ABSTRACT
(1) Background: The aim of this study was to produce in-house ELISAs which can be used to determine SARS-CoV-2-specific antibody levels directed against the spike protein (S), the S1 subunit of S and the receptor binding domain (RBD) of S in SARS-CoV-2 vaccinated and infected humans. (2) Methods: Three in-house ELISAs were developed by using recombinant proteins of SARS-CoV-2, namely the S, S1 and RBD proteins. Specificity and sensitivity evaluations of these tests were performed using sera from SARS-CoV-2-infected (n = 70) and SARS-CoV-2-vaccinated (n = 222; CoronaVac vaccine) humans in Istanbul, Turkey. The analyses for the presence of SARS-CoV-2-specific antibodies were performed using the in-house ELISAs, a commercial ELISA (Abbott) and a commercial surrogate virus neutralization test (sVNT). We also analyzed archival human sera (n = 50) collected before the emergence of COVID-19 cases in Turkey. (3) Results: The sensitivity of the in-house S, S1 and RBD ELISAs was found to be 88.44, 90.17 and 95.38%, while the specificity was 72.27, 89.08 and 89.92%, respectively, when compared to the commercial SARS-CoV-2 antibody test kit. The area under curve (AUC) values were 0.777 for the in-house S ELISA, 0.926 for the S1 ELISA, and 0.959 for the RBD ELISA. The kappa values were 0.62, 0.79 and 0.86 for the S, S1 and RBD ELISAs, respectively. (4) Conclusions: The in-house S1 and RBD ELISAs developed in this study have acceptable performance characteristics in terms of sensitivity, specificity, AUC and kappa values. In particular, the RBD ELISA seems viable to determine SARS-CoV-2-specific antibody levels, both in infected and vaccinated people, and help mitigate SARS-CoV-2 outbreaks and spread.
ABSTRACT
Amyotrophic lateral sclerosis (ALS) is characterized by predominant vulnerability and central degeneration of both corticospinal/corticobulbar motor neurons (CSMN; "upper motor neurons") in cerebral cortex, and spinal/bulbar motor neurons (SMN; "lower motor neurons") in spinal cord and brainstem. Increasing evidence indicates broader cerebral cortex pathology in cognitive, sensory, and association systems in select cases. It remains unclear whether widely accepted transgenic ALS models, in particular hSOD1(G93A) mice, undergo degeneration of CSMN and molecularly/developmentally closely related populations of nonmotor projection neurons [e.g., other subcerebral projection neurons (SCPN)], and whether potential CSMN/SCPN degeneration is specific and early. This relative lack of knowledge regarding upper motor neuron pathology in these ALS model mice has hindered both molecular-pathophysiologic understanding of ALS and their use toward potential CSMN therapeutic approaches. Here, using a combination of anatomic, cellular, transgenic labeling, and newly available neuronal subtype-specific molecular analyses, we identify that CSMN and related nonmotor SCPN specifically and progressively degenerate in hSOD1(G93A) mice. Degeneration starts quite early and presymptomatically, by postnatal day 30. Other neocortical layers, cortical interneurons, and other projection neuron populations, even within layer V, are not similarly affected. Nonneuronal pathology in neocortex (activated astroglia and microglia) is consistent with findings in human ALS cortex and in affected mouse and human spinal cord. These results indicate previously unknown neuron type-specific vulnerability of CSMN/sensory and association SCPN, and identify that characteristic dual CSMN and SMN degeneration is conserved in hSOD1(G93A) mice. These results provide a foundation for detailed investigation of CSMN/SCPN vulnerability and toward potential CSMN therapeutics in ALS.
