Bovine viral diarrhea virus (BVDV) belongs to the genus Pestivirus in the family Flaviviridae (Su et al., 2022). Two kind of BVDV species have been recognized as BVDV-1 and BVDV-2, which were proposed to be re-named as Pestivirus A and Pestivirus B (King et al., 2018, Postel et al., 2021). The genus Pestivirus also comprises classical swine fever virus (CSFV, Pestivirus C), border disease virus (BDV, Pestivirus D) and another fifteen species (Pestivirus E to Pestivirus S) (King et al., 2018, Postel et al., 2021). Bovine viral diarrhea (BVD), caused by either BVDV-1 or BVDV-2, is prevalent worldwide and is clinically manifested by diarrhea, respiratory disease, reproductive failure, congenital defect, mucosal disease and hemorrhagic syndrome (Su et al., 2022). BVDV-1 contains at least 22 subgenotypes of 1a-1v and BVDV-2 contains 4 subtypes of 2a-2d (Mosena et al., 2020, Su et al., 2022, Tian et al., 2021, Zhu et al., 2022).

BVDV mainly infects cattle, it can also infect sheep, goat, pigs and other cloven-hoofed animals (Mao et al., 2016, Oliveira et al., 2020, Vilček and Nettleton, 2006). In addition to causing acute or sub-clinical disease, the ability of BVDV to cross the placenta during the first trimester of pregnancy can result in the birth of persistently infected (PI) calves. These PI animals play critical roles in the transmission of BVDV and maintaining viral infection in a herd (Neill, 2013). Furthermore, BVDV infection usually induces immunosuppression, which subsequently increases the susceptibility to other viral or bacterial pathogens (Song et al., 2022). Recently, BVDV infection and related diseases are also widespread in China, causing serious economic losses to the animal husbandry (Deng et al., 2020, Shah et al., 2022, Wu et al., 2023; Zhou et al., 2023).

BVDV encodes a polyprotein that cleaves into four structural proteins (C, Erns, E1 and E2) and eight nonstructural proteins (Npro, P7, NS2, NS3, NS4A, NS4B, NS5A and NS5B). E2 protein is the major envelope glycoprotein with good immunogenicity, which is important for the development of diagnostic methods and vaccines. After BVDV infection or vaccination, neutralizing antibodies against E2 protein are induced (A-Kubatir et al., 2021, Ridpath, 2013). Control of BVD relies on removing PI animals from a herd, ensuring biosecurity and vaccination of susceptible animals (Antos et al., 2021, Moennig et al., 2005, Thulke et al., 2018). The NS3 (p80) and/or Erns monoclonal antibodies (mAbs)-based antigen capture ELISA detects BVDV antigen in blood and tissue samples, and has been successfully used to identify PI animals in BVDV control program (Safarpoor, 2011, Sandvik and Krogsrud, 1995, Synge et al., 1999). As for high seroprevalence countries or regions, vaccination is often an important measure of BVD control and eradication strategies. According to the reported epidemiological studies, BVDV-1 was the predominant species in China (Chang et al., 2021, Deng et al., 2020, Guo et al., 2021, Shah et al., 2022, Zhang et al., 2022; Zhou et al., 2023). Inactivated vaccines based on BVDV-1a strains (NM01 and NMG strains) have been licensed and used in China from 2016 (http://vdts.ivdc.org.cn:8081/cx/#). While, there is still a lack of commercial ELISA kit for immune evaluation. Traditional virus neutralization test (VNT) is the “gold standard” method for vaccine efficacy evaluation and is widely used, but it is time-consuming and laborious. The commercial blocking ELISA (bELISA) kit detecting of p80 antibodies is not suitable for antibody detection after vaccination (Raue et al., 2011). The indirect ELISA kit (such as IDEXX and Svanova) detected the antibodies to both of BVDV-1 and BVDV-2. Several other domestic ELISA assays are still under laboratory study (Ge et al., 2020, Wang et al., 2023, Xiao et al., 2019, Zoth and Taboga, 2006).

In this study, mAbs against BVDV-1 E2 protein were prepared and systemically identified. After the optimization of the reaction conditions, a bELISA using one neutralizing mAb 1E2B3 for the detection of BVDV-1 antibodies was successfully established. It provides a novel and effective detection method for the evaluation of BVDV vaccines and epidemiological investigation, which will be beneficial to better control the spread of BVDV.