Growth Phase Influences Complement Resistance ofBordetella pertussis

Abstract

The BrkA protein of Bordetella pertussis inhibits killing by the antibody-dependent classical pathway of complement; however, susceptibility to complement can be highly variable. Log-phase bacteria grown in Stainer-Scholte (SS) broth plated on Bordet-Gengou (BG) agar were about 500 times more sensitive to killing by complement than stationary-phase SS-BG cultures. While always more susceptible to complement than the wild-type strain, a BrkA mutant displayed a similar growth phase variation in susceptibility to complement. Growth phase susceptibility to complement was also observed for a mutant constitutive for Bvg activation of BrkA, suggesting that modulation of virulence factor expression was not responsible for sensitivity to complement. Susceptibility was not due to differential antigenic expression, since serum adsorbed with complement-resistant, stationary-phase SS-BG cultures lacked bactericidal activity against B. pertussis harvested at all times during the growth cycle. These results suggest that log-phase susceptibility to complement is not due to variable expression of BrkA or antigenic differences and may be an inherent property of rapidly growing cultures. Implications for vaccine development are discussed.

Bordetella pertussisAcquires Resistance to Complement-Mediated Killing In Vivo

“…We tested the ⌬brkA mutant RFBP 2152 in order to determine whether contributions to the acquired resistance which we observed are made by BrkA, a BvgAS-regulated protein already known to act in classical pathway inhibition in the presence of antibodies (3,4,13). We found that this mutant does acquire a significant amount of resistance in vivo (Fig.…”

Opsonophagocytic Activity and Other Serological Indications ofBordetella pertussisInfection in Military Recruits in Norway

“…The presence of BrkA protein is reported to inhibit complement activation by the classical pathway (5). We did not analyze the actual BrkA content of the bacterial preparations we used, but our bacterial growth procedures on Bordet-Gengou agar have been reported to sustain BrkA expression (4). Various amounts of C3b deposition on the bacterial surface were induced by the serum samples, and we observed a positive correlation with the levels of IgG antibody against live B. pertussis, supporting classical complement activation.…”

Importance of (antibody-dependent) complement-mediated serum killing in protection againstBordetella pertussis

“…Whereas a number of studies demonstrate that wild-type B. pertussis is (relatively) resistant to killing via the alternative complement pathway [41,46,[49][50][51][52], others showed that B. pertussis is rapidly killed also by naïve serum [30,50]. The explanation for these contradicting findings are most likely associated with differences in experimental setup, where the amount and source of complement, the source and preparation of strains and the length and read-out of the experiment are all important variables [53][54][55][56][57]. Direct investigation of the impact of wlb mutations demonstrated that in the presence of low amounts of naïve serum (~10-20%), truncation or deletion of [19] Guinea pig Several SBA: IZ Naïve, convalescing, 2aP; adults Bactericidal activity demonstrated [41] No Several OPK: THP-1; MI and CFU Naïve, 3aP, wP; children…”

“…BrkA shows homology to pertactin (PRN) and tracheal colonization factor -primarily in its C-terminal b-domain -and contains a number of amino acid motifs implicated in protein-protein (RGD) or protein-glycan (SGXG) interactions [47,49]. Further characterization demonstrated the brkA coding sequence was present in various Bordetella species and that B. pertussis BrkA mediates serum resistance by inhibiting the classical (antibodydependent) complement pathway [41,49,50,53,54,72].…”