Limits...
Addition of histamine to subcutaneously injected Plasmodium berghei sporozoites increases the parasite liver load and could facilitate whole-parasite vaccination.

Pfeil J, Heine JF, Mueller AK - Malar. J. (2015)

Bottom Line: The parasite liver load following subcutaneous SPZ administration can be significantly increased by co-administration of histamine and heparin.However, despite a relatively high parasite liver load, the protective efficacy of histamine-supplemented subcutaneous immunization remains inferior as compared to intravenous SPZ administration.Further investigations are needed to reveal the effect of histamine supplementation and subcutaneous SPZ administration on the acquisition of protective immunity.

View Article: PubMed Central - PubMed

Affiliation: Centre for Childhood and Adolescent Medicine (General Paediatrics), University Hospital, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany. Johannes.Pfeil@med.uni-heidelberg.de.

ABSTRACT

Background: Whole-parasite immunization remains the benchmark in malaria vaccine development. A major bottleneck in the translation of whole-parasite immunization towards routine vaccination is the mode of administration, since high degrees of protection are currently only achieved by intravenous, and not by intradermal or subcutaneous injection of viable parasites. It is known that only a small proportion of subcutaneously administered parasites reach the subsequent liver stage and low parasite liver load was shown to be associated with low protective efficacy. The objective of this analysis was to evaluate whether the liver load following subcutaneous parasite injection could be augmented by co-administration of pro-inflammatory or anti-coagulatory drugs.

Methods: In the C57BL/6 Plasmodium berghei ANKA model, the clinical outcome (time to patent blood stage infection and survival) and relative parasite liver load was assessed in mice infected by subcutaneous or intramuscular sporozoite (SPZ) administration in the presence or absence of histamine and heparin supplementation in comparison to intravenously administered SPZ. In addition, a vaccination experiment was carried out to assess the protective efficacy of an improved, histamine-supplemented subcutaneous immunization regimen.

Results: The parasite liver load following subcutaneous SPZ administration can be significantly increased by co-administration of histamine and heparin. A dose-dependent relation between parasite liver load and histamine dosage was observed. However, despite a relatively high parasite liver load, the protective efficacy of histamine-supplemented subcutaneous immunization remains inferior as compared to intravenous SPZ administration.

Conclusions: Histamine supplementation might facilitate the future development of a non-intravenous whole-parasite vaccine. Further investigations are needed to reveal the effect of histamine supplementation and subcutaneous SPZ administration on the acquisition of protective immunity.

Show MeSH

Related in: MedlinePlus

In vivoliver load in relation to intravenously infected control animals. Mice were infected with 104 SPZ supplemented with either 3 μg histamine and 5 IU heparin sc (3 μg s.; n = 8) or 100 μg histamine and 5 IU heparin sc (100 μg sc; n = 8) or 100 μg histamine with (n = 4) or without (n = 4) 5 IU heparin im (mice are displayed combined in group 100 μg im; total n = 8). The intrahepatic flux was obtained at 48 hrs post-infection and is expressed in relation to the median flux measurement of four iv-infected control mice.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4318155&req=5

Fig6: In vivoliver load in relation to intravenously infected control animals. Mice were infected with 104 SPZ supplemented with either 3 μg histamine and 5 IU heparin sc (3 μg s.; n = 8) or 100 μg histamine and 5 IU heparin sc (100 μg sc; n = 8) or 100 μg histamine with (n = 4) or without (n = 4) 5 IU heparin im (mice are displayed combined in group 100 μg im; total n = 8). The intrahepatic flux was obtained at 48 hrs post-infection and is expressed in relation to the median flux measurement of four iv-infected control mice.

Mentions: To validate the results obtained from qRT-PCR analysis, in vivo imaging was applied as a second read-out for parasite liver development. Intrahepatic flux was measured in mice infected sc with 104 luciferase-expressing SPZ plus 5 IU of heparin and either 3 μg (3 μg sc; n = 8) or 100 μg (100 μg sc; n = 8) histamine. In addition, a group of mice receiving intramuscular injections of 104 luciferase-expressing SPZ and 100 μg histamine with (n = 4) or without (n = 4) 5 IU of heparin was included in the in vivo experiments. In this small experiment, the addition or absence of heparin did not influence the parasite liver load of im infected mice (Figure 5), and all animals were thus summarized in a single group (100 μg im). As before, the intrahepatic flux was expressed in relation to the median of four simultaneously iv-infected control animals. The median relative parasite liver load was 2, 9 and 7% for the sc 3 μg, sc 100 μg and im 100 μg group, respectively (Figure 6).Figure 5


Addition of histamine to subcutaneously injected Plasmodium berghei sporozoites increases the parasite liver load and could facilitate whole-parasite vaccination.

