Evaluation of passive immune therapies for the oral treatment of cryptosporidiosis

Abstract

Cryptosporidium parvum is a ubiquitous parasite affecting a wide range of mammals. In immune competent hosts it causes profuse self-resolving diarrhea. In those with impaired immunity, diarrhea persists while the deficiency prevails because there are no effective therapies available. Previous studies reported the benefits of polyclonal antibodies for treating cryptosporidiosis. Data from preliminary studies supported the anti-parasitic efficacy of bovine and hen egg yolk polyclonal antibody preparations. Preliminary in vivo testing showed significant reductions in the parasite loads (p < 0.05) of animals treated with yolk antibodies when compared to controls. Preparations of anti-C. parvum polyclonal antibodies from human breast milk, bovine colostrum and chicken egg yolks were obtained and tested in vitro for activity and potency and subsequently tested for efficacy in comparative in vivo studies. Hen egg yolk preparations were significantly more efficacious (p < 0.01) and subsequently evaluated in human clinical trials. Analysis of data from the trial showed beneficial therapeutic value and also the need for improvements in the egg yolk formulations. Further work directed towards antibody concentration and lipid reductions were performed. The dilution of egg yolks with water precipitated the lipids and the lipid-reduced supernatant fluids were lyophilized resulting in an enhanced formulation with increased anti-cryptosporidial potency and about 90% reduction in the lipid contents. The efficacy of the enhanced preparations was also tested in vivo with parasite reductions in the order of 90%. Hen egg yolk antibodies could be a valuable component for treating or controlling enteric cryptosporidiosis.