075 - THE ANTIGEN SIGNATURE OF PNEUMOCOCCI COLONIZING THE NASOPHARYNX (ID 575)
Abstract
Background
Pneumococci encounter various host niches and hence, the proteome of pneumococci reflects the specific adaptation to these host niches. By employing an in vivo pathoproteomics approach we recently identified pneumococcal proteins/antigens essential for pneumococcal meningitis (Schmidt et al., 2019 PLoS Pathog 15: e1007987). Here we deciphered the in vivo proteome and antigen repertoire of Streptococcus pneumoniae 19F during colonization of mice.
Methods
Mice were intranasally infected with GFP-expressing S. pneumoniae serotype 19F, strain EF3030. Pneumococci were recovered from the nasopharyngeal compartment and separated from eukaryotic cells by fluorescence-activated cell sorting. After tryptic on-filter digestion peptides were measured using LC-MS/MS in a data-independent acquisition mode (DIA) and the generated data were analysed with the SpectronautTM software.
Results
The in vivo pathoproteome analysis of the 19F samples with 1.0 – 5.0 million pneumococci resulted in the identification of approximately 1000 bacterial proteins per sample, reflecting approximately 50% of the theoretical total proteome. After 3 and 5 days of colonization, respectively, the in vivo proteome profiles of strain 19F were compared to in vitro proteome profiles of 19F, which was cultured in a complex medium or chemically defined medium. S. pneumoniae 19F showed host-niche and media specific-proteome profiles as demonstrated by principal component analysis. The in vivo proteome signatures and host compartment-specific adaptation including regulated proteins of S. pneumoniae 19F will be shown.
Conclusions
Host-compartment specific antigens are identified and their immunogenic properties will be elucidated.
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