Serodiagnosis of Scrub Typhus at a Tertiary Care Hospital from Southern India

Roopa, K S; Karthika, K; Sugumar, Madhan; Bammigatti, Chanaveerappa; Shamanna, Suryanarayana Bettadpura; Harish, Belgode Narasimha

doi:10.7860/jcdr/2015/15871.6759

Cited by 22 publications

(22 citation statements)

References 14 publications

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“…30 The 46-kDa HtrA protein was shown to be closely related among all global strains of O. tsutsugamushi, and the translated amino acid sequence was reported to have 96.4% to 100% identity. 32 The 56-kDa antigen was reported to show high antigenic variation and the antibodies are not cross-reactive. IgM enzymelinked immunosorbent assay (ELISA) based on 56-kDa antigen is also described.…”

Section: Discussionmentioning

confidence: 99%

Identification of B‐ and T‐cell epitopes on HtrA protein of Orientia tsutsugamushi

Sankar

Saravanan

Rajendiran

et al. 2018

J of Cellular Biochemistry

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Orientia tsutsugamushi, a cause of scrub typhus is emerging as an important pathogen in several parts of the tropics. The control of this infection relies on rapid diagnosis, specific treatment, and prevention through vector control. Development of a vaccine for human use would be very important as a public health measure. Antibody and T‐cell response have been found to be important in the protection against scrub typhus. This study was undertaken to predict the peptide vaccine that elicits both B‐ and T‐cell immunity. The outer‐membrane protein, 47‐kDa high‐temperature requirement A was used as the target protein for the identification of protective antigen(s). Using BepiPred2 program, the potential B‐cell epitope PNSSWGRYGLKMGLR with high conservation among O. tsutsugamushi and the maximum surface exposed residues was identified. Using IEDB, NetMHCpan, and NetCTL programs, T‐cell epitopes MLNELTPEL and VTNGIISSK were identified. These peptides were found to have promiscuous class‐I major histocompatibility complex (MHC) binding affinity to MHC supertypes and high proteasomal cleavage, transporter associated with antigen processing prediction, and antigenicity scores. In the I‐TASSER generated model, the C‐score was −0.69 and the estimated TM‐score was 0.63 ± 0.14. The location of the epitope in the 3D model was external. Therefore, an antibody to this outer‐membrane protein epitope could opsonize the bacterium for clearance by the reticuloendothelial system. The T‐cell epitopes would generate T‐helper function. The B‐cell epitope(s) identified could be evaluated as antigen(s) in immunodiagnostic assays. This cocktail of three peptides would elicit both B‐ and T‐cell immune response with a suitable adjuvant and serve as a vaccine candidate.

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Section: Discussionmentioning

confidence: 99%

Identification of B‐ and T‐cell epitopes on HtrA protein of Orientia tsutsugamushi

Sankar

Saravanan

Rajendiran

et al. 2018

J of Cellular Biochemistry

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“…There is a paucity of data regarding genotypes prevalent in India. [ 19 21 22 ] At present, only four genotypes are included in the IFA kits: Kato, Karp, Gilliam, and Boryong. Local strains as well as prevalent genotypes in India need to be incorporated in IFA kits, which might indicate the true prevalence of ST and specifically identify more number of positive ST patients.…”

Section: Discussionmentioning

confidence: 99%

“…Scrub typhus (ST) caused by Orientia tsutsugamushi and transmitted by the chigger mites was once considered a disease of the shrub jungle/war and confined to “Tsutsugamushi triangle.”[ 1 ] Now ST is spreading across the world with more endemic foci being identified in India, where ST is an emerging infectious disease and reported from almost every state. [ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 ] A few minor ST epidemics have occurred in Southern India, with the diagnosis mostly based on the serological evidence along with clinical presentation. [ 2 3 4 5 6 8 9 10 11 12 13 14 15 18 20 23 24 25 ] Application of molecular techniques for diagnosing ST has been reported by very few Indian researchers in the recent past.…”

