A quest for universal anti-SARS-CoV-2 T cell assay: systematic review, meta-analysis, and experimental validation.

Measuring SARS-CoV-2-specific T cell responses is crucial to understanding an individual's immunity to COVID-19. However, high inter- and intra-assay variability make it difficult to define T cells as a correlate of protection against COVID-19. To address this, we performed systematic review and meta-analysis of 495 datasets from 94 original articles evaluating SARS-CoV-2-specific T cell responses using three assays - Activation Induced Marker (AIM), Intracellular Cytokine Staining (ICS), and Enzyme-Linked Immunospot (ELISPOT), and defined each assay's quantitative range. We validated these ranges using samples from 193 SARS-CoV-2-exposed individuals. Although IFNγ ELISPOT was the preferred assay, our experimental validation suggested that it under-represented the SARS-CoV-2-specific T cell repertoire. Our data indicate that a combination of AIM and ICS or FluoroSpot assay would better represent the frequency, polyfunctionality, and compartmentalization of the antigen-specific T cell responses. Taken together, our results contribute to defining the ranges of antigen-specific T cell assays and propose a choice of assay that can be employed to better understand the cellular immune response against viral diseases.

Comparison of 1-day versus 3-day intravenous terlipressin in cirrhosis patients with variceal bleeding: A pilot randomised controlled trial.

BACKGROUND: In cirrhosis patients with acute variceal bleeding (AVB), the optimal duration of vasoconstrictor therapy after endoscopic haemostasis is unclear. AIMS: We aimed to compare efficacy of 1-day versus 3-day terlipressin therapy in cirrhosis patients with AVB post-endoscopic intervention. The primary objective was to compare rebleeding at 5 days between the two arms. Secondary objectives included rebleeding and mortality rates at 6 weeks. METHODS: In this open-label, randomised controlled trial, cirrhosis patients with AVB were randomised to either 1-day or 3-day terlipressin therapy. RESULTS: A total of 150 cirrhosis patients with AVB were recruited to receive either 1 day (n = 75) or 3 days (n = 75) of terlipressin therapy. One patient from 1-day arm was excluded. Modified intention-to-treat analysis included 149 patients. Baseline characteristics were comparable between the two groups. Rebleeding at 5 days: 3 (4.1%; 95% confidence interval [CI]: 0.4-9.0) versus 4 (5.3%; 95% CI: 2.0-10.0), risk difference (RD) p = 0.726 and 5-day mortality rates: 1 (1.4%; 95% CI: 0-7.3) versus 1 (1.3%; 95% CI: 0.2-7.0), RD p = 0.960 were similar. Rebleeding at 42 days: 9 (12.2%; 95% CI: 7.0-20.0) versus 10 (13.3%; 95% CI: 7.0-20.0), RD p = 0.842 and mortality at 42 days: 5 (6.8%; 95% CI: 3.0-10.0) versus 4 (5.3%; 95% CI: 2.0-10.0), RD p = 0.704 were also similar. Patients in the 1-day terlipressin therapy arm experienced significantly fewer adverse effects compared with those receiving 3 days of terlipressin therapy: 28 (37.8%) versus 42 (56%), p = 0.026. CONCLUSIONS: Our results suggest that 1 day of terlipressin therapy is associated with similar 5-day and 42-day rebleeding rates, 42-day mortality and an overall superior safety profile compared with 3-day of terlipressin therapy. These findings require to be validated in double-blinded, larger, multiethnic and multicentre studies across the various stages of cirrhosis (CTRI/2019/10/021771).

Cell-Mediated Immunity (CMI) for SARS-CoV-2 Infection Among the General Population of North India: A Cross-Sectional Analysis From a Sub-sample of a Large Sero-Epidemiological Study.

