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Neurological complications, both acute and chronic, are reported commonly in COVID-19 affected individuals. In this context, the understanding of pathogenesis of SARS-CoV-2 in specific cells of central nervous system (CNS) origin is relevant. The present study explores infection biology of a clinical isolate of SARS-CoV-2 in human cell lines of neural origin such as the glioblastoma (U87-MG), neuroblastoma (SHSY5Y) and microglia (C20). Despite showing clear evidence of infection by immunofluorescence with an anti-spike protein antibody, all the three neural cell lines were observed to be highly restrictive to the replication of the infecting virus. While the U87-MG glioblastoma cells demonstrated no cytopathic effects and a low viral titre with no signs of replication, the SHSY5Y neuroblastoma cells exhibited cytopathic effects with bleb formation but no evidence of viable virus. The C20 microglial cells showed neither signs of cytopathic effects nor viable virus. Ultrastructural studies demonstrated intracellular virions in infected neural cells. The presence of lipid droplets in infected SHSY5Y cells suggested an impact on host cell metabolism. The decrease in viral RNA levels over time in all the neural cell lines suggested restricted viral replication. In conclusion, this study highlights the limited susceptibility of neural cells to SARS-CoV-2 infection. This reduced permissibility of neural cell lines to SARS-CoV-2 may point to their inherent lower expression of receptors that support viral entry in addition to the intracellular factors that potently inhibit viral replication. The study findings prompt further investigation into the mechanisms of SARS-CoV-2 infection of neural cells., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Acute encephalitis syndrome (AES) in children poses a significant public health challenge in India. This study aims to explore the utility of host inflammatory mediators and neurofilament (NfL) levels in distinguishing etiologies, assessing disease severity, and predicting outcomes in AES. We assessed 12 mediators in serum (n = 58) and 11 in cerebrospinal fluid (CSF) (n = 42) from 62 children with AES due to scrub typhus, viral etiologies, and COVID-associated multisystem inflammatory syndrome (MIS-C) in Southern India. Additionally, NfL levels in serum (n = 20) and CSF (n = 18) were examined. Clinical data, including Glasgow coma scale (GCS) and Liverpool outcome scores, were recorded. Examining serum and CSF markers in the three AES etiology groups revealed notable distinctions, with scrub typhus differing significantly from viral and MIS-C causes. Viral causes had elevated serum CCL11 and CCL2 compared with scrub typhus, while MIS-C cases showed higher HGF levels than scrub typhus. However, CSF analysis showed a distinct pattern with the scrub typhus group exhibiting elevated levels of IL-1RA, IL-1β, and TNF compared with MIS-C, and lower CCL2 levels compared with the viral group. Modeling the characteristic features, we identified that age ≥3 years with serum CCL11 < 180 pg/mL effectively distinguished scrub typhus from other AES causes. Elevated serum CCL11, HGF, and IL-6:IL-10 ratio were associated with poor outcomes (p = 0.038, 0.005, 0.02). Positive CSF and serum NfL correlation, and negative GCS and serum NfL correlation were observed. Median NfL levels were higher in children with abnormal admission GCS and poor outcomes. Measuring immune mediators and brain injury markers in AES provides valuable diagnostic insights, with the potential to facilitate rapid diagnosis and prognosis. The correlation between CSF and serum NfL, along with distinctive serum cytokine profiles across various etiologies, indicates the adequacy of blood samples alone for assessment and monitoring. The association of elevated levels of CCL11, HGF, and an increased IL-6:IL-10 ratio with adverse outcomes suggests promising avenues for therapeutic exploration, warranting further investigation., (© 2024 Wiley Periodicals LLC.)

