Vaccines have been responsible for preventing millions of deaths and extending the average human lifespan. Effective vaccines stimulate the cells of the immune system to activate genes and associated functions that bring about protective immunity.This study aims to define cellular functions and genes important for the hepatitis B (HBV) vaccine immune response in healthy individuals. The investigators hypothesize that many genes associated with innate and adaptive immune functions are important for an effective HBV vaccine response.

Vaccines have been responsible for preventing millions of deaths and extending the average human lifespan. Effective vaccines stimulate the cells of the immune system to activate genes and associated functions that bring about protective immunity. Knowledge of those genes and cellular functions activated by effective vaccination can improve our understanding of how the immune system works and define the features necessary for a successful vaccine response. This study aims to define cellular functions important for the hepatitis B (HBV) vaccine immune response in healthy individuals. The investigators will identify those genes that are activated or suppressed in immune cells at various times after each dose of the HBV vaccine. The investigators will explore these vaccine-induced "gene signatures" to characterize the cellular functions associated with an effective immune response to HBV vaccination. The investigators hypothesize that many genes associated with innate and adaptive immune functions are important for an effective HBV vaccine response.

Inclusion Criteria:

• Healthy volunteer without significant medical problems
• Willing to receive three doses of an FDA-approved Hepatitis B vaccine

Exclusion Criteria:

• Male or female < 18 and > 60 years of age
• Received any vaccine within a month prior to study vaccine
• History of Hepatitis B infection
• History of previous Hepatitis B vaccination(s)
• History of Hepatitis C virus (HCV) infection or positive HCV antibody test
• Participation in another clinical study of an investigational product currently or within the past 90 days, or expected participation during this study
• Positive serum antibody against Hep B surface antigen and/or core Hep B core antigen
• human immunodeficiency virus (HIV) positive
• In the opinion of the investigator, the volunteer is unlikely to comply with the study protocol
• Any clinically significant abnormality or medical history or physical examination including history of immunodeficiency or autoimmune disease
• Is pregnant or lactating
• Currently taking systemic steroids or other immunomodulatory medications including anticancer medications and antiviral medications
• Any clinically significant acute or chronic medical condition requiring care by a primary care provider (e.g., diabetes, coronary artery disease, rheumatologic illness, malignancy, substance abuse) that, in the opinion of the investigator, would preclude participation
• Unable to continue participation for 30 weeks

Although RNA-Seq analysis was effective in measuring gene expression levels, additional study subjects (more samples) may have improved statistical power to detect subtle changes in gene expression over time post-vaccination.