WHEN SHOULD I BE TESTED?
LABORATORY TESTS
HSV testing is used to detect the presence of the herpes simplex virus (HSV) in those who have genital sores or encephalitis and in newborns suspected of having neonatal herpes, a rare but serious condition in which herpes is contracted during vaginal birth.
Direct Method
1. Viral Isolation (Culture)
2. Antigen Detection
3. Tzanck Smears
4. Electron Microscopy
5. Virus DNA Detection
Indirect Serological Test (Type Specific)
1. Western Blot
2. Commercial IgG-based Type-specific tests
Antiviral Resistance Tests
1. Drug Sensitivity Assay
RESULTS
A positive herpes simplex culture or HSV DNA test from a vesicle scraping indicates an active HSV-1 or HSV-2 infection. A negative test result indicates that the herpes simplex virus was not isolated but does not definitely rule out the presence of virus. If the specimen taken does not contain actively replicating virus, or if the sample was not transported under optimum conditions, no viable virus may be detectable, resulting in a false-negative result.
The presence of HSV-1 or HSV-2 IgM antibodies indicates an active or recent infection. HSV-1 or HSV-2 IgG antibodies indicate a previous infection. A significant increase in HSV IgG antibodies, measured by comparing acute and convalescent samples, indicates an active or recent infection. Negative HSV antibody results mean that it is unlikely that the person has been exposed to HSV or that the body has not had time to begin producing HSV antibodies
- A herpes culture (or HSV DNA testing) may be ordered when someone has a blister or vesicle on their genitals.
- HSV DNA testing is ordered when a person has encephalitis that the doctor suspects may be caused by a virus.
- HSV testing may be ordered regularly when a pregnant woman has herpes. A mother and newborn may be tested for HSV when a baby shows signs of HSV infection, such as meningitis or skin lesions that could be caused by the herpes virus.
- HSV antibody testing is ordered primarily when someone is being screened for a previous exposure to HSV. Occasionally, acute and convalescent
- HSV antibody testing may be ordered when a current infection is suspected.
- A doctor may also order an HSV antibody test if someone has another STD and is at risk for the infection. Risk factors include having multiple sex partners, having a sex partner with herpes, being infected with HIV, or being at risk for HIV because the person is a man who has sex with men.
LABORATORY TESTS
HSV testing is used to detect the presence of the herpes simplex virus (HSV) in those who have genital sores or encephalitis and in newborns suspected of having neonatal herpes, a rare but serious condition in which herpes is contracted during vaginal birth.
Direct Method
1. Viral Isolation (Culture)
- Standard Viral Culture
- Shell Vial or Centrifugation-enhanced Culture
2. Antigen Detection
- The slide is examined using a fluorescence microscope, with a positive test indicated by the presence of a characteristic pattern of apple-green fluorescence in the nucleus and cytoplasm of the basal and parabasal cells
3. Tzanck Smears
- Does not distinguish between HSV-1 and HSV-2, nor between HSV and varicella zoster virus infection.
- Slides are stained with a Wright-Giemsa stain and then examined under light microscopy.
- Hematoxylin and eosin or the Papanicolaou stains may also be used
4. Electron Microscopy
- Direct examination of vesicle fluid or other clinical material by electron microscopy
5. Virus DNA Detection
- Viral DNA may be detected by hybridization techniques using radiolabelled or biotinylated probes.
- Amplification of target HSV DNA by polymerase chain reaction (PCR)
Indirect Serological Test (Type Specific)
1. Western Blot
- The gold standard for the detection of antibodies to HSV
- The patterns of antibody binding bands are highly predictive of infection with either HSV-1 or HSV-2.
2. Commercial IgG-based Type-specific tests
- HSV-1and HSV-2 enzyme-linked immunosorbent assays, and an immunoblot test for both HSV-1 and HSV-2
Antiviral Resistance Tests
1. Drug Sensitivity Assay
- Only performed by specialized laboratories.
- Acyclovir is the most commonly used
- Using method of plaque reduction assays and dye uptake assays or DNA hybridization assays
- The viral genes encoding the two targets of antiviral drugs (TK and DNA polymerase) are amplified by PCR; the PCR products are then sequenced.
RESULTS
A positive herpes simplex culture or HSV DNA test from a vesicle scraping indicates an active HSV-1 or HSV-2 infection. A negative test result indicates that the herpes simplex virus was not isolated but does not definitely rule out the presence of virus. If the specimen taken does not contain actively replicating virus, or if the sample was not transported under optimum conditions, no viable virus may be detectable, resulting in a false-negative result.
The presence of HSV-1 or HSV-2 IgM antibodies indicates an active or recent infection. HSV-1 or HSV-2 IgG antibodies indicate a previous infection. A significant increase in HSV IgG antibodies, measured by comparing acute and convalescent samples, indicates an active or recent infection. Negative HSV antibody results mean that it is unlikely that the person has been exposed to HSV or that the body has not had time to begin producing HSV antibodies
Adapted from:
CANADIAN STI BEST PRACTICE LABORATORY GUIDELINES: The laboratory diagnosis of herpes simplex virus infections; 2005, 16, 92-98
Herpes Testing: Lab Test Online
CANADIAN STI BEST PRACTICE LABORATORY GUIDELINES: The laboratory diagnosis of herpes simplex virus infections; 2005, 16, 92-98
Herpes Testing: Lab Test Online
By
Norasyikin Binti Saopi Co-writer: Nurdina Binti Zainol |
Department of Medical Laboratory Technology,
UiTM Puncak Alam Campus
UiTM Puncak Alam Campus