The purpose of this study is to evaluate the drug-drug-interaction (DDI), pharmacokinetics (PK) and tolerability of Morphothiadine Mesilate/Ritonavir combined with Entecavir or Tenofovir Disoproxil Fumarate in healthy subjects

This is a 2-part study with each part is an open-label, crossover study in healthy adult subjects.

Total 56 subjects will be enrolled into the study and divided into 2 part (Part A and Part B), 28 subjects in each part. Part A is to evaluate the drug-interaction between GLS4/RTV and ETV, Part B is to evaluate the drug-interaction between GLS4/RTV and TDF. With each part, the subject will be split into two groups and receive study drug per the defined treatment periods of Day 1, Day 11-20 and Day 21.

Inclusion Criteria:

• Sign the informed consent form before the trial and fully understand the contents of the trial, the process and possible adverse reactions
• Be able to complete the study according to the trail protocol
• Subjects (including partners) have no pregnancy plan within 1 year after the last dose of study drug and voluntarily take effective contraceptive measures
• Male subjects and must be 18 to 45 years of age inclusive
• Body weight ≥ 50 kg and body mass index（BMI）between 18 and 28 kg / m2, inclusive
• Physical examination and vital signs without clinically significant abnormalities.

Exclusion Criteria:

• Use of >5 cigarettes per day during the past 3 months
• Known history of allergy to study drugs，or allergies constitution ( multiple drug and food allergies)
• History of alcohol abuse (14 units of alcohol per week: 1 unit = 285 mL of beer, or 25 mL of spirits or 100 mL of wine)
• Donation or loss of blood over 450 mL within 3 months prior to screening
• 12-lead ECG with clinically significant
• Positive for Viral hepatitis (including hepatitis B and C), HIV and syphilis
• Subjects deemed unsuitable by the investigator for any other reason.