title: Seroprevalence of antibodies against gram-negative core antigens in rabbits, using an Escherichia coli J5 antigen-capture enzyme-linked immunosorbent assay.
abstract: OBJECTIVE
  To determine the seroprevalence of antibodies to gram-negative core antigens (GNCA) in specific-pathogen-free (SPF) rabbits (ie, free of Pasteurella multocida) and rabbits of undefined bacterial status (conventional).
  
  
  METHODS
  Serum samples were obtained from 7 groups of rabbits. The SPF rabbits comprised 2 adult groups and 1 immature group, whereas the 4 groups of conventional rabbits were all adults.
  
  
  METHODS
  A seroprevalence survey was conducted on rabbit sera for antibodies against GNCA, using an Escherichia coli J5 antigen-capture ELISA.
  
  
  RESULTS
  Collective geometric mean titer (GMT) of adult rabbits was 1:6,463. The GMT of each of the 6 groups of adult rabbits was 1:956, 1:1,133, 1:4,525, 1:5,338, 1:7,669, and 1:25,600. Titers of populations differed significantly.
  
  
  CONCLUSIONS
  Data analysis revealed there were anti-GNCA antibodies in rabbits. Similar to other species, the prevalence of IgM and IgG anti-GNCA antibodies increased with age. The IgG response was more marked than the IgM response. The SPF rabbits had lower IgG anti-GNCA titers than conventional rabbits, indicating possible cross-reactive epitopes between P multocida and Enterobacteriaceae. Rabbits with the highest anti-GNCA titers were those used in polyclonal antibody production, possibly stemming from endotoxin contamination of antigen or adjuvant.
  
  
  CONCLUSIONS
  The possible cross-reactive antibodies directed at homologous wall components of Pasteurellaceae and Enterobacteriaceae could prove to be a possible heterotypic vaccination strategy for the protection of rabbits against pasteurellosis. Investigators should determine whether antigen impurity (endotoxin contamination) influences epitope focus during polyclonal antibody production and whether it affects sera variability among rabbits.
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Ruble
authors.forename: J S
authors.initials: JS
authors.lastname: Cullor
authors.forename: D L
authors.initials: DL
authors.lastname: Brooks
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis*; D016950:Bordetella bronchiseptica; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D004926:Escherichia coli / Q000276:immunology*; D006304:Health Status; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D008070:Lipopolysaccharides / Q000276:immunology*; D016979:Pasteurella multocida; D011817:Rabbits; D013047:Specific Pathogen-Free Organisms
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C089614:J-5 lipopolysaccharide; D008070:Lipopolysaccharides