Hindawi Publishing Corporation e Scienti�c World �ournal Volume 2013, Article ID 363652, 7 pages http://dx.doi.org/10.1155/2013/363652 Research Article Development of a Novel Rapid Immunodiagnostic Kit Based on Flagellar 40 kDa Antigen Epitope for the Detection of Typhoid Fever in Indian Patients Rahul Mitra, 1 Surya Bhan, 2 Gopal Nath, 3 Narender Kumar, 1 and Ziledar Ali 4 1 Department of Biochemistry, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India 2 Department of Biochemistry, NEHU, Shillong 793022, India 3 Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India 4 Department of Biochemistry, SRMS Institute of Medical Sciences, Bareilly 243202, India Correspondence should be addressed to Ziledar Ali; ziledarali_biochem@rediffmail.com Received 8 November 2012; Accepted 17 December 2012 Academic Editors: R. Diel and R. Hasan Copyright © 2013 Rahul Mitra et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To aid the clinical diagnosis of typhoid fever in India, where most hospitals and primary health centres have no facilities for culture, we report on the development of a novel and rapid immunodiagnostic kit for the direct detection of Salmonella Typhi�speci�c Ig� antibodies against S. Typhi �agellar H antigen. e disease o�en does not show a speci�c clinical picture, and can be confused with other febrile illness such as malaria, dengue fever and Staphylococcus aureus. To overcome the problem of cross reactivity speci�c epitope of the �agellar H antigen was immobilised on the testing kit strip eliminating chances of cross reactivity and false positive results thereby increasing the speci�city of the test. Since the immunodiagnostic kit, uses the �agellar H antigen from bacteria present in our country, the antibodies present in the serum of patients of our country will have maximum binding affinity, enhancing the sensitivity of our test kit. e immunodiagnostic kit on analysis gave a positive result with clinically diagnosed typhoid positive patient serum and negative results were obtained with the sera of clinically diagnosed malaria, abscess of Staphylococcus aureus and Visceral leishmaniasis (Kala-azar) patients. 1. Introduction Typhoid fever is an enteric fever of humans caused by infection with Salmonella enterica serovar Typhi (S. Typhi). Although the isolation of S. Typhi on blood culture remains the gold standard for diagnosing typhoid fever, this may pose a major challenge in resource-limited settings where traditional laboratory methods of diagnosing typhoid are not available. India being an agriculturist economy, most of the population is concentrated in rural areas where most hospitals and primary health centres have no laboratory facilities; the diagnosis of typhoid fever is mostly based on clinical grounds, sometimes supported by the Widal test. Although, S. Typhi is a relatively invariant pathogen to antigenic variation, many of the surface antigens, therefore, may be conserved across the genera and induce antibodies that are cross reactive. Further, with an advancing age of an individual, he/she may accumulate cross reactive antibodies to S. Typhi. It means that it is just impossible to develop a speci�c diagnostic kit for typhoid using crude or semi- puri�ed antigens. Essentially all serological tests for typhoid are based on the detection of antibodies to lipopolysaccharide (LPS) antigens (O9 and O12) [1–6]. As shown in the lateral �ow assay for the detection of S. Typhi LPS speci�c antibodies, antibodies �rst start to develop at a time when the pathogen is already disappearing from the blood-stream [7]. e natural course and magnitude of the immune response seems to limit the sensitivity of serological testing for typhoid. Further, antigenicity of �agellar (H) proteins is higher than somatic (O) polysaccharide antigens [8]. Moreover, Brodie [9] has stated that agglutinins against �agella of S. Typhi are more frequent than O somatic (TO-9, 12) during an outbreak in Aberdeen in 1964. Simple, reliable, point-of-care rapid diagnostic tests (RDTs) for typhoid fever have been a long-felt need of