Current concepts on immunopathogenesis of hepatitis B virus infection.

Hepatitis B virus (HBV) infection is a leading cause of liver damage and hepatic inflammation. Upon infection, effective antiviral responses by CD8+ T cells, CD4+ T cells, Natural killer (NK) cells, and monocytes can lead to partial or complete eradication of the viral infection. To date, many studies have shown that the production of inhibitory cytokines such as Interleukin 10 (IL-10), Transforming growth factor beta (TGF-ß), along with dysfunction of the dendritic cells (DCs), and the absence of efficient innate immune responses could lead to T cell exhaustion, development of persistent infection, and inability to eradicate the viral infection from liver. Understanding the immunopathogenesis of the virus could be useful in providing further insights toward novel strategies in the eradication of HBV infection.

Understanding Amino Acid Mutations in Hepatitis B Virus Proteins for Rational Design of Vaccines and Drugs.

The hepatitis B virus (HBV) genome encodes four proteins, i.e., DNA polymerase, surface protein, X, and core proteins. HBV undergoes different selective pressures for drug resistance and immune/vaccine escape and mutations are common for the HBV proteins. We here collected all the reported amino acid mutations happened in these four HBV proteins and studied their patterns. The relationship between the mutations and epitopic functions are investigated with bioinformatics tools, based on their sequence information. Some interesting results are observed for the mutation patterns, such as we found the serine and threonine are both for frequently mutated residues and mutant residues, while the tryptophan and methionine have low mutability. The results provide important information for the understanding of the molecular mechanism of virus evolution and therefore will facilitate the future rational design of HBV vaccines or drugs.

Synthesis, characterization and evaluation of novel triblock copolymer based nanoparticles for vaccine delivery against hepatitis B.

Poly lactic acid (PLA) is one of widely used biodegradable polymer in vaccine delivery. However, the use is restricted due to hydrophobic nature and generation of acidic microenvironment upon its degradation, rendering it unfavorable to the encapsulated antigen. In the present study we have synthesized PEG derivatized block copolymers of PLA for development of nanoparticles encapsulating HBsAg for mucosal vaccination against hepatitis B. The copolymers of compositions AB, ABA and BAB (PLA as A-block and PEG as B-block) were synthesized and characterized by 1H NMR spectroscopy and gel permeation chromatography. Nanoparticles were characterized to determine the effect of copolymer. Among all, BAB produced nanoparticles of smallest size and lowest zeta potential, suggesting highest PEG density on their surface. The in vitro release experiments were performed in PBS (pH7.4). SDS-PAGE analysis confirmed the structural stability and integrity of the released antigen. Results were compared for immunogenicity with plain PLA nanoparticles and conventional alum-HBsAg based vaccine. BAB nanoparticles produced better humoral response as compared to other polymeric nanoparticles. The extent of humoral response obtained in single dose of BAB nanoparticles was comparable to the response produced by alum based vaccine (which received a booster dose). Block copolymeric nanoparticles also produced better sIgA level at all local and distal mucosal sites as compare of PLA nanoparticles, where alum based formulation failed to give any considerable response. Additionally, IgG1 and IgG2a isotype were determined to confirm the T(H)1/T(H)2 mixed immune response. These data demonstrate the potential of BAB nanoparticles as mucosal vaccine delivery system capable of eliciting high and prolonged immune response.

One-pot synthesis, purification, and formulation of bionanoparticle-CpG oligodeoxynucleotide hepatitis B surface antigen conjugate vaccine via tangential flow filtration.

The synthesis and characterization of a Hepatitis B virus vaccine (HBsIC-ISS) candidate composed of Hepatitis B surface antigen (HBsAg) bionanoparticles conjugated to multiple copies of immunostimulatory sequence oligodeoxynucleotides is presented. An efficient tangential flow filtration (TFF) method has been developed to purify the conjugated bionanoparticles from the excess conjugation reagents. The TFF technique presented can serve as a rapid and convenient alternative to current methods like ultracentrifugation for the separation of excess small molecule/polymeric conjugation reagents from chemically modified viruses and other viruslike particles.