Purpose: The study aims to isolate and understand cytopathogenesis, ultrastructure, genomic characteristics and phylogenetic analysis of SARS-CoV-2 virus of B.1.210 lineage, that circulated in India during first wave of the pandemic., Methods: Clinical specimen from an interstate traveller from Maharashtra to Karnataka, in May 2020, who was positive by RT PCR for SARS-CoV-2 infection was subjected to virus isolation and Whole Genome Sequencing. Vero cells were used to study cytopathogenesis and ultrastructural features by Transmission Electron Microscopy (TEM). Phylogenetic analysis of the whole genome sequences of several SARS-CoV-2 variants downloaded from GISAID was performed in comparison with the B.1.210 variant identified in this study., Results: The virus was isolated in Vero cells and identified by immunofluorescence assay and RT PCR. The growth kinetics in infected Vero cells revealed a peak viral titre at 24 ​h post-infection. Ultrastructural studies revealed distinct morphological changes with accumulation of membrane-bound vesicles containing pleomorphic virions in the cytoplasm, with single or multiple intranuclear filamentous inclusions and dilated rough endoplasmic reticulum with viral particles. Whole genome sequence of the clinical specimen as well as the isolated virus revealed the virus to be of lineage B.1.210 with the D614G mutation in the spike protein. Phylogenetic analysis of the whole genome sequence in comparison with other variants reported globally revealed that the isolated SARS-CoV-2 virus of lineage B.1.210 is closely related to the original Wuhan virus reference sequence., Conclusions: The SARS-CoV-2 variant B.1.210 virus isolated here showed ultrastructural features and cytopathogenesis similar to that of the virus reported during early phase of pandemic. Phylogenetic analysis showed that the isolated virus is closely related to the original Wuhan virus, thereby suggesting that the SARS-CoV-2 lineage B.1.210 that was circulating in India during the early phase of pandemic is likely to have evolved from the original Wuhan strain., (Copyright © 2022 Indian Association of Medical Microbiologists. Published by Elsevier B.V. All rights reserved.)

Background: Since inception of the COVID-19 pandemic, early detection and isolation of positive cases is one of the key strategies to restrict disease transmission. Real time reverse transcription polymerase chain reaction (qRTPCR) has been the mainstay of diagnosis. Most of the qRTPCR kits were designed against the target genes of original strain of SARS-CoV-2. However, with the emergence of variant strains of SARS-CoV-2, sensitivity of the qRTPCR assays has reportedly reduced. In view of this, it is critical to continuously monitor the performance of the qRTPCR kits in the backdrop of variant strains of SARS-CoV-2. Real world monitoring of assay performance is challenging. Therefore, we developed a two-step in-silico screening process for evaluating the performance of various qRTPCR kits used in India., Results: We analysed 73 qRT-PCR kits marketed in India, against the two SARS-CoV-2 VoCs. Sequences of both Delta (B.1.617.2) and Omicron (B.1.1.529) VoCs submitted to GISAID within a specific timeframe were downloaded, clustered to identify unique sequences and aligned with primer and probe sequences. Results were analysed following a two-step screening process. Out of 73 kits analysed, seven were unsatisfactory for detection of both Delta and Omicron VoCs, 10 were unsatisfactory for Delta VoC whereas 2 were unsatisfactory for only Omicron VoC., Conclusion: Overall, we have developed a useful screening process for evaluating the performance of qRTPCR assays against Delta and Omicron VoCs of SARS-CoV-2 which can be used for detecting SARS-CoV-2 VoCs that may emerge in future and can also be redeployed for other evolving pathogens of public health importance., (© 2022. The Author(s).)

