A DNA fusion vaccine induces bactericidal antibodies to a peptide epitope from the PorA porin of Neisseria meningitidis.
An experimental DNA plasmid vaccine was developed based on a well-characterized and protective peptide epitope derived from a bacterial porin protein. For this study, we used the P1.16b serosubtype epitope, located in variable region (VR)2 in loop 4 of the PorA outer membrane (OM) porin from Neisseria meningitidis serogroup B strain MC58. A plasmid that encoded the entire loop (pPorAloop4) was prepared, as well as a fusion plasmid that encoded the loop in tandem with the fragment C (FrC) immunostimulatory sequence from tetanus toxin (pPorAloop4-FrC). The constructs were used for intramuscular immunization without exogenous adjuvant. Murine antisera raised to the pPorAloop4-FrC DNA fusion plasmid reacted significantly with OMs in enzyme-linked immunosorbent assay and with whole bacteria by immunofluorescence, whereas antisera raised to the pPorAloop4 DNA plasmid and to control plasmid showed little or no reactivity. Significantly, only the pPorALoop4-FrC plasmid induced bactericidal antibodies, demonstrating that the intrinsic immunostimulatory sequence was essential for inducing a protective immune response. The antibodies raised to the P1.16b pPorALoop4-FrC plasmid were serosubtype specific, showing no significant immunofluorescence reactivity or bactericidal activity against other PorA variants. These data provide proof of principle for a DNA fusion plasmid strategy as a novel approach to preparing vaccines based on defined, protective epitopes.
Zhu
Delin
D
Genetic Vaccine Group, Cancer Sciences Division, University of Southampton Medical School, Southampton General Hospital, Southampton SO16 6YD, United Kingdom.
Williams
Jeannette N
JN
Rice
Jason
J
Stevenson
Freda K
FK
Heckels
John E
JE
Christodoulides
Myron
M
D000818:Animals; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines / Q000276:immunology*; D000939:Epitopes; D008589:Meningococcal Infections / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009345:Neisseria meningitidis / Q000276:immunology*; D010957:Plasmids; D018272:Porins; D019444:Vaccines, DNA / Q000276:immunology*
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D000939:Epitopes; D018272:Porins; D019444:Vaccines, DNA; C057699:porin protein, Neisseria