Background Cell-mediated immunity (CMI), or specifically T-cell-mediated immunity, is proven to remain largely preserved against the variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including Omicron. The persistence of cell-mediated immune response in individuals longitudinally followed up for an extended period remains largely unelucidated. To address this, the current study was planned to study whether the effect of cell-mediated immunity persists after an extended period of convalescence or vaccination. Methods Whole blood specimens of 150 selected participants were collected and tested for Anti-SARS-CoV-2 Interferon-gamma (IFN-γ) response. Ex vivo SARS-CoV-2-specific interferon-gamma Enzyme-linked Immunospot (IFN-γ ELISpot) assay was carried out to determine the levels of virus-specific IFN-γ producing cells in individual samples. Findings Out of all the samples tested for anti-SARS-CoV-2 T-cell-mediated IFN-γ response, 78.4% of samples were positive. The median (interquartile range) spots forming units (SFU) per million levels of SARS-CoV-2-specific IFN-γ producing cells of the vaccinated and diagnosed participants was 336 (138-474) while those who were vaccinated but did not have the disease diagnosis was 18 (0-102); the difference between the groups was statistically significant. Since almost all the participants were vaccinated, a similar pattern of significance was observed when the diagnosed and the never-diagnosed participants were compared, irrespective of their vaccination status. Interpretations Cell-mediated immunity against SARS-CoV-2 persisted, irrespective of age and sex of the participant, for more than six months of previous exposure. Participants who had a history of diagnosed COVID-19 infection had better T-cell response compared to those who had never been diagnosed, in spite of being vaccinated.

Clinical and experimental evidence suggest omicron variant of SARS-CoV-2 is inherently less pathogenic than delta variant independent of previous immunity.

OBJECTIVES: To study clinical disease outcomes in both human and animal models to understand the pathogenicity of omicron compared to the delta variant. METHODS: In this cross-sectional observational study, clinical outcomes of adults who tested positive at 2 testing centres in Delhi National Capital Region between January 2022 and March 2022 (omicron-infected; N = 2998) were compared to a similar geographical cohort (delta-infected; N = 3292). In addition, disease course and outcomes were studied in SARS-CoV-2-infected golden Syrian hamsters and K-18 humanized ACE2 transgenic mice. RESULTS: Omicron variant infection was associated with a milder clinical course [83% (95% CI 61, 94) reduced risk of severity compared against delta] adjusting for vaccination, age, sex, prior infection and occupational risk. This correlated with lower disease index and vir comparing omicron with other variants in animal models. CONCLUSIONS: Infections caused by the omicron variant were milder compared to those caused by the delta variant independent of previous immunity.

Percutaneous Endoscopic Necrosectomy.

Patients with acute pancreatitis might develop infected necrotic fluid collections which are associated with significant morbidity and mortality. Patients with infected necrotizing pancreatitis not responding to antibiotics require drainage and subsequent necrosectomy (Step-up approach). Percutaneous endoscopic necrosectomy (PEN) has evolved as a minimally invasive approach for necrosectomy through the percutaneous catheter route using a flexible endoscope and can be done under conscious sedation. It is best suited for predominantly laterally placed infected necrotic fluid collections and also can be performed at the bedside for sick patients admitted to an ICU. PEN has a clinical success rate of 80% with minimal adverse events.

Omicron sub-lineage BA.5 infection results in attenuated pathology in hACE2 transgenic mice.

A recently emerged sub-lineage of Omicron, BA.5, together with BA.4, caused a fifth wave of coronavirus disease (COVID-19) in South Africa and subsequently emerged as a predominant strain globally due to its high transmissibility. The lethality of BA.5 infection has not been studied in an acute hACE2 transgenic (hACE2.Tg) mouse model. Here, we investigated tissue-tropism and immuno-pathology induced by BA.5 infection in hACE2.Tg mice. Our data show that intranasal infection of BA.5 in hACE2.Tg mice resulted in attenuated pulmonary infection and pathology with diminished COVID-19-induced clinical and pathological manifestations. BA.5, similar to Omicron (B.1.1.529), infection led to attenuated production of inflammatory cytokines, anti-viral response and effector T cell response as compared to the ancestral strain of SARS-CoV-2, Wuhan-Hu-1. We show that mice recovered from B.1.1.529 infection showed robust protection against BA.5 infection associated with reduced lung viral load and pathology. Together, our data provide insights as to why BA.5 infection escapes previous SARS-CoV-2 exposure induced-T cell immunity but may result in milder immuno-pathology and alleviated chances of re-infectivity in Omicron-recovered individuals.

