Immunoreactivity Of Rotavirus VP7Epitope Chimeric Proteins

Rotavirus (RV) is the leading pathogenic agent of viral diarrhea among human, mammals and birds. In fact, the RV infection rate is so high that almost every child has been infected by RV, regardless of race or nations. Worldwide, every year, there is a large number of RV infections related to death, especially in children. Due to the high incidence of RV infection and, once accured at early age, the possible severe consequence, research and development of RV vaccines become a major focus to many institutions and governments around the world. However, RVs form a large family with various subtypes, each has unique biological, pathological and immunological characteristics, and this makes it difficult to develop RV vaccines.Unfortunately the currently available RV vaccines reveal many shortages in function and also safety problems. For example, whether today’s RV vaccination could provide enough protection on both the individual level and the population level deserve more consideration. Moreover, one reported RV vaccine could lead to intussusceptions, although in low/rare cases. In certain situations, vaccines could be contaminated by porcine circoviruses during the vaccine production. With the development of biotechnology and progress in genetic engineering, recombinant vaccines become a better way to solve these problems.The structural protein VP6is the group antigenic protein of RV, highly conserved during evolution, and more importantly capable of providing cross protection. This protein is also the most abundant, constituting about39%of the viral structure proteins by weight. While VP4and VP7from RV can induce specific neutralizing antibodies of the human body, and major neutralizing antigenic epitopes exist on VP4and VP7. In fact, both VP4and VP7are the main protective antigens that contribute to the production of critical neutralizing antibodies.In this study, by genetic recombination technology, highly conserved antigenic epitopes G[1]142, G[4]208, G[2]87which come from structure protein VP7are inserted into the surface of VP6vector protein. The chimeric proteins that carrying the VP7epitopes were expressed in E. coli cells and their immunological characteristics were further evaluated. The results showed that the expressed recombinant chimeric proteins could react with serum antibodies elicited in guinea pig immunized by recombinant vector protein (rVP6F), RV SAl1and Wa. The serum antibodies collected from guinea pigs immunized by the expressed recombinant chimeric proteins could react with the VP6vector protein (rVP6F), could react with the proteins VP6and VP7of Wa and SA11, and could neutralize Wa and SA11infections in MA104cells. The VP7epitopes presented on recombinant chimeric protein could improve immunoreactivity of VP6vector protein. This VP6-based epitope presenting system and the VP7epitope chimeric proteins will be valuable for and contribute to the development of novel RV vaccines in future.