RESUMEN
Bovine viral diarrhea virus (BVDV) exists in two main biotypes: cytopathic (cp) and noncytopathic (ncp). Although some studies were done on the effect of interferon alpha (IFN-α) on BVDV, the effect of exogenous IFN against BVDV biotypes remains unclear. In the present study, we evaluated the comparative effect of exogenous human IFN-α (HuIFN-α) on different BVDV biotypes and genotypes. The results showed that exogenous HuIFN-α greatly inhibited the growth of different BVDV biotypes and genotypes. However, HuINF-α has a significant inhibitory effect on cp biotype compared to ncp one without significant variation between different genotypes. The effect of HuIFN-α on BVDV reached the maximum level at early stages of infection (0-20 h post infection) and increased in a dose-dependent manner (10-500 U/ml). Quantitative real-time RT-PCR was used to evaluate the effect of exogenous HuIFN-α on RNA synthesis of both BVDV biotypes. HuIFN-α reduced RNA production of cp by 4 logs compared to only 2 logs for ncp strains. Additionally, the antiviral effect of IFN-α against both BVDV biotypes seems to be independent of the RNA-dependent protein kinase (PKR) activation as assayed by direct analysis of in vivo phosphorylation of eIF2-α and by 2-aminopurine (2-AP) treatment. Collectively, these results indicated that the exogenous HuIFN-α treatment has an inhibitory effect not only on cp BVDV biotype but also on the ncp BVDV. The antiviral effect of exogenous HuIFN-α was biotype, time, dose but not genotype dependent. PKR has no role in the inhibitory effect suggesting that other IFN-antiviral pathways were involved. Keywords: BVDV biotypes; HuIFN-α; RNA synthesis; PKR-independent.
Asunto(s)
Diarrea Mucosa Bovina Viral , Virus de la Diarrea Viral Bovina , Interferón-alfa , Animales , Antivirales/farmacología , Antivirales/uso terapéutico , Diarrea Mucosa Bovina Viral/tratamiento farmacológico , Diarrea Mucosa Bovina Viral/virología , Bovinos , Virus de la Diarrea Viral Bovina/efectos de los fármacos , Humanos , Interferón-alfa/farmacología , Interferón-alfa/uso terapéutico , Replicación Viral/efectos de los fármacosRESUMEN
Exposure to bovine viral diarrhea viruses (BVDV) results in acute and persistent infections. Persistent infections result from in utero exposure during the first trimester of gestation. Clinical presentation, in persistently infected cattle (PI), is highly variable. The reasons for this variation is largely unknown. The BVDV circulating in PI exist as quasispecies (swarms of individual viruses). An outbreak resulting in 34 PI cattle presented an opportunity to compare a large number of PI׳s. Methods were developed to compare the circulating viral populations within PI animals. It was found that PI animals generated in the same outbreak carry circulating viral populations that differ widely in size and diversity. Further, it was demonstrated that variation in PI viral populations could be used as a quantifiable phenotype. This observation makes it possible to test the correlation of this phenotype to other phenotypes such as growth rate, congenital defects, viral shed and cytokine expression.
Asunto(s)
Diarrea Mucosa Bovina Viral/epidemiología , Diarrea Mucosa Bovina Viral/virología , Virus de la Diarrea Viral Bovina/clasificación , Virus de la Diarrea Viral Bovina/genética , Brotes de Enfermedades , Regiones no Traducidas 5' , Secuencia de Aminoácidos , Animales , Bovinos , Secuencia de Consenso , Variación Genética , Genotipo , Datos de Secuencia Molecular , Filogenia , Virus Reordenados/genética , Alineación de Secuencia , Proteínas Virales/genéticaRESUMEN
Peripheral blood mononuclear cells (PBMCs) from 5 calves (3 controls and 2 vaccinates) used in a bovine herpesvirus 1 (BHV-1) vaccine study with a BHV-1 Cooper strain challenge were collected 6 months after challenge. The PBMCs from the control animals were positive by immunofluorescence for the BHV-1 glycoprotein D (gD) while the vaccinates were negative. The PBMC samples from 4 of the 5 animals were examined for BHV-1 DNA by polymerase chain reaction (PCR) and for gD immunofluorescence at 8 months after challenge. The BHV-1 DNA and viral antigen were detected in PBMC samples at 8 months postinfection, but no virus was isolated.