Molecular epidemiology of respiratory adenovirus detection in hospitalized children in Shenzhen, China.

OBJECTIVE This study aimed to understand the molecular type of respiratory adenovirus in hospitalized children in Shenzhen and the relation to clinical diagnoses. METHODS Nasopharyngeal swab specimens were obtained from 6,479 hospitalized children younger than 14 years with respiratory tract diseases in Shenzhen Children's Hospital from December 2012 to November 2013. Nasopharyngeal swabs were routine examined by direct immunofluorescence assay to detect respiratory agents including seven respiratory viruses. Multiplex PCR of adenovirus types 3, 7, 11 and 21 in a single tube based on the sequence of the encoding gene for hexon was used to type for adenovirus positive specimens. For those strains that could not be typed by multiplex PCR, the gene fragment was amplified by a universal primer pair for all adenovirus types and the PCR products were sequenced directly. RESULTS A total of 1,066 of 6,479 (16.45%) specimens were positive for at least one of the seven viruses and 228 of 6,479 (3.52%) specimens were positive for adenovirus. 86.4% of children with adenovirus infection occurred less than 5 years of age and just over half of the children (54.4%) less than two years old. There was no significant difference in infection rates between males and females. AdV3 (46.3%) and AdV7 (36.3%) were the genotypes most commonly found followed by AdV1 (6.0%), AdV4 (5.0%), AdV2 (3.0%), AdV6 (1.5%), AdV5 (1.5%) and AdV3/7 (0.5%). No type 11, type 21, and other types of adenovirus were detected. Seven children had type 3 or type 7 and one had type 3/7 mixed infection in 15 severe pneumonia cases. CONCLUSIONS Our study demonstrated that respiratory adenovirus infection is an important cause of hospitalizations in children in Shenzhen, China. Types 3 and 7 were the most common followed by types 1 and 4. AdV3 and AdV7 were similarly contributed to the severe cases.