Harmonization of Zika serological assays and comparative evaluation of two commercial ZIKA IgG ELISA kits

The interpretation for Zika virus serology results is challenging due to high antibody cross reactivity with other flaviviruses. This limits availability of reliable and accurate methods for serosurveillance studies to understand the disease burden. Therefore, we conducted study to harmonize anti-Zika IgG antibody detection assays with 1st WHO International Standard (16/352) and working standard (16/320) for anti-Zika virus antibody.Additionally, evaluated NuGenTMZIKA-IgG and NovaLisa®ZIKA virus IgG-Capture ELISA using a panel of 278 seraFurther, 106 samples positive for other-flavi viruses were taken for assessing cross-reactivity of the assay, all serums were further tested by Zika-PRNT. The results of this study indicates satisfactory performance of both the assays. Serological and neutralization assays were calibrated according to the international standards. This will help in understanding antibody dynamics in serosurveillance and vaccine studies. However the performance of the kits with possibilities of cross-reactivity will have to be verified by coupling ZIKV and DENV specific ELISA.

Breast-to-brain metastasis is exacerbated with chemotherapy through blood-cerebrospinal fluid barrier and induces Alzheimer's-like pathology

Control of breast-to-brain metastasis remains an urgent unmet clinical need. While chemotherapies are essential in reducing systemic tumor burden, they have been shown to promote non-brain metastatic invasiveness and drug-driven neurocognitive deficits through the formation of neurofibrillary tangles (NFT), independently. Now, in this study, we investigated the effect of chemotherapy on brain metastatic progression and promoting tumor-mediated NFT. Results show chemotherapies increase brain-barrier permeability and facilitate enhanced tumor infiltration, particularly through the blood-cerebrospinal fluid barrier (BCSFB). This is attributed to increased expression of matrix metalloproteinase 9 (MMP9) which, in turn, mediates loss of Claudin-6 within the choroid plexus cells of the BCSFB. Importantly, increased MMP9 activity in the choroid epithelium following chemotherapy results in cleavage and release of Tau from breast cancer cells. This cleaved Tau forms tumor-derived NFT that further destabilize the BCSFB. Our results underline for the first time the importance of the BCSFB as a vulnerable point of entry for brain-seeking tumor cells post-chemotherapy and indicate that tumor cells themselves contribute to Alzheimer's-like tauopathy.

External quality assurance of serological diagnosis of dengue, chikungunya and Japanese encephalitis virus infection

INTRODUCTION

Dengue, chikungunya and Japanese encephalitis are the most common arthropod-borne viral diseases in India. Due to overlapping clinical symptoms, accurate, high-quality and timely laboratory-based differential diagnosis is essential for control and containment of outbreaks. This is most commonly done by detection of IgM antibodies in serum using enzyme-linked immunosorbent assays. The Resource Centre for Virus Research and Diagnostic Laboratories (VRDLs) in Pune, India organized an external quality assurance (EQA) study to check the accuracy of serological diagnostics in the VRDL network.

METHODS

Three panels, one each for anti-dengue virus, anti-chikungunya virus and anti-Japanese encephalitis virus IgM antibodies, comprising six human serum samples (two positive and four negative) were distributed to test the sensitivity, specificity and reproducibility of serological testing in 124 VRDLs across India in 2018-19 and 2019-20.

RESULTS

Among the 124 VRDLs, the average concordance for both 2018-19 and 2019-20 was 98%. In 2018-19, 78.33%, 13.33% and 6.66% of VRDLs reported 100% concordance, 91-99% concordance and 81-90% concordance with the reference results, respectively, and 1.66% of VRDLs had concordance <80%. In 2019-20, 79.68%, 14.06% and 4.68% of VRDLs reported 100% concordance, 91-99% concordance and 81-90% concordance with the reference results, respectively, and 1.56% of VRDLs had concordance <80%.

CONCLUSION

The EQA programme was beneficial for assessing and understanding the performance of the VRDLs. The study data indicate good proficiency in serological diagnosis of dengue, chikungunya and Japanese encephalitis in the VRDL network laboratories. Further expansion of the EQA programme to cover other viruses of public health importance will increase confidence among the VRDL network, and generate evidence of high-quality testing.

Understanding the dynamics of IgM & IgG antibodies in COVID-19-positive patients

Background & objectives

The pandemic caused by the SARS-CoV-2 has been a threat to humankind due to the rapid spread of infection and appearance of multiple new variants. In the present study, we report the dynamics and persistence of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in asymptomatic and symptomatic COVID-19 patients by chemiluminescent assay.

