attenuated Streptococcus pneumoniae strain II

Attenuated Streptococcus pneumoniae strain II (primarily evaluated as SpnA3) is an investigational live attenuated bacterial vaccine candidate developed by the Liverpool School of Tropical Medicine (LSTM) in collaboration with University College London. It is a genetically modified (GM) biosynthesis gene mutant of Streptococcus pneumoniae serotype 6B. The strain is engineered with deletions in the *proABC* operon (involved in proline biosynthesis) and the *piaA* gene (encoding an iron transporter required for systemic virulence). These modifications render the strain virulence-attenuated while retaining its ability to colonize the nasopharynx without causing disease. Administered intranasally, the vaccine is designed to induce mucosal and systemic immunity against wild-type pneumococcus, thereby reducing subsequent nasopharyngeal colonization and preventing pneumococcal diseases such as pneumonia, meningitis, and bacteremia. In the clinical trial ISRCTN22467293, 'attenuated strain II' initially referred to SpnA2 (Δcps/proABC) but was replaced by SpnA3 (ΔproABC/piaA) due to low colonization rates of SpnA2.

Other names

SpnA3SpnA-3SpnA 3SpnA2SpnA-2SpnA 2live attenuated Streptococcus pneumoniae strain SpnA3ΔproABC/piaA Streptococcus pneumoniaeStreptococcus pneumoniae SpnA3