Abstract
Streptococcus pneumonia is an important human pathogen that causes various severe diseases such as pneumonia, otitis and meningitis. Vaccination against S. pneumoniae is implemented in many developed countries. The presently used vaccines are safe, well tolerated but relatively expensive and require modification due to the immunological changes of the epidemic strains. This paper describes the development of a new pneumococcal vaccine candidate for immunization on mucosal surfaces. For this purpose the antigens of chimeric protein PSPF, previously suggested for an injectable S. pneumoniae vaccine, were expressed on the surface of the live probiotic strain Enterococcus faecium L3. Experiments on laboratory mice vaccinated with live bacteria demonstrated the appearance of the specific IgA and IgG which provide protection against the lethal S. pneumoniae infection.
Highlights
Streptococcus pneumoniae is an important human pathogen which causes severe pneumonia, meningitis, otitis and often resulting in death
A chimeric construct with the genetic element pspf encoding for pneumococcal vaccine was inserted in frame into enterococcal gene d2 by polymerase chain reaction (PCR), as described in the Material and Methods section (Fig 1)
Ent-pspf was re-cloned in suicidal plasmid pT7ermB, which is unable to replicate in gram-positive bacteria
Summary
Streptococcus pneumoniae is an important human pathogen which causes severe pneumonia, meningitis, otitis and often resulting in death. Contemporary vaccines against S. pneumoniae based on targeting the capsule polysaccharides saved millions of lives but have some limitations related to the heterogeneity of capsule polysaccharides of the epidemic S. pneumoniae strains and short T-independent immunological memory [1]. This fact made it necessary to use the method of the conjugation of the capsular polysaccharides to toxoid molecules (which is not entirely safe) and requires a constant increase in the number of polysaccharides included in the vaccine due to the antigenic shift in the bacterial population (Red Queen Dynamics) [2,3].
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