title: Immuno-fluorescence based Vi capsular polysaccharide detection for specific recognition of Salmonella enterica serovar Typhi in clinical samples.
abstract: Typhoid fever is a life threatening bacterial infection that remains a major global health concern. This continued high burden associated with significant morbidity and mortality rate demands specific and rapid detection technique. This work reports a new sandwich type fluorescence immunoassay format using polymyxin B, a cationic receptor molecule, as a binder agent while anti-Vi antibody served as the capturing agent for specifically detecting Salmonella enterica serovar Typhi. Anti-Vi IgG antibody raised against Vi-BSA conjugate revealed affinity of 7.779nM(-1) signifying immunodominancy of O-acetyls groups in Vi polysaccharide. The detection limit of the developed assay was around 10(1) cellsmL(-1) of Vi expressing Salmonella enterica serovar Typhi with a correlation coefficient (R(2)) equal to 0.97. Positive response obtained for all the tested serovar Typhi clinical isolates as well as the pathogen spiked blood samples recommended specificity and accuracy of Vi antigen as a biomarker during typhoid fever. The intra- and inter-assay precision with Vi spiked samples were satisfactory revealing coefficient of variance (CV%) with a mean of 4.05% and 5.97% respectively. This may be the novel attempt and constructive report on the fluorescence based detection of Vi antigen of serovar Typhi in the epidemic as well as pandemic outbreaks.
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh 160036, India; Department of Microbiology, Panjab University, Chandigarh 160014, India.
authors.forename: Satish K
authors.initials: SK
authors.lastname: Pandey
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh 160036, India.
authors.forename: Aaydha C
authors.initials: AC
authors.lastname: Vinayaka
authors.affiliation: Department of Mathematics, Panjab University, Chandigarh 160014, India.
authors.forename: Dharam B
authors.initials: DB
authors.lastname: Rishi
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh 160014, India. Electronic address: rishipraveen@yahoo.com.
authors.forename: Praveen
authors.initials: P
authors.lastname: Rishi
authors.affiliation: CSIR-Institute of Microbial Technology, Chandigarh 160036, India. Electronic address: raman@imtech.res.in.
authors.forename: C Raman
authors.initials: CR
authors.lastname: Suri
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods* / Q000592:standards; D019963:Clinical Chemistry Tests; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D057230:Limit of Detection; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D012485:Salmonella typhi / Q000378:metabolism*; D014435:Typhoid Fever / Q000175:diagnosis / Q000382:microbiology
chemical_list: D011135:Polysaccharides, Bacterial
keywords: Immunoassay; Polymyxin B; Salmonella; Typhoid fever; Vi-BSA antigen