Recombinant VLP-based vaccines have already been successfully used against 3 diseases caused by viral infections: Hepatitis B, cervical cancer and hepatitis E. and stabilization Baricitinib of these epitopes in the recombinant antigens. Delineating the critical epitopes is essential for antigen design in the early phase of vaccine development and for critical quality attribute analysis in the commercial phase of vaccine manufacturing. system and Baricitinib self-assembled into particles with a diameter of 20C30?nm in purified antigen preparations.8 A total of 112,604 healthy adult participants were enrolled in a randomized, controlled phase III clinical trial. The vaccine was also well-tolerated, protected against hepatitis E disease with an efficacy of 100% and had 78% efficacy against HEV infection.9 This VLP-based vaccine was licensed for human use in China in 2011 (Fig.?1 and Table?1).26 Figure 1. Presentation of different truncated versions of HEV pORF2. E2s (aa 459C606), the shortest version to form dimer, harbors the major neutralizing epitopes, and its crystal structure was determined with a high resolution of 2.0 ?. p239 (aa … HEV vaccine could play an important role in preventing HEV infection which is responsible for acute viral hepatitis in the developing world, especially resulting in the high mortality in pregnant women about 20C30%.23 HEV infection in animal models can elicit a strong humoral immune response that results in effective immune protection.8 Furthermore, clinical cases have shown that the serum antibodies raised against specific epitopes can protect humans Baricitinib Baricitinib from severe HEV infection-related illness.10,27,28 The HEV genome is approximately 7.2?kb long, single stranded, positive sense and includes 3 ORFs, among which the ORF2 encodes the viral capsid protein (Fig.?1 and Table?1).29 A series of B cell epitopes have been identified, particularly for the neutralizing mAb 8C11, which improves the understanding of the neutralization mechanism (Figs.?2 and 3).16,30 More importantly, because of the importance of the 8C11 epitope, this neutralizing mAb was used to design assays to assess the p239 particle integrity and antigen stability.21,31 Monitoring product consistency and process reproducibility is essential in the lifetime management of a licensed vaccine. Figure 2. The binding sites of representative neutralizing antibodies on the HEV VLP surface. (A) The pORF2 monomer is divided into 3 sections named the S domain (aa 118C313), the P1 domain (aa 314C453) or P domain (aa 320C455) and the P2 … Shape 3. The crystal structure of 8C11Fab in complicated with the E2s domain. (A) The structures of the E2s-8C11Fab complexes. (B) The epitope of mAb 8C11 on E2s, including E479, T497, R512, K534, H577 and R578 around the recombinant HEV capsid protein at the interface … In addition to the 8C11 epitope determined by the crystal structure, additional important neutralizing epitopes localized in the pORF2 were studied using classical molecular biology techniques. Zhou indicated that a truncated ORF2 protein (aa 112C607) contains the most antigenic epitopes region in the pORF2 (Figs.?1 and 2).30 Three distinct antigenic regions were identified, localized at aa 25C38, aa 341C354 and aa 517C530 of the pORF2. The same group also exhibited that this C- (aa 12C147) and N- (aa 573C660) termini of pORF2 contain strong IgG and IgM epitopes by using synthetic peptides.32 Zhang reported that this recombinant capsid protein p166Chn (amino acids Rabbit polyclonal to HYAL2. 464C629) harbors the major antigenic epitopes of pORF2.33 Another study showed that in the main structural protein encoded by ORF2, 2 immuno dominant antigenic regions were identified at aa 394C470 and aa 546C580.34 Li utilized some GST-ORF2 fusion proteins to identify that aa 394C660 of the pORF2 was strongly reactive with both acute and convalescent sera but aa 394C473 alone was poorly reactive.35 These findings suggest that the reactive epitopes are discontinuous and conformational (Fig.?2). The immuno dominant and shorter epitope region was further identified. Riddell suggested that this sequence spanning aa 394 to 457 of the capsid protein participates in the formation of strongly immuno dominant epitopes on the surface of HEV particles. The presence of Baricitinib those epitopes may be important in developing immunity to HEV contamination.36 Meng showed that this truncated version of pORF2 containing aa 452C617 elicited antibodies with specific HEV neutralizing activity.37 This was the first identification of the smallest fragment of pORF2 that can efficiently present virion-like neutralizing epitopes. Zhang expressed a 23?kDa.