Herpes Simplex Virus (HSV)

Epidemiology and Etiology:

· Herpesvirus family

· Large encapsulated dsDNA

· ~70 proteins

· Latency

· Inability to recover infectious particles from cells that harbor the virus

· Risk groups

· Neonates

· Immune compromised

· hospitalized

· Virulence factors

· Evade CTLs by inhibiting MHC class I recognition pathway

· Evade humoral defenses by producing receptors for the Fc domain of immunoglobulin and inhibitors of complement

· Immune-mediated corneal stromal disease as well as direct viral damage to epithelium

·

Common sites:

· Acute infection in epithelial cells

· Oropharynx

· Gingivostomatitis (HSV-1)

· Genitals (HSV-2, or HSV-1)

· Cervix

· Vulva

· cornea

· Latency in neuron cell bodies

· Brain

· Temporal lobes and orbital gyri

· Sporadic encephalitis

· Fingers or palm (herpetic whitlow)

· Infants, healthcare workers

· Disseminated in neonates or immune compromised

· Esophagus

· Lymphadenopathy

· Splenomegaly

· Lungs

· Liver

· Adrenals

· CNS

Gross features:

·

Histologic features:

· Large, pink to purple intranuclear inclusions (Cowdry type A) in epithelial cells

· Push darkly stained host chromatin to the periphery of the nucleus

· Nuclear size increases only slightly

· Multinucleated inclusion-bearing syncitia

· Erosions, ulcerations

· Herpes stromal keratitis

· Mononuclear infiltrates around keratinocytes and endothelial cells

· Neovascularization

· Scarring

· Necrotizing visceral lesions in disseminated infection

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· During latency, only latency-associated transcripts (LATs) are synthesized

Other features:

· Superinfection by bacteria or fungi

References:

· Kumar V, Fausto N, Abbas A. Robbins & Cotran Pathologic Basis of Disease, Seventh Edition. 7th ed. Saunders; 2004.