Antiviral activity of crude extracts of Guarea guidona

Crude extracts of leaves and fruits of Guarea guidona were tested antiviral activity against pseudorabies virus and foot-and-mouth disease virus in the IB-RS-2 pig cell line and against bovine herpesvirus-1 (BHV-1) in the GBK bovine Cell line. The highest nontoxic doses of extracts from fruits and leaves were 125 mug/ml and 500 mug/ml, respectively. Crude extracts presented antiviral activity against pseudorabies virus with a decrease in virus titer of 3.0 log units at 500 mug/ml. Virucidal activity was not observed at 62.5 mug/ml. Preformed cell monolayers showed no cytotoxic effect after 48 h in the presence of 500 mug/ml in pig cells. G. guidona leaves did not induce an antiviral state but exhibited antiviral effects during the early stage of viral infection.

Non-pathogenic strains of Aujeszky's disease virus are not reactivated in swine after corticosteroid treatment

The Bartha-K and NIA-4 strain of Aujeszky's disease virus (ADV) were readily isolated from oropharyngeal swabs up to 7 days after intranasal vaccination of young piglets. Neither strain could be reisolated 14 days after starting treatment with 10 mg of the corticosteroid isoflupredone acetate per kg of body weight, administered intramuscularly for 4 consecutive days when pigs were 7-9 months of age. Similar treatment with corticosteroid pigs infected with two virulent ADV strains resulted in the reactivation of infection and recovery of ADV from oropharyngeal swabs. Serum neutralizing antibodies were present in all pigles vaccinated twice (2 week interval) intranasally with the attenuated ADV strains, 4 weeks after primary vaccination. However, these antibodies were no longer detectable in some pigs at 12(NIA-4) and 20(Bartha-K) weeks of age even in undilluted sera. Neutralizing antibodies resulting from infection virulent ADV were always detectable, were higher in titer than those produced by the vaccine strains and did not vary in a clear pattern after corticosteroid treatment. These results indicated that the Bartha-K and NIA-4 strains undergo little or no latency in swine and confirm the latency of virulent strains of ADV

Inhibición del virus de pseudorrabia (Suid herpesvirus 1) por acción de un antiviral aislado de hojas de Melia azedarach / Inhibition of the pseudorabies virus (Suid herpesvirus 1) by an antiviral agent isolated from the leaves of Melia azedarach

Los extractos crudos y purificados de hojas verdes de Melia azedarach L (nombre vulgar: árbol del Paraíso) inhiben la acción citopática y la producción de viriones del virus de pseudorrabia (Suid herpesvirus 1) en células Vero. Para que esto ocurra el antiviral debe agregarse después de la adsorción viral y conservarse en el medio de cultivo hasta la cosecha del virus. La acción del antiviral vegetal es específica ya que se manifiesta en concentraciones que no son tóxicas para la célula huésped. El inhibidor no tiene propiedades virucidas ni impide la adsorción ni la penetración viral. Su blanco de acción es intracelular y se expresa aún agregado a las células infectadas cuatro horas después que el virus. De acuerdo con estos resultados se postula que su blanco de acción probable es la transcripción temprana de los genes virales