Species-specific and cross-reactive IgG1 antibody binding to viral capsid protein 1 (VP1) antigens of human rhinovirus species A, B and C.
BACKGROUND
Human rhinoviruses (HRV) are associated with upper and lower respiratory illnesses, including severe infections causing hospitalization in both children and adults. Although the clinical significance of HRV infections is now well established, no detailed investigation of the immune response against HRV has been performed. The purpose of this study was to assess the IgG1 antibody response to the three known HRV species, HRV-A, -B and -C in healthy subjects.


METHODS
Recombinant polypeptides of viral capsid protein 1 (VP1) from two genotypes of HRV-A, -B and -C were expressed as glutathione S-transferase (GST) fusion proteins and purified by affinity and then size exclusion chromatography. The presence of secondary structures similar to the natural antigens was verified by circular dichroism analysis. Total and species-specific IgG1 measurements were quantitated by immunoassays and immunoabsorption using sera from 63 healthy adults.


RESULTS
Most adult sera reacted with the HRV VP1 antigens, at high titres. As expected, strong cross-reactivity between HRV genotypes of the same species was found. A high degree of cross-reactivity between different HRV species was also evident, particularly between HRV-A and HRV-C. Immunoabsorption studies revealed HRV-C specific titres were markedly and significantly lower than the HRV-A and HRV-B specific titres (P<0.0001). A truncated construct of HRV-C VP1 showed greater specificity in detecting anti-HRV-C antibodies.


CONCLUSIONS
High titres of IgG1 antibody were bound by the VP1 capsid proteins of HRV-A, -B and -C, but for the majority of people, a large proportion of the antibody to HRV-C was cross-reactive, especially to HRV-A. The improved specificity found for the truncated HRV-C VP1 indicates species-specific and cross-reactive regions could be defined.
Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Australia.
Jua
J
Iwasaki
Wendy-Anne
WA
Smith
Shane R
SR
Stone
Wayne R
WR
Thomas
Belinda J
BJ
Hales
D000328:Adult; D000595:Amino Acid Sequence; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D000937:Antigen-Antibody Reactions / Q000276:immunology; D001483:Base Sequence; D002942:Circular Dichroism; D003429:Cross Reactions / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010850:Picornaviridae Infections / Q000097:blood / Q000276:immunology* / Q000821:virology; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D012229:Rhinovirus / Q000145:classification / Q000235:genetics / Q000276:immunology*; D013045:Species Specificity; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D055815:Young Adult
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; C074995:viral protein 1, rhinovirus; D005982:Glutathione Transferase