Rapid detection of HSV with an enzyme-linked virus inducible system (ELVIS) employing a genetically modified cell line.
BACKGROUND
Infections with herpes simplex viruses (HSV) are common and may cause severe disease in immunocompromised hosts and in neonates. Isolation of infectious HSV in tissue culture is the most sensitive method of detection, but is not the most rapid. Recently, however, an Enzyme-Linked Virus Inducible System (ELVIS) for rapid detection of HSV in culture has been developed. The system employs genetically engineered baby hamster kidney (BHK) cells (ELVIS cells) whose DNA bears and HSV inducible promoter gene chimerically linked to an E. coli LacZ "reporter" gene. Induction of the promoter by HSV leads to the production of LacZ product, beta-galactosidase, which is readily detected histochemically.


OBJECTIVE
To evaluate these ELVIS cells, as a test for HSV, in comparison with HSV detection in MRC-5 cells in shell vial cultures confirmed by staining with fluorescent antibodies.


METHODS
Over a period of one month, 167 specimens submitted to the laboratory for detection of HSV were evaluated. Specimens were inoculated onto MRC-5 cells growing on glass coverslips in each of two shell vials and into two wells of a 24-well cluster plate containing ELVIS cells. MRC-5 shell vial cultures were observed daily for cpe for up to 7 days. With the appearance of cpe, the coverslips were fixed and the cells were typed for HSV-1 and HSV-2 with monoclonal antibodies. Specimens inoculated onto ELVIS cells were incubated for 16-24 h, then substrate was added to stain for beta-galactosidase. ELVIS cells, induced by HSV infection to express beta-galactosidase, stained blue upon reaction with substrate.


RESULTS
Of 167 specimens inoculated onto MRC-5 cells, 13 were excluded because of contamination or toxicity. Among the remaining 154 specimens, 24 were positive for HSV in the MRC-5 shell vials. Of 166 specimens inoculated into the ELVIS cell, all were completed within 24 h. Twenty-three (23) of the 24 shell-vial-positive cultures also were positive on the ELVIS cells. All 23 specimens detected in the ELVIS cells were positive within 24 h, whereas only nine were positive within 24 hours in MRC-5 shell vial cultures. The remaining 15 became positive after 24 h. Specimens positive for viruses other than HSV-1 or HSV-2 were not positive on the ELVIS cells.


CONCLUSIONS
The ELVIS assay for HSV is simple to perform, is rapid, sensitive, and specific. The assay detects both HSV-1 and HSV-2. No antibodies are required unless typing, which can be done on the ELVIS cells, is necessary.
Proffitt
M R
MR
Department of Clinical Pathology, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio, USA.
Schindler
S A
SA