Methods

A total of 463 serum samples from 218 SARS-CoV-2 PCR-positive patients were collected over a period of 124 days post-onset of disease (POD). Antibody levels were measured by chemiluminescence bioanalyzer. Neutralizing antibody titres were assessed by plaque reduction neutralization test (PRNT) for SARS-CoV-2.

Results

Both IgM and IgG started appearing from day five post-infection in symptomatic and asymptomatic patients. IgM antibody response peaked around day 35 POD and rapidly diminished thereafter, with the last IgM-positive sample observed at 90 days POD. IgG antibody response peaked around 45 days POD and persisted till 124 days. The chemiluminescence immunoassay (CLIA) results showed a moderate correlation (R=0.5846, P<0.001) compared with PRNT. Additional analysis indicated a neutralizing titre of 250 corresponded to 12.948 AU/ml of YHLO iFlash SARS-CoV-2 IgG units.

Interpretation & conclusions

Both symptomatic and asymptomatic COVID-19 patients seem to initiate production of antibody responses from day five of onset of disease. Although the CLIA gives high sensitivity and specificity and also its binding IgG antibody titres may correlate moderately with protective immunity, our results indicate that the values of binding antibody alone may not be a perfect guide to represent virus neutralization titre during donor selection for plasma therapy. However, IgM and IgG antibody detection may help in monitoring the status of disease progression and burden in the community.

Performance assessment of seven SARS-CoV-2 IgG enzyme-linked immunosorbent assays

The pandemic of COVID-19 has caused enormous fatalities worldwide. Serological assays are important for detection of asymptomatic or mild cases of COVID-19, and sero-prevalence and vaccine efficacy studies. Here, we evaluated and compared the performance of seven commercially available enzyme-linked immunosorbent assay (ELISA)s for detection of anti-severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) immunoglobulin G (IgG). The ELISAs were evaluated with a characterized panel of 100 serum samples from qRT-PCR confirmed COVID-19 patients, collected 14 days post onset disease, 100 SARS-CoV-2 negative samples and compared the results with that of neutralization assay. Results were analysed by creating the receiver operating characteristic curve of all the assays in reference to the neutralization assay. All kits, were found to be suitable for detection of IgG against SARS-CoV-2 with high accuracy. The DiaPro COVID-19 IgG ELISA showed the highest sensitivity (98%) among the kits. The assays demonstrated high sensitivity and specificity in detecting the IgG antibodies against SARS-CoV-2. However, the presence of IgG antibodies does not always correspond to neutralizing antibodies. Due to their good accuracy indices, these assays can also aid in tracing mild infections, in cohort studies and in pre-vaccine evaluations.

Development of indigenous IgG ELISA for the detection of anti-SARS-CoV-2 IgG

BACKGROUND & OBJECTIVES

Since the beginning of the year 2020, the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacted humankind adversely in almost all spheres of life. The virus belongs to the genus Betacoronavirus of the family Coronaviridae. SARS-CoV-2 causes the disease known as coronavirus disease 2019 (COVID-19) with mild-to-severe respiratory illness. The currently available diagnostic tools for the diagnosis of COVID-19 are mainly based on molecular assays. Real-time reverse transcription-polymerase chain reaction is the only diagnostic method currently recommended by the World Health Organization for COVID-19. With the rapid spread of SARS-CoV-2, it is necessary to utilize other tests, which would determine the burden of the disease as well as the spread of the outbreak. Considering the need for the development of such a screening test, an attempt was made to develop and evaluate an IgG-based ELISA for COVID-19.

METHODS

A total of 513 blood samples (131 positive, 382 negative for SARS-CoV-2) were collected and tested by microneutralization test (MNT). Antigen stock of SARS-CoV-2 was prepared by propagating the virus in Vero CCL-81 cells. An IgG capture ELISA was developed for serological detection of anti-SARS-CoV-2 IgG in serum samples. The end point cut-off values were determined by using receiver operating characteristic (ROC) curve. Inter-assay variability was determined.

RESULTS

The developed ELISA was found to be 92.37 per cent sensitive, 97.9 per cent specific, robust and reproducible. The positive and negative predictive values were 94.44 and 98.14 per cent, respectively.

INTERPRETATION & CONCLUSIONS

This indigenously developed IgG ELISA was found to be sensitive and specific for the detection of anti-SARS-CoV-2 IgG in human serum samples. This assay may be used for determining seroprevalence of SARS-CoV-2 in a population exposed to the virus.

First light from a kilometer-baseline Scintillation Auroral GPS Array

We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100-1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies.

KEY POINTS

A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed.

