| Rotaviruses are the major pathogen of acute gastroenteritis in human beings, mammals and birds. RV with high variability, can easy to evade the host immune surveillance. Despite some great success received in development of RV vaccines, a lot of issues in RV vaccine defects need to overcome. Up to know, all RV vaccines currently used in humans are live attenuated vaccines, Rotarix, Rotateq are the most popular worldwide. LLR is the only vaccine developed in China. It was demonstrated that Rotarix, Rotateq had good immunogenicity, could induce neutralizing antibodies against, protect infections from G1-G4types. Although these vaccines had very good protective effect on severe diarrhea, were not ideal to protect mild or moderate cases. In addition, attenuated live vaccines could not avoid virulence reversion problem. The security issue of RV vaccines also attracted popular attention. Recently, Rotarix and Rotateq vaccines were found have contamination with genomic DNA of porcine circovirus. Taking into account not has been confirmed the virus in the humans can cause adverse reaction and balancing social effect of the current state of RV vaccines, these two vaccines are still remained in use. LLR vaccine, for the lack of information about its adverse reaction monitoring and long-term evaluation, its clinic protection efficacy is still not clear. RV vaccines in other modes still need to study. Development of more safe, economic and effective vaccines is urgently expected. In this paper, RV recombinant chimeric epitope vaccines were studied, the results obtained had great value in development of RV recombinant vaccines.RV genome consists of11segments of double-stranded RNA (dsRNA), which encodes6structural proteins (VP1-VP4, VP6, VP7) and6non-structural proteins (NSP1-NSP6). It was shown that in previous studies, the VP6, the major structural protein, plays a key role in the morphogenesis of the virion, acts as a physical adaptor in cell entry, able of self-assembling into VLP.In addition, the VP6possesses at least two Th epitopes for CD4+T cells and cross reactive CTL cell epitopes, and can induce protective efficacy in animals. With these specific characteristics, the VP6was considered as a useful carrier for displaying foreign epitopes.The VP4is a main protective antigen, able to induce neutralizing antibodies. The VP4is a non-glycosylated protein, containing serotype specific sites between aa80-aa180. The VP4is the major crossing neutralizing antigen, has characteristics of haemagglutinin and trypsin cleavage enhancing virus infectivity. The VP4content is only of11.7%among viral structural proteins. Up to now, RVs found in group A could be divided into at least33genotypes based on VP4homology, of them12species infected humans, P[8] and P[4] are the most common genotypes. With a single serotype specific VP4protein, neither a live attenuated vaccine nor recombinant vaccine is able to fully protect from RV infections. As the group (subgroup) antigen, with high homology and the characteristics mentioned above, the VP6in theory might remedy this defect.In this study, using gene cloning and recombinant techniques, the VP6coding cDNA derived from TB-Chen strain RV was cloned, modified, some restriction endonuclease sites were induced on lateral VP6protein molecular, and a recombinant plasmid carrying the modified VP6(pETP6v) was constructed. The modified VP6v that can be used as a vector for foreign epitopes insertion was expressed and studied. Using this vector system, aa223-aa235, aa56-aa72and aa296-aa315derived from RV VP4with highly conserved neutralization epitopes were selected and insereted into the corresponding sites on the rVP6v protein, and three recombinant chimeric proteins carrying the VP4epitopes were highly expressed in prokaryotic cells. The findings obtained in this study indicated that the VP4epitopes presented on molecule surface of the VP6vector posed good immunological reactivity and immunogenicity. The recombinant VP6-based VP4epitope chimeric vaccines provided a foundation for development of improved vaccines that can confer more broadly protective immunity against diverse rotaviruses. |
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