Development of Immunoassays for Detection of Francisella tularensis Lipopolysaccharide in Tularemia Patient Samples

Abstract

Francisella tularensis is the causative agent of tularemia, a zoonotic bacterial infection that is often fatal if not diagnosed and treated promptly. Natural infection in humans is relatively rare, yet persistence in animal reservoirs, arthropod vectors, and water sources combined with a low level of clinical recognition make tularemia a serious potential threat to public health in endemic areas. F. tularensis has also garnered attention as a potential bioterror threat, as widespread dissemination could have devastating consequences on a population. A low infectious dose combined with a wide range of symptoms and a short incubation period makes timely diagnosis of tularemia difficult. Current diagnostic techniques include bacterial culture of patient samples, PCR and serological assays; however, these techniques are time consuming and require technical expertise that may not be available at the point of care. In the event of an outbreak or exposure a more efficient diagnostic platform is needed. The lipopolysaccharide (LPS) component of the bacterial outer leaflet has been identified previously by our group as a potential diagnostic target. For this study, a library of ten monoclonal antibodies specific to F. tularensis LPS were produced and confirmed to be reactive with LPS from type A and type B strains. Antibody pairs were tested in an antigen-capture enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay format to select the most sensitive pairings. The antigen-capture ELISA was then used to detect and quantify LPS in serum samples from tularemia patients for the first time to determine the viability of this molecule as a diagnostic target. In parallel, prototype lateral flow immunoassays were developed, and reactivity was assessed, demonstrating the potential utility of this assay as a rapid point-of-care test for diagnosis of tularemia.

Development of a dual antigen lateral flow immunoassay for detecting Yersinia pestis

“…Evaluation of LFI and ELISA mAb pairs for Ebola glycoprotein and F . tularensis in our laboratory have also shown differences between the two formats [ 64 , 65 ]. Though both LFIs and ELISAs are antigen-capture immunoassays, there are notable differences in the assay formats.…”

Application of immunomagnetic separation for accelerated detection of <i>F. tularensis</i> cells in soil samples using an immunochromatographic test

“…и, несомненно, окажется полезной при проведении эпизоотологического обследования природных очагов. Кроме того, методика может быть использована для определения липополисахарида в клинических образцах при диагностике заболевания туляремией [14].…”