Application of EM to differentiate herpes virus from pox virus in genital specimens

Abstract

Confirmation of herpes simplex virus (HSV) from genital lesions of obstetrical (OB) patients may affect both the management of the delivery and of the neonate.(l,2) During 1992 and 1993, 4,450 genital specimens from OB patients were submitted in viral transport media for herpes culture. The specimens were inoculated into MRC-5, Vero, and A-549 tissue culture tubes, incubated, and examined daily for 7 days for cytopathic effect (CPE). The original specimens were frozen at −70° C until final reports were issued. Culture tubes with CPE were tested by the Dupont Herpchek enzyme immuno assay (EIA) to confirm the presence of herpes simplex virus (HSV). (3,4) 170 OB patient specimens were positive by culture and confirmed by EIA.There were also 63 cultures exhibiting CPE ressembling HSV which were negative by EIA testing, which failed to pass in fresh tissue culture cells or progress to more enhanced CPE in culture. These original specimens were screened by electron microscopy after direct ultracentrifugation employing the Beckman airfuge with the EM 90 rotor on to formvar carbon-coated 300 mesh copper grids and negatively stained with 2% PTA.