Herpes simplex virus: isolation, cytopathological characterization and antiviral sensitivity

BACKGROUND: Herpes simplex virus (HSV) infection is an endemic disease and it is estimated that 6095% of the adult population are infected with symptoms that are usually self-limiting, though they can be serious, extensive and prolonged in immunocompromised individuals, highlighted by the emergence of drug-resistant strains. The study of the wild-type HSV strains based on the cytopathogenic features and its antiviral sensitivity are important in the establishment of an antivirogram for controlling the infection. OBJECTIVE: This study sought to isolate and examine the cytopathological characteristics of circulating strains of the Herpes simplex virus, from clinical specimens and their sensitivity to commercially available antiherpesvirus drugs, acyclovir, phosphonophormic acid and trifluridine. METHODS: Herpes simplex virus isolation, cytopathological features and antiviral sensitivity assays were performed in cell culture by tissue culture infectious dose or plaque forming unit assay. RESULTS: From twenty-two clinical specimens, we isolated and adapted nine strains. Overall, the cytopathic effect was detected 24 h post-infection (p.i.) and the presence of syncytia was remarkable 48 h p.i., observed after cell staining. Out of eight isolates, four developed plaques of varying sizes. All the isolates were sensitive to acyclovir, phosphonophormic and trifluridine, with the percentage of virus inhibition (%VI) ranging from 49.7-100%. CONCLUSIONS: The methodology for HSV isolation and characterization is a straightforward approach, but the drug sensitivity test, regarded as being of great practical importance, needs to be better understood. .

Antiviral susceptibility of cytomegakovirus isolated

Two wild-types clinical cytomegalovirus [CMV] isolates were plaque purified and the individual plaque variants were then randomly picked and passed 3-5 times in human foreskin fibroblast [MRHF] to increase viral titer and test for susceptibility to the antiviral ganciclovir [DHPG]. Different susceptibility pattern to DHPG has been identified among the individual plaques tested with an inhibitory concentration 50 [ID50] ranged from 0.08-14.2 muM. Also, a fully sensitive [DHPG ID50 <5 muM], intermediate resistant [DHPG ID50 between 6-10 muM] and resistant [DHPG ID50 >10 muM] plaque purified viral isolates were further tested for susceptibility to other antiviral agents [foscarnet and HPMPC]. All the tested individual strains [DHPG sensitive and resistant] remained susceptible to foscarnet and HPMPC. It may be concluded that within any resistant population of CMV to DHPG, there was a marked heterogenicity with some subsets of the population remaining susceptible to the drug and others exhibiting considerable level of resistance. DHPC resistant CMV isolates remained susceptible to the other antiviral drugs [foscarnet and HPMPC meaning that therapy with these two antiviral agents would still be available

Estudio de la acción combinada de meliacina y foscarnet contra distintas cepas del virus herpes simplex tipo 1 empleando un modelo tridimensional / Evaluation of the antiviral activity of meliacine-foscarnet combination against different strains of herpes simplex virus type 1 by a three-dimensional model

Se estudió la actividad antiviral y citotóxica de varias combinaciones de meliacina y foscarnet in vitro con el objeto de identificar aquellas combinaciones que podrían presentar una mayor actividad antiviral sobre la multiplicación del virus herpes simplex tipo 1 (HSV-1) cepa F y la cepa deficiente en timidina quinasa (TK) B2006. En las condiciones ensayadas, la concentración efectiva 50 o/o (CE50) de meliacina contra HSV-1 (F) fue 12,5 mg/ml y 15,7 mg/ml para foscarnet; mientras que contra HSV-1 (B2006) fueron 3,1 mg/ml y 126 mg/ml respectivamente. El análisis de los resultados, utilizando un modelo tridimensional, reveló que algunas de las combinaciones inhiben en forma sinérgica la multiplicación de estas cepas en concentraciones que no reducen la viabilidad celular