Virus Simplex Virus II
Antigen, from Lesion Smear
PCR molecular testing is near. But this is a classical DFA type of test (direct fluorescent antibody) for
HSV II antigen (Ag) within infected cells from the patient (if any infected cells were actually dislodged into the sample from the patient). HSV II is a DNA virus of the herpes
group. This HSV II virus is closely related to HSV I, the "fever
blister" virus. Both produce painful blisters and ulcerations,
and the virus can be dormant in the location and erupt and re-erupt
with sores. Since about 1990, there are antiviral agents which
may cure an initial infection if caught and treated very early;
cures are less likely once established, though treatment may help
decrease the severity. Since oral sex has become so prevalent in
modern times, the differentiation between an infection with HSV
I and HSV II is less reliable for purposes of blaming an etiology.
That is, a person could engage in oral sex with one partner and
acquire HSV II from that infected partner. The person may or may
not have an obvious sore to indicate having caught the disease;
then, through kissing only, that person may pass the HSV II on
to another person who has not engaged in any sort of genital sex.
That is, it is possible for a righteous virgin to get HSV II of
the lips or mouth.
In testing, there can be serious test cross-reactions in
serological (blood serum) tests of the patient's blood for HSV antibodies, but that is not a problem in the HSV I & II antigen test.
An air-dried Pap smear of the cervix or vagina, or air-dried
smear or scrape or touch prep of vulvar, penile, oral, or cutaneous
lesions can be tested. A reagent antibody against HSV II Ag is
layered onto the slide followed by attachment of a fluorescing reagent which
attaches to any HSV II Ag-Ab complexes. These are viewed under a
fluorescent microscope, and appropriately shaped ("morphospecific") fluorescent targets
are indicative of a positive test. The virus is located in epithelial
cells; so, it is of great importance that any test sample include
(often requiring scraping) those cells and not just pus or protein and salve and
ulcer crust (the greatest likelihood of an optimal sample is when
dealing with what seems to still be a blister/vesicular lesion). A Tzank prep smear could
be prepared exactly similarly as a duplicate sample in order to
obtain faster preliminary results. The "positive" DFA test is to be overstained by Wright's or Pap staining and the positivity correlated with viropathic epithelial cells. If there is DFA "positivity" but smear is devoid of viropathic cells, it is a situation of "indeterminate positive staining for HSV, etc.". A blood sample for possible HSV
II serological testing (should the DFA and/or Tzank be negative or indeterminate)
can be drawn at the same time and serum removed and reserved for
possible further testing. But, remember that a small primary lesion may fail to generate a detectible primary antibody response! See HSV I.
Negative test status:
- unsatisfactory sample (the single greatest source of "false
negatives") in an HSV II lesion in an infected person...the
lab may indicate this with a message such as "acellular
smear" and may suggest this possibility with a message such
as "minimal cellular material present"..."indeterminate due to scant cellularity.
- sample from a virus-particle-poor stage in the evolution of an HSV II lesion
in an infected person (a rare reason for a "false negative")
- some other type of herpes-like lesion in a person who does
not have HSV II [HERE].
(1) DFA positive and (2) morphologically positive test
HSV II infection
- false positive (no particular reason...all tests have at least an extremely low false positive rate & no test is free of this defect)...guard against this by overstaining
the DFA prep as a Tzank prep to make sure that the "positivity" is morphospecific.
Other names for this exact or approximate agent are:
(posted about 2000; latest adjustment 21 September 2012)
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