NDST1 and infection: In striking contrast, however, while the intracellular replication of VACV was also clearly compromised by the loss of NDST1, we found that the spread of VACV in both NDST1-/- cell lines was significantly increased compared to that seen in the NDST1+ cells at both 48 and 72 hours post infection (2.0±0.1-fold larger in NDST1-/- cells, p<0.005) (Fig 5B).