Microbiology
Viruses
HSV1 / HSV2

Author: Christopher Hale, M.D. (see Authors page)

Revised: 28 April 2016, last major update February 2014

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: HSV1 / HSV2

Definition / General
  • Alpha subfamily of Herpesviridae = Herpes simplex virus-1, herpes simplex virus-2, and herpes B virus (a zoonotic pathogen found in primates)
  • Herpes simplex virus-1 = Human herpes virus-1 (HHV1)
  • Herpes simplex virus-2 = Human herpes virus-2 (HHV2)
  • See also topics in these chapters: Cervix, Cervix - cytology, Penis and scrotum, Vulva
Etiology
  • HSV1: more often "oral herpes" (gingivostomatitis, fever, lymphadenopathy), although increasingly a cause of genital infections

  • HSV2: "genital herpes" (vesicles, fever, lymphadenopathy, dysuria)

  • Neonatal herpes: maternal to infant transmission of HSV1 or 2 → CNS, skin, ocular, systemic infection

  • Meningitis or encephalitis: severe complication of HSV1 or HSV2 infection, often involves temporal lobe, often fatal

  • Ocular infection: conjunctivitis / uveitis / retinitis

  • Esophageal infection

  • Cutaneous infections:
    • Herpes gladiatorum: cutaneous herpes infection affecting wrestlers, transmitted through contact
    • Herpetic whitlow: infection of fingertip
    • Eczema herpeticum: "Kaposi varicelliform eruption" sometimes used as synonym; disseminated cutaneous herpes infection with overlapping features of atopic dermatitis (PLoS Med 2004;1:e17)
Laboratory
  • Culture conditions:
    • Culture less sensitive than molecular, but near 100% specific if confirmatory tests run
    • Must collect in viral transport medium (VTM)
    • Richards viral transport and HH medium best transport media when transport is > 1 day or if low levels of virus (Diagn Microbiol Infect Dis 1994;19:137)
    • Transport specimen cold, but not frozen
    • Avoid swabs with wooden shafts or calcium alginate heads (J Infect Dis 1982;145:399)
    • Culture techniques include growth in standard eukaryotic cell lines such as Hep-2 or human diploid fibroblasts (Diagn Microbiol Infect Dis 1991;14:373)
    • Infected cell cultures may be examined for characteristic viral cytopathic effects (inclusions, multinucleation, etc.)

  • Newer molecular techniques increasingly preferred (PCR, multiplex PCR) over viral culture (Clin Microbiol Rev 2008;21:716)
  • Serology (change in titer, IgM to IgG switch) may assist in determining exposure or time course of disease
  • Direct fluorescent antibody (DFA) kits
  • Enzyme immunoassay (EIA) kits

  • Tzanck smear:
    • A Giemsa or Wright stain used for morphologic identification of viral cytopathic effects
    • Cytopathic effects include the "3 Ms:" molding of nuclei, multinucleation, and margination of chromatin to the periphery of the nucleus
    • Cannot distinguish HSV1, HSV2, and Varicella Zoster Virus by Tzanck smear
Treatment
Clinical Images

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HSV infected cell

Gross Description
Molecular / Cytogenetics Description
  • Molecular identification techniques (nucleic acid amplification testing) replacing traditional diagnostics in some settings (Curr Issues Mol Biol 2007;9:87)
  • PCR: most sensitive method of detecting HSV infections, used for CSF / ocular / neonatal infections