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Neutralising antibodies against ricin toxin.

Prigent J, Panigai L, Lamourette P, Sauvaire D, Devilliers K, Plaisance M, Volland H, Créminon C, Simon S - PLoS ONE (2011)

Bottom Line: An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin.We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy.Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro.

View Article: PubMed Central - PubMed

Affiliation: CEA, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, CEA Saclay, Gif sur Yvette, France.

ABSTRACT
The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC(50) of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg) protected mice from intranasal challenges with ricin (5 LD(50)). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention.

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In vivo neutralising activity of anti-ricin antibodies combination administered after ricin challenge.(A) Survival curve. CD1 mice were intranasally challenged with 5 LD50 of ricin alone (Δ) or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. (B) Weight change. In the same experiment, mice were weighed at 0, 2, 7, 14 and 21 days, taking the weight at day zero as reference (100%), for female CD1 mice as a control (▾), mice injected with ricin (Δ), or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. The data are representative of two independent experiments.
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pone-0020166-g006: In vivo neutralising activity of anti-ricin antibodies combination administered after ricin challenge.(A) Survival curve. CD1 mice were intranasally challenged with 5 LD50 of ricin alone (Δ) or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. (B) Weight change. In the same experiment, mice were weighed at 0, 2, 7, 14 and 21 days, taking the weight at day zero as reference (100%), for female CD1 mice as a control (▾), mice injected with ricin (Δ), or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. The data are representative of two independent experiments.

Mentions: The ability of the RB34, RB37 and RA36 antibodies to neutralise ricin simultaneously was studied using a mouse model for ricin poisoning by intranasal challenge. Ricin was used at 5 LD50 (7.5 µg/kg) with several doses of antibodies and survival rate was followed for 21 days (Fig. 5). The antibody combination afforded mice effective protection against ricin poisoning, effectiveness increasing proportionally with the quantity of antibodies. The lowest dose of antibodies (antibody/ricin ratio = 2) did not protect mice, but improved their survival compared with control. With the dose of antibodies corresponding to a ratio 5, a significant protection of mice as compared to the non specific control antibodies was observed (50% viability, fig. 5A). The increase of antibodies concentration (R = 10) allows to reach 100% of protection (Fig. 5A). The analysis of mice weight provided comparable results since the weight loss decreased as the antibody/ricin ratio increased (from −24 to −7%, for a ratio increase from 5 to 20). This mix of antibodies neutralised ricin with great efficiency in vivo, and protected the mice against ricin poisoning (5 LD50) with a low concentration of antibodies. Combination of antibodies was also tested in a curative protocol, in which 5 LD50 of ricin were administered intranasally and antibodies at 5 mg/kg intravenously 10 min, 1 h, 5 h, 7.5 h, 10 h and 24 h after ricin challenge (Figure 6). Antibodies showed a good efficiency to neutralise ricin toxicity up to 7.5 hours after intoxication (Fig. 6A), allowing a 90% mice survival. If mAbs were administered 10 h after intoxication, mice survival falls to 60%, while 24 h after intoxication, antibodies were only able to delay mice death. No visible difference was observed in weight loss between 1 h, 5 h, 7.5 h and 10 h, and weight recovery occurred rapidly (2 days after intoxication). More surprisingly, weight loss was more important and recovery more difficult for the mice injected with antibodies 10 min after ricin challenge (Fig. 6B). In order to evaluate the ability of each antibody to neutralise in vivo ricin toxicity, each neutralising antibody was administered intravenously 1 h after intranasal ricin challenge (5DL50 of ricin and 5 mg/kg of antibody) (Figure 7). Each of anti-RTB antibodies (RB34 and RB37) proved to be sufficient to neutralise ricin toxin (90% and 100% of mice survival respectively, fig. 7A). Anti-RTA RA36 antibody was less effective to neutralise the toxin with 60% of mice survival. Weight loss appeared the more limited for RB37 antibody and the more important for RA36 (Fig. 7B).


Neutralising antibodies against ricin toxin.

