Potential factors involved in virulence of Cronobacter sakazakii isolates by comparative transcriptome analysis

Cronobacter species are important foodborne pathogens causing severe infections in neonates through consumption of contaminated powdered infant formula. However, the virulence-associated factors in Cronobacter are largely unknown. In this study, the transcriptome analysis between highly virulent Cronobacter sakazakii G362 and attenuated L3101 strains was used to reveal the potential factors involved in virulence. The total transcripts were grouped into 20 clusters of orthologous group categories and summarized in 3 gene ontology categories (biological process, cellular component, and molecular function). In addition, the differentially expressed genes (DEG) between these isolates were analyzed using Volcano plots and gene ontology enrichment. The predominant DEG were flagella-associated genes such as flhD, motA, flgM, flgB, and fliC. Furthermore, the expression abundance of outer membrane protein or lipoprotein genes (ompW, slyB, blc, tolC, and lolA), potential virulence-related factors (hlyIII and hha), and regulation factors (sdiA, cheY, Bss, fliZ) was also significantly different between G362 and L3101. Interestingly, 3 hypothetical protein genes (ESA_01022, ESA_01609, and ESA_00609) were found to be expressed only in G362. Our findings provide valuable transcriptomic information about potential virulence factor genes, which will be needed in future molecular biology studies designed to understand the pathogenic mechanism of Cronobacter.