Distribution and epidemiological analysis of type V secretion system (T5SS) in avian pathogenic Escherichia coli

Abstract:

[Background] Systemic infections caused by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide. Type V secretion system (T5SS) plays an important role during the infection of APEC. [Objective] This study was carried out to analyze the distribution of T5SS in APEC and its correlation with E. coli phylogenetic group and other virulence factors. [Methods] The 15 E. coli T5SS were selected for primers designing, and the distribution of these T5SS in APEC clinical isolates were detected by PCR. The phylogenetic group and virulence factor of APEC strains were determined. The correlations between T5SS distribution and phylogenetic group and other virulence factors of APEC were analyzed. [Results] T5SS was widely distributed in APEC isolates. T5SS ydeK and pplfP was present in 98.55% and 92.03% of the APEC isolates, respectively. However, the distribution rates of T5SS upaC and pic in APEC were less than 10.00%. Most APEC isolates belonged to A, B1 and D phylogenetic groups, following by B2. The combinations analysis showed that T5SS ehaA, ehaB, pic and vat were predominated present in phylogenetic group D APEC isolates. While, the phylogenetic groups A and B1 were the predominated groups that harbor the ehaG, ag43/flu and apaC. However, no significant correlation between the distribution of T5SS and other virulence genes in APEC were found. [Conclusion] T5SS is widely distributed in APEC, and some T5SS was correlated with the phylogenetic group of APEC.