Section: Introductionmentioning

confidence: 99%

“…[ 2 3 4 5 6 8 9 10 11 12 13 14 15 18 20 23 24 25 ] Application of molecular techniques for diagnosing ST has been reported by very few Indian researchers in the recent past. [ 7 16 19 21 22 ] In this study, we compare ST patients' IgM antibody response in enzyme-linked immunosorbent assay (ELISA) and presence of O. tsutsugamushi 56-kDa type-specific gene in real time polymerase chain reaction (PCR) quantitative PCR (qPCR), using a commercial kit, which has become available in India only recently and being validated for the first time. The relevance of Weil-Felix (WF) test, particularly OXK agglutination, a nonspecific serological test for ST diagnosis has been critically analyzed.…”

Section: Introductionmentioning

confidence: 99%

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Validation of Geno-Sen's scrub typhus real time polymerase chain reaction kit by its comparison with a serological ELISA Test

Anitharaj

Spellman

Pradeep

et al. 2017

J Global Infect Dis

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Background:In the recent past, scrub typhus (ST) has been reported from different parts of India, based on Weil-Felix/enzyme-linked immunosorbent assay (ELISA)/indirect immunofluorescence assay (IFA). Molecular tests are applied only by a few researchers.Aims:Evaluation of a new commercial real time polymerase chain reaction (PCR) kit for molecular diagnosis of ST by comparing it with the commonly used IgM ELISA is our aim.Settings and Design:ST has been reported all over India including Puducherry and surrounding Tamil Nadu and identified as endemic for ST. This study was designed to correlate antibody detection by IgM ELISA and Orientia tsutsugamushi DNA in real time PCR.Materials and Methods:ST IgM ELISA (InBios Inc., USA) was carried out for 170 consecutive patients who presented with the symptoms of acute ST during 11 months (November, 2015– September, 2016). All 77 of these patients with IgM ELISA positivity and 49 of 93 IgM ELISA negative patients were subjected to real time PCR (Geno-Sen's ST real time PCR, Himachal Pradesh, India).Statistical Analysis:Statistical analysis for clinical and laboratory results was performed using IBM SPSS Statistics 17 for Windows (SPSS Inc., Chicago, USA). Chi-square test with Yates correction (Fisher's test) was employed for a small number of samples.Results and Conclusion:Among 77 suspected cases of acute ST with IgM ELISA positivity and 49 IgM negative patients, 42 and 7 were positive, respectively, for O. tsutsugamushi 56-kDa type-specific gene in real time PCR kit. Until ST IFA, the gold standard diagnostic test, is properly validated in India, diagnosis of acute ST will depend on both ELISA and quantitative PCR.

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“…We thank Kaushik Tripathi, Rohan Chawla and co-authors for their interest in our article and giving us the opportunity to re-look and clarify a few points from our work [ 1 ]. We would like to reply to their comments in the following manner: For our study, Weil-Felix test (WFT) was performed using the commercially available kit (Plasmatech, UK) as per the manufacturer’s instructions which gives a positive result to agglutination titres of ≥160 [ 2 ]. We are completely aware that WFT is not a gold standard test to diagnose rickettsial diseases and hence, we used a term “presumed rickettsial retinitis” in the report.…”

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confidence: 99%

Author’s reply to ‘Rickettsia retinitis cases in India: a few comments’

Kawali

Mahendradas

Gupta

et al. 2016

J Ophthal Inflamm Infect

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Diagnosis of rickettsial retinitis remains presumptive when gold standard tests are not available or not done due to financial constrains. History of tick bite followed by fever with skin rash particularly in winter and spring season may point towards Rickettsiosis. The absence of scarring post resolution of rickettsial retinitis suggests inner retinal involvement in contrast to toxoplasmosis. Bilaterality of the disease, 2–4 weeks of latent period, and multifocal nature of retinitis lesions (cotton wool spot-like lesions) especially around the disc and posterior pole may suggest an immune response to recent systemic infection. The use of only antibiotics or only steroids or both together for treatment of rickettsial retinitis is controversial and warrants randomized controlled trials.

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Serodiagnosis of Scrub Typhus at a Tertiary Care Hospital from Southern India

Cited by 22 publications

References 14 publications

Identification of B‐ and T‐cell epitopes on HtrA protein of Orientia tsutsugamushi

Identification of B‐ and T‐cell epitopes on HtrA protein of Orientia tsutsugamushi

Validation of Geno-Sen's scrub typhus real time polymerase chain reaction kit by its comparison with a serological ELISA Test

Author’s reply to ‘Rickettsia retinitis cases in India: a few comments’

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