Trends of humoral immune responses to heterologous antigenic exposure due to vaccination & omicron SARS-CoV-2 infection: Implications for boosting.

Background & objectives: Vaccination and natural infection can both augment the immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but how omicron infection has affected the vaccine-induced and hybrid immunity is not well studied in Indian population. The present study was aimed to assess the durability and change in responses of humoral immunity with age, prior natural infection, vaccine type and duration with a minimum gap of six months post-two doses with either ChAdOx1 nCov-19 or BBV152 prior- and post-emergence of the omicron variant. Methods: A total of 1300 participants were included in this observational study between November 2021 and May 2022. Participants had completed at least six months after vaccination (2 doses) with either ChAdOx1 nCoV-19 or an inactivated whole virus vaccine BBV152. They were grouped according to their age (≤ or ≥60 yr) and prior exposure of SARS-CoV-2 infection. Five hundred and sixteen of these participants were followed up after emergence of the Omicron variant. The main outcome was durability and augmentation of the humoral immune response as determined by anti-receptor-binding domain (RBD) immunoglobulin G (IgG) concentrations, anti-nucleocapsid antibodies and anti-omicron RBD antibodies. Live virus neutralization assay was conducted for neutralizing antibodies against four variants - ancestral, delta and omicron and omicron sublineage BA.5. Results: Before the omicron surge, serum anti-RBD IgG antibodies were detected in 87 per cent participants after a median gap of eight months from the second vaccine dose, with a median titre of 114 [interquartile range (IQR) 32, 302] BAU/ml. The levels increased to 594 (252, 1230) BAU/ml post-omicron surge (P<0.001) with 97 per cent participants having detectable antibodies, although only 40 had symptomatic infection during the omicron surge irrespective of vaccine type and previous history of infection. Those with prior natural infection and vaccination had higher anti-RBD IgG titre at baseline, which increased further [352 (IQR 131, 869) to 816 (IQR 383, 2001) BAU/ml] (P<0.001). The antibody levels remained elevated after a mean time gap of 10 months, although there was a decline of 41 per cent. The geometric mean titre was 452.54, 172.80, 83.1 and 76.99 against the ancestral, delta, omicron and omicron BA.5 variants in the live virus neutralization assay. Interpretation & conclusions: Anti-RBD IgG antibodies were detected in 85 per cent of participants after a median gap of eight months following the second vaccine dose. Omicron infection probably resulted in a substantial proportion of asymptomatic infection in the first four months in our study population and boosted the vaccine-induced humoral immune response, which declined but still remained durable over 10 months.

Universal prophylactic rectal nonsteroidal anti-inflammatory drugs with a policy of selective pancreatic duct stenting significantly reduce post-endoscopic retrograde cholangiopancreatography pancreatitis.

