FIG 3.

Influence of zinc on ETEC growth and virulence gene expression in vitro. (A) Growth of ETEC strain H10407 in the presence of zinc. Bacteria were incubated with select concentrations of zinc and monitored spectrophotometrically. *, no zinc versus 1 mM zinc; OD600, optical density at 600 nm. (B to F) Bacterial mRNA was isolated from ETEC strain H10407 after incubation with non-growth-inhibitory zinc concentrations. Reverse transcription-qPCR (RT-qPCR) was performed for measurement of expression of specific genes (cfaA, cexE, sta2, eltA, and degP). *, P < 0.05 (comparing the findings seen with zinc exposure to those seen in the absence of zinc exposure) (n = 5/group).