Production and characterization of anti-idiotypic antibodies for the control of Escherichia coli infections in mammals

Thumbnail Image
Jaradat, Ziad Waheed
Journal Title
Journal ISSN
Volume Title
Enterotoxigenic 'Escherichia coli' (ETEC) cause diarrheal diseases in both humans and domestic animals. It is a prominent problem in swine industry and it is responsible for high mortality in neonatal piglets. Therapeutic antibodies offer an alternative approach to the use of antibiotics for solving these problems. An experimental program was undertaken to evaluate the efficacy of therapeutic antibodies in both mice and neonatal piglets. Polyclonal anti-idiotypic antibodies (anti-antibody, for short pAb2) were produced in laying hens against anti-fimbrial antibodies obtained from mice (mouse monoclonal antibodies, mAb1) and rabbits (rabbit polyclonal antibodies, pAb1). The survival rates in mice that were immunized with six different Ab2 and then challenged with an IP injection of 'E. coli' K88 were 100% in the two experiments, while the corresponding survival rates in the ' E. coli' treated, non-immunized groups was only 25 and 18%. A second study was undertaken to evaluate efficacy of two pAb2 preparations produced against rabbit IgG2a and its Fab2 fragments as therapeutic agents for neonatal diarrhea in piglets infected with 'E. coli' K88. Unlike the mice protection experiment, treatment of piglets with oral doses of pAb2 yielded only partial protection (50% survival rate) among the challenged piglets, while only 13.5% of control group survived. In addition, anti-idiotypic antibodies were used for 'E. coli ' K88 receptor identification in porcine intestinal mucus. Four major proteins corresponding to 40, 45, 50 and 70 kDa were identified when probed with K88 fimbriae. However, when probed with the pAb2 preparations, only the70 kDa protein was recognized by pAb2 produced against rabbit pAb1, while pAb2 produced against mAb1 failed to recognize any of these proteins. Sugar staining suggested that only the 45 kDa protein contained a sugar moiety. The effect of non-reducing sugars (sucrose, lactose and trehalose), complex carbohydrates (cyclodextrin and dextran), infant formula and egg-yolk on the stability of chicken IgY was also studied under different conditions. These studies have indicated that therapeutic antibodies can be successfully utilized to control infections in humans and animals. In addition, they can be used as diagnostic agents for receptor identification. Specific chicken IgY can be added as a supplement to the human diet particularly infant formula as they are able to resist certain processing and digestive conditions. (Abstract shortened by UMI.)