Enveloped DNA Viruses

Published on 18/02/2015 by admin

Filed under Allergy and Immunology

Last modified 18/02/2015

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Chapter 22

Enveloped DNA Viruses

Herpesviridae

• This family comprises large viruses with an enveloped, icosadeltahedral capsid and a linear, double-stranded DNA genome.

• All three subfamilies (alpha, beta, and gamma) contain significant human pathogens, which can establish primary lytic or persistent infection, as well as latent and recurrent infections (Table 22-1).

Herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2)

1. Pathogenesis

2. HSV diseases

• Overview

• Classic HSV lesions are vesicular with an erythematous base.

• Oral herpes (herpes labialis and gingivostomatosis) is caused primarily by HSV-1 in children and also by HSV-2 in young adults.

• Genital herpes is most commonly caused by HSV-2.

• Encephalitis and keratoconjunctivitis are usually due to HSV-1.

• Disseminated infection and more severe disease occur in individuals with compromised cell-mediated immunity and in neonates.

3. Laboratory identification

4. Transmission and incidence

5. Treatment

Varicella-zoster virus (VZV)

1. Overview

2. Chickenpox

• Primary VZV disease (Fig. 22-1)

• Skin lesions first appear on the trunk, 10 to 14 days after exposure (maximum, 90 days), and then on the peripheral regions of the body, including the scalp.

a. Lesions progress from initial macule → papule → vesicle → pustule → crusts.

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