SP5 and infection: In the BS, early infection of the inferior olive (IO) and hypoglossal nucleus (12N) was noted from 4 to 24 hpi (Fig. 4IV, VI), followed by Sp5 (8–72 hpi; Fig. 4V), nucleus ambiguus (Amb; 16–24 hpi; Fig. 4III), and nucleus of the solitary tract (Sol; 16–48 hpi; Fig. 4VI).