Antibody Production Remains Intact Despite Loss of Bone Marrow B cells in Murine Norovirus Infected Mice.

Murine norovirus (MNV), which can be used as a model system to study human noroviruses, can infect macrophages/ monocytes, neutrophils, dendritic, intestinal epithelial, T and B cells, and is highly prevalent in laboratory mice. We previously showed that MNV infection significantly reduces bone marrow B cell populations in a -dependent manner. We show here that while MNV-infected mice have significant losses of bone marrow B cells, splenic B cells capable of mounting an antibody response to novel antigens retain the ability to expand. We also investigated whether increased granulopoiesis after MNV infection was causing B cell loss. We found that administration of anti-G-CSF antibody inhibits the pronounced bone marrow granulopoiesis induced by MNV infection of mice, but this inhibition did not rescue bone marrow B cell losses. Therefore, MNV-infected mice can still mount a robust humoral immune response despite decreased bone marrow B cells. This suggests that further investigation will be needed to identify other indirect factors or mechanisms that are responsible for the bone marrow B cell losses seen after MNV infection. In addition, this work contributes to our understanding of the potential physiologic effects of related disruptions in research mouse colonies that may be endemically infected with MNV.