Laboratory Diagnosis of Varicella-Zoster virus
المؤلف:
Stefan Riedel, Jeffery A. Hobden, Steve Miller, Stephen A. Morse, Timothy A. Mietzner, Barbara Detrick, Thomas G. Mitchell, Judy A. Sakanari, Peter Hotez, Rojelio Mejia
المصدر:
Jawetz, Melnick, & Adelberg’s Medical Microbiology
الجزء والصفحة:
28e , p485
2025-11-11
158
Rapid diagnostic procedures are clinically useful for varicella-zoster virus. Direct fluorescent antigen detection and PCR assays are useful for sensitivity, specificity, and rapidity. Viral DNA can be detected in vesicle fluid, skin scrapings, CSF, body fluids, and tissue samples.
In stained smears of scrapings or swabs of the base of vesicles (Tzanck smear), multinucleated giant cells are seen (see Figure 1). These are absent in nonherpetic vesicles. Intracellular viral antigens can be demonstrated by immunofluorescence staining of similar smears. Herpesviruses can be differentiated from poxviruses by the morphologic appearance of particles in vesicular fluids examined by electron microscopy (Figure 2).
Fig1. Characteristic histologic changes of varicella zoster virus infection. Punch biopsies of varicella-zoster virus vesicles were fixed and stained with hematoxylin and eosin. A: Early infection showing “balloon degeneration” of cells with basophilic nuclei and marginated chromatin (reduced from 480×). B: Later infection showing eosinophilic intranuclear inclusions surrounded by wide clear zones (reduced from 480×). C: Multinucleated giant cell in the roof of a varicella vesicle (reduced from 480×). D: Low power view of an early vesicle showing separation of the epidermis (acantholysis), dermal edema, and mononuclear cell infiltration (reduced from 40×). (Reproduced with permission from Gelb LD: Varicella-zoster virus. In Fields BN, Knipe DM [editors-in-chief]. Virology, 2nd ed. Raven Press, 1990.)
Fig2. Top: Herpesvirus particles from human vesicle fluid stained with uranyl acetate to show DNA core (140,000×). Bottom: Virions stained to show protein capsomeres of the virus coat (140,000×). Note: Different herpesviruses cannot be distinguished by electron microscopy. (Courtesy of KO Smith and JL Melnick.)
Virus can be isolated from vesicle fluid early in the course of illness using cultures of human cells in 3–7 days.
Varicella-zoster virus in vesicle fluid is very labile, and cell cultures are not particularly sensitive.
VZV PCR is the preferred method for diagnosis of VZV encephalitis. However, viral DNA may be undetectable in the CSF at the time of presentation. Some studies have shown that inclusion of CSF IgM antibodies to VZV can improve the sensitivity of diagnosis.
A rise in specific antibody titer can be detected in the patient’s serum by various tests, including fluorescent anti body and enzyme immunoassay. The choice of assay to use depends on the purpose of the test and the laboratory facilities available. Cell-mediated immunity is important but is difficult to demonstrate.
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