Role of anti-Giardia recombinant cyst wall protein IgG polyclonal antibodies in diagnosis and protection

Abstract

AbstractGiardia duodenalis(G. duodenalis) is an infectious protozoan that has a global distribution especially in the hot climate. Around 200 million people are infected worldwide annually byGiardia, but infection is not always accompanied by symptoms, especially in endemic countries. Using traditional microscopy techniques in diagnosis, both in stool and water samples were less sensitive when compared to immunological methods; and the need for new diagnostic methods was necessary. Also, protection from infection is required in endemic areas. Therefore, the study aimed to produce anti-G. duodenalisIgG polyclonal antibodies (pAbs) by immunizing rabbit byG. duodenaliscyst recombinant protein. The produced antibodies were evaluated in the detection ofG. duodenalisantigens in patients’ stool and water samples from endemic areas across River Nile; where pAbs were used as a coating and a peroxidase conjugate antibody in sandwich ELISA. Moreover, pAbs were tested for the protection of mice from giardiasis. Sandwich ELISA using pAb has succeeded in the detection ofG. duodenaliscoproantigens in stool samples by a sensitivity of 97% and a specificity of 92.72%. Moreover,G. duodenaliscyst was detected in only seven water samples by ordinary microscopy; while sandwich ELISA revealed nineteen positive results. IgG pAb (1/200 µg/ml) protected mice from giardiasis; which was evident from the reduction in cysts and trophozoites numbers. We recommended the use of sandwich ELISA to monitor water quality, investigate environmental contamination and diagnosis in patients' stools. The pAbs can be prepared in large amount and used in field diagnosis and protection. This will help in the early diagnosis ofG. duodenalisin water, which in turn can control outbreaks in rural areas.