Differentiation of Antibodies against Selected Simbu Serogroup Viruses by a Glycoprotein Gc-Based Triplex ELISA

Abstract

The Simbu serogroup of orthobunyaviruses includes several pathogens of veterinary importance, among them Schmallenberg virus (SBV), Akabane virus (AKAV) and Shuni virus (SHUV). They infect predominantly ruminants and induce severe congenital malformation. In adult animals, the intra vitam diagnostics by direct virus detection is limited to only a few days due to a short-lived viremia. For surveillance purposes the testing for specific antibodies is a superior approach. However, the serological differentiation is hampered by a considerable extent of cross-reactivity, as viruses were assigned into this serogroup based on antigenic relatedness. Here, we established a glycoprotein Gc-based triplex enzyme-linked immunosorbent assay (ELISA) for the detection and differentiation of antibodies against SBV, AKAV, and SHUV. A total of 477 negative samples of various ruminant species, 238 samples positive for SBV-antibodies, 36 positive for AKAV-antibodies and 53 SHUV antibody-positive samples were tested in comparison to neutralization tests. For the newly developed ELISA, overall diagnostic specificities of 84.56%, 94.68% and 89.39% and sensitivities of 89.08%, 69.44% and 84.91% were calculated for SBV, AKAV and SHUV, respectively, with only slight effects of serological cross-reactivity on the diagnostic specificity. Thus, this test system could be used for serological screening in suspected populations or as additional tool during outbreak investigations.

The Adaptive Immune Response against Bunyavirales

“…Mouse-derived monoclonal antibodies (mAbs) against LACV, TAHV, and SBV envelope glycoproteins and N were shown to be both specific and cross-reactive, but only the glycoprotein mAbs had neutralizing effects [ 153 , 154 ]. These findings were supported by several other studies on CSG and SSG serogroups, demonstrating the effect of nAbs against Gc [ 146 , 155 , 156 ]. However, the complex arrangement of envelope glycoproteins on the orthobunyavirus virion, characterized by trimeric spikes, has posed challenges in determining precise nAb epitopes [ 157 ].…”

“…A distinctive characteristic of orthobunyaviruses is the genetic relatedness of viruses within serogroups, leading to cross-reactive Abs across the genus, including CSG and SSG members [ 145 , 146 , 147 ]. However, whether cross-reactive Abs can protect against multiple infections remains uncertain.…”

Serological screening in wild ruminants in Germany, 2021/2022: No evidence of SARS‐CoV‐2, bluetongue virus or pestivirus spread but high seroprevalences against Schmallenberg virus

“…All samples collected in the 2021/2022 hunting season were tested for the presence of anti‐SBV antibodies by a glycoprotein Gc‐based enzyme‐linked immunosorbent assay (ELISA) performed as described previously (Wernike, Aebischer, Sick, et al., 2021 ). For the detection of antibodies against BTV and ruminant pestiviruses, the VP7‐based ID Screen Bluetongue Competition ELISA and the ID Screen BVDV p80 Ab competition test, respectively, were applied (both Innovative Diagnostics).…”

Characterization of experimental Shuni virus infection in the mouse

“…The sera collected at necropsy were analyzed for SHUV-specific antibodies by a previously described multispecies ELISA. 26…”