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Nobuyo Yawata, Yu-Chi Liu, Jay Siak, Makoto Yawata, Jodhbir S Mehta; New method of typing and quantification for human adenoviruses in tear fluid of patients with adenovirus conjunctivitis . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1873.
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© ARVO (1962-2015); The Authors (2016-present)
Currently, conjunctival swab samples are used in diagnostic tests for epidemic keratoconjunctivitis (EKC) caused by group D human adenoviruses (HAdVs) such as HAdV-8, 19a, 37, 53 and 54. However, this method is not suitable to quantify virus load. We have established novel methodology to type and quantify HAdVs using small amounts of tear fluid obtained from patients with adenovirus conjunctivitis.
Tear fluid was collected using Schirmer strips from 25 eyes of 13 patients with acute follicular conjunctivitis in the Singapore National Eye Centre. The viral gDNA was extracted and virus copy numbers were determined using qPCR of the hexon gene. Virus type was determined using sequence-based typing of the 554bp of hexon gene and fiber gene. Clinical symptoms were studied in correlation with virus types and virus load.
In patients diagnosed with acute viral conjunctivitis, we detected five different HAdV types and have found that HAdV-8 is a dominant type in Singapore. Of interest, HAdV-8 was detected from all cases with corneal subepithelial infiltration. HAdV gDNA was detected from as little as 1ul of tear fluid. Virus copy numbers in the tear fluid were 2.5x10^4-1x10^12/ml at the first clinical visit. Virus gDNA was not detected after two weeks. Of interest, we found equivalent copy numbers of viral gDNA in both eyes although the eye with first onset showed more severe inflammation, and this observation implies that factors specific in the second onset eye may suppress development of severe inflammation that is characteristic of EKC.
The new method for HAdV quantification using tear fluid makes maximum use of ocular material and will be useful in understanding the mechanisms of inflammation in EKC. Further, the method is suitable in clinical studies such as in evaluating the effects of new anti-viral therapies.
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