IMMUNOGENICITY OF THE THIRD GENERATION HEPATITIS B VACCINE (pre-S1/pre-S2/S)

Currently, second-generation hepatitis B vaccines are widely used. They are produced in biotechnological eukaryotic yeast-based systems and contain the S-protein domain of HBsAg particle in the complete absence of pre-S1 and pre-S2 domains. At the same time, these antigens were proved to significantly influence immunogenicity, which makes the development and use of third-generation vaccines containing all antigenic determinants a long-range objective. A randomized, double-blind clinical study was conducted to compare immunogenicity of second- and third-generation vaccines Engerix-B™ and Sci-B-Vac™, respectively. Healthy subjects of both sexes aged 18 to 45 years (n = 94) who are seronegative for HBsAg, HBsAb, HBcAb at screening and who previously had not received immunobiological agents for hepatitis B prophylaxis were included in the study. Group I (n = 47) received the second-generation vaccine Engerix-B™, Group II (n = 47) — the third-generation vaccine Sci-B-Vac™. Subjects received vaccines three times — on days 1, 28 and 180 of the study. HBsAb levels, rates of seroconversion (the proportion of subjects with HBsAb levels 2.1 mIU/mL) and seroprotection (the proportion of subjects with HBsAb levels ≥ 10 mIU/mL) were assessed on days 28, 90, 180 and 210 of the study. Early seroconversion rate assessed on Day 28 was 76.60% in Group I and 93.88% in Group II (p 0.05); seroprotection rate was 51.06 and 61.22%, respectively. These differences in the proportion of subjects who achieved seroconversion on Day 28 may indicate a faster immunological response to Sci-B-Vac™ vaccine. Statistically significant differences between the level of antibodies on days 90 and 180 (p 0.05) were observed when analyzing the average values of HBsAb concentration in Groups I and II. The concentration of HBsAb on Day 90 was 378.68±60.95 mIU/mL in Group I, and 618.31±58.34 mIU/mL in Group II. On Day 180, the concentration of HBsAb reached 441.34±63.83 mIU/mL in Group I, and 757.72±55.14 mIU/mL in Group II. The significance of dependence of antibody level on sex, age and body weight was analyzed. It was revealed that the age of a vaccinated subject affects antibody level after administration of Engerix-B™ (p 0.05). The results obtained suggest that there is a rapid and strong immune response to the third-generation vaccine Sci-B-Vac™. This may indicate advantage of the vaccine containing all three recombinant proteins of hepatitis B virus envelope, which, in turn, can play a key role in clinical practice for urgent prophylaxis of hepatitis B, as well as for treatment of immunocompromised conditions.