Universal enzyme-linked immunosorbent assays (ELISA) and utility in the immunodiagnosis of Salmonellosis

Abstract

The aim of this study was to confirm the feasibility of using hybrid immunoglobulin-binding reagents in ELISAs for IgG/IgY detection and detection of specific antibodies against an infectious microorganism (Salmonella spp.) in various animal species using a universal diagnostic ELISA. Hybrid immunoglobulin-binding bacterial proteins (IBP), including recombinant protein LA, recombinant protein LG, and recombinant protein AG, have been produced to improve their binding affinity to a much larger number of immunoglobulins. Thus, this hybrid bacterial protein represents a powerful tool for the binding, detection, and purification of immunoglobulins and their fragments. However, SpLA-LG-peroxidase and SpLAG-anti-IgYperoxidase were produced using the periodate method. These compounds have been shown to be effective as reagents. Their binding affinity to immunoglobulins surpasses that of previously reported hybrid IgG-binding proteins, including the most known SpAG, SpLA, and SpLG. The IgY fraction was isolated from the egg yolks of various birds, including chicken, bantam hen, guinea hen, quail, goose, duck, wild and domestic pigeons, parakeets, cattle egrets, pheasants, and ostrich. The IgY fraction was isolated using the chloroform-polyethylene glycol (PEG) method. An ELISA for anti-Salmonella spp. antibodies was employed with some modifications to determine the presence of antibodies in humans, laying hens, geese, quails, and pigeons. Salmonella is a motile, flagellated, rod-shaped zoonotic pathogen that can survive in the presence or absence of oxygen. They belong to the family Enterobacteriaceae and are implicated in typhoid fever and food-borne illnesses. This pathogen is associated with several diseases, which may become fatal and negatively impact the health of individuals and various economies globally. The poultry industry is most vulnerable to the influence of this pernicious microbe. The authors concluded that universal enzyme-linked immunosorbent assays were effective and reproducible in detecting immunoglobulins from both avian and mammalian species, but ELISA using the SpLAG-anti-IgY-HRP conjugate only reacted with the whole panel of animal antibodies. This conjugate was further used to standardize a universal ELISA for the determination of anti-Salmonella antibodies, in which human and avian species were serologically assessed.