Narrative Review: Use of Competent Stimulating Peptide in Gene Transfer Via Suicide Plasmid in Streptococcus pneumoniae

Natural competency for genetic transformation of Streptococcus pneumoniae causes the emergence of novel or non-vaccine preventable pneumococcal serotypes. This phenomenon has become a global concern as it can spread quickly in the population through inhalation and close contact. The colonisation of S. pneumoniae at the upper respiratory tract can either become commensal or pathogenic. Once the bacterium invades into the body system, it will secrete its toxin and virulence protein to facilitate the invasion. Besides, S. pneumoniae can undergo natural biological transformation via uptake of exogenous DNA by horizontal gene transfer for integration and recombination of the genome. S. pneumoniae natural transformation is aided by competence-stimulating peptide (CSP) that induces the competence of bacteria. Natural transformation cascade of S. pneumoniae via CSP is triggered in the presence of conserved 17-amino acids peptide which is regulated and encoded by comC, comD and comE operon, where comC is responsible in secreting precursor CSP. Nowadays, researchers transforming S. pneumoniae by inserting the mutated S. pneumoniae gene through a vector, suicide plasmid. Suicide plasmids such as pID701, pAUL-A and pVA891 can be transferred but cannot replicate in the bacteria. Homologous recombination process occurs once the mutated gene of suicide plasmid is integrated with wild-type S. pneumoniae. Previous studies had used the transformation of suicide plasmid into S. pneumoniae as it can integrate with host DNA at specific insert for gene transfer. But there is no evidence on the role of CSP in horizontal/gene replacement via suicide plasmid in Streptococcus pneumoniae. This narrative review's scope as per defined purpose statement is to relate and recommend the use of competent stimulating peptide in efficient horizontal gene transfer via suicide plasmids in Streptococcus pneumoniae.Keywords: Streptococcus pneumoniae transformation; CSP-based transformation; Gene transfer via suicide plasmid; Genetic exchange; Competence-stimulating peptid