Ann L. Warford

Direct detection of Molluscum contagiosum virus in clinical specimens by in situ hybridization using biotinylated probe.

Molluscum contagiosum virus (MCV) is an unclassified poxvirus which has recently become recognized as causing a major sexually transmitted disease. At present no assay is available for specific detection of MCV because the virus cannot be serially propagated in cell culture. Since MCV produces an abortive, limited growth with some cytopathic effect in certain cell lines, we were able to develop an in situ hybridization assay for detection of MCV genome in clinical specimens. Human fetal diploid lung cell monolayers were infected with clinical specimens, and after proper incubation and fixation in paraformaldehyde, hybridization was performed under full stringency conditions with a molecularly cloned biotinylated probe. Only MCV infected cells showed homology to the MCV probe with a purple-brown cytoplasmic staining. Additionally, we have described an in situ hybridization assay for direct detection of MCV genome in formalin-fixed, paraffin-embedded biopsies. Characteristic intracytoplasmic Molluscum bodies (Henderson-Paterson bodies) were detected in stratum spinosum cells of the epidermis. Striking staining similarities have been observed between in situ hybridization and haematoxylin-eosin cytostaining. These procedures are the first successful identification of MCV genome in clinical samples by molecular hybridization, with sensitivity and specificity equal to or greater than electron microscopy.

Herpes simplex virus testing of an obstetric population with an antigen enzyme-linked immunosorbent assay

Commercial herpes simplex virus antigen enzyme-linked immunosorbent assay kits were compared to conventional culture for herpes simplex virus with 3237 genital specimens from obstetric patients. These rapid enzyme-linked immunosorbent assay tests had a sensitivity of 34.3% and specificity of 98.1% with primarily cervical specimens from asymptomatic patients. Specimens from vulvar swabs had higher positive rates than those from cervical swabs from the same patient, whether symptomatic or asymptomatic with both culture and enzyme-linked immunosorbent assay. Fifty-six women had enzyme-linked immunosorbent assay false positive tests; use of enzyme-linked immunosorbent assay testing alone could have resulted in 1.7% unnecessary cesarean deliveries. Six cases of neonatal herpes simplex virus infection were identified; two of the mothers had negative cervical cultures the week of delivery preceded by positive vulvar cultures.

Newer Approaches to Perinatal Herpes Simplex Virus Testing

The prevalence of genital herpes simplex virus (HSV) infections in the United States as estimated from “first office visits” has increased 9-fold over the period from 1966 to 1984 (Centers for Disease Control, 1986). The incidence of neonatal HSV infections has also increased, as reported from King County, Washington, from 2.6 to 28.2 per 100,000 live births over the period from 1966 to 1982 (Sullivan-Bolyai et al. 1983). In Southern California we have experienced similar increases from 2 cases in 1982 (8.2/100,000 live births) to 6 and 7 cases in 1985 and 1986 (25.5/100,000). The mortality associated with neonatal HSV infections has decreased with antiviral therapy from 80% to 15% of the cases with central nervous system (CNS) and to 50% of cases with disseminated disease (Stagno and Whitley, 1985). One third to one-half of these treated infants, however, have neurologic sequelae which may appear as late as 1 to 2 years after treatment (Whitley et al. 1980, 1986).