Background: India has experienced the second largest outbreak of COVID-19 globally, yet there is a paucity of studies analysing contact tracing data in the region which can optimise public health interventions (PHI's)., Methods: We analysed contact tracing data from Karnataka, India between 9 March and 21 July 2020. We estimated metrics of transmission including the reproduction number (R), overdispersion (k), secondary attack rate (SAR), and serial interval. R and k were jointly estimated using a Bayesian Markov Chain Monte Carlo approach. We studied determinants of risk of further transmission and risk of being symptomatic using Poisson regression models., Findings: Up to 21 July 2020, we found 111 index cases that crossed the super-spreading threshold of ≥8 secondary cases. Among 956 confirmed traced cases, 8.7% of index cases had 14.4% of contacts but caused 80% of all secondary cases. Among 16715 contacts, overall SAR was 3.6% [95% CI, 3.4-3.9] and symptomatic cases were more infectious than asymptomatic cases (SAR 7.7% vs 2.0%; aRR 3.63 [3.04-4.34]). As compared to infectors aged 19-44 years, children were less infectious (aRR 0.21 [0.07-0.66] for 0-5 years and 0.47 [0.32-0.68] for 6-18 years). Infectors who were confirmed ≥4 days after symptom onset were associated with higher infectiousness (aRR 3.01 [2.11-4.31]). As compared to asymptomatic cases, symptomatic cases were 8.16 [3.29-20.24] times more likely to cause symptomatic infection in their secondary cases. Serial interval had a mean of 5.4 [4.4-6.4] days, and case fatality rate was 2.5% [2.4-2.7] which increased with age., Conclusion: We found significant heterogeneity in the individual-level transmissibility of SARS-CoV-2 which could not be explained by the degree of heterogeneity in the underlying number of contacts. To strengthen contact tracing in over-dispersed outbreaks, testing and tracing delays should be minimised and retrospective contact tracing should be implemented. Targeted measures to reduce potential superspreading events should be implemented. Interventions aimed at children might have a relatively small impact on reducing transmission owing to their low symptomaticity and infectivity. We propose that symptomatic cases could cause a snowballing effect on clinical severity and infectiousness across transmission generations; further studies are needed to confirm this finding., Competing Interests: The authors have declared that no competing interests exist.

Sudden emergence and rapid spread of COVID-19 created an inevitable need for expansion of the COVID-19 laboratory testing network across the world. The strategy to test-track-treat was advocated for quick detection and containment of the disease. Being the second most populous country in the world, India was challenged to make COVID-19 testing available and accessible in all parts of the country. The molecular laboratory testing network was augmented expeditiously, and number of laboratories was increased from one in January 2020 to 2951 till mid-September, 2021. This rapid expansion warranted the need to have inbuilt systems of quality control/ quality assurance. In addition to the ongoing inter-laboratory quality control (ILQC), India implemented an External Quality Assurance Program (EQAP) with assistance from World Health Organization (WHO) and Royal College of Pathologists, Australasia. Out of the 953 open system rRTPCR laboratories in both public and private sector who participated in the first round of EQAP, 891(93.4%) laboratories obtained a passing score of > = 80%. The satisfactory performance of Indian COVID-19 testing laboratories has boosted the confidence of the public and policy makers in the quality of testing. ILQC and EQAP need to continue to ensure adherence of the testing laboratories to the desired quality standards., Competing Interests: The authors have declared that no competing interests exist.

Background: In the situation where COVID-19 pandemic has placed unprecedented demands and pressure on the health care system, we wanted to analyze how the medical microbiologists of our country were affected. Was it actually an opportunity to showcase the specialty or was it a doom? A debate was organized as a key session in the national e-conference of the Indian Association of Medical Microbiologists, held on 10 December 2020., Objectives: The objective of the debate was to examine and analyze the various positive as well as negative impacts of COVID-19 on the discipline of the medical microbiology of our country., Content: Before the debate a voting session was conducted to assess the opinion of the audience followed by a very interesting debate where both the speakers presented their view points. The points in favor of the discipline were, mainly up-gradation of the specialty of microbiology in terms of learning, skill development, infrastructure, networking & research opportunities related to COVID-19. While the main points against were, nerve wracking work load without much acknowledgement, performance pressure from hospital administration to maintain rapid turnaround time, and a forceful neglect of all other infectious diseases like tuberculosis and antimicrobial resistance which were the key battle fields of the medical microbiologists. Postgraduate & even undergraduate training programs got completely derailed to their disadvantage. By the end of the debate, it was concluded that COVID-19 was neither a boon nor a bane to the microbiologists. A balanced approach to the problem in hand is required without ignoring the pre-existing infectious diseases in our country. The post debate voting swayed the audience considerably for it to be a bane & the faculty debating for boon had a huge margin to begin with but finally won with a whisker indicating the intensity of the debate., (Copyright © 2022 Indian Association of Medical Microbiologists. Published by Elsevier B.V. All rights reserved.)

