Antiparasite activity of sea-anemone cytolysins on Giardia duodenalis and specific targeting with anti-Giardia antibodies.
The killing activity of sea-anemone cytolysins on Giardia duodenalis was investigated. Three different toxins, sticholysin I and II from Stichodactyla helianthus (St I and St II) and equinatoxin II from Actinia equina (EqtII) were all found to be active in an acute test, with a C50 in the nanomolar range (St I, 0.5 nM; St II, 1.6 nM; and EqtII, 0.8 nM). A method to target the cytolysin activity more specifically towards the parasite cells by using anti-Giardia antibodies was then investigated. Parasite cells were sensitised with a primary murine monoclonal or polyclonal antibody followed by a biotinylated secondary anti-mouse-IgG monoclonal antibody. Subsequently, avidin and a biotinylated EqtII mutant were added, either in two separate steps or as a pre-formed conjugate. When the monoclonal antibody was used, the C50 of biotinylated EqtII was 1.3 nM with sensitised cells and 5 nM with non-sensitised cells, indicating a four-fold enhancement of activity with the cell treatment. Treatment with the polyclonal antibody was somehow more effective than with the monoclonal antibody in an acute test. This indicates that sea-anemone cytolysins can efficiently kill Giardia cells, and that it is possible to improve, to a certain extent, the anti-parasite specificity of these toxins with anti-Giardia antibodies. However, the feasibility of this approach "in vivo" remains to be demonstrated.
Tejuca
M
M
CNR-ITC, Centro di Fisica degli Stati Aggregati, Povo (Trento), Italy.
Anderluh
G
G
Macek
P
P
Marcet
R
R
Torres
D
D
Sarracent
J
J
Alvarez
C
C
Lanio
M E
ME
Dalla Serra
M
M
Menestrina
G
G
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology; D000913:Antibodies, Protozoan / Q000276:immunology* / Q000378:metabolism; D001360:Avidin / Q000378:metabolism; D001710:Biotin / Q000378:metabolism; D019921:Biotinylation; D003064:Cnidarian Venoms / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D003603:Cytotoxins / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D016829:Giardia lamblia / Q000187:drug effects / Q000276:immunology*; D005873:Giardiasis / Q000469:parasitology; D000922:Immunotoxins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D012615:Sea Anemones
D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan; D003064:Cnidarian Venoms; D003603:Cytotoxins; D000922:Immunotoxins; D001360:Avidin; C012307:equinatoxin; D001710:Biotin