Human Adenovirus 31 is a member of species A human adenoviruses of the Mastadenovirus genus. This non‑enveloped virus has a roughly 90 nm icosahedral capsid that encloses a linear double‑stranded DNA genome of approximately 34 kilobases. HAdV‑31 has been identified as a major cause of enteric infection; it is particularly associated with pediatric gastroenteritis. While usually self‑limiting, infection can occasionally progress to systemic disease in immunocompromised individuals.
Virology and genetic features
The HAdV‑31 virion is composed of 240 hexon trimers, 12 penton bases and 12 protruding fiber proteins. The fiber knob interacts with cellular receptors to mediate attachment and entry via clathrin‑mediated endocytosis. After uncoating, the viral genome is transported into the nucleus where early genes are transcribed to modulate host responses and replicate DNA, followed by late gene expression and assembly of capsid proteins. HAdV‑31 belongs to subgenus A along with types 12 and 18, and its genome encodes distinctive immunomodulatory proteins in the E3 region, including an immunoglobulin‑like domain and a RGD motif in protein IX. Molecular studies have shown that HAdV‑31 strains diverge into multiple lineages with relatively slow evolution but with variability concentrated in fiber gene regions. The virus is stable in the environment and resistant to detergents and moderate heat, contributing to its spread via the fecal‑oral route.
Clinical manifestations and epidemiology
HAdV‑31 primarily affects children and is one of the most common adenovirus types causing diarrhea after types 40 and 41. Patients present with watery diarrhea, vomiting and low‑grade fever; respiratory symptoms are uncommon. In immunocompromised hosts, especially recipients of hematopoietic stem cell transplants, the virus can disseminate to the liver, lungs and central nervous system, leading to life‑threatening disease. Outbreaks have been reported in hospital wards and daycare centers where poor hygiene facilitates transmission. Diagnosis relies on polymerase chain reaction of stool or blood specimens and sometimes antigen detection. There is no licensed adenovirus vaccine or approved antiviral for enteric infection; management is supportive, focusing on fluid replacement. Preventive measures include strict hand hygiene, disinfection of surfaces and isolation of infected patients in healthcare settings. Although often overlooked, human adenovirus 31 represents an important enteric pathogen in pediatrics. Awareness of its clinical spectrum and transmission routes is essential for prompt diagnosis, infection control and protection of vulnerable patients. Related Terms: gastroenteritis, adenovirus 40, adenovirus 41, species A, diarrhea