Use ofLactococcus lactisExpressing Pili from Group BStreptococcusas a Broad‐Coverage Vaccine against Streptococcal Disease

Abstract

Recent data indicate that the human pathogen group B Streptococcus (GBS) produces pilus-like structures encoded in genomic islands with similar organization to pathogenicity islands. On the basis of the amino acid sequence of their protein components, 3 different types of pili have been identified in GBS, at least 1 of which is present in all isolates. We recently demonstrated that recombinant pilus proteins protect mice from lethal challenge with GBS and are thus potential vaccine candidates. Here, we show that GBS pilin island 1, transferred into the nonpathogenic microorganism Lactococcus lactis, leads to pilus assembly. We also show that systemically or mucosally delivered Lactococcus expressing pilin island 1 protects mice from challenge with GBS isolates carrying pilus 1. Furthermore, lactococci engineered to express hybrid pili containing GBS pilus 1 and pilus 2 components confer protection against strains expressing either of the 2 pilus types. These data pave the way to the design of pilus-based, multivalent live vaccines against streptococcal pathogens.

Dominance of Serotype Ia among Group B Streptococci Causing Invasive Infections in Nonpregnant Adults in Portugal

“…The isolates found in cluster L 10 were fully susceptible to all antimicrobials tested, including tetracycline, causing serotype V to be the only serotype significantly associated with tetracycline susceptibility.…”

“…Polysaccharide-protein conjugate vaccines, showing more favorable immune responses than polysaccharide-only vaccines, have undergone clinical trials with promising, although still preliminary, results (2,22). Currently, purely protein vaccines, based on components of the recently described GBS pilus-like structures, are being discussed in the literature (10,38).…”

SpyAD, a Moonlighting Protein of Group A Streptococcus Contributing to Bacterial Division and Host Cell Adhesion

“…This nonpathogenic bacterium does not significantly adhere to human epithelial cells but is capable of efficiently expressing and exporting functional exogenous proteins to the cell surface (15,35). Expression of wild-type SpyAD was obtained in L. lactis MG1363 using the pAM episomal vector in which protein synthesis is driven by the strong P80 promoter from Streptococcus agalactiae (15).…”

“…This nonpathogenic bacterium does not significantly adhere to human epithelial cells but is capable of efficiently expressing and exporting functional exogenous proteins to the cell surface (15,35). Expression of wild-type SpyAD was obtained in L. lactis MG1363 using the pAM episomal vector in which protein synthesis is driven by the strong P80 promoter from Streptococcus agalactiae (15). Figure 7A shows that the expression of wild-type SpyAD in L. lactis resulted only in a partial shift of bacterial fluorescence after staining with anti-SpyAD polyclonal antibodies (central panel) compared to the negative-control strain containing the empty vector only (left panel).…”

“…The genomic region between the ribosome binding site and the stop codon of spyAD gene was amplified, and the PCR product was digested with BamHI and NotI restriction sites and ligated to BglII/NotI-digested pAM401 (21). The spyAD gene was inserted into pAM-p80, under the control of the GBS pilus island promoter (15). The expression of the protein SpyAD in the ⌬spyAD(pAMspyAD) complemented strain was confirmed by cytofluorimetry analysis and immunoblotting on bacterial total cell extracts.…”