AUTHOR=Nakae Koji , Ooka Tadasuke , Murakami Koichi , Hara-Kudo Yukiko , Imuta Naoko , Gotoh Yasuhiro , Ogura Yoshitoshi , Hayashi Tetsuya , Okamoto Yasuhiro , Nishi Junichiro 

TITLE=Diversification of Escherichia albertii H-Antigens and Development of H-Genotyping PCR

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.737979

DOI=10.3389/fmicb.2021.737979

ISSN=1664-302X

ABSTRACT=<p><italic>Escherichia albertii</italic> is a recently recognized human enteropathogen that is closely related to <italic>Escherichia coli</italic>. As <italic>E. albertii</italic> sometimes causes outbreaks of gastroenteritis, rapid strain typing systems, such as the O- and H-serotyping systems widely used for <italic>E. coli</italic>, will be useful for outbreak investigation and surveillance. Although an O-genotyping system has recently been developed, the diversity of <italic>E. albertii</italic> H-antigens (flagellins) encoded by <italic>fliC</italic> genes remains to be systematically investigated, and no H-serotyping or genotyping system is currently available. Here, we analyzed the <italic>fliC</italic> genes of 243 genome-sequenced <italic>E. albertii</italic> strains and identified 73 sequence types, which were grouped into four clearly distinguishable types designated <italic>E. albertii</italic> H-genotypes 1–4 (EAHg1–EAHg4). Although there was a clear sign of intraspecies transfer of <italic>fliC</italic> genes in <italic>E. albertii</italic>, none of the four <italic>E. albertii</italic> H-genotypes (EAHgs) were closely related to any of the 53 known <italic>E. coli</italic> H-antigens, indicating the absence or rare occurrence of interspecies transfer of <italic>fliC</italic> genes between the two species. Although the analysis of more <italic>E. albertii</italic> strains will be required to confirm the low level of variation in their <italic>fliC</italic> genes, this finding suggests that <italic>E. albertii</italic> may exist in limited natural hosts or environments and/or that the flagella of <italic>E. albertii</italic> may function in a limited stage(s) in their life cycle. Based on the <italic>fliC</italic> sequences of the four EAHgs, we developed a multiplex PCR-based H-genotyping system for <italic>E. albertii</italic> (EAH-genotyping PCR), which will be useful for epidemiological studies of <italic>E. albertii</italic> infections.</p>