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The adhesin complex protein (ACP) of Neisseria meningitidis is a new adhesin with vaccine potential.

Hung MC, Heckels JE, Christodoulides M - MBio (2013)

Bottom Line: ACP functioned as an adhesin, as demonstrated by reduced adherence of acp knockout (MC58 ΔACP) meningococci to human cells in vitro and the direct surface binding of rACP and by the ability of anti-rACP sera to inhibit adherence of wild-type bacteria.Infections caused by Neisseria meningitidis serogroup B are still significant causes of mortality and morbidity worldwide, and broadly protective vaccines of defined antigen composition are not yet licensed.We also report that a recombinant ACP protein vaccine induces murine antibodies that significantly kill meningococci expressing different ACP.

View Article: PubMed Central - PubMed

Affiliation: Neisseria Research Group, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton, Faculty of Medicine, Southampton General Hospital, Southampton, United Kingdom.

ABSTRACT

Unlabelled: The acp gene encoding the 13-kDa adhesin complex protein (ACP) from Neisseria meningitidis serogroup B strain MC58 was cloned and expressed in Escherichia coli, and the purified recombinant ACP (rACP) was used for immunization studies. Analysis of the ACP amino acid sequences from 13 meningococcal strains, isolated from patients and colonized individuals, and 178 strains in the Bacterial Isolate Genome Sequence (BIGS) database showed the presence of only three distinct sequence types (I, II, and III) with high similarity (> 98%). Immunization of mice with type I rACP in detergent micelles and liposomes and in saline solution alone induced high levels of serum bactericidal activity (SBA; titers of 1/512) against the homologous strain MC58 and killed strains of heterologous sequence types II and III with similar SBA titers (1/128 to 1/512). Levels of expression of type I, II, or III ACP by different meningococcal strains were similar. ACP functioned as an adhesin, as demonstrated by reduced adherence of acp knockout (MC58 ΔACP) meningococci to human cells in vitro and the direct surface binding of rACP and by the ability of anti-rACP sera to inhibit adherence of wild-type bacteria. ACP also mediated the invasion of noncapsular meningococci into human epithelial cells, but it was not a particularly impressive invasin, as the internalized bacterial numbers were low. In summary, the newly identified ACP protein is an adhesin that induces cross-strain bactericidal activity and is therefore an attractive target antigen for incorporation into the next generation of serogroup B meningococcal vaccines.

Importance: Infections caused by Neisseria meningitidis serogroup B are still significant causes of mortality and morbidity worldwide, and broadly protective vaccines of defined antigen composition are not yet licensed. Here, we describe the properties of the adhesin complex protein (ACP), which we demonstrate is a newly recognized molecule that is highly conserved and expressed to similar levels in meningococci and facilitates meningococcal interactions with human cells. We also report that a recombinant ACP protein vaccine induces murine antibodies that significantly kill meningococci expressing different ACP. Taken together, these properties demonstrate that ACP merits serious consideration as a component of a broadly protective vaccine against serogroup B meningococci.

