Human adenovirus 6 identification in tonsillar tissue of children with tonsillar hypertrophy

Tonsillar hypertrophy is a common disorder in children that its pathogenesis has not been fully understood. The possible role of respiratory viral infections in tonsillar hypertrophy is still under investigation. Human adenovirus (HAdV) is one of the probable candidates, which might cause cell growth induction, apoptosis inhibition and finally tonsillar hypertrophy. This study was designed to determine the rate of HAdV genome detection, as well as identifying the virus species and types in tonsil tissues of children aged 15 years and younger with tonsillar hypertrophy. To reach the goals, 50 tonsillar tissue specimens were collected from children with hypertrophy who underwent tonsillectomies. A nested PCR with specific primers targeting a part of HAdV hexon gene was performed on these samples. PCR products of positive cases were subjected to sequencing and phylogenetic tree was drawn. The results showed that, HAdV genome was detected in 16 (32%) tissue samples, in which HAdV-C6 (31.3%, 5/16) was identified as the predominant type, followed by HAdV-C1 (25%, 4/16), HAdV-C5 (18.7%, 3/16), HAdV-C2 (12.5%, 2/16) and HAdV-B7 (12.5%, 2/16). Remarkably, in this study HAdV-C6 was the most common identified type with the potency of latency in children diagnosed with tonsillar hypertrophy. This type of adenovirus mostly causes asymptomatic infection which results in underestimation of this type by screening symptomatic patients. In conclusion, HAdV-C was the predominant species of HAdV detected in hypertrophic tonsil tissues. Latency-associated transcripts of this virus might be involved in pathogenesis of tonsillar hypertrophy.