Blocking ELISA for distinguishing infectious bovine rhinotracheitis virus (IBRV)-infected animals from those vaccinated with a gene-deleted marker vaccine.
A sensitive and specific blocking enzyme-linked immunosorbent assay (ELISA) was developed to distinguish infectious bovine rhinotracheitis virus (IBRV)-infected animals from those immunized with a glycoprotein gIII deletion mutant, IBRV(NG)dltkdlgIII. For this ELISA, undiluted test sera are used to block the binding of an anti-IBRV gIII monoclonal antibody (mAbgIII)-horseradish peroxidase (HRPO) conjugate to gIII antigen. TMB substrate is used for color development. Negative S/N values (defined as the absorbance at 650 nm of test sera/absorbance at 650 nm of negative control sera) of > 0.80 were obtained with immune sera from gnotobiotic cattle immunized with several bovine viruses, with bovine antisera to bovine herpesvirus-2, and vesicular stomatitis virus, with porcine antisera to pseudorabies virus and parvovirus, and with normal sera from heterologous species. Negative S/N values were also obtained with sera from rabbits twice vaccinated with IBRV(NG)dltkdlgIII. However, the S/N values became positive (S/N < 0.8) 10 to 17 days after the rabbits were challenge exposed to virulent IBRV(Cooper). Most of 116 sera (84%) from feedlot cattle with virus neutralization (VN) titers of < 1:2 or < 1:4 had negative S/N values > 0.8, but 18 sera with negative VN titers had positive S/N values, consistent with observations indicating that an IBRV outbreak was occurring in one of the feedlot herds. Thirty nine sera (98%) from feedlot cattle with VN titers of 1:2 to 1:128 had positive S/N values (< 0.8). One serum with a VN titer of 1:2 had a borderline (+/-) S/N value of 0.81. After immunization with a commercial gIII-positive IBRV vaccine, 115/116 sera with VN titers of 1:2 to 1:256 had positive S/N values (< 0.8). One serum with a VN titer of 1:2 had a negative S/N value of 0.83. Serum from one vaccinated animal that failed to seroconvert after vaccination (VN < 1:4) showed a strongly positive ELISA S/N of 0.48.
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Division of Biochemical Virology, Baylor College of Medicine, Houston, TX.
Otsuka
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D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002417:Cattle; D004196:Disease Outbreaks / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D017353:Gene Deletion; D005856:Germ-Free Life; D007242:Herpesvirus 1, Bovine / Q000276:immunology*; D007241:Infectious Bovine Rhinotracheitis / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology*; D014765:Viral Vaccines / Q000276:immunology*
D000914:Antibodies, Viral; D014614:Vaccines, Synthetic; D014764:Viral Proteins; D014765:Viral Vaccines; C046998:bovine herpesvirus type-1 glycoproteins