BACKGROUND: Although rectal nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to be effective for the prevention of post-ERCP (endoscopic retrograde cholangiopancreatography) pancreatitis (PEP) in high-risk patients, the benefit in average-risk patients is unclear. We aimed at assessing the benefit of prophylactic rectal NSAIDs in unselected consecutive patients to prevent PEP. METHODS: All patients undergoing index ERCP procedures from January 2018 until March 2020 were included. All patients received prophylactic rectal diclofenac. A prophylactic pancreatic duct (PD) stent was placed if there was repeated PD cannulation, at the discretion of the endoscopist. The frequency of PEP was compared with historical controls. RESULTS: Of 769 patients who underwent ERCP, 34 (4.4%) developed PEP (mild in 29 [85.3%], moderate in four [11.8%] and severe in one [2.9%]). Female gender, precut sphincterotomy, inadvertent PD cannulation and procedural time of > 30 minutes predicted PEP in univariate analysis. Inadvertent PD cannulation (OR 4.6, 95% CI: 1.8-11.7; p < 0.001) and procedural time of > 30 minutes (OR 8.5, 95% CI: 3.7-10.1; p < 0.001) were independent risk factors on multivariate analysis. When compared with historical controls, the odds of PEP with prophylactic use of rectal NSAIDs and selective PD stenting was 0.54 (CI: 0.31-0.93, p = 0.027). The number needed to treat (NNT) was 22 to prevent one PEP with prophylactic rectal NSAIDs. CONCLUSION: Routine use of prophylactic rectal NSAIDs effectively prevents the occurrence of PEP in unselected consecutive patients in a real-world scenario.

Ancestral SARS-CoV-2-Driven Antibody Repertoire Diversity in an Unvaccinated Individual Correlates with Expanded Neutralization Breadth.

Understanding the quality of immune repertoire triggered during natural infection can provide vital clues that form the basis for development of a humoral immune response in some individuals capable of broadly neutralizing pan-SARS-CoV-2 variants. In the present study, we report variations in neutralization potential against Omicron variants of two novel neutralizing monoclonal antibodies (MAbs), THSC20.HVTR11 and THSC20.HVTR55, isolated from an unvaccinated convalescent individual that represent distinct B cell lineage origins and epitope specificity compared to five MAbs we previously reported that were isolated from the same individual. In addition, we observed neutralization of Omicron variants by plasma antibodies obtained from this particular individual postvaccination with increased magnitude. Interestingly, this observation was found to be comparable with six additional individuals who initially were also infected with ancestral SARS-CoV-2 and then received vaccines, indicating that hybrid immunity can provide robust humoral immunity likely by antibody affinity maturation. Development of a distinct antigen-specific B cell repertoire capable of producing polyclonal antibodies with distinct affinity and specificities offers the highest probability of protecting against evolving SARS-CoV-2 variants. IMPORTANCE Development of robust neutralizing antibodies in SARS-CoV-2 convalescent individuals is known; however, it varies at the population level. We isolated monoclonal antibodies from an individual infected with ancestral SARS-CoV-2 in early 2020 that not only varied in their B cell lineage origin but also varied in their capability and potency to neutralize all the known variants of concern (VOCs) and currently circulating Omicron variants. This indicated establishment of unique lineages that contributed in forming a B cell repertoire in this particular individual immediately following infection, giving rise to diverse antibody responses that could complement each other in providing a broadly neutralizing polyclonal antibody response. Individuals who were able to produce polyclonal antibody responses with higher magnitude have a higher chance of being protected from evolving SARS-CoV-2 variants.

Use of Critical View of Safety and Proctored Preceptorship in Preventing Bile Duct Injury During Laparoscopic Cholecystectomy-Experience of 3726 Cases From a Tertiary Care Teaching Institute.

INTRODUCTION: Bile duct injury (BDI) continues to occur despite technological advances and improvements in surgical training over the past 2 decades. This study was conducted to audit our data on laparoscopic cholecystectomies performed over the past 2 decades to determine the role of Critical View of Safety (CVS) and proctored preceptorship in preventing BDI and postoperative complications. MATERIALS AND METHODS: All patients undergoing elective laparoscopic cholecystectomy were analyzed retrospectively. The data were obtained from a prospectively maintained database from January 2004 to December 2019. Proctored preceptorship was used in all cases. Intraoperative details included the number of patients where CVS was defined, number of BDI and conversions. Postoperative outcomes, including hospital stay, morbidity, and bile duct stricture, were noted. RESULTS: Three thousand seven hundred twenty-six patients were included in the final analysis. Trainee surgeons performed 31.6% of surgeries and 9.5% of these surgeries were taken over by the senior surgeon. A CVS could be delineated in 96.6% of patients. The major BDI rate was only 0.05%. CONCLUSION: This study reiterates the fact that following the basic tenets of safe laparoscopic cholecystectomy, defining and confirming CVS, and following proctored preceptorship are critical in preventing major BDI.

