Induction of a strong and long-lasting neutralizing immune response by dPreS1-TLR2 agonist nanovaccine against hepatitis B virus

Hepatitis B virus remains a major medical burden with more than 250 million chronically infected patients worldwide and 900,000 deaths each year, due to the disease progression towards severe complications (cirrhosis, hepatocellular carcinoma). Despite the availability of a prophylactic vaccine, this infection is still pandemic in Western Pacific and African regions, where around 6% of the adult population is infected. Among novel anti-HBV strategies, innovative drug delivery systems, such as nanoparticle platforms to deliver vaccine antigens or therapeutic molecules have been investigated. Here, we developed polylactic acid-based biodegradable nano-particles as an innovative and efficient vaccine. They are twice functionalized by (i) the entrapment of Pam3CSK4, an immunomodulator and ligand to Toll-Like-Receptor 1/2, and by (ii) the adsorption/coating of myristoylated (2-48) derived PreS1 from the HBV surface antigen, identified as the major viral attachment site on hepatocytes. We demonstrate that such formulations mimic HBV virion with an efficient peptide recognition by the immune system, and elicit potent and durable antibody responses in naive mice during at least one year. We also show that the most efficient in vitro viral neutralization was observed with NP-Pam3CSK4-dPreS1 sera. The immunogenicity of the derived HBV antigen is modulated by the likely synergistic action of both the dPreS1 coated nanovector and the adjuvant moiety. This formulation represents a promising vaccine alternative to fight HBV infection.