RESUMEN
BACKGROUND: Bovine herpesvirus type 1 (BoHV-1) is the causative agent of respiratory and genital tract infections; causing a high economic loss in all continents. Use of marker vaccines in IBR eradication programs is widely accepted since it allows for protection of the animals against the disease while adding the possibility of differentiating vaccinated from infected animals.The aim of the present study was the development and evaluation of safety and efficacy of a glycoprotein E-deleted (gE-) BoHV-1 marker vaccine strain (BoHV-1ΔgEßgal) generated by homologous recombination, replacing the viral gE gene with the ß-galactosidase (ßgal) gene. RESULTS: In vitro growth kinetics of the BoHV-1ΔgEßgal virus was similar to BoHV-1 LA. The immune response triggered by the new recombinant strain in cattle was characterized both as live attenuated vaccine (LAV) and as an inactivated vaccine. BoHV-1ΔgEßgal was highly immunogenic in both formulations, inducing specific humoral and cellular immune responses. Antibody titers found in animals vaccinated with the inactivated vaccine based on BoHV-1ΔgEßgal was similar to the titers found for the control vaccine (BoHV-1 LA). In the same way, titers of inactivated vaccine groups were significantly higher than any of the LAV immunized groups, independently of the inoculation route (p < 0.001). Levels of IFN-γ were significantly higher (p < 0.001) in those animals that received the LAV compared to those that received the inactivated vaccine. BoHV-1ΔgEßgal exhibited an evident attenuation when administered as a LAV; no virus was detected in nasal secretions of vaccinated or sentinel animals during the post-vaccination period. BoHV-1ΔgEßgal, when used in either formulation, elicited an efficient immune response that protected animals against challenge with virulent wild-type BoHV-1. Also, the deletion of the gE gene served as an immunological marker to differentiate vaccinated animals from infected animals. All animals vaccinated with the BoHV-1ΔgE ßgal strain were protected against disease after challenge and shed significantly less virus than control calves, regardless of the route and formulation they were inoculated. CONCLUSIONS: Based on its attenuation, immunogenicity and protective effect after challenge, BoHV-1ΔgEßgal virus is an efficient and safe vaccine candidate when used either as inactivated or as live attenuated forms.
Asunto(s)
Infecciones por Herpesviridae/veterinaria , Herpesvirus Bovino 1/metabolismo , Proteínas Virales/metabolismo , Vacunas Virales/inmunología , Animales , Bovinos , Línea Celular , Perros , Femenino , Eliminación de Gen , Regulación Viral de la Expresión Génica/fisiología , Infecciones por Herpesviridae/prevención & control , Infecciones por Herpesviridae/virología , Herpesvirus Bovino 1/genética , Herpesvirus Bovino 1/inmunología , Embarazo , Complicaciones Infecciosas del Embarazo/prevención & control , Complicaciones Infecciosas del Embarazo/veterinaria , Complicaciones Infecciosas del Embarazo/virología , Vacunas Atenuadas , Vacunas de Productos Inactivados , Proteínas Virales/genética , Vacunas Virales/efectos adversosRESUMEN
BACKGROUND: Bovine herpesvirus 5 (BoHV-5) is a member of the subfamily Alphaherpesvirinae responsible for meningo-encephalitis in young cattle. The first case of bovine meningo-encephalitis associated with a herpesvirus infection was reported in Australia. The current geographical distribution of BoHV-5 infection is mainly restricted to South America, especially Brazil and Argentina. Outbreaks of BoHV-5 are regularly observed in Argentina suggesting the circulation of the virus in the bovine population. RESULTS: Seventeen field strains of BoHV-5 isolated from 1984 to now were confirmed by differential PCR and subjected to restriction endonuclease analysis (REA). Viral DNA was cleaved with BstEII which allows the differentiation among subtypes a, b and non a, non b. According to the REA with BstEII, only one field strain showed a pattern similar to the Argentinean A663 strain (prototype of BoHV-5b). All other isolates showed a clear pattern similar to the Australian N569 strain (prototype of BoHV-5a) consistent with the subtypes observed in Brazil, the other South-American country where BoHV-5 is known to be prevalent. The genomic region of subtype b responsible for the distinct pattern was determined and amplified by PCR; specifically a point mutation was identified in glycoprotein B gene, on the BstEII restriction site, which generates the profile specific of BoHV-5b. CONCLUSIONS: This is the first report of circulation of BoHV-5a in Argentina as the prevailing subtype. Therefore the circulation of BoHV-5b was restricted to a few years in Argentina, speculating that this subtype was not able to be maintained in the bovine population. The mutation in the gB gene is associated with the difference in the restriction patterns between subtypes "a" and "b".
Asunto(s)
Enfermedades de los Bovinos/virología , Brotes de Enfermedades/veterinaria , Encefalitis/veterinaria , Infecciones por Herpesviridae/veterinaria , Herpesvirus Bovino 5/aislamiento & purificación , Animales , Argentina/epidemiología , Bovinos , Enfermedades de los Bovinos/epidemiología , ADN Viral/química , ADN Viral/genética , Encefalitis/epidemiología , Encefalitis/virología , Infecciones por Herpesviridae/epidemiología , Infecciones por Herpesviridae/virología , Herpesvirus Bovino 5/genética , Mutación Puntual/genética , Reacción en Cadena de la Polimerasa/veterinaria , Mapeo Restrictivo/veterinaria , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/genéticaRESUMEN
This study reports 3 cases of spontaneous papillomavirus infection in 1-week-old calves. Thickening of the omasum and abomasum wall, with acute inflammation, necrosis, ulceration, and neoplastic changes were seen in 1 calf. In the other 2, small papillomas were observed in the omasal mucosa, exhibiting proliferation of the parakeratinized epithelium. Papillomavirus antigens were detected by immunohistochemistry and virus-like particles were seen through electron microscopy.