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.

Rapid diagnosis in varicella and herpes zoster: re-evaluation of direct smear (Tzanck test) and electron microscopy including colloidal gold immuno-electron microscopy in comparison with virus isolation.

The Tzanck test and electron microscopy with the technique of colloidal gold labelling in varicella-zoster virus (VZV) infections were compared with virus isolation in 54 patients with clinically suspected varicella or herpes zoster infection. The Tzanck test and direct electron microscopy can determine whether or not an eruption is herpetic but cannot distinguish between herpes simplex virus (HSV) and VZV infection. However, colloidal gold immuno-electron microscopy, using monoclonal antibodies against HSV and anti-VZV IgG, can distinguish between these two herpes viruses. This achieves the same specificity as virus isolation followed by virus neutralization or virus typing using immunofluorescence techniques. The Tzanck test was positive in 91%, virus isolation, under optimal conditions of sampling and transportation, in 80%, direct electron microscopy (negative staining) in 80%, and colloidal gold immuno-electron microscopy after a virus concentration procedure in 95% of the cases. The colloidal gold technique offers a rapid diagnosis in patients with suspected VZV infection.

Tzanck smear in diagnosing genital herpes.

In 126 patients with anogenital lesions, in which herpes simplex virus (HSV) infection was suspected or included in the differential diagnosis, the results of cytodiagnosis of herpetic infection (Tzanck smear) were compared with virus culture. Cervical lesions were excluded from this study. HSV infection was proved by culture in 78 patients and was absent or non-active in 41 patients. Excluded from this study were seven patients who did not yield the virus on culture but had positive Tzanck smear results from three investigators. The characteristic cytopathic effect of herpetic infection was found in 78 patients who yielded HSV on culture. Tzanck smear sensitivity for skin lesions was 79% and for mucous membrane lesions was 81% in men and 52% in women. Tzanck smear specificity for the 41 patients without herpetic infection proved by virus culture was 93%. Differences in sensitivity and specificity between the results found by three investigators (double blind screening) were not significant. The Tzanck smear is reliable, inexpensive, and easy and quick to perform; it is suitable for office diagnosis because it does not require a specialised laboratory.

Diagnostic value of Tzanck smear in herpetic and non-herpetic vesicular and bullous skin disorders in pediatric practice.

The diagnostic value of the Tzanck smear was investigated in 76 patients of a pediatric hospital population suffering from vesicular, erosive or bullous skin disorders. Examination took place by two investigators together (AB), besides the smears were examined by two others (C and D) double blind. Sensitivity for patients with clinical herpetic infections was greater than 80%, specificity for those without herpetic infections was greater than 90%. These figures are higher than expected from literature. Reliability was also high; between the three investigators no significant differences were found. The Tzanck smear is simple, inexpensive, easy to perform and rapid; it does not require a specialized laboratory, but experience and correct technique of sampling is required.