A Genome-Wide Screening of Novel Immunogenic TrLSDV103 Protein of Lumpy Skin Disease Virus and Its Application for DIVA.

Lumpy skin disease (LSD) is an infectious cattle disease caused by the lumpy skin disease virus (LSDV), posing a serious threat to the livestock industry. This study aimed to identify specific immunogenic targets for differential diagnosis and potential vaccine development. Using a phage display library covering the entire LSDV proteome, we screened sera from naturally LSDV-infected cattle and those vaccinated with the live attenuated goatpox virus vaccine (GTPV AV41) to identify differential antibody-binding viral peptides, leading to the identification of peptides within the LSDV103 protein. A truncated recombinant LSDV103 protein (TrLSDV103) was expressed and showed strong reactivity with sera from LSDV-infected cattle, significantly higher than that with sera from GTPV-vaccinated cattle. An indirect enzyme-linked immunosorbent assay (iELISA) based on the TrLSDV103 protein was developed, with a cutoff value of 0.361, demonstrating the diagnostic specificity of 100% (95% CI: 90.11-100) and the diagnostic sensitivity of 86.67% (95% CI: 70.32-94.69). The lowest detection limit for positive serum was 1:6400, with no cross-reactivity with five other bovine pathogens. Among 210 serum samples tested, 11 were suspected of LSDV infection. Additionally, TrLSDV103 protein immunization in BALB/c mice induced strong humoral and cellular immune responses, including significantly elevated IgG levels and antibody titers up to 1:204800. Cytokine detection assays showed a significant increase in IFN-γ and IL-1β levels. Flow cytometry analysis further revealed a marked increase in CD3+CD4+ T cells. In conclusion, TrLSDV103 is a highly immunogenic protein with strong diagnostic specificity, showing great potential as a differential diagnostic antigen and vaccine candidate against LSDV.