Amplification of reiterated sequences of herpes simplex virus type 1 (HSV-1) genome to discriminate between clinical HSV-1 isolates

Herpes simplex virus type 1 (HSV-l)-related disease ranges from a localized , self-limiting illness to fatal disease in immunocompromised individuals, The corneal disease herpetic keratitis may develop after reactivation of a latent virus or reinfection with an exogenous herpesvirus. Molecular analys is of the virus involved may allow distinction between these two options, T he HSV-1 genome contains several hypervariable regions that vary in numbers of reiterating regions (reiterations I to VTH [ReI to ReVIII]) between ind ividual strains. Twenty-four HSV-1 clones, derived by subcloning of HSV-1 ( strain F) twice in limiting dilutions, were tested in a PCR-based assay to analyze the stabilities of ReI, ReIII, ReIV, and ReVII. ReI and ReIII prove d to vary in size upon subcloning, whereas ReIV and ReVII were stable. Subs equently, 37 unrelated isolates and 10 sequential isolates from five patien ts, all with HSV-1-induced keratitis, were genotyped for ReIV and ReVII. Of the 37 unrelated samples, 34 (92%) could be discriminated, while the genot ypes of the viruses in sequential samples were identical for each individua l. Conclusively, the data show that the approach presented allows the rapid and accurate discrimination of HSV-1 strains in studies that address the t ransmission and pathogenesis of HSV-1 infections.