Detection and Molecular Characterization of Human Adenoviruses from Acute Conjunctivitis Cases

Human adenoviruses (hAdV) can cause a wide range of clinical diseases in children and adults that mainly affect respiratory, eye and gastrointestinal systems. Ocular hAdV infections have various clinical manifestations such as epidemic keratoconjunctivitis, pharyngoconjunctival fever and non-specific follicular conjunctivitis. The hAdV genotypes which can cause conjunctivitis vary according to geographic distribution. In the study, we aimed to determine the frequency of the presence of hAdV by molecular methods and to determine the types with phylogenetic analysis in conjunctival swab samples taken from patients diagnosed clinically as acute conjunctivitis. Conjunctival swab samples (n= 100) were taken from the patients with acute conjunctivitis who have admitted to Mersin University Faculty of Medicine Hospital Ophthalmology Clinic and 50 conjunctival swab samples taken from healthy individuals as a control, between September 2014-July 2017 were included in the study. Following the DNA isolation from swab samples, polimerase chain reaction (PCR) amplification was performed using specific primer sequences targeting the hexon gene region of the hAdV genome. In order to determine hAdV types, direct DNA sequence analysis of hexon gene products was performed in "ABI PRISM 3130XL Genetic Analyzer" (Applied Biosystems, Foster City, CA, USA). The obtained hAdV DNA sequences were typed by BLAST analysis and the identified genotypes were compared phylogenetically with the reference hAdV sequences of the NCBI In the study, 30 (30%, 30/100) of the swab samples of the patients with acute conjunctivitis were found positive for hAdV hexon gene PCR. The hAdV DNA was not found in the conjunctival swab samples belonging to the healthy individuals included as controls. A total 27 samples found as positive of the hexon gene PCR were genotyped by direct DNA sequence analysis. A total of 5 genotypes were identified and the most common genotypes were hAdV-8 (n= 17, 63%) and followed by hAdV-53 (n= 4, 14.8%), hAdV-4 (n= 4, 14.8%), hAdV-7 (n= 1, 3.7%) and hAdV-37 (n= 1, 3.7%). In this study, the prevalence of adenoviral conjunctivitis determined by hexon gene PCR in patients with clinical diagnosis of acute conjunctivitis was similar to the prevalence rate reported in other regions of the world. In our region, more than one type of hAdV type was associated with acute conjunctivitis. The predominant type was determined as hAdV-8 with a 63% ratio. These results will significantly contribute to the molecular epidemiology of hAdV types in conjunctivitis cases.