Prigent J, Panigai L, Lamourette P, Sauvaire D, Devilliers K, Plaisance M, Volland H, Créminon C, Simon S - PLoS ONE (2011)

In vivo neutralising activity of anti-ricin antibodies combination administered after ricin challenge.(A) Survival curve. CD1 mice were intranasally challenged with 5 LD50 of ricin alone (Δ) or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. (B) Weight change. In the same experiment, mice were weighed at 0, 2, 7, 14 and 21 days, taking the weight at day zero as reference (100%), for female CD1 mice as a control (▾), mice injected with ricin (Δ), or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. The data are representative of two independent experiments.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3102095&req=5

pone-0020166-g006: In vivo neutralising activity of anti-ricin antibodies combination administered after ricin challenge.(A) Survival curve. CD1 mice were intranasally challenged with 5 LD50 of ricin alone (Δ) or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. (B) Weight change. In the same experiment, mice were weighed at 0, 2, 7, 14 and 21 days, taking the weight at day zero as reference (100%), for female CD1 mice as a control (▾), mice injected with ricin (Δ), or ricin followed by intravenous injection of 5 mg/kg of antibodies 10 min (▪), 1 h (•), 5 h (♦), 7.5 h (▴), 10 h (○) and 24 h (□) after challenge. The data are representative of two independent experiments.
Mentions: The ability of the RB34, RB37 and RA36 antibodies to neutralise ricin simultaneously was studied using a mouse model for ricin poisoning by intranasal challenge. Ricin was used at 5 LD50 (7.5 µg/kg) with several doses of antibodies and survival rate was followed for 21 days (Fig. 5). The antibody combination afforded mice effective protection against ricin poisoning, effectiveness increasing proportionally with the quantity of antibodies. The lowest dose of antibodies (antibody/ricin ratio = 2) did not protect mice, but improved their survival compared with control. With the dose of antibodies corresponding to a ratio 5, a significant protection of mice as compared to the non specific control antibodies was observed (50% viability, fig. 5A). The increase of antibodies concentration (R = 10) allows to reach 100% of protection (Fig. 5A). The analysis of mice weight provided comparable results since the weight loss decreased as the antibody/ricin ratio increased (from −24 to −7%, for a ratio increase from 5 to 20). This mix of antibodies neutralised ricin with great efficiency in vivo, and protected the mice against ricin poisoning (5 LD50) with a low concentration of antibodies. Combination of antibodies was also tested in a curative protocol, in which 5 LD50 of ricin were administered intranasally and antibodies at 5 mg/kg intravenously 10 min, 1 h, 5 h, 7.5 h, 10 h and 24 h after ricin challenge (Figure 6). Antibodies showed a good efficiency to neutralise ricin toxicity up to 7.5 hours after intoxication (Fig. 6A), allowing a 90% mice survival. If mAbs were administered 10 h after intoxication, mice survival falls to 60%, while 24 h after intoxication, antibodies were only able to delay mice death. No visible difference was observed in weight loss between 1 h, 5 h, 7.5 h and 10 h, and weight recovery occurred rapidly (2 days after intoxication). More surprisingly, weight loss was more important and recovery more difficult for the mice injected with antibodies 10 min after ricin challenge (Fig. 6B). In order to evaluate the ability of each antibody to neutralise in vivo ricin toxicity, each neutralising antibody was administered intravenously 1 h after intranasal ricin challenge (5DL50 of ricin and 5 mg/kg of antibody) (Figure 7). Each of anti-RTB antibodies (RB34 and RB37) proved to be sufficient to neutralise ricin toxin (90% and 100% of mice survival respectively, fig. 7A). Anti-RTA RA36 antibody was less effective to neutralise the toxin with 60% of mice survival. Weight loss appeared the more limited for RB37 antibody and the more important for RA36 (Fig. 7B).

Bottom Line: An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin.We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy.Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro.

View Article: PubMed Central - PubMed

Affiliation: CEA, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, CEA Saclay, Gif sur Yvette, France.

ABSTRACT
The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC(50) of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg) protected mice from intranasal challenges with ricin (5 LD(50)). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention.

Show MeSH
Related in: MedlinePlus