TITLE:
A Comparison of the Clinical and Molecular Diagnosis of Herpes Simplex Keratitis
AUTHORS:
Victoria E. McGilligan, Jonathan E. Moore, Mohammad Tallouzi, Sarah D. Atkinson, Hugh O’Neill, Susan Feeney, Elena S. Novitskaya, Anant Sharma, Sunil Shah, Jonathan A. Jackson, David G. Frazer, Tara C. B. Moore
KEYWORDS:
Herpes Simplex Keratitis, PCR, Antivirals, Viralgenotype
JOURNAL NAME:
Open Journal of Ophthalmology,
Vol.4 No.3,
July
29,
2014
ABSTRACT: Purpose: To compare the clinical and molecular diagnoses of Herpes
Simplex Keratitis (HSK). Materials and Methods: Conjunctival swabs (after
fluorescein and anaesthetic wash out) and detailed questionnaire data were
obtained from 146 participants. Corneal rims and conjunctival epithelial cells
were infected with Herpes Simplex Virus (HSV) type 1 or HSV2 and supernatant
collected. HSV1; HSV2; Varicella Zoster Virus (VZV) and Adenovirus (ADV) DNA
was assessed using two real time Polymerase Chain Reaction (PCR) methods.
Results: Of the 146 participants recruited, 54 were clinically diagnosed with
typical epithelial lesions and 38 with atypical epithelial lesions, 17 with old
inactive HSK and 37 healthy volunteers. HSV1 DNA was detected in 28 (30%) of
the 92 participants with clinically suspect HSK. Patients who presented with
typical epithelial lesions had a higher positive rate (46%) than those who
presented with atypical type lesions (8%), when using primers against the
Glycoprotein (Gp) G region of the virus. When the same samples were retested
with primers against the GpB region, the positive rate for the typical and
atypical cases increased to 52% and 11% respectively. Antiviral use at the time
of sampling reduced the rate of PCR positivity by 20% (p in
vitro control investigations of HSV1 and 2 infected corneal rims and
conjunctival epithelial cells were 100% positive for infected and 100% negative
for uninfected samples when assessed using both PCR methods. Conclusions: Clinical
diagnosis of typical HSK is not always confirmed by PCR. Concomitant use of an
antiviral reduces levels of PCR positivity. Given this and the findings that
other ocular surface pathogens may mimic HSK pathology, and that choice of gene
amplification region can also affect accurate detection of HSV1 by PCR, we
propose the use of a multiplex assay. This would perform PCR using primers
spanning a number of different regions within one gene and would also target a
number of different viral genes to ensure potentially different HSV1 viral
strains or other viruses do not affect the test and lead to disagreements
between the clinical and molecular diagnosis of HSK. From these findings, this
paper proposes a clinical supportive algorithmic guide to manage such
disagreements.