Structural Studies of the Lipopolysaccharide of <i>Aeromonas veronii </i>bv. <i>sobria</i> Strain K133 which Represents New Provisional Serogroup PGO1 Prevailing among Mesophilic Aeromonads on Polish Fish Farms

• Main Authors: Katarzyna Dworaczek, Maria Kurzylewska, Magdalena Laban, Dominika Drzewiecka, Agnieszka Pękala-Safińska, Anna Turska-Szewczuk
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Aeromonas</i>; fish pathogen; lipopolysaccharide (LPS); structure elucidation; O-antigen; O-polysaccharide
• Online Access: https://www.mdpi.com/1422-0067/22/8/4272

In the present work, we performed immunochemical studies of LPS, especially the O-specific polysaccharide (O-PS) of <i>Aeromonas veronii</i> bv. <i>sobria</i> strain K133, which was isolated from the kidney of carp (<i>Cyprinus carpio</i> L.) during an outbreak of motile aeromonad infection/motile aeromonad septicemia (MAI/MAS) on a Polish fish farm. The structural characterization of the O-PS, which was obtained by mild acid degradation of the LPS, was performed with chemical methods, MALDI-TOF mass spectrometry, and ¹H and ¹³C NMR spectroscopy. It was revealed that the O-PS has a unique composition of a linear tetrasaccharide repeating unit and contains a rarely occurring sugar 2,4-diamino-2,4,6-trideoxy-D-glucose (bacillosamine), which may determine the specificity of the serogroup. Western blotting and ELISA confirmed that <i>A. veronii</i> bv. <i>sobria</i> strain K133 belongs to the new serogroup PGO1, which is one of the most commonly represented immunotypes among carp and trout isolates of <i>Aeromonas </i>sp. in Polish aquacultures. Considering the increase in the MAI/MAS incidences and their impact on freshwater species, also with economic importance, and in the absence of an effective immunoprophylaxis, studies of the <i>Aeromonas</i> O-antigens are relevant in the light of epidemiological data and monitoring emergent pathogens representing unknown antigenic variants and serotypes.