Evaluation of ELVIS HSV ID/Typing System for the detection and typing of herpes simplex virus from clinical specimens.

BACKGROUND

Herpes simplex virus (HSV) is a common pathogen with two serotypes: HSV-1 and HSV-2. HSV infection does not pose much of a threat to an immunocompetent host but to an immunocompromised host or a neonate the infection can be fatal. The Enzyme-Linked Virus Inducible System (ELVIS) employs a genetically altered baby hamster kidney (BHK) cell line that allows for the rapid overnight detection of HSV but also includes an immunofluorescent stain for the simultaneous detection and typing of HSV-1 and HSV-2.

OBJECTIVE

To evaluate the ELVIS HSV ID/Typing System in comparison with HSV identification and typing in primary rabbit kidney (PRK) cells grown in shell vials.

STUDY DESIGN

Over a period of 6 weeks, 130 specimens were submitted to the diagnostic virology laboratory and cultured for the presence of HSV. Two PRK shell vials and one ELVIS BHK shell vial were inoculated with patient specimen. PRK shell vials were observed for cytopathic effect (CPE) for up to 4 days. When CPE was observed the PRK shell vials were fixed and one shell vial was stained with HSV-1 monoclonal antibody (Mab) and the other was stained with HSV-2 Mab. The coverslips were observed under the fluorescent microscope for specific apple-green fluorescence. The BHK shell vials were incubated overnight, fixed, and stained with galactopyranoside (X-Gal). If blue cells were present, the specimen was positive for HSV. The coverslip was then observed under the fluorescent microscope for the presence of specific apple-green fluorescence, indicating HSV-2. If no specific apple-green stain was observed, the coverslip was stained with a fluorescent conjugated goat anti-mouse IgG to determine the presence of HSV-1.

RESULTS

Of the 130 specimens, PRK shell vials detected 43 positive HSV; 30 were HSV-2 and 13 were HSV-1. The ELVIS BHK shell vials detected 42 positive HSV; 30 were HSV-2 and 12 were HSV-1. One low titer specimen was not identified as being HSV positive. Two specimens were not directly typed by the ELVIS system. One specimen had only one blue cell present and did not show specific staining for either HSV-1 or HSV-2. The other specimen had only five blue cells present and only one fluorescent cell present that was difficult to type. As suggested by the manufacturer's instructions, both specimens that were not directly typed were re-grown overnight from their supernatants and were correctly identified and typed.

CONCLUSION

The ELVIS HSV ID/Typing System is a rapid, highly specific and sensitive method of overnight HSV detection and typing.