Hepatitis B Vaccines Based On preS1, preS2 and S Domains

Hepatitis B virus (HBV) remains a global health problem, one of the leading causes of liver cirrhosis and carcinogenesis. Vaccination is the only effective way to fight HBV, as the prevalence rate of the virus in children under 5 years of age dropped to 1.3 from 4.7 by the end of 2018 following the implementation of a global vaccination program in 189 countries. Despite the admirable impact of the global vaccination program, the vaccine continues to be non-responsive or hypo-responsive in some susceptible and specific groups. Due to the absence of a standard treatment protocol for the complete elimination of the virus from the body, the design of therapeutic vaccines or those with both therapeutic and prophylactic roles in patients with chronic HBV is of interest to researchers in this field. In this regard, the focus is on fragments with greater immunogenicity and the use of more efficient adjuvant compounds. The use of other protein fragments such as Pres1, Pres2, and S has also been more successful in designing both therapeutic and prophylactic vaccines. Different adjuvants targeting humoral and cell-mediated immune pathways, such as CpG oligonucleotide motifs, are used alongside different fragments of viral coat protein now in different phases of clinical and preclinical trials.