Comparative genomic analysis provides insights into HGE mediated hya and virD4 gene horizontal transfer in Streptococcus equi subsp. zooepidemicus

Abstract

Abstract Background Prophages and genomic islands are associated with the modulation of bacterial pathogenic characteristics. Streptococcus equi subsp. zooepidemicus (SEZ) is an opportunistic and zoonotic pathogen that causes infections in humans and animals. Genetic alterations are frequently observed in Streptococcus genomes and usually confer advantages for enhanced survival or virulence. In addition, the complete genome of the SEZ donkey strain has not been reported. In this study, to investigate the genomic characteristics, virulence, and fitness of SEZ JMC 111 (an equine isolate) and HT 321 (a donkey isolate) isolated in China, whole genome sequencing was performed. Then a comparative genome analysis of these two strains was carried out to comprehensively and systematically explore the factors that led to differences in their genetic diversity and pathogenicity. Results We found the hya and virD4 genes were carried and horizontally transferred by mobile genetic elements like prophages and genome islands during the evolution of these strains. Our results revealed that the HT321 exhibited higher levels of antimicrobial resistance and biofilm formation, whereas the JMC 111 displayed higher virulence. Conclusions our study highlights the critical role of genome islands and prophages in the rapid adaptation and response to clinical stress, such as antimicrobial treatment and mobile genetic elements, which is one of the drivers for the evolution of SEZ.