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(A) ACP mediates adhesion of meningococci to human cells. Chang, Hep2, HUVEC, and meningioma monolayers were infected at an MOI of 100 to 200 with MC58, MC58 ∆ACP, and the MC58 ΔACP complemented (com) strains. Representative experiments for each cell line are shown, as reported by Virji et al. (15). Experiments were repeated 3 to 4 times for each cell line, and the patterns of association of the different bacterial strains were reproducible between experiments, regardless of any quantitative variations between experiments. (B) Anti-rACP serum inhibits bacterial association to epithelial cells. Chang epithelial cells were infected with different MOI of MC58 (ACP+) in the presence of decomplemented rabbit preimmune (1% vol/vol) and postimmune (1% vol/vol) anti-rACP serum, and bacterial association was measured after 3 h. The data are representative of n = 4 experiments, and the percentage of reduction in bacterial adherence was calculated from the following formula: 100 × (adherent bacteria with preimmune serum − adherent bacteria with postimmune serum)/adherent bacteria with preimmune serum. For both panels, the columns represent the mean associated bacterial numbers and the error bars show the standard deviations of the results determined with triplicate wells. *, P < 0.05.
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fig7: (A) ACP mediates adhesion of meningococci to human cells. Chang, Hep2, HUVEC, and meningioma monolayers were infected at an MOI of 100 to 200 with MC58, MC58 ∆ACP, and the MC58 ΔACP complemented (com) strains. Representative experiments for each cell line are shown, as reported by Virji et al. (15). Experiments were repeated 3 to 4 times for each cell line, and the patterns of association of the different bacterial strains were reproducible between experiments, regardless of any quantitative variations between experiments. (B) Anti-rACP serum inhibits bacterial association to epithelial cells. Chang epithelial cells were infected with different MOI of MC58 (ACP+) in the presence of decomplemented rabbit preimmune (1% vol/vol) and postimmune (1% vol/vol) anti-rACP serum, and bacterial association was measured after 3 h. The data are representative of n = 4 experiments, and the percentage of reduction in bacterial adherence was calculated from the following formula: 100 × (adherent bacteria with preimmune serum − adherent bacteria with postimmune serum)/adherent bacteria with preimmune serum. For both panels, the columns represent the mean associated bacterial numbers and the error bars show the standard deviations of the results determined with triplicate wells. *, P < 0.05.

Mentions: The potential role of ACP in pathogenesis was investigated by infecting human cell cultures in vitro with wild-type MC58 and MC58 ∆ACP and comparing bacterial association and invasion. Compared with MC58, there was a significant reduction in association of MC58 ΔACP bacteria with all human cell types (Fig. 7A). Reduced association of MC58 ΔACP was greatest with both Chang and Hep2 epithelial cells (~75% reduction; P < 0.05), and approximately 30% to 50% with both human umbilical vein endothelial cells (HUVECs) and meningioma cells (P < 0.05). Furthermore, the MC58 ΔACP complemented strain restored the numbers of associated bacteria for all three cell types to levels similar to those of the wild-type strain (P > 0.05).


The adhesin complex protein (ACP) of Neisseria meningitidis is a new adhesin with vaccine potential.

Hung MC, Heckels JE, Christodoulides M - MBio (2013)

(A) ACP mediates adhesion of meningococci to human cells. Chang, Hep2, HUVEC, and meningioma monolayers were infected at an MOI of 100 to 200 with MC58, MC58 ∆ACP, and the MC58 ΔACP complemented (com) strains. Representative experiments for each cell line are shown, as reported by Virji et al. (15). Experiments were repeated 3 to 4 times for each cell line, and the patterns of association of the different bacterial strains were reproducible between experiments, regardless of any quantitative variations between experiments. (B) Anti-rACP serum inhibits bacterial association to epithelial cells. Chang epithelial cells were infected with different MOI of MC58 (ACP+) in the presence of decomplemented rabbit preimmune (1% vol/vol) and postimmune (1% vol/vol) anti-rACP serum, and bacterial association was measured after 3 h. The data are representative of n = 4 experiments, and the percentage of reduction in bacterial adherence was calculated from the following formula: 100 × (adherent bacteria with preimmune serum − adherent bacteria with postimmune serum)/adherent bacteria with preimmune serum. For both panels, the columns represent the mean associated bacterial numbers and the error bars show the standard deviations of the results determined with triplicate wells. *, P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585444&req=5

