Detection of Salivary IgA Antibodies Against the HlyE Antigen as a Diagnosis of Typhoid Fever

Abstract

Introduction: The Salmonella typhi (S. typhi) haemolysin E protein (HlyE) has been shown to be a sensitive and specific antigen for the detection of typhoid fever through the detection of anti-HlyE antibodies in sera. Saliva can also be a useful diagnostic fluid as it also contains antibodies against bacterial pathogens. Aim: This study aims to evaluate the potential detection of salivary anti-HlyE antibodies as a diagnosis of typhoid fever. Materials and Methods: Saliva was collected from acute typhoid patients (n=16) who presented at Hospital Universiti Sains Malaysia with prolonged fever of more than five days and were positive for S. Typhi blood culture. Saliva was also collected from convalescent typhoid patients (n=11), patients with other febrile fevers (n=15), and from healthy individuals (n=25). An ELISA was developed to detect the presence of IgA antibodies against HlyE in the saliva of typhoid patients. Results: The acute typhoid group had a higher mean absorbance value of 1.496 compared to the convalescent typhoid (0.538), other febrile fevers (0.678), and healthy individuals (0.457) group. Conclusion: This study demonstrated the utility of salivary antiHlyE IgA antibody as a biomarker for the diagnosis of typhoid fever. Follow-up studies with a larger sample size will allow the optimization of the sensitivity and specificity of the assay. This non-invasive method can be useful for mass screening programs.

Keywords

• salmonella
• elisa
• saliva