Pfeil J, Heine JF, Mueller AK - Malar. J. (2015)

In vivoliver load in relation to intravenously infected control animals. Mice were infected with 104 SPZ supplemented with either 3 μg histamine and 5 IU heparin sc (3 μg s.; n = 8) or 100 μg histamine and 5 IU heparin sc (100 μg sc; n = 8) or 100 μg histamine with (n = 4) or without (n = 4) 5 IU heparin im (mice are displayed combined in group 100 μg im; total n = 8). The intrahepatic flux was obtained at 48 hrs post-infection and is expressed in relation to the median flux measurement of four iv-infected control mice.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4318155&req=5

Fig6: In vivoliver load in relation to intravenously infected control animals. Mice were infected with 104 SPZ supplemented with either 3 μg histamine and 5 IU heparin sc (3 μg s.; n = 8) or 100 μg histamine and 5 IU heparin sc (100 μg sc; n = 8) or 100 μg histamine with (n = 4) or without (n = 4) 5 IU heparin im (mice are displayed combined in group 100 μg im; total n = 8). The intrahepatic flux was obtained at 48 hrs post-infection and is expressed in relation to the median flux measurement of four iv-infected control mice.
Mentions: To validate the results obtained from qRT-PCR analysis, in vivo imaging was applied as a second read-out for parasite liver development. Intrahepatic flux was measured in mice infected sc with 104 luciferase-expressing SPZ plus 5 IU of heparin and either 3 μg (3 μg sc; n = 8) or 100 μg (100 μg sc; n = 8) histamine. In addition, a group of mice receiving intramuscular injections of 104 luciferase-expressing SPZ and 100 μg histamine with (n = 4) or without (n = 4) 5 IU of heparin was included in the in vivo experiments. In this small experiment, the addition or absence of heparin did not influence the parasite liver load of im infected mice (Figure 5), and all animals were thus summarized in a single group (100 μg im). As before, the intrahepatic flux was expressed in relation to the median of four simultaneously iv-infected control animals. The median relative parasite liver load was 2, 9 and 7% for the sc 3 μg, sc 100 μg and im 100 μg group, respectively (Figure 6).Figure 5

Bottom Line: The parasite liver load following subcutaneous SPZ administration can be significantly increased by co-administration of histamine and heparin.However, despite a relatively high parasite liver load, the protective efficacy of histamine-supplemented subcutaneous immunization remains inferior as compared to intravenous SPZ administration.Further investigations are needed to reveal the effect of histamine supplementation and subcutaneous SPZ administration on the acquisition of protective immunity.

View Article: PubMed Central - PubMed

Affiliation: Centre for Childhood and Adolescent Medicine (General Paediatrics), University Hospital, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany. Johannes.Pfeil@med.uni-heidelberg.de.

ABSTRACT

Background: Whole-parasite immunization remains the benchmark in malaria vaccine development. A major bottleneck in the translation of whole-parasite immunization towards routine vaccination is the mode of administration, since high degrees of protection are currently only achieved by intravenous, and not by intradermal or subcutaneous injection of viable parasites. It is known that only a small proportion of subcutaneously administered parasites reach the subsequent liver stage and low parasite liver load was shown to be associated with low protective efficacy. The objective of this analysis was to evaluate whether the liver load following subcutaneous parasite injection could be augmented by co-administration of pro-inflammatory or anti-coagulatory drugs.

Methods: In the C57BL/6 Plasmodium berghei ANKA model, the clinical outcome (time to patent blood stage infection and survival) and relative parasite liver load was assessed in mice infected by subcutaneous or intramuscular sporozoite (SPZ) administration in the presence or absence of histamine and heparin supplementation in comparison to intravenously administered SPZ. In addition, a vaccination experiment was carried out to assess the protective efficacy of an improved, histamine-supplemented subcutaneous immunization regimen.

Results: The parasite liver load following subcutaneous SPZ administration can be significantly increased by co-administration of histamine and heparin. A dose-dependent relation between parasite liver load and histamine dosage was observed. However, despite a relatively high parasite liver load, the protective efficacy of histamine-supplemented subcutaneous immunization remains inferior as compared to intravenous SPZ administration.

Conclusions: Histamine supplementation might facilitate the future development of a non-intravenous whole-parasite vaccine. Further investigations are needed to reveal the effect of histamine supplementation and subcutaneous SPZ administration on the acquisition of protective immunity.

Show MeSH
Related in: MedlinePlus