Evaluation of recombinant extracellular enveloped virion protein candidates for the detection of serological responses to lumpy skin disease virus in cattle

Lumpy skin disease virus (LSDV) is a significant threat to cattle, particularly in countries like Thailand, where outbreaks have necessitated the importation of diagnostic kits and vaccines. This study aimed to evaluate several recombinant extracellular enveloped virion (EEV) protein candidates, including F13L, A33R, A34R, and B5R, for their potential use in serological detection assays for LSDV specific antibodies in cattle. Given the challenges associated with LSDV research, such as its classification as a Class III biological agent in Thailand, gene synthesis was employed to produce these proteins. The recombinant proteins were expressed in a prokaryotic system and analyzed using SDS-PAGE and Western blotting. Among the candidates, F13L demonstrated the highest correlation with the results from a commercially available and validated ELISA, yielding 85.7%, and 75% positive for the infected and vaccinated groups, respectively, identifying it a promising candidate for serosurveillance activities during active LSDV outbreaks. Sequence analysis confirmed a 100% match between the F13L designed from the Neethling type strain 2490 and various Thai LSDV strains from the 2021 outbreaks, underscoring its potential as a conserved diagnostic marker. The availability of recombinant F13L and its reactivity with cattle sera from LSDV infected or vaccinated animals, demonstrated in this study, suggests it could also serve as a potential candidate for vaccine development. The study concludes that recombinant F13L shows great promise for the development of LSDV serological assays, though further optimization and validation are necessary to harness its diagnostic potential.