Development and validation of an indirect ELISA as a confirmatory test for surveillance of infectious bovine rhinotracheitis in vaccinated herds

Luigi Bertolotti, Elvira Muratore, Chiara Nogarol, Claudio Caruso, Laura Lucchese, Margherita Profiti, Laura Anfossi, Loretta Masoero, Stefano Nardelli, Sergio Rosati

Bovine herpesvirus 1 (BoHV1) is a member of the viral subfamily of Alphaherpesvirinae that infects various species, including cattle, sheep, and goats. The virus causes infectious bovine rhinotracheitis (IBR), which is included in a European list of diseases that may require control and eradication programs. The lack of confirmatory tests affects the validity of diagnostic tools, especially those used for vaccinated herds. In this study, we report the development and validation of an indirect enzyme-linked immunosorbent assay (ELISA) based on BoHV1 glycoprotein E, which was expressed as a secreted recombinant antigen in a mammalian cell system. The performance of the new rec-gE ELISA was compared with that of commercially available indirect and/or blocking ELISAs. The sample set included blood sera from animals from IBR-positive farms, IBR-free farms, and marker-vaccinated farms. The indirect ELISA proposed in this study is based on antibody reactivity against BoHV1 gE, and showed high sensitivity and specificity (98.41 and 99.76 %, respectively). The ELISA performed well, in terms of both its diagnostic sensitivity and specificity, and as a confirmatory methodology, and therefore should improve the diagnostic protocols used for IBR surveillance.