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Table 3 Direct laboratory methods for HSV diagnosis

From: Diagnosis of genital herpes simplex virus infection in the clinical laboratory

Method

Principle

Sample

Sensitivity

Specificity

Advantages

Disadvantages

Viral antigen detection

Immunopreoxidase staining

Swab

Middle (80%)

High (90%)

Reagent cost

Fresh vesicles

Smears from lesions

Rapid (<4 hours possible)

Suboptimal sensitivity

Smear or vesicular fluid of exudate from base of vesicle

Does no require the integrity of the specimen

Typing possible

 

Capture ELISA

Swab

High (Genital ulcer: >95%)

High (62-100%)

 

Fresh vesicles

Vesicular fluid or exudate from base of vesicle

No viral typing

 

Rapid test device

Swab

Unknown

Unknown

Point-of-care testing

Not yet evaluated

Vesicular fluid or exudate from base of vesicle

Virus culture

HSV isolation susceptible cells

Swab

Low to high depending of the clinical context

High (≈100%)

Allows virus isolation

Less sensitive than PCR

Skin lesions

Sample storage and transport conditions influence sensitivity

Classically, “gold standard” method

Vesicular fluid or exudate from base of vesicle

Vesicular content :>90%

( Rapid transport, cooled, protected from light in virus transport medium)

Currently, “preferred” test (CDC 2010)

Ulcer : 95%

Swab : 70%-80%

Labor-intensive

Mucosal sample without lesions Biopsies

Mucosa without lesion: 30%

Simplicity of sampling

Expensive

Virus typing

Specialized laboratories

Resistance

Results in 2/7 days

Phenotype testing*

Arrangement with laboratory necessary

Conjunctival/corneal smear

Neonates

Molecular biology

HSV DNA detection and/or quantitation by NAAT, including in-house classical PCR, real-time PCR and commercial assays

Swab

Highest

High.

High sensitivity.

Only in specialized laboratories

Skin lesions

(98%)

(≈100%)

Vesicular fluid or exudate from base of vesicle

Containment of potential cross-contamination important

Currently, “preferred” test (CDC 2010)

Not standardized

Allows virus detection and typing in the same test

Not validated for all samples

Mucosal sample without lesions

Risk of contamination (PCR)

May be relatively expensive (real-time PCR)

Rapid

Aqueous/vitreous humor

May be automated.

Labor efficient

Routine resistance genotyping not available

Cortico-spinal fluid

Result within 24–48 h, possibly in <3 hours

Blood

Resistance genotyping

Method of choice for CSF

Real-time PCR:

Rapid amplification

Quantitative analysis

Reduced risk of contamination

Method of choice for skin lesions

Cytological examination

Tzanck smears

Skin/mucosal lesions

Low

Low

Inexpensive

Fresh lesions

Papanicolaou or Romanovsky stain

low sensitivity and no distinction between HSV-1 and HSV-2, nor between HSV and varicella zoster virus infection

Biopsies

Conjunctival/corneal smears

 

Detection of infected cells by direct immunoflorescence

Smears, Tissue section Smear from base of vesicle

Middle

High

Inexpensive

Fresh vesicles

(Genital ulcer: 70-90%

(>95%)

Rapid (<4 hours possible)

Suboptimal sensitivity

Asymptomatic : < 40-50%)

Typing possible

Time-consuming

Labor-intensive

      

Not standardized

  1. *The detection of resistance mutations to anti-herpetic drugs (aciclovir) by HSV drug resistance genotyping is likely to supplant phenotypic testing in the next few years.
  2. NAAT: nucleic acid amplification test; CDC : Centers for Disease Control.