The use of colloidal gold immunoelectron microscopy to diagnose varicella-zoster virus (VZV) infections by rapid discrimination between VZV, HSV-1 and HSV-2.

Colloidal gold immunoelectron microscopy was used to diagnose rapidly 53 cases clinically suspected of varicella-zoster virus (VZV) infection and one special case selected from another study on typical herpes simplex virus (HSV) infections. The viruses were identified and subsequently typed within 2.5 h by a direct labelling test for VZV, and within 3.5 h by an indirect labelling test with monoclonal antibodies against HSV type 1 and type 2. The protein A purified IgG fraction of human anti-VZV immunoglobulins was adsorbed to colloidal gold particles, and the specificity of the gold-labelled antibodies was tested with several human and animal herpesviruses. Viral envelopes did not crossreact in the direct labelling test. However, an indirect labelling procedure revealed that a small fraction of the anti-VZV antibodies crossreacted with the cores of herpes simplex virus and pseudorabies virus (Aujeszky disease virus). Virus-infected cellular material taken from typical herpetic lesions was used directly without virus propagation for virus typing. All cases (N = 54) were analyzed without knowing the clinical description of the results of cytopathologic examination (Tzanck smear) and viral culture. Forty-four cases were identified as VZV; however, 5 of the supposed VZV infections were proved to be HSV infections. Although the viral culture of the one HSV case was HSV- and VZV-negative, colloidal gold labelling identified the case as VZV infection. In 16 cases virus immunoglobulin complexes were detected by using gold-tagged antibodies against human immunoglobulins. Immunoglobulins on the viral envelopes did not interfere with virus typing by immunogold labelling.