Immunotoxicological studies of genetically modified rice expressing PHA-E lectin or Bt toxin in Wistar rats.
As part of the SAFOTEST project the immunmodulating effect of Cry1Ab protein from Bacillus thuringiensis (Bt) and PHA-E lectin from kidney bean (Phaseolus vulgaris erythroagglutinin) was examined in 28- and 90-day feeding studies in Wistar rats. PHA-E lectin was chosen as positive control. Rats were fed control rice, transgenic rice expressing Cry1Ab protein or PHA-E lectin, or transgenic rice spiked with the purified recombinant protein. Total immunoglobulin levels, mitogen-induced cell proliferation, T-dependent antibody response to sheep red blood cells and the antigen-specific antibody response in serum were examined at the end of the studies. A dose-dependent increase in mesenteric lymph node weight and total immunoglobulin A was seen when feeding PHA-E transgenic rice alone or spiked with 0.1% purified PHA-E lectin for 90 days indicating a local effect of PHA-E in the intestine. No adverse effects of Cry1Ab protein were found. An anti-PHA-E and anti-Cry1Ab antibody response was induced both after inhalation (control groups) and after inhalation/ingestion (groups fed recombinant protein alone or together with transgenic rice). In conclusion, only PHA-E lectin was found to have an immunomodulating effect when feeding rats for 90 days with approximately 70 mg PHA-E/kg bodyweight per day. As both PHA-E lectin and Cry1Ab protein were capable of inducing an antigen-specific antibody response it is important to make careful considerations when designing future animal studies to avoid intake of proteins from the other groups by inhalation as well as to examine the sensitization and elicitation potential of 'foreign' proteins before introduction to the world market.
Kroghsbo
Stine
S
Department of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark. sck@food.dtu.dk
Madsen
Charlotte
C
Poulsen
Morten
M
Schrøder
Malene
M
Kvist
Peter H
PH
Taylor
Mark
M
Gatehouse
Angharad
A
Shu
Qingyao
Q
Knudsen
Ib
I
D000821:Animal Feed; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D001413:Bacillus thuringiensis / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001427:Bacterial Toxins / Q000096:biosynthesis*; D049109:Cell Proliferation / Q000187:drug effects; D004306:Dose-Response Relationship, Immunologic; D004731:Endotoxins / Q000096:biosynthesis*; D005260:Female; D030841:Food, Genetically Modified / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000096:biosynthesis*; D007136:Immunoglobulins / Q000097:blood; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology; D008297:Male; D008643:Mesentery / Q000187:drug effects / Q000276:immunology; D012275:Oryza / Q000235:genetics*; D010835:Phytohemagglutinins / Q000096:biosynthesis* / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D036401:Toxicity Tests, Chronic / Q000379:methods
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007136:Immunoglobulins; D010835:Phytohemagglutinins; C067494:erythroagglutinating phytohemagglutinin; C030956:insecticidal crystal protein, Bacillus Thuringiensis