title: Biofilm and planktonic pneumococci demonstrate disparate immunoreactivity to human convalescent sera.
abstract: BACKGROUND
  Streptococcus pneumoniae (the pneumococcus) is the leading cause of otitis media, community-acquired pneumonia (CAP), sepsis, and meningitis. It is now evident that S. pneumoniae forms biofilms during nasopharyngeal colonization; the former which facilitates persistence, the latter, a prerequisite for subsequent development of invasive disease. Proteomic evaluation of S. pneumoniae suggests the antigen profile available for host-recognition is altered as a consequence of biofilm growth. This has potentially meaningful implications in regards to adaptive immunity and protection from disseminated disease. We therefore examined the antigen profile of biofilm and planktonic pneumococcal cell lysates, tested their reactivity with human convalescent sera and that generated against biofilm pneumococci, and examined whether immunization with biofilm pneumococci protected mice against infectious challenge.
  
  
  RESULTS
  Biofilm pneumococci have dramatically altered protein profiles versus their planktonic counterparts. During invasive disease the humoral immune response is skewed towards the planktonic protein profile. Immunization with biofilm bacteria does not elicit a strong-cross-reactive humoral response against planktonic bacteria nor confer resistance against challenge with a virulent isolate from another serotype. We identified numerous proteins, including Pneumococcal serine-rich repeat protein (PsrP), which may serve as a protective antigens against both colonization and invasive disease.
  
  
  CONCLUSIONS
  Differential protein production by planktonic and biofilm pneumococci provides a potential explanation for why individuals remain susceptible to invasive disease despite previous colonization events. These findings also strongly suggest that differential protein production during colonization and disease be considered during the selection of antigens for any future protein vaccine.
authors: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 78229, USA.
authors: Carlos J
authors: CJ
authors: Sanchez
authors: Brady J
authors: BJ
authors: Hurtgen
authors: Anel
authors: A
authors: Lizcano
authors: Pooja
authors: P
authors: Shivshankar
authors: Garry T
authors: GT
authors: Cole
authors: Carlos J
authors: CJ
authors: Orihuela
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology* / Q000378:metabolism; D001426:Bacterial Proteins / Q000276:immunology / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D005260:Female; D006801:Humans; D056724:Immunity, Humoral; D051379:Mice; D008807:Mice, Inbred BALB C; D009305:Nasopharynx / Q000382:microbiology*; D010641:Phenotype; D011008:Pneumococcal Infections / Q000382:microbiology*; D020543:Proteome / Q000032:analysis*; D013296:Streptococcus pneumoniae / Q000254:growth & development
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D020543:Proteome