Comparative Analysis Of Two Rotavirus VP4 Epitopes Carried On The Same Site Of VP6 Vector Protein

Rotaviruses (RVs) cause diarrhea in humans, mammals and birds. Group A Rotaviruses (RVAs) are the leading pathogenic agents of acute gastroenteritis in infants and young children. The intact viral particle of RV has three layers of capsids. The virus’s genomeconsists of 11 segments of double-stranded RNA(dsRNA), surrounded by the icosahedral protein capsid which is made of concentric capsid proteins. RV VP6, the middle layer of the capsids, is the most abundant protein and group specific antigen of the virus. The amino acid sequence of theVP6 in the same group has a high degree of identity, so VP6 has strong antigen cross reactivity. The VP4 and VP7 of RVAs are the major neutralizing antigen priteins. The VP4 forms spikes on the outer capsid and can induce neutralizing antibodies. To date, commercially used RV vaccines are attenuated live ones and still potential shortages, it is valuable to develop new alternatives of more safe and effective vaccines. In the present study, two high conservative epitopes derived from residues aa296-313 and 381-401 ofthe VP4 of RVA selected for construction of chimeric proteins, and their immunogenicity is studied.By genetic recombination technology, the VP6 vector protein (VP6F) derived from RVA strain TB-Chen is constructed. The above mentioned VP4 epitopes were respectively inserted into the VP6F protein, and two chimeric proteins carrying VP4 epitopes were constructed. The two epitopes of the VP4 were designed inserted on the surface of VP6 vector protein. The chimeric proteins were further expressed via E.coli and immunoreactivities were studied. The results showed that the expressed chimeric proteins could react with antibodies against VP6 of rotavirus, could elicit production of antibodies in inoculated guinea pigs; the antibodies could react with vector protein VP6F, VP6 and VP4 of strain Wa virus, and neutralize infectivities of Wa virus in MA 104 cell. The results indicate that chimeric proteins carrying the VP4 epitopes on the same insertion site retained its original backbone structure and had good immunoreactivity; the VP4 epitopes carried on the chimeric proteins enhanced immunogenicity of the vector protein VP6F. Results obtained in the present study are valuable for development of novel rotavirus vaccines.