A simpler, more sensitive competitive inhibition enzyme-linked immunosorbent assay for detection of antibody to malignant catarrhal fever viruses.
An earlier competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA) was developed for detection of specific antibody against malignant catarrhal fever (MCF) viruses (MCFV) in ruminants. In this study, the indirect CI-ELISA was improved by conjugating the monoclonal antibody 15-A directly with horseradish peroxidase and by developing a method of producing precoated, dried antigen plates. This new test is referred to as a direct CI-ELISA. The reformatted test yielded a significantly improved sensitivity, and the time required was reduced to about one-sixth of the previous time. Of 37 MCF cases in cattle that were confirmed by histopathology and polymerase chain reaction (PCR) assay, 37 (100%) were positive by the new test, whereas the indirect CI-ELISA detected only 23 (62%). The direct CI-ELISA detected antibody to MCFV in 100% of 48 sheep that had been defined as infected with ovine herpesvirus 2 (OvHV-2) by PCR, whereas the indirect CI-ELISA detected only 41 (85%). Comparison of antibody titers measured by the 2 assays for sera collected from OvHV-2-infected sheep and from cattle, bison, and deer with clinical sheep-associated MCF revealed that the direct CI-ELISA offered a 4-fold increase in analytical sensitivity over the indirect format. The number of seropositive animals detected by the direct CI-ELISA among apparently normal cattle and bison was 2-3 times greater than the number detected by the indirect CI-ELISA, indicating that a significant percentage of normal cattle and bison are subclincally infected with MCFV.
Li
H
H
Animal Diseases Research Unit, USDA, ARS, Washington State University, Pullman, USA.
McGuire
T C
TC
Müller-Doblies
U U
UU
Crawford
T B
TB
D000818:Animals; D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral / Q000032:analysis*; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D006564:Herpesviridae / Q000235:genetics*; D006735:Horseradish Peroxidase; D008304:Malignant Catarrh; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D006735:Horseradish Peroxidase