Spatiotemporal Analysis of Intranuclear Inclusion Body and Virus Formation in Human Adenovirus Type 5-Infected Cells

Human adenovirus type 5 (HAdV-5) forms a characteristic intranuclear inclusion body in infected cells. However, the relationship between the intranuclear inclusion body and virus formation in HAdV-5-infected cells remains unclear. This study conducted a detailed investigation of the relationship between the structure of the inclusion body and the localization of the virus in HAdV-5-infected cells using electron microscopy and three-dimensional (3D) tomography analytical techniques. Immunostaining for viral proteins was also performed to determine their colocalization with the intranuclear inclusion body. 3D analysis revealed the intranuclear inclusion body as the major site of viral particle accumulation in the cells. Viral particles were identified within the intranuclear inclusion body and arranged in a crystalline structure parallel to the fibrous structures of this body. Moreover, mature viral particles were predominantly distributed around the intranuclear inclusion body. Certain viral proteins were also detected in the intranuclear inclusion body by immunoelectron microscopy. We propose that intranuclear inclusion bodies serve as sites of viral replication in HAdV-5-infected cells. Through the 3D analysis, we clarified the relationship between the distribution and localization of intranuclear inclusion bodies and viral particles in HAdV-5-infected cells. These findings can improve our understanding of adenoviral infection mechanisms and may contribute toward developing novel antiviral strategies.