Objective: To estimate the burden of active infection and anti-SARS-CoV-2 IgG antibodies in Karnataka, India, and to assess variation across geographical regions and risk groups. Methods: A cross-sectional survey of 16,416 people covering three risk groups was conducted between 3–16 September 2020 using the state of Karnataka’s infrastructure of 290 healthcare facilities across all 30 districts. Participants were further classified into risk subgroups and sampled using stratified sampling. All participants were subjected to simultaneous detection of SARS-CoV-2 IgG using a commercial ELISA kit, SARS-CoV-2 antigen using a rapid antigen detection test (RAT) and reverse transcription-polymerase chain reaction (RT-PCR) for RNA detection. Maximum-likelihood estimation was used for joint estimation of the adjusted IgG, active and total prevalence (either IgG or active or both), while multinomial regression identified predictors. Results: The overall adjusted total prevalence of COVID-19 in Karnataka was 27.7% (95% CI 26.1–29.3), IgG 16.8% (15.5–18.1) and active infection fraction 12.6% (11.5–13.8). The case-to-infection ratio was 1:40 and the infection fatality rate was 0.05%. Influenza-like symptoms or contact with a COVID-19-positive patient were good predictors of active infection. RAT kits had higher sensitivity (68%) in symptomatic people compared with 47% in asymptomatic people. Conclusion: This sentinel-based population survey was the first comprehensive survey in India to provide accurate estimates of the COVID-19 burden. The findings provide a reasonable approximation of the population immunity threshold levels. Using existing surveillance platforms coupled with a syndromic approach and sampling framework enabled this model to be replicable.

Background: As the coronavirus disease 2019 (COVID-19) pandemic continues, the selection of genomic variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with higher transmission, more severe disease, re-infection, and immune escape are a cause for concern. Such variants have been reported from the UK (B.1.1.7), South Africa (B.1.351) and, Brazil (P.1/B.1.1.28). We performed this study to track the importation, spread, and emergence of variants locally. Methods: We sequenced whole genomes of SARS-CoV-2 from international travellers (n=75) entering Karnataka, South India, between Dec 22, 2020 and Jan 31, 2021, and from positive cases in the city of Bengaluru (n=108), between Nov 22, 2020- Jan 22, 2021, as well as a local outbreak. We present the lineage distribution and analysis of these sequences. Results: Genomes from the study group into 34 lineages. Variant B.1.1.7 was introduced by international travel (24/73, 32.9%). Lineage B.1.36 and B.1 formed a major fraction of both imported (B.1.36: 20/73, 27.4%; B.1: 14/73, 19.2%), and circulating viruses (B.1.36: 45/103; 43.7%,. B.1: 26/103; 25.2%). The lineage B.1.36 was also associated with a local outbreak. We detected nine amino acid changes, previously associated with immune escape, spread across multiple lineages. The N440K change was detected in 45/162 (27.7%) of the sequences, 37 of these were in the B.1.36 lineage (37/65, 56.92%) Conclusions: Our data support the idea that variants of concern spread by travel. Viruses with amino acid replacements associated with immune escape are already circulating. It is critical to check transmission and monitor changes in SARS-CoV-2 locally.

This document is a correction notice for an article titled "Contact tracing of COVID-19 in Karnataka, India: Superspreading and determinants of infectiousness and symptomatic infection." The correction states that the affiliation for the corresponding author is incorrect and provides the correct affiliation as the Department of Population Medicine, College of Medicine, QU Health, Qatar University, Doha, Qatar. The authors of the article are listed as Mohak Gupta, Giridara G. Parameswaran, Manraj S. Sra, Rishika Mohanta, Devarsh Patel, Amulya Gupta, Bhavik Bansal, Vardhmaan Jain, Archisman Mazumder, Mehak Arora, Nishant Aggarwal, Tarun Bhatnagar, Jawaid Akhtar, Pankaj Pandey, Vasanthapuram Ravi, and Giridhara R Babu. [Extracted from the article]