Collect, boil and amplify--a simple approach for the detection of three common viruses associated with epidemic keratoconjunctivitis, conjunctivitis and dendritic ulcers

Abstract

During 2011' an outbreak of epidemic keratoconjunctivitis led to increased clinical requests for molecular screening of viruses from conjunctival swabs. To maximise throughput with minimal cost, a simple boil extraction on dry swabs followed by amplification and real-time detection using 'in-house' assays for herpes simplex viruses (HSV) and adenoviruses with RNaseP as an internal control was validated and introduced. Data from 541 patients who were tested for one or more viral targets was analysed. Adenovirus was most frequently detected accounting for 30% of all cases including the community outbreak. Genotyping of the hexon gene identified the cause as an adenovirus type 8. HSV was detected in 7% of the samples tested, predominantly HSV-1 with a single case of HSV-2. Invalid results due to poor RNaseP signals were reported in 10.5% of samples but for the HSV-1 assay 23% of the samples were invalid due to interference of the fluorescein dye used by ophthalmologists resulting in repeat sampling to obtain a valid result. Despite this, when compared to conventional techniques such as direct immunofluorescence, collect, boil and amplify increased significantly the detection of DNA viruses in conjunctival samples ensuring improved diagnosis, patient management and infection control measures at a modest cost.