Working channel endoscope in lumbar spine surgery

Percutaneous endoscopic lumbar discectomy (PELD) is a well established modality in the treatment of patients with herniated lumbar discs. Since the time of its inception towards the end of 20th century, this technique has undergone significant modifications. With better understanding of the patho-anatomy and development of instrumentation the indications for PELD are on the rise. In the modern era of knowledge exchange there have been considerable variations among different endoscopic surgeons about classical indications and the implications of a particular technique pertaining to those indications. During last 15 years of experience in practicing endoscopic surgery, Choi has published many articles, regarding the techniques of PELD, across many scientific journals. In our practice there has been considerable shift from central debulking to discectomy to selective fragmentectomy. With further advancements the span of this technique is definitely on the rise. Here, we wish to share all the published data along with my current practice trends in more precise manner to help newer endoscopic spine surgeons understand the implications and limitations of a working channel endoscope in lumbar spine pathologies.

Health care seeking among individuals with cough and tuberculosis: a population-based study from rural India

SETTING

Ujjain district, Madhya Pradesh, India.

OBJECTIVE

To describe and compare health care seeking among men and women with cough of >3 weeks, with special focus on the utilisation of private and public health care.

DESIGN

A population-based cross-sectional survey including 45 719 individuals aged > or = 15 years.

RESULTS

The prevalence of cough was respectively 2.8% and 1.2% among men and women. The majority of men and women reported seeking health care for their symptoms (69% vs. 71%), but only 23% visited a public provider at some point during their illness. A similar health care seeking pattern was found for patients diagnosed with tuberculosis (TB) in our survey. No significant differences in health care seeking were found between men and women. Only 13% of those seeking care reported having had a sputum smear examination since the onset of cough. Factors associated with sputum examination were history of TB, haemoptysis and visiting a public provider.

CONCLUSION

The low utilisation of public health care services and the few sputum examinations reported in this rural Indian setting illustrate the need for improved diagnostic practices as well as involvement of private providers in TB control activities.

Diltiazem overdose haemodynamic response to hyperinsulinaemia-euglycaemia therapy: a case report

A 59-year-old woman was admitted to the intensive care unit after ingesting 5.76 g of an extended release preparation of diltiazem. The patient was hypotensive and bradycardic and was treated initially with intravenous fluids, adrenaline, noradrenaline, vasopressin and standard insulin doses to maintain the blood glucose levels between 6-10 mmol/L. As the patient remained inotrope dependent the insulin dose was increased to 25 U/hr with an infusion of 50% dextrose to maintain the blood glucose levels between 6-8 mmol/L. Within 30 minutes, the mean arterial pressure increased from 65 mmHg to 80 mmHg and within 60 minutes all vasoactive agents were discontinued. A right heart catheter inserted before the increased dose of insulin revealed that the predominant haemodynamic effect of the hyperinsulinaemia-euglycaemia therapy appeared to be an increase in the peripheral vascular resistance.

Candida parapsilosis fungaemia treated unsuccessfully with amphotericin B and fluconazole but eliminated with caspofungin: a case report

A case of Candida parapsilosis Hickman catheter infection with fungaemia presenting with severe hypoxia, lactic acidosis and renal failure is described. Four months previously, the Hickman catheter had become infected with Candida parapsilosis (sensitive to fluconazole and amphotericin B) with blood cultures remaining positive despite an intravenous course of fluconazole 200 mg 12-hourly increasing to 400 mg-12-hourly. Subsequently, treatment with an amphotericin B infusion (30 mg over 24 hours) for five days was associated with a progressive increase in serum creatinine from 0.042 mmol/L to 0.278 mmol/L with blood cultures remaining positive. While arrangements were being made to remove and replace the catheter via a thoracotomy, the patient developed severe hypoxia, lactic acidosis and renal failure and was admitted to the intensive care unit for further management. An intravenous course of caspofungin (70 mg over 1 hour followed by 50 mg over 1 hour, daily) was associated with negative blood cultures and a normal plasma C-reactive protein for the first time in four months. The hypoxia was managed with spontaneous ventilation and high inspired oxygen concentrations, and the anaemia was treated with red blood cell transfusions. A rapid reversal of the respiratory failure and lactic acidosis occurred and the patient was discharged home from the intensive care unit after 10 days to continue the caspofungin infusions for a total of 6 weeks. She has subsequently remained well with negative blood cultures two months later.

Isolated fluvoxamine poisoning presenting with hypertonia and seizures: a case report

Pharmacological management of depressed patients has often relied upon the use of agents that are toxic when taken in large quantities. The recent introduction of selective serotonin reuptake inhibitors (SSRIs) has represented a major advance in the management of depression. While a 'serotonin syndrome' may develop if these drugs are taken in association with other agents, these drugs are believed to have minimal toxicity when taken as an isolated overdose. A case of fluvoxamine poisoning presenting with hypertonicy and seizures is described, highlighting the fact that the SSRI's may not be harmless when taken in isolation, particularly when taken in large amounts.