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Vaccination against Streptococcus pneumoniae using truncated derivatives of polyhistidine triad protein D.

Plumptre CD, Ogunniyi AD, Paton JC - PLoS ONE (2013)

Bottom Line: In this study, we purified recombinant truncated derivatives of PhtD and examined their secondary structural composition, as well as their capacity to bind antibodies from polyclonal murine serum generated against the full length protein.This allowed the identification of a particularly immunogenic fragment of PhtD, which was also purified and characterised.These experiments revealed that whilst the immunogenic region identified may be a promising candidate to protect against sepsis, the full length PhtD was ineffective at conferring significant protective immunity.

View Article: PubMed Central - PubMed

Affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.

ABSTRACT
Polyhistidine triad protein D (PhtD) has been described as a promising vaccine candidate for use against Streptococcus pneumoniae, but there has been a lack of examination of its structure and of which region(s) of the protein are targeted by protective immune responses. In this study, we purified recombinant truncated derivatives of PhtD and examined their secondary structural composition, as well as their capacity to bind antibodies from polyclonal murine serum generated against the full length protein. This allowed the identification of a particularly immunogenic fragment of PhtD, which was also purified and characterised. The truncated derivatives were tested as vaccine antigens in mouse models of pneumococcal sepsis and colonisation, using alum and E. coli heat labile toxin B subunit respectively as adjuvants. These experiments revealed that whilst the immunogenic region identified may be a promising candidate to protect against sepsis, the full length PhtD was ineffective at conferring significant protective immunity. These results are significant for the potential for PhtD to be used in novel vaccines, which are currently being tested in clinical trials.

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Related in: MedlinePlus

CFU of pneumococci recovered from the nasopharynges of vaccinated mice.After three immunisations with the indicated antigens, mice were challenged intranasally with wild-type D39 pneumococci. After 96 hours, pneumococci from the nasopharynx were enumerated. Median CFU recovered is indicated by the solid lines; the dashed line indicates the limit of detection.
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pone-0078916-g006: CFU of pneumococci recovered from the nasopharynges of vaccinated mice.After three immunisations with the indicated antigens, mice were challenged intranasally with wild-type D39 pneumococci. After 96 hours, pneumococci from the nasopharynx were enumerated. Median CFU recovered is indicated by the solid lines; the dashed line indicates the limit of detection.

Mentions: To further investigate the protective roles of different regions of PhtD, protection against colonisation by S. pneumoniae was examined by immunising groups of eight mice via the intranasal route with full length PhtD and truncated derivatives using E. coli labile toxin B subunit (LTB) as adjuvant. 10 µg of PhtD was given per dose; amounts of truncated derivatives of PhtD were adjusted such that equimolar quantities of these antigens to that of full-length PhtD were given. Control groups were immunised with adjuvant alone (negative control) or with adjuvant and PspA (positive control). Mice were subsequently challenged with strain D39 intranasally under anaesthesia. After 96 hours, mice were euthanized and numbers of pneumococci in the nasopharynx were enumerated. This model was chosen since immunisation with PhtD has previously been shown to significantly reduce pneumococcal colonisation under similar experimental conditions [16]. Results are shown in Figure 6. A small number of mice died from invasive pneumococcal disease before the 96 hours had elapsed; results from these mice were excluded. Whilst modest differences in median CFU recovered can be seen between groups, statistical analysis revealed that none of the groups were significantly different from the adjuvant alone negative control group. This includes the PhtD and PspA positive control groups, which was unexpected since these antigens have previously been shown to confer protective immunity in this model [16].


Vaccination against Streptococcus pneumoniae using truncated derivatives of polyhistidine triad protein D.

Plumptre CD, Ogunniyi AD, Paton JC - PLoS ONE (2013)

CFU of pneumococci recovered from the nasopharynges of vaccinated mice.After three immunisations with the indicated antigens, mice were challenged intranasally with wild-type D39 pneumococci. After 96 hours, pneumococci from the nasopharynx were enumerated. Median CFU recovered is indicated by the solid lines; the dashed line indicates the limit of detection.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814962&req=5

pone-0078916-g006: CFU of pneumococci recovered from the nasopharynges of vaccinated mice.After three immunisations with the indicated antigens, mice were challenged intranasally with wild-type D39 pneumococci. After 96 hours, pneumococci from the nasopharynx were enumerated. Median CFU recovered is indicated by the solid lines; the dashed line indicates the limit of detection.
Mentions: To further investigate the protective roles of different regions of PhtD, protection against colonisation by S. pneumoniae was examined by immunising groups of eight mice via the intranasal route with full length PhtD and truncated derivatives using E. coli labile toxin B subunit (LTB) as adjuvant. 10 µg of PhtD was given per dose; amounts of truncated derivatives of PhtD were adjusted such that equimolar quantities of these antigens to that of full-length PhtD were given. Control groups were immunised with adjuvant alone (negative control) or with adjuvant and PspA (positive control). Mice were subsequently challenged with strain D39 intranasally under anaesthesia. After 96 hours, mice were euthanized and numbers of pneumococci in the nasopharynx were enumerated. This model was chosen since immunisation with PhtD has previously been shown to significantly reduce pneumococcal colonisation under similar experimental conditions [16]. Results are shown in Figure 6. A small number of mice died from invasive pneumococcal disease before the 96 hours had elapsed; results from these mice were excluded. Whilst modest differences in median CFU recovered can be seen between groups, statistical analysis revealed that none of the groups were significantly different from the adjuvant alone negative control group. This includes the PhtD and PspA positive control groups, which was unexpected since these antigens have previously been shown to confer protective immunity in this model [16].

Bottom Line: In this study, we purified recombinant truncated derivatives of PhtD and examined their secondary structural composition, as well as their capacity to bind antibodies from polyclonal murine serum generated against the full length protein.This allowed the identification of a particularly immunogenic fragment of PhtD, which was also purified and characterised.These experiments revealed that whilst the immunogenic region identified may be a promising candidate to protect against sepsis, the full length PhtD was ineffective at conferring significant protective immunity.

View Article: PubMed Central - PubMed

Affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.

ABSTRACT
Polyhistidine triad protein D (PhtD) has been described as a promising vaccine candidate for use against Streptococcus pneumoniae, but there has been a lack of examination of its structure and of which region(s) of the protein are targeted by protective immune responses. In this study, we purified recombinant truncated derivatives of PhtD and examined their secondary structural composition, as well as their capacity to bind antibodies from polyclonal murine serum generated against the full length protein. This allowed the identification of a particularly immunogenic fragment of PhtD, which was also purified and characterised. The truncated derivatives were tested as vaccine antigens in mouse models of pneumococcal sepsis and colonisation, using alum and E. coli heat labile toxin B subunit respectively as adjuvants. These experiments revealed that whilst the immunogenic region identified may be a promising candidate to protect against sepsis, the full length PhtD was ineffective at conferring significant protective immunity. These results are significant for the potential for PhtD to be used in novel vaccines, which are currently being tested in clinical trials.

Show MeSH
Related in: MedlinePlus