Oral Administration of Valganciclovir Reduces Clinical Signs, Virus Shedding and Cell-Associated Viremia in Ponies Experimentally Infected with the Equid Herpesvirus-1 C2254 Variant

Côme Thieulent (1, 2, 3) , Gabrielle Sutton (1, 2) , Marie-Pierre Toquet (1, 2) , Samuel Fremaux (1) , Erika Hue (1, 2, 4) , Christine Fortier (1, 2, 4) , Alexis Pléau (5) , Alain Deslis (5) , Stéphane Abrioux (5) , Edouard Guitton (5) , Stéphane Pronost (1, 2, 4) , Romain Paillot (1, 2, 6)

1 LABÉO - LABÉO, Pôle d’analyses et de recherche de Normandie
2 BIOTARGEN - Biologie, génétique et thérapies ostéoarticulaires et respiratoires
3 Louisiana Animal Disease Diagnostic Laboratory and Department of Pathobiological Sciences
4 ImpedanCELL
5 PFIE - Plateforme d'Infectiologie Expérimentale
6 School of Equine and Veterinary Physiotherapy

Equid alphaherpesvirus-1 (EHV-1) is one of the main pathogens in horses, responsible for respiratory diseases, ocular diseases, abortions, neonatal foal death and neurological complications such as equine herpesvirus myeloencephalopathy (EHM). Current vaccines reduce the excretion and dissemination of the virus and, therefore, the extent of an epizooty. While their efficacy against EHV-1-induced abortion in pregnant mares and the decreased occurrence of an abortion storm in the field have been reported, their potential efficacy against the neurological form of disease remains undocumented. No antiviral treatment against EHV-1 is marketed and recommended to date. This study aimed to measure the protection induced by valganciclovir (VGCV), the prodrug of ganciclovir, in Welsh mountain ponies experimentally infected with an EHV-1 ORF30-C2254 strain. Four ponies were administered VGCV immediately prior to experimental EHV-1 infection, while another four ponies received a placebo. The treatment consisted in 6.5 mg/kg body weight of valganciclovir administered orally three times the first day and twice daily for 13 days. Clinical signs of disease, virus shedding and viraemia were measured for up to 3 weeks. The severity of the cumulative clinical score was significantly reduced in the treated group when compared with the control group. Shedding of infectious EHV-1 was significantly reduced in the treated group when compared with the control group between Day + 1 (D + 1) and D + 12. Viraemia was significantly reduced in the treated group when compared with the control group. Seroconversion was measured in all the ponies included in the study, irrespective of the treatment received. Oral administration of valganciclovir induced no noticeable side effect but reduced clinical signs of disease, infectious virus shedding and viraemia in ponies experimentally infected with the EHV-1 C2254 variant.

Mots clés: valganciclovir; ganciclovir; EHV-1; equid alphaherpesvirus-1; herpesvirus; antiviral; experimental infection; pony

Domaines: Médecine vétérinaire et santé animale

Côme Thieulent, Gabrielle Sutton, Marie-Pierre Toquet, Samuel Fremaux, Erika Hue, et al.. 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), 17 p. ⟨10.3390/pathogens11050539⟩. ⟨hal-03665741⟩