Position statement on the definition, incidence, diagnosis and outcome of acute on chronic pancreatitis.

BACKGROUND: Acute on chronic pancreatitis (ACP) is a relatively common condition, but there are significant gaps in our knowledge on the definition, incidence, diagnosis, treatment and prognosis. METHODS: A systematic review that followed PICO (Population; Intervention; Comparator; Outcome) recommendation for quantitative questions and PICo (Population, Phenomenon of Interest, Context) for qualitative research was done to answer 10 of the most relevant questions about ACP. Quality of evidence was judged by the GRADE criteria (Grades of Recommendation, Assessment, Development and Evaluation). The manuscript was sent for review to 12 international experts from various disciplines and continents using a Delphi process. RESULTS: The quality of evidence, for most statements, was low to very low, which means that the recommendations in general are only conditional. Despite that, it was possible to reach strong levels of agreement by the expert panel for all 10 questions. A new consensus definition of ACP was reached. Although common, the real incidence of ACP is not known, with alcohol as a major risk factor. Although pain dominates, other non-specific symptoms and signs can be present. Serum levels of pancreatic enzymes may be less than 3 times the upper limit of normal and cross-sectional imaging is considered more accurate for the diagnosis in many cases. It appears that it is less severe and with a lower mortality risk than acute pancreatitis. CONCLUSIONS: Although the evidence base is poor, this position statement provides a foundation from which to advance management of ACP.

Electrocardiography Assessment of Sympatico-Vagal Balance during Resting and Pain Using the Texas Instruments ADS1299.

Sympatico-vagal balance is essential for regulating cardiac electrophysiology and plays an important role in arrhythmogenic conditions. Various noninvasive methods, including electrocardiography (ECG), have been used for clinical assessment of the sympatico-vagal balance. This study aimed to use a custom-designed wearable device to record ECG and ECG-based cardiac function biomarkers to assess sympatico-vagal balance during tonic pain in healthy controls. Nineteen healthy volunteers were included for the ECG measurements using the custom-designed amplifier based on the Texas Instruments ADS1299. The ECG-based biomarkers of the sympatico-vagal balance, (including heart rate variability, deceleration capacity of the heart rate, and periodic repolarization dynamic), were calculated and compared between resting and pain conditions (tonic pain). The custom-designed device provided technically satisfactory ECG recordings. During exposure to tonic pain, the periodic repolarization dynamics increased significantly (p = 0.02), indicating enhancement of sympathetic nervous activity. This study showed that custom-designed wearable devices can potentially be useful in healthcare as a new telemetry technology. The ECG-based novel biomarkers, including periodic repolarization dynamic and deceleration capacity of heart rate, can be used to identify the cold pressor-induced activation of sympathetic and parasympathetic systems, making it useful for future studies on pain-evoked biomarkers.

Pancreatic Mass Characterization Using IVIM-DKI MRI and Machine Learning-Based Multi-Parametric Texture Analysis.

