Characterisation of invasive group B streptococci based on investigation of surface proteins and genes encoding surface proteins

Abstract

The joint distributions of the six genes bca, bac, epsilon/alp1, alp2, alp3 and rib (encoding alpha-C-protein, beta-C-protein, epsilon/Alp1, Alp2, Alp3, and Rib, respectively) and the proteins alpha-C-protein, beta-C-protein and Rib were investigated in invasive isolates of group B streptococcus (GBS). In total, 297 invasive isolates (123 from neonates, 174 from adults) from south-west Sweden were collected during a 13-year period. Genes were detected using multiplex and specific PCRs, and expression of the surface proteins was demonstrated using monoclonal antibodies. The genes studied were found alone or in combinations in 294 (99%) of the invasive isolates. The most common genes were rib (n = 127 isolates, 43%), alp3 (n = 78, 26%) and epsilon/alp1 (n = 42, 14%). The bac gene was never found alone, but was found in combination with one other gene in 36 isolates. The surface proteins studied were detected alone or in combinations in 152 (51%) isolates, with the most common being Rib (n = 80, 27%), alpha-C-protein (n = 68, 23%) and beta-C-protein (n = 24, 8%). Several genes were associated significantly with particular serotypes (e.g., epsilon/alp1 with serotype Ia; bca and bac with serotypes Ib and II; rib with serotype III; alp3 with serotype V). Overall, it was concluded that demonstration of different genes and surface proteins of GBS strains can be useful in epidemiological studies and in formulation of vaccines, but disappointingly, no single gene or surface protein included in the study was sufficiently common for it to be considered as the basis for a successful GBS vaccine.

Putative Novel Surface-Exposed Streptococcus agalactiae Protein Frequently Expressed by the Group B Streptococcus from Zimbabwe

“…Irrespective of this, the frequency of expression of the Z antigen was high and in the strain collection evaluated in the present study was similar to the frequency of expression of the R3 protein and to the frequency of possession of alp1 and bca (19), the genes encoding Alp1 and C␣, respectively; but the frequency of Zantigen expression was lower than the frequency of possession of rib (19), the gene encoding the R4 (Rib) protein (31). Surface-anchored and strain-variable GBS protein antigens show associations with CPSs, such as the CPS type Ia/Alp1, type Ib/C␣, Cß, type III/R4 (Rib), and type V/Alp3 associations (9,11,22,24). The Z protein showed a strong preference for strains of CPS types Ib and V. Alp3 is known to be the predominating surface-anchored and strain-variable protein in CPS type V strains (9,11,24), but this was not the case with the type V GBS strains from Zimbabwe.…”

“…Surface-anchored and strain-variable GBS protein antigens show associations with CPSs, such as the CPS type Ia/Alp1, type Ib/C␣, Cß, type III/R4 (Rib), and type V/Alp3 associations (9,11,22,24). The Z protein showed a strong preference for strains of CPS types Ib and V. Alp3 is known to be the predominating surface-anchored and strain-variable protein in CPS type V strains (9,11,24), but this was not the case with the type V GBS strains from Zimbabwe. Only 6.8% of the Zimbabwean type V strains possessed alp3, which encodes Alp3, while the R3 protein occurred in 75.9% of the type V isolates (19).…”

“…alp3, which encodes Alp3, was found in only 5% of one of the Zimbabwean strain collections and in only 6.9% of the type V strains (19). With GBS from Western countries, Alp3 (or alp3) has been detected in 60% to 90% of type V strains (1,11,13,24).In our work on carrier GBS strains from Zimbabwe, we have used a murine monoclonal anti-R3 antibody (R3 MAb) for the detection of R3 expression (12,19,22). When R3 MAb-negative strains were tested by using a polyclonal antibody (PAb) considered specific for the R3 protein, we recorded findings which led us to suspect the expression by certain isolates of a…”

“…alp3, which encodes Alp3, was found in only 5% of one of the Zimbabwean strain collections and in only 6.9% of the type V strains (19). With GBS from Western countries, Alp3 (or alp3) has been detected in 60% to 90% of type V strains (1,11,13,24).…”

Characterization of Invasive Group B Streptococcus Strains from the Greater Toronto Area, Canada

“…PCR typing schemes have been developed which target the serotype-determining region of the cps locus and permit the prediction of GBS serotypes. A substantial proportion of EOD and the majority of LOD in neonates are associated with CPS type III, while, among adults, CPS types V, Ia, III, and Ib are all recognized as significant causes of invasive disease (7)(8)(9)(10)(11)(12)(13)(14).…”