Bianca A Trombetta
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Researcher at Department of Neurology, Massachusetts General Hospital, Harvard Medical School
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Video Abstract (AI generated)
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BackgroundCOVID-19 has resulted in significant morbidity and mortality worldwide. Lateral flow assays can detect anti-Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) antibodies to monitor transmission. However, standardized evaluation of their accuracy and tools to aid in interpreting results are needed. MethodsWe evaluated 20 IgG and IgM assays selected from available tests in April 2020. We evaluated the assays performance using 56 pre-pandemic negative and 56 SARS-CoV-2-positive plasma samples, collected 10-40 days after symptom onset, confirmed by a molecular test and analyzed by an ultra-sensitive immunoassay. Finally, we developed a user-friendly web app to extrapolate the positive predictive values based on their accuracy and local prevalence. ResultsCombined IgG+IgM sensitivities ranged from 33.9% to 94.6%, while combined specificities ranged from 92.6% to 100%. The highest sensitivities were detected in Lumiquick for IgG (98.2%), BioHit for both IgM (96.4%), and combined IgG+IgM sensitivity (94.6%). Furthermore, 11 LFAs and 8 LFAs showed perfect specificity for IgG and IgM, respectively, with 15 LFAs showing perfect combined IgG+IgM specificity. Lumiquick had the lowest estimated limit-of-detection (LOD) (0.1 g/mL), followed by a similar LOD of 1.5 g/mL for CareHealth, Cellex, KHB, and Vivachek. ConclusionWe provide a public resource of the accuracy of select lateral flow assays with potential for home testing. The cost-effectiveness, scalable manufacturing process, and suitability for self-testing makes LFAs an attractive option for monitoring disease prevalence and assessing vaccine responsiveness. Our web tool provides an easy-to-use interface to demonstrate the impact of prevalence and test accuracy on the positive predictive values.
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Video Abstract (AI generated)
Paper
Preprint
Although the molecular mechanisms underlying amyotrophic lateral sclerosis (ALS) are not yet fully understood, recent studies have described alterations in tau protein in both sporadic and familial ALS. However, it is unclear whether alterations in tau contribute to ALS pathogenesis. Here, we leveraged the ALS Knowledge Portal and Project MinE data sets and identified specific genetic variants clustering within the microtubule-binding domain of MAPT, which were unique to ALS cases. Furthermore, our analysis in a large post-mortem cohort of ALS and control motor cortex demonstrates that although there was no significant difference in the presence of phosphorylated tau (pTau) neuropil threads and neurofibrillary tangles between the two groups, pTau-S396 and pTau-S404 mis-localized to the nucleus and synapses in ALS. This was specific to the C-terminus phosphorylation sites as there was a significant decrease in pTau-T181 in ALS synaptoneurosomes compared to controls. Lastly, while there was no change in total tau or pTau-T181 in ALS CSF, there was a decrease in pTau-T181:tau ratio in ALS CSF, as previously reported. Importantly, CSF tau levels were increased in ALS patients diagnosed with bulbar onset ALS, while pTau-T181:tau ratio was decreased in ALS patients diagnosed with both bulbar and limb onset. Additionally, there was an inverse correlation between tau levels in the CSF and the revised ALS functional rating scale (ALSFRS-R) as well as a correlation between pTau-T181:tau ratio and ALSFRS-R. While there were no longitudinal alterations in tau, pTau-T181 and pTau-T181:tau ratio, there was an increase in the rate of ALSFRS-R decline per month associated with increases in tau levels. This decline was also inversely correlated with increases in pTau-T181 in relation to tau levels. Taken together, our findings demonstrate that, like Alzheimers disease, hyperphosphorylated tau is mis-localized in ALS and that decreases in CSF pTau-T181 may serve as a biomarker in ALS.