
Full text loading...
Category: Clinical Microbiology
Varicella-Zoster Virus * , Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap97-1.gif /docserver/preview/fulltext/10.1128/9781555816728/9781555814632_Chap97-2.gifAbstract:
Varicella-zoster virus (VZV) belongs to the family Herpesviridae, based on morphological criteria, and is one of the eight human-pathogenic herpesviruses identified so far. The viral genome has an approximate length of 125,000 bp, making it the smallest of the human herpesviruses, and it encodes at least 70 viral genes. Prevaccination seroepidemiological studies in 11 European countries have shown that in most areas, more than 90% of 10 to 15-year-olds were already seropositive for VZV. The association between the clinical syndrome and VZV has been confirmed by detection of viral DNA by polymerase chain reaction (PCR) in fetal tissue. Real-time PCR assays based on sequence polymorphisms, especially in open reading frame (ORF) 62 or ORF 38, have also been established for detection of VZV. The enzyme-linked immunosorbent assay (ELISA) is usually used to determine VZV-specific antibodies (Abs) in blood, but it may also serve to detect Abs in cerebrospinal fluid (CSF). Screening for drug-resistant virus strains is rarely performed. Antiviral susceptibility of VZV strains can be determined. Changes in virus replication in the presence of different concentrations of various drugs are measured in most cases by plaque reduction assay. The major importance of Ab assays, of which ELISAs are currently the most commonly used, lies in their ability to identify previously infected individuals, as indicated by anti-VZV IgG Abs in the absence of immunoglobulin M (IgM). This information can be used to guide further vaccination decisions.
Full text loading...
Electron micrograph of VZV in skin vesicle fluid from a patient with varicella (magnification, ×100,000). Reprinted from reference 16.
Electron micrograph of VZV in skin vesicle fluid from a patient with varicella (magnification, ×100,000). Reprinted from reference 16.
Schematic of the VZV linear double-stranded DNA genome. UL, long unique segment (100 kbp); US, short unique segment (5.4 kbp); TRS and TRL, terminal repeats; IRS and IRL, internal repeats. The arrows indicate the direction of the transcription of the viral genes indicated. RR, ribonucleotide reductase; DBP, DNA binding protein. Reprinted from reference 40
Schematic of the VZV linear double-stranded DNA genome. UL, long unique segment (100 kbp); US, short unique segment (5.4 kbp); TRS and TRL, terminal repeats; IRS and IRL, internal repeats. The arrows indicate the direction of the transcription of the viral genes indicated. RR, ribonucleotide reductase; DBP, DNA binding protein. Reprinted from reference 40
Giemsa-stained preparation of material from the base of a vesicular lesion. Magnification, ×102. The arrow indicates a giant cell with a folded nucleus characteristic of VZV or HSV.
Giemsa-stained preparation of material from the base of a vesicular lesion. Magnification, ×102. The arrow indicates a giant cell with a folded nucleus characteristic of VZV or HSV.
Comparison of the amount of VZV DNA in CSF according to the neurological diagnosis (A), the severity of disease (B), and the presence of acute peripheral facial palsy (C). The geometric mean value is shown by a horizontal line. The P value was calculated using the Mann- Whitney U test. (Modified from reference 1 , with permission.)
Comparison of the amount of VZV DNA in CSF according to the neurological diagnosis (A), the severity of disease (B), and the presence of acute peripheral facial palsy (C). The geometric mean value is shown by a horizontal line. The P value was calculated using the Mann- Whitney U test. (Modified from reference 1 , with permission.)
Immunofluorescence assay for the detection of VZVpositive cells from a patient with zoster. A smear of a skin vesicle was fixed and stained with MAb to VZV gE. Magnification, 3200.
Immunofluorescence assay for the detection of VZVpositive cells from a patient with zoster. A smear of a skin vesicle was fixed and stained with MAb to VZV gE. Magnification, 3200.
Diagnostic tests for VZV-induced disease
Diagnostic tests for VZV-induced disease
Quantitative VZV DNA results with different clinical materials from patients with different VZV-associated diseases a
a Abbreviations: co, copies; GC, ganglion cells.
Quantitative VZV DNA results with different clinical materials from patients with different VZV-associated diseases a
a Abbreviations: co, copies; GC, ganglion cells.