Evaluation of an enzyme immunoassay for the detection of herpes simplex virus (HSV) antigen from clinical specimens in viral transport media

Microbiologic investigations for head and neck infections

A variety of methods, including direct examination of stained smears, antigen detection, routine and special cultures, and histopathologic evaluation are available for investigation of head and neck infections. Newer rapid molecular techniques with increased sensitivity and specificity are becoming available at many centers. Evaluation of specific causes in head and neck infections is complicated by the tendency for polymicrobial infections, difficulty in obtaining adequate specimens, and the presence of a diverse endogenous microflora at various mucosal sites that also can include true pathogens. These aspects of laboratory investigation for head and neck infections are reviewed in this article.

Diagnosis of herpes simplex virus infections in the clinical laboratory by LightCycler PCR

Herpes simplex virus (HSV) causes several clinical manifestations in both normal and immunocompromised hosts; this agent is the most frequently detected virus in diagnostic laboratories. Recovery of the virus in cell culture is considered the "gold standard" for detection of this virus from sources other than cerebrospinal fluid. LightCycler is a newly developed, commercially available system designed to rapidly perform PCR, with real-time detection of PCR products by a fluorescence resonance energy transfer assay. We compared the detection of HSV for 200 specimens (number of genital specimens, 160; number of dermal specimens, 38; number of ocular specimens, 2) by shell vial cell cultures (MRC-5) and by LightCycler PCR. Of a total of 88 (44%) HSV strains detected, 69 (78%) were detected by both shell vial cell cultures and LightCycler PCR (DNA polymerase target). A total of 19 (22%) specimens were detected exclusively by LightCycler PCR. No specimens were positive by the shell vial assay only. All 19 discrepant samples had HSV DNA detected by an independent PCR directed to the thymidine kinase gene of the virus. The melting curve analysis feature of the LightCycler instrument identified identical genotype results for HSV type 1 (HSV-1) and HSV-2 from 84 of 88 (96%) positive samples. Specimens can be extracted, target HSV DNA can be amplified, and HSV PCR products can be identified by genotype within 2 h after receipt of specimen into the laboratory. The increased level of accurate identification (all 88 positive samples) compared with that of shell vial cell culture (69 of 88 samples identified as positive) and the agreement of LightCycler PCR results with all shell vial positive results indicate the potential for routine implementation of this technology for laboratory diagnosis of HSV infections.

Evaluation of new transport medium for detection of herpes simplex virus by culture and direct enzyme-linked immunosorbent assay

The transport medium Multi-Microbe Media (M4) was evaluated prospectively by culture and direct enzyme-linked immunosorbent assay (ELISA) for detection of herpes simplex virus from 473 specimens. In addition, 377 specimens in Bartels Viral Transport Medium were evaluated. By using culture as a "gold standard," the ELISA sensitivity was approximately 85%, while the specificities exceeded 96% for both media.

Evaluation of an automated immunodiagnostic assay system for direct detection of herpes simplex virus antigen in clinical specimens

The Vitek ImmunoDiagnostic Assay System (VIDAS) is a 2 1/3-h automated qualitative enzyme-linked fluorescent immunoassay developed for the direct detection of herpes simplex virus (HSV) antigen in clinical specimens. A total of 356 clinical specimens submitted for HSV isolation were prospectively evaluated with the VIDAS, and the results of the technique were compared with those of both HSV isolation in cell culture and Herpchek, a nonautomated enzyme immunoassay. Compared to cell culture, VIDAS had a sensitivity of 91.6% and a specificity of 89.3%, with positive and negative predictive values of 82.6 and 95.0%, respectively. In comparison to Herpchek, VIDAS had a sensitivity of 93.7% and a specificity of 93.0%, with positive and negative predictive values of 89.4 and 95.9%, respectively. The results demonstrated that the VIDAS required minimal manipulation in order to produce results comparable to those of Herpchek and HSV isolation in cell culture.

Improved detection of HSV by electron microscopy in clinical specimens using ultracentrifugation and colloidal gold immunoelectron microscopy: comparison with viral culture and cytodiagnosis

Three tests were compared to diagnose herpes virus infection: electron microscopy (EM), viral culture (VC) and cytodiagnosis (Tzanck smear). The study comprised 67 patients with skin or mucous membrane lesions suggestive of herpes simplex virus (HSV) infection. The sensitivity of EM increased 25% after virus concentration by ultracentrifugation. Herpes virus infection was confirmed in 55 of the 67 cases by EM or VC or both. EM detected 53 herpes virus-positive lesion samples of which 14 were not detected by VC; only two lesion samples that were herpes virus-positive in VC were not detected by EM. The sensitivities of EM, VC, and Tzanck smear for the group of 55 herpes virus-positive cases were 96%, 75% and 76%, respectively. The specificity of the Tzanck smear was 83% (prevalence 82%). Colloidal gold immuno-EM was used to rapidly type HSV-1, HSV-2 and varicella zoster virus (VZV) present in skin and mucous membrane lesions in less than 4 h. Immuno-EM was able to detect antiviral antibodies on viral envelopes and viral cores in lesion samples with negative VC. Antiviral antibodies do not interfere with typing of herpes viruses by immuno-EM. It is suggested that formation of viral immune complexes and inactivation of virus particles by antibodies may have caused a negative VC. Improved EM is discussed for its applicability to special cases that cannot rely on VC and cytodiagnosis or when rapid diagnosis is required.