Vaccine, Vol. 13, No. 4. pp. 331-338, 1995 Copyright 0 1995 Elsevier Sciencs Ltd Printed in Great Britain. All rights reserved 0264-410)(/95 $10.00+0.00 zyxwvutsrqpon Priming and induction of anti-rotavirus antibody response by synthetic peptides derived from zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA VP7 and VP4 M K. Ijaz*7, T.O. Alkarmi*, A.W. El-Mekkit, S.H.I. Galadar?, F.K. Dar* anh L.A. Babiuk”II zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Synthetic peptides derived from bovine rotavirus C-486 (BRV) outer capsid (VP7 and VP4) and inner capsid (VP6) proteins were tested to evaluate their ability to prime and induce an anti-rotavirus antibody response. Peptides corresponding to the amino acid residues 232-255 of VP4 (VP4-peptide), 275- 295 of VP7 (VP7-peptide) and 40-60 of VP6 (VP&peptide) of BRV were chemically synthesized. These peptides were coupled to carrier proteins (either keyhole limpet haemocyanin (KLH) or recombinant rotavirus inner capsid protein- VP6 assembled into virus-like particles ( VP6-carrier) were used as carrier to link the synthetic peptides under study), and the resulting conjugates were used to immunize rotavirus seronegative mice. An enzy me- linked immunosorbent assay (ELISA) was used to determine anti-peptide and anti-rotavirus antibody titres in serum samples collected after immunization. All peptides were immunogenic in mice and induced the production of anti-peptide antibodies, but with the exception of VP6-peptide they were not able to induce anti-rotavirus antibodies as measured by ELISA. W estern blot analysis indicated that antibodies against each peptide were able to react with the respective authentic viral proteins oj’ various rotavirus serotypes. To determine if a peptide-primed animal would respond to native viral proteins, animals were subsequently injected with purljied BRV. A rapid ailzd high anti-rotavirus antibody titre, in addition to a rise in anti-peptide antibody titre, was observed in peptide-primed mice. Furthermore, the sera obtained from these mice neutralized the virus under in vitro conditions. The significance of these results in relation to a potential rotavirus synthetic peptide-based vaccine is discussed. Keywords: Rotavirus; antibody response; synthetic peptides Rotaviruses are causative agents of neonatal enteritis in a number of mammalian species and in human beings cause disease in infants, young children and adultsle4. They constitute a genus of the family Reouiridae and the infectious viral particles are characterized by a 70 nm double-shelled capsid surrounding a core that contains 11 segments of double-stranded RNA. The outer capsid contains two proteins. The major outer capsid glycopotein, called VP7, has a molecular weight of 38 000 *Department of Medical Micf,obiology and +Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, PO Box 17888, Al-Ain, United Arab Emirates. SDepartment of Microbiology, College of medicine, King Saud Universiiy, Abha Branch, PO BOX 481, Abha, Kingdom of Saudi Arabia, ?eterinary Infectious Diseases Organization (VIDO) and “Department of Veterinary Microbiology, W estern College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, S7N OWO, Canada. ~To whom correspondence should be addressed. (Received 28 March 1994; revised 24 June 1994; accepted 27 June 1994) (38 kDa) in its unreduced and 41 kDa in reduced form. This protein has been shown to bind to the host cells, and neutralizing monoclonal antibodies directed against this protein inhibit attachment of the virus to the host cells5,6. The second outer-capsid protein designated VP4 has a molecular weight of 84 kDa and has been shown to be involved in virus attachment to both permissive cells and erythrocytes (haemagglutinin). VP4 has also been shown to play a role in the penetration of virus into the host cell after its adsorption7-9. The mechanism of penetration involves the cleavage of VP4 by trypsin into two fragments, VP5 (approximately 60 kDa) and VP8 (approximately 28 kDa). The most abundant protein of the virion (50% of the total virion proteins) is the inner capsid protein, VP6, with a molecular weight of 45 kDa2. Following infection or immunization, antibodies develop against both outer (VP7 and VP4) and inner (VP6) capsid proteins ‘*lo. Previously, we have mapped the location of highly conserved epitopes on these proteins5 and have prepared synthetic peptides corres- ponding to these domains which are highly conserved in different rotavirus isolates’ l-12. Specifically, VP7 (amino Vaccine 1995 Volume 13 Number 4 331