ITGA4 and infection: CD11a and CD49d, subunits of the LFA-1 and VLA-4 integrins, respectively, involved in CNS entry by circulating T cells [36, 37], were upregulated in circulating TCR-V cells at day 8 p.i. irrespective of infection with MuPyV.TagV, Tag(AN), or Tag(QN) viruses.