Identification of Immunodominant Epitopes of Dengue Virus 2 Envelope and NS1 Proteins: Evaluating the Diagnostic Potential of a Synthetic Peptide.

BACKGROUND AND OBJECTIVE: Dengue is a major infectious disease with potential for outbreaks and epidemics. A specific and sensitive diagnosis is a prerequisite for clinical management of the disease. We designed our study to identify epitopes on the Dengue virus (DENV) envelope (E) and non-structural protein 1 (NS1) with potential for diagnosis. METHODS: Serology and immunoinformatic approaches were employed. We collected DENV-positive, DENV-negative and Japanese encephalitis virus-positive samples from collaborating hospitals in 2019 and 2022-2023. Seropositive peptides in 15-18 mer peptide arrays of E and NS1 proteins of DENV2 were determined by an indirect enzyme-linked immunosorbent assay. B-cell linear and conformational epitopes were predicted using BepiPred2.0 and ElliPro, respectively. A consensus recombinant peptide was designed, synthesised and evaluated for its diagnostic potential using patient sera. RESULTS: Eight peptides of E protein and six peptides of NS1 protein were identified to be the most frequently recognised by Dengue-positive patients. These peptide sequences were compared with B-cell epitope regions and found to be overlapped with predicted B-cell linear and conformational epitopes. EP11 and NSP15 showed a 100% amino acid sequence overlap with B-cell epitopes. EP1 and NSP15 had 14 whereas EP28, EP31, EP60 16, NSP12 and NSP32 had more than 15 interacting interface residues with a neutralising antibody, suggesting a strength of interaction. Interestingly, potential epitopes identified were localised on the surface of proteins as visualised by PyMOL. Validation with a recombined synthetic peptide yielded 92.3% sensitivity and 91.42% specificity. CONCLUSIONS: Immunodominant regions identified by serology and computationally predicted epitopes overlapped, thereby showing the robustness of the methodology and the peptide designed for diagnosis.

Low-cost conventional PCR techniques enable simultaneous detection of bacterial sexually transmitted infections with enhanced sensitivity and specificity.

PURPOSE: Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT) and Mycoplasma hominis (MH), the three most common treatable bacterial sexually transmitted infections (STIs) worldwide can lead to many complications if remain untreated. Screening of high-risk population with highly sensitive methods will lead to significant improvement in patient outcomes and will prevent downward transmission. The advantages of Polymerase chain reaction (PCR) based assay are not only high sensitivity and specificity, but also detection of multiple organisms in a single reaction which reduce the result turn-around time. The aim of the present study was to evaluate the feasibility of a multiplex PCR assay method targeting 16S rRNA gene for simultaneous detection of NG, CT and MH infection along with their trend and occurrence among high-risk population in Assam, Northeast India. METHODS: A cross-sectional study was undertaken, where a total of 200 randomly selected patients from high-risk population were included. After validation of singleplex PCR, Multiplex PCR (M-PCR) was performed along with the traditional culture method for NG. RESULTS & CONCLUSION: The overall agreement of M-PCR with singleplex PCR was very high (100%). The occurrence of STI was found to be very high (101/200; 50.5%). Furthermore, co-infection was detected in 10/200; 5%) individuals. Infection was more common among young individuals (p < 0.05) and males out-numbered females (p < 0.05). The most common organism detected was CT (42/200; 21%) followed by NG (41/200; 20.5%) and MH (20/200; 10%). The M-PCR assay workflow is simple, cost effective and can be used in routine diagnostic laboratories with basic molecular facilities.

Scrub Typhus- An Underestimated Infectious Disease Attributable to Community Acquired Acute Kidney Injury.

Acute Kidney Injury (AKI) associated with Scrub typhus is an emerging health problem which is more common in the tropics including India. This study intended to find out the occurrence of Scrub typhus among the Community Acquired Acute Kidney Injury patients in a tertiary care hospital in Assam, North East India. AKI patients with acute febrile illness admitted to Gauhati Medical College and Hospital, Guwahati, Assam were included in the study and demographic characteristics along with clinical features were recorded. The detection of Scrub typhus was done by IgM Enzyme Linked Immunosorbent Assay (ELISA) test (Optical Density > 0.5) and polymerase chain reaction (PCR) analysis. Routine haematological and biochemical tests were performed. Molecular characterization of Orientia tsutsugamushi was done followed by phylogenetic analysis. The Graph Pad Prism software 9 was used for statistical analysis. Out of 221 AKI patients admitted to hospital, 45 patients (20.4%) were confirmed to be Scrub typhus positive and among them, 4 cases were co-infected with leptospirosis. Majority of Scrub typhus positive AKI patients were in Stage I (82.2%) under KDIGO guideline. "Karp" was the predominant circulating serotype. The study showed cases of Scrub typhus associated Acute Kidney Injury was high and mortality was 11.1%. Hence, in this region, further studies need to be done with large number of population and more emphasis need to be given on differential diagnosis. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01137-x.

Human subcutaneous dirofilariasis: A diagnostic dilemma.

Human dirofilariasis is a rare infection caused by filarial worms of genus Dirofilaria. Humans may be infected as aberrant (accidental) hosts, mainly by Dirofilaria repens and Dirofilaria immitis. Most of the cases reported in India are of ocular dirofilariasis, with a few reports on subcutaneous dirofilariasis. We hereby report one such case of human subcutaneous dirofilariasis affecting the neck region of a 63-year male patient from Assam. This case indicates that this infection is a potentially emerging zoonosis in Assam and there is scope of finding more such cases with surveillance.