Parvovirus infection alters the nucleolar structure

The nucleolus is a dynamic nuclear structure which plays important roles in ribosome biogenesis and cellular stress response to stressors such as viral infection. The nucleolus and nucleolar proteins are essential for the progression of infection by several viruses. Consequently, viral infection often induces alterations in nucleolar structure and composition. Here, we applied a deep learning algorithm segmentation and nucleolin labeling to analyze the nucleolar changes induced by autonomous parvovirus infection. Our results show that the size of nucleoli decreases and nucleolin is released into the nucleoplasm in late infection. Analyses of ki-67, one of the NS2-associated nucleolar proteins and a key factor in nucleolar organization, showed that the interaction between ki-67 with DNA increases in infection. The infection initiated by a viral clone lacking an intact NS2 failed to decrease the nucleolar size, however, the orientation of the nucleoli was changed. Our results suggest that parvoviruses modify and exploit nucleoli and nucleolar proteins during infection, and NS2 protein might play a role in the regulation of these processes. ### Competing Interest Statement The authors have declared no competing interest.