Genotype prevalance of adenoviruses causing keratoconjunctivitis

Adenoviruses are common human pathogens that cause infections in eye, urinary system and gastrointestinal system. Keratoconjunctivitis is the most common type of adenoviral infection which is usually related to genotype 3, 4, 8, 19 and 37. Rapid and accurate diagnosis of adenoviral keratoconjunctivitis is necessary since it is very contagious and can cause epidemics. PCR is the most-preferred diagnostic method due its rapid, sensitive and specific nature. Genotyping of the adenovirus is also required in order to determine the relation between a specific type and clinical presentation and follow the geographical distribution of the virus. Many studies, especially from Japan and USA, have been published related to the topic, yet there is very limited data about ocular adenoviral infections in Turkey. This study aimed to determine the adenovirus genotypes among the patients with keratoconjunctivitis followed in Dokuz Eylül University Hospital between 2006 and 2010.Between January 2006 and August 2010, 488 conjunctival swab samples of patients with a diagnosis of viral conjunctivitis / keratoconjunctivitis have been sent to the Molecular Microbiology Laboratory of Dokuz Eylül University Hospital to be tested for adenoviruses. Forty-four percent of these samples (213 of 488) have been found to be positive for the adenoviral DNA with PCR and generated the study group. Forty-seven percent of (101 of 213) positive samples were randomly chosen and genotyped by sequence analysis. Fragment of the hexon gene made up of 605-629 nucleotides, containing ?Hypervariable Region 7? (HVR-7), has been targeted for the sequencing. Amplicons and the reference Gen-Bank sequences were analyzed by a phylogenetic tree. Genotyping studies were carried out in Erasmus University Virology Department.Seven genotypes including 3, 4, 8, 11, 19, 22 and 37 were determined in the samples of the study. Type 8 was the dominant genotype detected in 67 samples (66.3%) while the second common genotype was 4 which determined in 25 (24.7%) of the samples. Other five genotypes were isolated in 8.9% of the samples. Genotype 8 was the most common type detected during the five-year period, except 2008, in which genotype 4 was the dominant type.Genotype 8 was found to be the most common genotype between 2006 and 2010 in our center. Genotype 8 has been reported as the predominant genotype worldwide in both sporadic infections and during epidemics. There are two published studies about the adenovirus genotypes in ocular infections in Turkey. Although, sample size is very small and one of them is an investigation of an epidemic, genotype 8 is also the predominant genotype in both of the studies.In conclusion, this is the first comprehensive study, providing data related to genotypes of adenoviruses that cause ocular infections and their variations during a five-year period in Turkey. Main limitations of the study are that it evaluated a single center and only patients applying to the hospital. Further studies are needed to understand the epidemiology of adenoviral ocular infections in Turkey.Key words : adenoviruses, genotype, keratoconjunctivitis