ACTA1 and infection: Also, aggregates of L. monocytogenes have been previously observed in vitro in culture broth and in vivo in the intestine during infection of mice, and have been shown to be PrfA and ActA-mediated, and specifically facilitated by the extracellular C terminal domain (amino acids-393-585) of ActA (Figure 1F) (Travier et al., 2013).