Herpes simplex virus: isolation, cytopathological characterization and antiviral sensitivity

Abstract

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.

FIGURE 1

HEp-2 cell cultures infected with the isolate S8. Multinucleate giant cell (syncytium) (arrow) is shown in cultures stained with hematoxylin- eosin 48h post-infection (40X)

FIGURE 2

HEp-2 cell cultures infected with the isolate S8. Control noninfected cell cultures (A) and cultures with cytopathic effect 48h (B), 72h (C) and 96h (D) post-infection. Unstained fresh cultures (50X))

FIGURE 3

Plaques developed by isolate S4 (lines 3 and 4 - duplicate) in HEp-2 cell cultures 72h postinfection after crystal violet staining (lanes B-F). Non-infected cell control (lines 1 and 2, and lane A)