Field application of an indirect gE ELISA on pooled milk samples for the control of IBR in free and marker vaccinated dairy herds

Abstract

BackgroundThe aim of the present study was to assess the reliability of a new strategy for monitoring the serological response against Bovine Herpesvirus 1 (BoHV1), the causative agent of infectious bovine rhinotracheitis (IBR). Bulk milk samples have already been identified as cost effective diagnostic matrices for monitoring purposes. Nevertheless, most eradication programs are still based on individual standard assays. In a region of northwestern Italy (Piedmont), the voluntary eradication program for IBR has become economically unsustainable. Being the prevalence of infection still high, glycoprotein E-deleted marker vaccines are commonly used but gE blocking ELISAs are less sensitive on bulk milk samples compared to blood serum.ResultsA recently developed indirect gE ELISA showed high versatility when applied to a wide range of matrices. In this study, we applied a faster, cost effective system for the concentration of IgG from pooled milk samples. The IgG enriched fractions were tested using a gE indirect ELISA for monitoring purposes in IBR-positive and IBR-marker-vaccinated herds. Official diagnostic tests were used as gold standard. During a 3 years study, a total 250 herds were involved, including more than 34,500 lactating cows. The proposed method showed a very good agreement with official diagnostic protocols and very good diagnostic performances: only 37 positive animals were not detected across the entire study.ConclusionsThe results highlighted the ability of the proposed method to support the surveillance of IBR in the Piedmont region, reducing the costs without affecting the diagnostic performances.

Protective immunity following vaccination with a recombinant multiple-epitope protein of bovine herpesvirus type I in a rabbit model

“…Moreover, the multiple-epitope recombinant protein was free of other BoHV-1 glycoproteins, such as gE and gG; thus, it could be considered a marker vaccine or used to differentiate infected from vaccinated animals. Vaccination of cowherds with the recombinant protein combined with gE or gG antibodies in the ELISA kit can contribute to the prevention and control of diseases associated with BoHV-1 infection in cattle herds (Colitti et al 2018;Sauerbrei and Wutzler 2004), especially in countries and regions where such infection remains a serious threat to the cow industry.…”

Validation of a Commercial Indirect ELISA Kit for the Detection of Bovine alphaherpesvirus1 (BoHV-1)-Specific Glycoprotein E Antibodies in Bulk Milk Samples of Dairy Cows

“…In particular, the commercial blocking ELISAs are used to detect specific antibodies against glycoprotein B (gB-ELISA) or gE (gE-ELISA) of BoHV-1, and they can be used in individual or pooled samples [ 21 ]. However, in IBR-free farms or marker-vaccinated herds, the blocking gE-ELISA only allows discrimination between infected and immunised animals with gE-deleted markers [ 21 , 22 , 23 , 24 ]. In the last 20 years, commercial blocking ELISAs, using both serum and milk samples, have been developed by different companies; however, the blocking ELISAs using milk samples are discouraged because of the chance of obtaining false positives [ 22 ].…”

“…However, in IBR-free farms or marker-vaccinated herds, the blocking gE-ELISA only allows discrimination between infected and immunised animals with gE-deleted markers [ 21 , 22 , 23 , 24 ]. In the last 20 years, commercial blocking ELISAs, using both serum and milk samples, have been developed by different companies; however, the blocking ELISAs using milk samples are discouraged because of the chance of obtaining false positives [ 22 ]. Therefore, few diagnostic tests on milk samples are commercially available for the surveillance or eradication of IBR programs.…”

“…Nevertheless, bulk milk (BM) testing could represent a useful tool for eradication and/or monitoring programmes because of the easier collection, lower sample collection costs, and reduced animal stress [ 22 , 24 , 33 ]. Recent studies have assessed the feasibility of using ELISA tests on BM samples to detect the antibodies for IBR control and estimate the BoHV-1 prevalence in a herd [ 21 ].…”

Genome editing of a hybridoma cell line via the CRISPR/Cas9 system: A new approach for constitutive high-level expression of heterologous proteins in eukaryotic system

“…Since recombinant gE expressed in mammalian system has been successfully used in an indirect ELISA for the detection of IgG against the BoHV1gE on pooled milk samples for an IBR surveillance program in a region of north-west Italy (Piedmont) (Bertolotti et al, 2015;Muratore et al, 2017;Colitti et al, 2018), the development of a stable system for the high-yield expression of this protein, would represent a significant advance in the development of tools for IBR disease control. This study was of relevance to develop the technique from its proof of concept to more specific diagnostic applications.…”