Non-invasive characterization of pancreatic masses aids in the management of pancreatic lesions. Intravoxel incoherent motion-diffusion kurtosis imaging (IVIM-DKI) and machine learning-based texture analysis was used to differentiate pancreatic masses such as pancreatic ductal adenocarcinoma (PDAC), pancreatic neuroendocrine tumor (pNET), solid pseudopapillary epithelial neoplasm (SPEN), and mass-forming chronic pancreatitis (MFCP). A total of forty-eight biopsy-proven patients with pancreatic masses were recruited and classified into pNET (n = 13), MFCP (n = 6), SPEN (n = 4), and PDAC (n = 25) groups. All patients were scanned for IVIM-DKI sequences acquired with 14 b-values (0 to 2500 s/mm2) on a 1.5T MRI. An IVIM-DKI model with a 3D total variation (TV) penalty function was implemented to estimate the precise IVIM-DKI parametric maps. Texture analysis (TA) of the apparent diffusion coefficient (ADC) and IVIM-DKI parametric map was performed and reduced using the chi-square test. These features were fed to an artificial neural network (ANN) for characterization of pancreatic mass subtypes and validated by 5-fold cross-validation. Receiver operator characteristics (ROC) analyses were used to compute the area under curve (AUC). Perfusion fraction (f) was significantly higher (p < 0.05) in pNET than PDAC. The f showed better diagnostic performance for PDAC vs. MFCP with AUC:0.77. Both pseudo-diffusion coefficient (D*) and f for PDAC vs. pNET showed an AUC of 0.73. ADC and diffusion coefficient (D) showed good diagnostic performance for pNET vs. MFCP with AUC: 0.79 and 0.76, respectively. In the TA of PDAC vs. non-PDAC, f and combined IVIM-DKI parameters showed high accuracy ≥ 84.3% and AUC ≥ 0.84. Mean f and combined IVIM-DKI parameters estimated that the IVIM-DKI model with TV texture features has the potential to be helpful in characterizing pancreatic masses.

International multidisciplinary survey on the initial management of acute pancreatitis: Perspective of point-of-care specialists focused on daily practice.

BACKGROUND: The initial management of patients with acute pancreatitis impacts both morbidity and mortality. Point-of-care decisions have been reported to differ from clinical guideline recommendations. METHODS: An online anonymous questionnaire was distributed through scientific associations and social media using REDCap. Multivariable logistic regression was used to identify the characteristics of participants associated with compliance with the recommendations. RESULTS: A total of 1054 participants from 94 countries completed the questionnaire; median age (IQR) was 39 (32-47) years; 30.7% were women. Among the participants, 37% opted for nonmoderate flow of i.v. fluid, 31% for fluid type other than Ringer's lactate; 73.4% were in favor of nil per os to patients who could eat, 75.5% for other than enteral feeding to patients with oral intolerance; 15.5% used prophylactic antibiotic in patients with severe acute pancreatitis, 34.1% in necrotizing acute pancreatitis, and 27.4% in patients with systemic inflammatory response syndrome; 27.8% delayed cholecystectomy after biliary acute pancreatitis. Participants with publications in PubMed on acute pancreatitis showed better compliance (OR, 1.62; 95% CI: 1.15-2.32; P = .007) with recommendations of the clinical guidelines. CONCLUSIONS: Feeding and nutrition require the greatest improvement efforts, but also the use of prophylactic antibiotics and timing of cholecystectomy should be improved.

A broadly neutralizing monoclonal antibody overcomes the mutational landscape of emerging SARS-CoV-2 variants of concern.

The emergence of new variants of SARS-CoV-2 necessitates unremitting efforts to discover novel therapeutic monoclonal antibodies (mAbs). Here, we report an extremely potent mAb named P4A2 that can neutralize all the circulating variants of concern (VOCs) with high efficiency, including the highly transmissible Omicron. The crystal structure of the P4A2 Fab:RBD complex revealed that the residues of the RBD that interact with P4A2 are a part of the ACE2-receptor-binding motif and are not mutated in any of the VOCs. The pan coronavirus pseudotyped neutralization assay confirmed that the P4A2 mAb is specific for SARS-CoV-2 and its VOCs. Passive administration of P4A2 to K18-hACE2 transgenic mice conferred protection, both prophylactically and therapeutically, against challenge with VOCs. Overall, our data shows that, the P4A2 mAb has immense therapeutic potential to neutralize the current circulating VOCs. Due to the overlap between the P4A2 epitope and ACE2 binding site on spike-RBD, P4A2 may also be highly effective against a number of future variants.