ALTERNATIVAS PARA LA PREVENCIN Y EL TRATAMIENTO DEL EXANTEMA COITAL EQUINO
Equine coital exantema (ECE), caused by equid alphaherpesvirus 3 (EHV-3), is a contagious vaenereal disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genitalia of both mares and stallions. EHV-3 infection does not result in systemic infection, infertil...
Guardado en:
| Autor principal: | |
|---|---|
| Otros Autores: | |
| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
| Publicado: |
Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2017
|
| Materias: | |
| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_7063 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_7063.dir/7063.PDF |
| Aporte de: |
| Sumario: | Equine coital exantema (ECE), caused by equid alphaherpesvirus 3 (EHV-3), is a contagious vaenereal disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genitalia of both mares and stallions. EHV-3 infection does not result in systemic infection, infertility and / or abortion. The negative impact of ECE lies on the need to temporarily interrupt reproductive activity,\nthe risk of iatrogenic dissemination of EHV-3, and the occurrence of outbreaks at artificial insemination (AI) and embryo transfer (ET) centers. This may translate into delayed foaling dates, and significant decreases in the number of mares mated and in pregnant rates, as opportunities of being mated are lost. ECE clinical lesions are usually characteristic enough for a clinical diagnosis, but as there are latently infected animals from which the virus can be re-activated and re-excreted without lesions, the identification of these animals is critical to\nprevent transmission, principally from mares to stallions during mating. There are quick diagnostic tests, such as conventional or real time PCR (qPCR), which can be carried out in the laboratory, but these techniques are not applicable for detection of\nexcretion of virus in situ before mating, AI and/or ET. Cessation of breeding of\nclinically affected animals until the end of the excretion period, heightened vigilance\nby the personnel for early recognition of new clinical cases and strict adherence to breeding shed hygiene procedures designed to eliminate mechanical transmission of the virus, are the primary ways to avoid the spread of infection if a case of ECE is observed during the breeding season. Treatment is palliative and is based on the application of antiseptic/astringents, anti-inflammatory agents and broad-spectrum antimicrobials, which contribute to a rapid and uncomplicated healing of genital lesions.The general objective of this work was to decrease the negative impact of ECE infections by the evaluation of antiviral compounds as topical treatment, and the implementation of a rapid detection field assay.\nInitially, the in vitro analysis of four synthetic antiviral compounds (acyclovir,\ncidofovir, ganciclovir and brivudin) and one natural (lamda-carragenan) antiviral\ncompound was carried out. With the results on the 50% effective concentration\n(CE50%) and the CE100%, three concentrations of each of the compounds acyclovir,\ncidofovir and ganciclovir, were selected to continue with the analysis of inhibition of viral production in cell cultures. Next, these three compounds were evaluated against six EHV-3 field strains, isolated in our laboratory between 2001 and 2009. By these assays, we demonstrated that 5 ug/ml of acyclovir, 2 ug/ml of cidofovir and 0.05 ug/ml of ganciclovir are effective to reduce the replication of EHV-3 in vitro, being ganciclovir the most efficient compound.\nWe proceeded then with the in vivo analysis of ganciclovir formulated in base cream at 0.01% p/p (GCV 0.01% p/p), as to be used topically, in a preventive and therapeutic treatment, in mares experimentally infected with EHV-3. While two groups of such mares received a preventive treatment, one of them at 4 h and the other at 4 and 24 h post-infection; a third group received the therapeutic treatment\nduring clinical manifestation of ECE. Two other groups were used as control: one of\nthem did not receive any treatment and the other received base cream without\nantiviral (placebo). To evaluate the in vivo efficacy of GCV 0.01% p/p, the following were assessed: clinical signs and lesions (evaluated by a numerical score); rectal temperature; viral excretion by qPCR and by infection of culture cells; and antibodies response by seroneutralization. In the groups which had received preventive treatment at 4 and 4/24 h (clinically healthy animals, but excreting virus), the clinical severity was significantly reduced, but the excretion of virus was only significantly reduced in one of them (treated 4 h post-infection). Regarding the animals treated during the clinical manifestation of ECE with GCV 0.01% p/p, the clinical severity and the intensity and period of excretion of infective virus (reduced in 8 days) were\nsignificantly reduced. This in vivo experiment represents an advance in the development of a treatment, either preventive or therapeutic, or both, based on the topical administration of ganciclovir to control infection by EHV-3. Adjustments in the concentration, presentation form or frequency of administration, should be\nconsidered in order to achieve complete inhibition of viral excretion.\nFinally, the technological platform known as insulated isothermal PCR (iiPCR),\nwas adopted for the rapid (1:30 h) diagnosis of EHV-3 infection in situ. The validation was carried out to determine the sensibility and specificity, both analytical and diagnostic, compared to qPCR for the detection of EHV-3. Results showed that iiPCR has a 98,2% concordance with qPCR, a technique which it is not practically useful for\nin situ diagnosis before mating. To conclude, both the topical administration of GCV as a treatment for the\ninfection of EHV-3 and the incorporation of the iiPCR technology for the rapid\ndiagnosis in situ, could contribute to decrease the negative impact of ECE in equine production. |
|---|