A new indirect ELISA for the discrimination of anti-equine herpes virus-1 and -4 antibodies in horse sera
Résumé
Background: Equine herpes virus-1 and -4 (EHV-1 and EHV-4) infections are widespread in horse populations around the world. Both viruses are responsible for respiratory syndromes, but EHV-1 can cause more severe signs, neurological disorders and abortions. Performances of sport horses are affected as well as equine breeding, resulting in considerable economic loss.
Objectives: EHV-1 and EHV-4 are closely related, making serological diagnosis difficult by conventional methods. Therefore, the ID Screen® EHV-1/EHV-4 Discrimination test Indirect ELISA kit1 was developed as a bi-well ELISA based on specific recombinant proteins, in order to distinguish between EHV-1 and EHV-4 antibodies in
equine sera.
Study design: Assay evaluation.
Methods: Diagnostic specificity and sensitivity were evaluated on VNT-pretested sera from France and Iceland. Seroconversion of 7 experimentally EHV-1 infected horses was monitored.[1] Horses were sampled between day 0 and 20 dpi. For EHV-4, eight horses were monitored during a natural EHV-4 epizootic (France).
Sera and nasal swabs were collected regularly from the first day of clinical signs (day 0) until day 77. All sera were tested by VNT and ID Screen® ELISA.1
Results: Specificity was evaluated for EHV-1 at 99% (95% CI [96.6%–99.7%], n = 208). For EHV-4 it was difficult to find seronegative horses, but the few VNT negative sera tested, showed negative results by ELISA (n = 5). EHV-1-antibodies were detected between 13 and 17 dpi. EHV-4 antibodies were detected between 6 and 10 days following first clinical signs. No cross-reactivity was observed between EHV-1 and EHV-4 antibodies during seroconversion studies.
Main limitations: Low number of EHV-4 seronegative samples.
Conclusion: The new ELISA is easy-to-use with both EHV-1 and EHV-4 testing performed within the same analytical run, thanks to its biwell plate format. It presents excellent discriminatory capacity between EHV-1 and EHV-4 infected horses.
Key manufacturer: 1 https://www.innovative-diagnostics.com/produit/id-screen-ehv-1-ehv-4-discrimination-test-indirect/.
Ethical animal research: Approved by the Loire Valley Ethical Review Board (CEEA VdL, committee number 19, authorisation number APAFiS#22708).
Informed consent: Owners gave consent for their animals' inclusion.
Competing interests: OM, SR, AC, KK and PP are employees of IDvet.
Funding: IDvet.
Reference:
[1] Thieulent CJ, Sutton G, Toquet M-P, Fremaux S, Hue E, Fortier C,Pléau A, Deslis A, Abrioux S, Guitton E, Pronost S, Paillot R. Oral administration of valganciclovir reduces clinical signs, virus shedding and cell-associated viremia in ponies experimentally infected with the Equid Herpesvirus-1 C2254 Variant. Pathogens 2022;11(5):539. 10.
3390/pathogens11050539.