Reduced specificity of E^rns antibody ELISAs for samples from piglets with maternally derived antibodies induced by vaccination of sows with classical swine fever marker vaccine CP7_E2alf

Abstract

Successful implementation of marker vaccines against classical swine fever virus is dependent on a reliable accompanying diagnostic assay that allows differentiation of infected from vaccinated animals (DIVA) as well as the development of a testing scheme during emergency vaccination. In this context, special attention needs to be paid to breeding farms, because the offspring of marker vaccinated sows possess maternally derived antibodies (MDAs). So far, limited information is available on the influence of MDAs on serological testing in the context of a DIVA strategy. Therefore, two commercially available E antibody ELISAs were compared, using serum samples of piglets with a high-to-moderate titre of MDAs against marker vaccine CP7_E2alf. False-positive results were detected by both E antibody ELISAs for serum samples of piglets with an age of up to 4 weeks. Interestingly, most samples tested false-positive in the first E antibody ELISA were identified correctly by the other E antibody ELISA and vice versa. In conclusion, in case of emergency vaccination of sows, the specificity of both ELISAs in newborn piglets younger than 4 weeks may be relatively low. This could be addressed in a testing strategy by either not sampling piglets up to the age of 4 weeks or using both ELISAs in a screening-confirmation set-up.

Characterization of the Humoral Immune Response Induced after Infection with Atypical Porcine Pestivirus (APPV)

“…Presence of maternally derived antibodies (MDA) was monitored in all piglets, independent of their health status. Half-life of porcine MDA is approximately 14 days for immunoglobulin IgG, the major isotype in pig colostrum, and levels gradually decline over time, which is in line with the presented results [33,34,35,36,37]. Previously, presence of MDA was also detected in CT affected piglets until 8 weeks of age [9].…”

Genetically distinct pestiviruses pave the way to improved classical swine fever marker vaccine candidates based on the chimeric pestivirus concept

“…So far, available MLVs with marker properties have been constructed by chimerization of CSFV genomes with BVDV sequences (Flc-LOM-BE rns ) or vice versa (CP7_E2Alf). At least for the latter it has been shown in different studies that cross-reactive Abs are induced that interfere with a robust negative serological marker for DIVA [ 8 , 9 , 24 , 25 ]. Comprehensive data about robustness of the DIVA principle Flc-LOM-BE rns vaccine are lacking.…”

The new emerging ovine pestivirus can infect pigs and confers strong protection against classical swine fever virus

“…In addition, the OVPV elicited humoural response to the CSFV E2 and E rns glycoproteins, which increased after CSFV challenge. Together with other previously described pestiviruses (Meyer et al., 2018; Postel & Becher, 2020), the new emerging OVPV complicates the differential diagnostic afforded by the E rns ELISA test, posing a threat for the implementation of the CSFV DIVA strategy based on this assay (Aebischer et al., 2013; Pannhorst et al., 2015). This might be highly impactful, considering the OIE and European Union (EU) guidelines for serological surveillance of CSFV (European Comission, 2002; OIE, 2019b).…”