Novel antigen panel for modern broad-spectrum recombinant rotavirus A vaccine

Abstract

Purpose Recombinant rotavirus A vaccines are being developed as an alternative to existing live oral attenuated vaccines. One of the main problems in the production of such vaccines is the genetic diversity of the strains that are in circulation. The goal of this study was to create an antigen panel for modern broad-spectrum recombinant rotavirus A vaccine. Materials and Methods The antigens of rotavirus were cloned and expressed in Escherichia coli . Antigenic specificity was investigated by Western blot analysis, which was performed using commercial polyclonal antisera to several RVA strains. Phylogenetic analysis was based on the amino acid sequences of the VP8 * protein fragment of human RVA isolates representing genotypes P[4], P[6], and P[8]. Results A universal panel of antigens was established, including consensus and conserved sequences of structural proteins VP8 * , VP5 * , and VP7, which are the main targets of neutralizing antibodies. For the first time, a consensus approach was used in the design of extended antigens based on VP8 * (genotypes P[4], P[6], and P[8]) and VP5 * (genotype P[8]) proteins' fragments. In addition, a gene coding the protein (ep-875) containing several copies of conserved short neutralizing epitopes of VP8 * , VP7, and VP5 * was created. Western blot analysis demonstrated that three synthetic VP8 * -based antigens were not recognized by commercial antiserum against rotavirus strains isolated more than 35 years ago, but the specific activity of the VP5 * and ep-875 antigens was confirmed. The problems of serological mismatch of vaccine strains and antigens with currently circulating strains are discussed. Conclusion Five antigens representing sequences of structural proteins belonging to different genotypes can be used in various combinations (from mono- to pentavalent mixtures) for the development of an effective broad-spectrum rotavirus vaccine.

Novel Universal Recombinant Rotavirus A Vaccine Candidate: Evaluation of Immunological Properties

“…For this reason, the lesser, N-terminal part of the URRA is represented by the short peptide ep8 corresponding to a linear neutralising B-cell epitope with the sequence 1 MASLIYRQLL 10 (1–10 aa of VP8*) [ 34 , 35 ], which is highly conserved among the vast majority of RV strains of all genotypes. The sequence of ep8 was obtained as described previously [ 28 ]. Peptide vaccines are supposed to induce specific immune responses to pathogens’ neutralising epitopes, including those epitopes that are otherwise inaccessible to the immune system.…”

“…The ep8 peptide sequence is followed by the sequence of the ∆VP8*P [8] towards the C-terminus of the protein. The ∆VP8*P [8] is the truncated VP8* subunit (65-223 aa of VP8*) obtained using a consensus approach based on a wide range of RVA isolates of genotype P [8], as described previously [28]. The C-terminus of the URRA contains a hexahistidine tag-coding sequence.…”

“…During infection, the VP4 spike protein is cleaved by intestinal trypsin into two subunits: VP8* and VP5*. Both of them provide a good basis for the development of a recombinant rotavirus vaccine [ 25 , 26 , 27 , 28 , 29 ]. In particular, it has been shown that a VP8*-induced immune response is sufficient for disease prevention [ 30 ].…”

“…For this, two methods were combined: the application of a conserved neutralising epitope and the use of the consensus of the extended protein's fragment. The resulting antigen, named URRA (Universal Recombinant Rotavirus Antigen), consists of a short peptide ep8 corresponding to a neutralising epitope (from 1 to 10 aa VP8*) highly conserved among RVA strains [34,35] and ∆VP8*, the truncated VP8* subunit (from 65 to 223 aa of VP8*), obtained using the consensus approach on the base of a wide range of RVA isolates of genotype P [8] [28]. The coding sequences of ep8 and ∆VP8* were designed previously [28].…”

“…The resulting antigen, named URRA (Universal Recombinant Rotavirus Antigen), consists of a short peptide ep8 corresponding to a neutralising epitope (from 1 to 10 aa VP8*) highly conserved among RVA strains [34,35] and ∆VP8*, the truncated VP8* subunit (from 65 to 223 aa of VP8*), obtained using the consensus approach on the base of a wide range of RVA isolates of genotype P [8] [28]. The coding sequences of ep8 and ∆VP8* were designed previously [28]. The potential impact of vaccines' selective pressure on RVA strains' genetic diversity and distribution, the emergence of previously uncommon RVA strains, and rapid evolutionary changes in the RVA population are all concerns that are widely discussed [14,[16][17][18][19]36,37].…”