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Kidney bean lectins (4d13)

Mixture of phytohaemagglutinin (PHA) isoforms: PHA-E4, PHA-E3L, PHA- E2L2, PHA-EL3, PHA-L4


Publication date
4 July 2011 (Last updated on: 6 June 2016)


Recommended Method

as of:

- Commission Implementing Regulation (EU) 2016/1833

For the quantification of the kidney bean lectin in the additive:

- Haemagglutination assay

6 JULY 2017

Executive Summary

In the current application authorisation is sought under article 4(1) for Suilectin under the category/functional group 4(d) "zootechnical additives"/"other zootechnical additives" (performance enhancer), according to the classification system of Annex I of Regulation (EC) No 1831/2003. According to the Applicant, Suilectin is a natural product in a form of a white to cream fine powder containing standardized lectins isolated from red kidney beans (Phaseolus vulgaris). The kidney bean lectin is a mixture of five phytohaemagglutinin (PHA) isoforms (PHA-E4, PHA-E3L, PHA-E2L2, PHA-EL3 and PHA-L4). Biological activity of the lectin is expressed as haemagglutination activity in Haemagglutination Activity Units (HAU). One haemagglutination unit (HAU) is defined as the amount of material (1 mg/mL) in the last dilution giving 50% agglutination (clumping) of the red blood cells. Therefore, one HAU describes the ability of 1 mg of the tested lectin preparation dissolved in 1 ml of physiological saline (1 mg/ml) to agglutinate at least 50% of the red blood cells. Specifically, authorisation is sought for the use of the feed additive for suckling piglets. The feed additive is intended to be applied at a dose ranging from 130 to 320 HAU /kg of body weight. It is distributed as a single use bottle with 50 g powder containing 64000 HAU, to be filled up with water prior to use. For the quantification of activity of kidney bean lectin in the feed additive, the Applicant proposed a single laboratory validated and further verified haemagglutination assay. The assay is based on the ability of lectins to agglutinate rat erythrocytes. The Applicant performed validation and verification studies, running a series of assays demonstrating reproducibility of the method by always obtaining haemagglutination of 50% erythrocytes at the fourth dilution. Furthermore, the Applicant reported a limit of detection (LOD) of 0.64 HAU/mL. The EURL considers haemagglutination assay suitable for official control for the quantification of kidney bean lectin in the feed additive. Further testing or validation of the methods to be performed through the consortium of National Reference Laboratories as specified by Article 10 (Commission Regulation (EC) No 378/2005) is not considered necessary.