Differential Virulence Gene Profiling and Expression of <em>Campylobacter </em>Species from Chicken and Human Fecal Samples in Egypt

Campylobacter is considered to be the most leading bacterial cause of human gastroenteritis worldwide. Consumption of undercooked or contaminated chicken food is the main source of human campylobacteriosis. Although Campylobacter is a leading cause of gastroenteritis, data on the comparative virulence gene profiles of Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) from chicken and human sources in Egypt remain scarce. This study aimed to characterize the virulence genes profiles of both C. jejuni and C. coli isolated from chicken and human fecal samples in Ismailia governorate, Egypt. A total of 20 isolates of each species were screened for 15 virulence genes. All isolates carried virB11, iam, racR, and tetO. In chicken isolates, the prevalence of additional virulence genes was higher, with pldA, dnaJ, flaA, cdtB, ciaB, and wlaN detected in 100%, 100%, 100%, 80%, 60%, and 0% of C. jejuni isolates and 100%, 100%, 60%, 60%, 40%, and 20% of C. coli isolates, respectively. In contrast, human isolates showed a markedly lower prevalence, with dnaJ, flaA, and cdtB detected in 20% of C. jejuni and 40% of C. coli isolates, while pldA, ciaB, and wlaN were absent in all human isolates. qPCR revealed significantly higher expression levels of dnaJ, virB11, flaA, and iam in chicken isolates compared to human isolates, with mean fold changes of 11.5, 7.16, 5.39, and 3.72 for C. jejuni, and 8.34, 5.21, 2.84, and 2.5 for C. coli, respectively. Differential expression of racR, cdtB, and tetO was not significant. Ganglioside mimicry genes (Cst11, wlaN, Waac, ggt, and cgtB) were absent in all human isolates. These findings underscore the significant variability in virulence gene profiles between chicken and human Campylobacter isolates and highlight the importance of molecular characterization in risk assessment and epidemiological surveillance of Campylobacter infections.