fig7: (A) ACP mediates adhesion of meningococci to human cells. Chang, Hep2, HUVEC, and meningioma monolayers were infected at an MOI of 100 to 200 with MC58, MC58 ∆ACP, and the MC58 ΔACP complemented (com) strains. Representative experiments for each cell line are shown, as reported by Virji et al. (15). Experiments were repeated 3 to 4 times for each cell line, and the patterns of association of the different bacterial strains were reproducible between experiments, regardless of any quantitative variations between experiments. (B) Anti-rACP serum inhibits bacterial association to epithelial cells. Chang epithelial cells were infected with different MOI of MC58 (ACP+) in the presence of decomplemented rabbit preimmune (1% vol/vol) and postimmune (1% vol/vol) anti-rACP serum, and bacterial association was measured after 3 h. The data are representative of n = 4 experiments, and the percentage of reduction in bacterial adherence was calculated from the following formula: 100 × (adherent bacteria with preimmune serum − adherent bacteria with postimmune serum)/adherent bacteria with preimmune serum. For both panels, the columns represent the mean associated bacterial numbers and the error bars show the standard deviations of the results determined with triplicate wells. *, P < 0.05.
Mentions: The potential role of ACP in pathogenesis was investigated by infecting human cell cultures in vitro with wild-type MC58 and MC58 ∆ACP and comparing bacterial association and invasion. Compared with MC58, there was a significant reduction in association of MC58 ΔACP bacteria with all human cell types (Fig. 7A). Reduced association of MC58 ΔACP was greatest with both Chang and Hep2 epithelial cells (~75% reduction; P < 0.05), and approximately 30% to 50% with both human umbilical vein endothelial cells (HUVECs) and meningioma cells (P < 0.05). Furthermore, the MC58 ΔACP complemented strain restored the numbers of associated bacteria for all three cell types to levels similar to those of the wild-type strain (P > 0.05).

Bottom Line: ACP functioned as an adhesin, as demonstrated by reduced adherence of acp knockout (MC58 ΔACP) meningococci to human cells in vitro and the direct surface binding of rACP and by the ability of anti-rACP sera to inhibit adherence of wild-type bacteria.Infections caused by Neisseria meningitidis serogroup B are still significant causes of mortality and morbidity worldwide, and broadly protective vaccines of defined antigen composition are not yet licensed.We also report that a recombinant ACP protein vaccine induces murine antibodies that significantly kill meningococci expressing different ACP.

View Article: PubMed Central - PubMed

Affiliation: Neisseria Research Group, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton, Faculty of Medicine, Southampton General Hospital, Southampton, United Kingdom.

ABSTRACT

Unlabelled: The acp gene encoding the 13-kDa adhesin complex protein (ACP) from Neisseria meningitidis serogroup B strain MC58 was cloned and expressed in Escherichia coli, and the purified recombinant ACP (rACP) was used for immunization studies. Analysis of the ACP amino acid sequences from 13 meningococcal strains, isolated from patients and colonized individuals, and 178 strains in the Bacterial Isolate Genome Sequence (BIGS) database showed the presence of only three distinct sequence types (I, II, and III) with high similarity (> 98%). Immunization of mice with type I rACP in detergent micelles and liposomes and in saline solution alone induced high levels of serum bactericidal activity (SBA; titers of 1/512) against the homologous strain MC58 and killed strains of heterologous sequence types II and III with similar SBA titers (1/128 to 1/512). Levels of expression of type I, II, or III ACP by different meningococcal strains were similar. ACP functioned as an adhesin, as demonstrated by reduced adherence of acp knockout (MC58 ΔACP) meningococci to human cells in vitro and the direct surface binding of rACP and by the ability of anti-rACP sera to inhibit adherence of wild-type bacteria. ACP also mediated the invasion of noncapsular meningococci into human epithelial cells, but it was not a particularly impressive invasin, as the internalized bacterial numbers were low. In summary, the newly identified ACP protein is an adhesin that induces cross-strain bactericidal activity and is therefore an attractive target antigen for incorporation into the next generation of serogroup B meningococcal vaccines.

Importance: Infections caused by Neisseria meningitidis serogroup B are still significant causes of mortality and morbidity worldwide, and broadly protective vaccines of defined antigen composition are not yet licensed. Here, we describe the properties of the adhesin complex protein (ACP), which we demonstrate is a newly recognized molecule that is highly conserved and expressed to similar levels in meningococci and facilitates meningococcal interactions with human cells. We also report that a recombinant ACP protein vaccine induces murine antibodies that significantly kill meningococci expressing different ACP. Taken together, these properties demonstrate that ACP merits serious consideration as a component of a broadly protective vaccine against serogroup B meningococci.

Show MeSH
Related in: MedlinePlus