune diseases;

6. History of chronic hepatitis ;

7. History of rabies virus infection;

8. Other acute or chronic diseases (within 6 months) that may interfere with the safety and efficacy evaluation of the subjects according to the investigator's judgment;

9. Receipt of an immunoglobulin or blood product within 90 days prior to study;

10. History of rabies vaccination;

11. Receipt of immunosuppressive medications included the inhaled or local immunosuppressant drugs within 45 days prior to Study;

12. Taken any prescribed, over-the-counter, vitamin product or herbal medicine within 14 days before screening;

13. Receipt of special diets (such as grapefruit) or endure strenuous physical exercise or any other factors affecting drug absorption, distribution, metabolism and excretion within 2 weeks before screening;

14. Had significant changes in diet or exercise habits recently;

15. Had been administrated with the investigational drug or participated in the clinical trial of the drug within three months before taking the investigational drug;

16. The evidence of clinically significant of the abnormalities of 12 lead ECG ;

17. Female subjects in lactation or positive for serum pregnancy test during screening for study;

18. Clinical significance of clinical laboratory results of screening, or suffered from the following diseases, including but not limited to gastrointestinal tract, kidney, liver, nerve, blood, endocrine, tumor, lung, immune, mental or cardio cerebrovascular diseases within 6 months;

19. Positive in the screening of viral hepatitis (including hepatitis B and C), AIDS antibody, and treponema pallidum antibody;

20. Acute disease or drug administration from the screening to the initial of the study;

21. History of taken chocolate, or any food or drink containing caffeine or rich xanthine 24 hours prior to administration of the study drug;

22. History of taken any alcoholic product within 24 hours prior to administration of the study drug;

23. Drug abuse ;

24. Not suitable for enrolling in the study according to the investigator's judgment.

    Additional exclusion criteria for Group B:

25. Clinical significance of Immunoglobulin A abnormalities according to the investigator's judgment;

26. Undergoing anti-tuberculosis prophylaxis or treatment;

27. History of thyroidectomy, or treatment due to thyroid diseases in the past 12 months;

28. Diagnosed with serious angioneurotic edema in past 3 years or with the treatment in the past two years prior to the study;

29. Advanced tumors, or neoplasm in treatment and shows no evidence of recovery, or may relapse during the study;

30. No spleen or history of splenectomy;

31. Guillain-Barre syndrome or other serious neuropathy;

32. Receipt of live-attenuated vaccine within 30 days prior to the study;

33. Receipt of subunit or inactivated vaccine (such as pneumococcal vaccine), or allergy treatment within 14 days prior to the study;