Title : Recombinant protein immunoblots supporting clinical diagnosis and differentiation of babesia microti and babesia duncani infections

Abstract:

Babesiosis is a worldwide tick-borne disease with an increasing incidence in North America. Several species of apicomplexan Babesia parasites, including B. microti and B. duncani, cause human babesiosis. Babesiosis exhibits many non-specific clinical manifestations. Direct and indirect laboratory diagnostic tests therefore have an important role in diagnosing babesiosis. Light microscopic examination of Giemsa-stained blood smears, PCR and Fluorescent in Situ Hybridization (FISH) are useful direct diagnostic methods in acute babesiosis.

Immunofluorescence assay (IFA) that detects antibodies in patient sera is a common indirect diagnostic method. Recombinant proteins used in line immunoblot (IB) tests previously described for detecting antibodies in Lyme disease, Tick-borne relapsing fever and COVID-19 have now been applied to detect antibodies against Babesia parasites in patients. Recombinant Babesia proteins were prepared by cloning hybrid gene constructs or portions of the selected genes into pET23 vectors, and expressing the encoded proteins in Escherichia coli.

The proteins were purified by metal affinity chromatography and gel filtration to >95% purity. Seventy-two patient sera, positive for babesiosis by IFA or FISH, and 24 control sera including nine from patients with other tick-borne diseases, were tested in Babesiosis IBs for IgM and IgG antibodies. All 24 control sera were negative in the Babesiosis IBs indicating 100% specificity. The estimated sensitivity for detecting either IgM or IgG antibodies in the Babesiosis IBs was 87.5% (63/72) for the genus Babesia. Additionally, 25/72 and 20/72 of patient sera contained antibodies reacting respectively only with B. microti and B. duncani specific-antigens in the IBs.

Audience Take Away: 

• Appreciate the complex immunodiagnostic needs in Babesiosis and other tick-borne diseases
• Assist teaching of immunodiagnostics and clinical immunology
• Improve application of immunodiagnostic tests for tick-borne and other infectious diseases
• Advance understanding of immune responses in Babesiosis
• Help develop better immunoassays for clinical and veterinary diagnostic purposes

Biography:

Ranjan Ramasamy graduated in 1971 and then a PhD in 1974 from the University of Cambridge, UK. He was the Chairman of the National Science Foundation of Sri Lanka, Professor of Life Sciences at the Institute of Fundamental Studies in Kandy in Sri Lanka, Professor of Biochemistry in the University of Jaffna in Jaffna Sri Lanka, Professor of Immunology in the University Brunei Darussalam Medical School and held institute appointments at the Babraham Institute, Cambridge, UK and Scripps Clinic and Research Foundation, La Jolla, USA. He has more than 280 publications.