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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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FACS analysis demonstrates expression of ACP on the surface of meningococci. (A and B) Reactivity of rabbit anti-rACP sera with MC58 and MC58 ∆ACP. The area within the red line shows the reactivity with preimmune rabbit sera (neat). The shaded area within the blue line shows the reactivity of rabbit anti-rACP sera (neat) with (A) MC58 (ACP+) and (B) MC58 ∆ACP (ACP−). (C) Reactivity of murine anti-rACP sera with MC58. Pooled murine antisera to rACP raised with the different adjuvants were reacted (1/10) with MC58. The areas within the red lines show the reactivity of sera from sham-immunized mice, and the shaded areas within the blue lines show the reactivity of sera from rACP-immunized mice.
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fig4: FACS analysis demonstrates expression of ACP on the surface of meningococci. (A and B) Reactivity of rabbit anti-rACP sera with MC58 and MC58 ∆ACP. The area within the red line shows the reactivity with preimmune rabbit sera (neat). The shaded area within the blue line shows the reactivity of rabbit anti-rACP sera (neat) with (A) MC58 (ACP+) and (B) MC58 ∆ACP (ACP−). (C) Reactivity of murine anti-rACP sera with MC58. Pooled murine antisera to rACP raised with the different adjuvants were reacted (1/10) with MC58. The areas within the red lines show the reactivity of sera from sham-immunized mice, and the shaded areas within the blue lines show the reactivity of sera from rACP-immunized mice.

Mentions: Expression of ACP on the surface of meningococci was examined by fluorescence-activated cell sorter (FACS) analysis using rabbit anti-rACP sera. Postimmune rabbit antisera (with ELISA titers of ~140,000 to 160,000 against rACP and ~3,000 against MC58 OM) were tested on wild-type (ACP+) MC58 bacteria and showed a significant increase in fluorescein isothiocyanate (FITC) fluorescence-recorded events with a right shift (Fig. 4A). In contrast, postimmune sera showed no significant reactivity with the MC58 ∆ACP (ACP−) strain (Fig. 4B). In addition, all murine anti-rACP sera raised using the different adjuvants and delivery vehicles reacted with wild-type MC58 as shown by FACS analysis (Fig. 4C).


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

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

FACS analysis demonstrates expression of ACP on the surface of meningococci. (A and B) Reactivity of rabbit anti-rACP sera with MC58 and MC58 ∆ACP. The area within the red line shows the reactivity with preimmune rabbit sera (neat). The shaded area within the blue line shows the reactivity of rabbit anti-rACP sera (neat) with (A) MC58 (ACP+) and (B) MC58 ∆ACP (ACP−). (C) Reactivity of murine anti-rACP sera with MC58. Pooled murine antisera to rACP raised with the different adjuvants were reacted (1/10) with MC58. The areas within the red lines show the reactivity of sera from sham-immunized mice, and the shaded areas within the blue lines show the reactivity of sera from rACP-immunized mice.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: FACS analysis demonstrates expression of ACP on the surface of meningococci. (A and B) Reactivity of rabbit anti-rACP sera with MC58 and MC58 ∆ACP. The area within the red line shows the reactivity with preimmune rabbit sera (neat). The shaded area within the blue line shows the reactivity of rabbit anti-rACP sera (neat) with (A) MC58 (ACP+) and (B) MC58 ∆ACP (ACP−). (C) Reactivity of murine anti-rACP sera with MC58. Pooled murine antisera to rACP raised with the different adjuvants were reacted (1/10) with MC58. The areas within the red lines show the reactivity of sera from sham-immunized mice, and the shaded areas within the blue lines show the reactivity of sera from rACP-immunized mice.
Mentions: Expression of ACP on the surface of meningococci was examined by fluorescence-activated cell sorter (FACS) analysis using rabbit anti-rACP sera. Postimmune rabbit antisera (with ELISA titers of ~140,000 to 160,000 against rACP and ~3,000 against MC58 OM) were tested on wild-type (ACP+) MC58 bacteria and showed a significant increase in fluorescein isothiocyanate (FITC) fluorescence-recorded events with a right shift (Fig. 4A). In contrast, postimmune sera showed no significant reactivity with the MC58 ∆ACP (ACP−) strain (Fig. 4B). In addition, all murine anti-rACP sera raised using the different adjuvants and delivery vehicles reacted with wild-type MC58 as shown by FACS analysis (Fig. 4C).

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