Abstract

This study aimed to evaluate the protective effects of sucralfate on immunoglobulin yolk (IgY) and to provide a theory basis for preparing IgY oral preparations which can tolerate acid and pepsin. Engineering bacteria DH5α-vacA-pQE30 were largely induced to express recombinant vacuolate cytotoxin antigen (VacA). VacA antigen was inoculated in Lohman hen and IgY was purified. Different concentrations of sucralfate were added into IgY solution including different concentrations of pepsin at different pH values. IgY solution containing different concentrations of sucralfate underwent seven times of repeated freeze thawing, and then placed at room temperature for 1 d, 4 w. The IgY residual antibody activity (A_R/A_C) of each experiment group was detected by ELISA. Helicobacter pylori infected mice were intragastrically administrated with 30% sucralfate and different concentrations of IgY solution and then chronic inflammatory reaction of gastric mucosa was observed to evaluate the protective effects of sucralfate on IgY. At pH = 1.5, 60% sucralfate could maintain 48.9% IgY residual antibody activity. At pH = 2.0, 30% sucralfate could enhance the IgY residual antibody activity to 86.5%, at 50% sucralfate could fully maintain the IgY antibody activity. At pH = 3.0, 30% sucralfate could maintain 87.6% IgY antibody activity, while over 40% sucralfate could almost fully maintain the IgY antibody activity. Under pH 1.5, 3.0 and 0.02 mg/ml pepsin conditions, the residual antibody activities of IgY solution containing 10, 30 and 50% sucralfate were 63.2, 72.4 and 82.2%, respectively. Over 30% sucralfate could enhance the anti-freeze thawing ability of IgY. After one month at room temperature, over 80% antibody activity could still be maintained. Intragastric administration with 0.5 mg IgY plus 30% sucralfate/day could effectively prevent and cure gastric mucosal injure caused by H. pylori infection, the effect of which increased eight folds as compared with the group without sucralfate. Over 30% sucralfate can enhance the tolerance of VacA IgY to low pH value and pepsin and enhance the anti-freeze thawing ability, therefore, it is an ideal IgY protective agent.

Key words: Helicobacter pylori, vacuolate cytotoxin antigen, immunoglobulin yolk, Sucralfate, antibody activity.