Molecular Epidemiology of Adenoviruses and Emergence of HAdV-D56 in Pediatric Patients With Gastroenteritis in Japan From 2018 to 2023

Human adenovirus (HAdV) is one of the leading causes of gastroenteritis, especially in children worldwide. This study aimed to investigate molecular epidemiology of HAdV infection in children with acute gastroenteritis in six different prefectures of Japan from 2018 to 2023 by using PCR method and sequencing at hypervariable regions and non-hypervariable region in hexon gene. The overall prevalence of HAdV infection was 10.8% before and during the COVID-19 pandemic (2018–2022), while it increased to 27.7% in the post-pandemic period (2022–2023). Eight HAdV genotypes, F41, C1, C2, C5, C6, B3, A31, and D56 were detected, and F41 was detected as the most prevalent genotype. It should be noted that HAdV-D56, which generally caused epidemic keratoconjunctivitis and respiratory diseases, was detected for the first time in a patient with acute gastroenteritis in Japan in this study. In addition, HAdV-F40 was detected as a co-predominant with HAdV-F41 genotype, whereas it was undetectable in this study. The findings indicated that the distribution of HAdV genotypes particularly enteric HAdV-F41 had changed over time. In addition, an emergence of HAdV-D56 in a patient with acute gastroenteritis is a potential implication of HAdV-D56 involvement in acute gastroenteritis and it is essential to be continually monitoring worldwide.