Development of a Competitive Enzyme-Linked Immunosorbent Assay Based on Purified Recombinant Viral Protein 7 for Serological Diagnosis of Epizootic Haemorrhagic Disease in Camels

Abstract

Epizootic haemorrhagic disease virus (EHDV) is a member of the Orbivirus genus in the Reoviridae family, and it is the etiological agent of an arthropod-transmitted disease that affects domestic and wild ruminants. Due to its significant economic impact, many attempts have been done in order to develop diagnostic immunoassays mainly based on the use of the viral protein 7 (VP7), that is, the immunodominant serogroup-specific antigen. In this work, a recombinant VP7 (recVP7) of EHDV serotype 2 was produced in a baculovirus system, and after purification using ion metal affinity chromatography, we obtained a high yield of recombinant protein characterized by a high degree of purity. We used the purified recVP7 as reagent to develop a competitive enzyme-linked immunoassay (c-ELISA), and we tested the presence of EHDV antibodies in 185 dromedary camel serum samples. The c-ELISA showed good performance parameters in recognising positive sera of naturally EHDV-infected dromedary camels; in particular, our developed test reached 85.7% of sensitivity, 98.1% of specificity, 93% of accuracy, and a high agreement value with results obtained by the commercial ELISA kit (Cohen’s kappa value of 0.85) that we adopted as the reference method. This c-ELISA could be a useful screening test to monitor the virus spread in camels that are sentinel animals for endemic areas of disease.

Epizootic Haemorrhagic Disease Virus Serotype 8 in Tunisia, 2021

“…Thus, we strongly believe that countermeasures must be taken. These include the establishment of EHDV surveillance in the European regions previously shown to be at high risk of Orbivirus incursions from Northern Africa [ 35 , 36 , 37 , 38 ], entomological studies to assess the biological vector of EHDV-8 in Tunisia, surveillance of the circulation of this virus in other animal species including camelids [ 39 ], and the production of specific EHDV-8 vaccines able to protect animals from clinical disease. In this regard, it should be noted that a vaccine designed on EHDV-6 could be also effective at preventing EHDV-8 clinical disease, but this must be proven in dedicated experimental in vivo trials.…”

Epizootic Hemorrhagic Disease Virus: Current Knowledge and Emerging Perspectives

“…VP7 is the immunodominant serogroup-specific protein and is used in serogroup specific enzyme-linked immunosorbent assays (ELISAs) for disease diagnosis [ 16 ]. Recently, researchers have shown the usefulness of purified and unpurified baculovirus-expressed VP7 for development of competitive enzyme-linked immunosorbent assays [ 17 , 18 ].…”