Influence of three-dimensional structure on the immunogenicity of a peptide expressed on the surface of a plant virus.
The influence of peptide structure on immunogenicity has been investigated by constructing a series of cowpea mosaic virus (CPMV) chimaeras expressing the 14 amino acid NIm-1A epitope from human rhinovirus 14 (HRV-14) at different positions on the capsid surface. Biochemical and crystallographic analysis of a CPMV/HRV chimaera expressing the NIm-1A epitope inserted into the betaC'-betaC" loop of the S protein revealed that, although the inserted peptide was free at its C-terminus, it adopted a conformation distinct from that previously found when a similarly cleaved peptide was expressed in the betaB-betaC loop of the S protein. Adjustment of the site of insertion within the betaB-betaC loop resulted in the isolation of a chimaera in which cleavage at the C-terminus of the epitope was much reduced. Crystallographic analysis confirmed that in this case the epitope was presented as a closed loop. Polyclonal antisera raised against the CPMV/ HRV chimaera presenting the NIm-1A epitope as a closed loop had a significantly enhanced ability to bind to intact HRV-14 particles compared with antisera raised against chimaeras presenting the same sequence as peptides with free C-termini. These results demonstrate that the mode of presentation of an epitope on a heterologous carrier can dramatically affect its immunological properties.
Taylor
K M
KM
Department of Virus Research, John Innes Centre, Norwich, UK.
Lin
T
T
Porta
C
C
Mosser
A G
AG
Giesing
H A
HA
Lomonossoff
G P
GP
Johnson
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002213:Capsid / Q000737:chemistry / Q000378:metabolism; D017798:Comovirus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006801:Humans; D007106:Immune Sera / Q000096:biosynthesis; D007273:Injections, Intramuscular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D011487:Protein Conformation; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D012229:Rhinovirus / Q000235:genetics*
D000939:Epitopes; D007106:Immune Sera; D010455:Peptides; D011993:Recombinant Fusion Proteins