AUTHOR=Sukhova Elena V. , Yashunsky Dmitry V. , Kurbatova Ekaterina A. , Akhmatova Elina A. , Tsvetkov Yury E. , Nifantiev Nikolay E. 

TITLE=Synthesis and Preliminary Immunological Evaluation of a Pseudotetrasaccharide Related to a Repeating Unit of the Streptococcus pneumoniae Serotype 6A Capsular Polysaccharide

JOURNAL=Frontiers in Molecular Biosciences

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2021.754753

DOI=10.3389/fmolb.2021.754753

ISSN=2296-889X

ABSTRACT=<p>2-Aminoethyl glycoside of the pseudotetrasaccharide α-<sc>d</sc>-Glc<italic>p</italic>-(1→3)-α-<sc>l</sc>-Rha<italic>p</italic>-(1→3)-<sc>d</sc>-Rib-ol-(5-<italic>P-</italic>2)-α-<sc>d</sc>-Gal<italic>p</italic> corresponding to a repeating unit of the <italic>Streptococcus pneumoniae</italic> type 6A capsular polysaccharide has been synthesized. A suitably protected pseudotrisaccharide α-<sc>d</sc>-Glc<italic>p</italic>-(1→3)-α-<sc>l</sc>-Rha<italic>p</italic>-(1→3)-<sc>d</sc>-Rib-ol with a free 5-OH group in the ribitol moiety and a 2-OH derivative of 2-trifluoroacetamidoethyl α-<sc>d</sc>-galactopyranoside have been efficiently prepared and then connected <italic>via</italic> a phosphate bridge using the hydrogen phosphonate procedure. Preliminary immunological evaluation of this pseudotetrasaccharide and the previously synthesized pseudotetrasaccharide corresponding to a repeating unit of the capsular polysaccharide of <italic>S. pneumoniae</italic> serotype 6B has shown that they contain epitopes specifically recognized by anti-serogroup 6 antibodies and are able to model well the corresponding capsular polysaccharides. Conjugates of the synthetic pseudotetrasaccharides with bovine serum albumin were shown to be immunogenic in mice.</p>