Detection of excretory/secretory coproantigens in experimental hookworm infection

This report describes the detection of hookworm excretory/secretory (ES) antigens in soluble hamster fecal extracts by an enzyme-linked immunosorbent assay (ELISA). A rabbit polyclonal IgG antibody against Ancylostoma ceylanicum ES was used to capture hookworm coproantigens that were then detected using pooled, high-titer, infected hamster serum. The ELISA was capable of detecting ES proteins over a range of 10 ng/mL to 10 mug/mL when the antigens were diluted in buffer or uninfected fecal extract, and ES could be detected in infected hamster feces at dilutions up to 1:256. Examination of the kinetics of coproantigen production demonstrated that detectable amounts of ES were produced as early as four days after A. ceylanicum infection, whereas fecal eggs were not observed until day 17. Moreover, fecal ES levels correlated well with intestinal worm burden and could be detected in wet or dry stool samples stored for 14 days over a temperature range of -80 degrees C to 37 degrees C. The fecal ELISA was then adapted to analyze the excretion of AceES-2, a novel immunogenic ES protein recently cloned from A. ceylanicum cDNA. AceES-2 was found to be excreted in feces with kinetics similar to that of whole ES. Examination of individual hookworm antigens by this method will provide new insights into the molecular host-parasite interaction and may form the basis for future diagnostic methods.