![]() ![]() A best-practice ELISA protocol from the Krammer group at Mt. Because antibody testing can be quite variable, there have been concerted efforts to standardize testing. Positivity rates for the detection of anti-SARS-CoV-2 IgG or IgM in patient serum have been shown to rise above 90% after an average of 11-13 days from symptom onset, though seroconversion timeframes for IgG as it relates to IgM are not necessarily comparable between patients ( 6). Rather than using real time RT-PCR to constantly test for active cases, serologic antibody testing has been proposed as an important tool to determine the prevalence and spread of SARS-CoV-2 in a community. Time since infection has proven to be an important source of variability in real time RT-PCR results due to difficulties in detecting SARS-CoV-2 RNA in patients prior to development of symptoms, or more than 5 days post-development of symptoms ( 5). Active infections, typically diagnosed by real time reverse transcription polymerase chain reaction (RT-PCR), have been plagued with false negative issues as well as availability issues in some countries, including the United States ( 2– 4). One hurdle to reducing spread of the disease is the difficulty in the identification of both actively infected individuals as well as those who have recovered. While vaccine and therapeutic interventions are under investigation by almost every qualified scientific body worldwide, thereremain significant challenges associated with reducing spread prior to effective therapeutic strategies. As of July 13, 2020, roughly 13 million people worldwide have been confirmed to have contracted COVID-19, leading to over 500,000 fatalities so far ( 1). In March of 2020, the novel coronavirus disease 2019 (COVID-19) joined the ranks of other infectious diseases such as influenza and plague to be categorized as a pandemic. We show here through a proof-of-concept study that these lateral flow devices can be as analytically sensitive as ELISAs and adopted into hospital protocols however, additional improvements to these devices remain necessary before their clinical deployment. Furthermore, during viral neutralization testing, one patient was discovered to harbor autoantibodies to ACE2, with implications for how immune responses are profiled. For comparison, this assay was also tested with saliva from the same patient population and showed reduced discrimination between cases and controls with AUC values of 0.6841 for IgG. Using the device with fingerstick blood on a cohort of 27 hospitalized PCR-positive patients and seven hospitalized controls, ROC curve analysis gave AUC values of 0.7646 for IgG. One of these devices was deployed in Northern Italy to test its sensitivity and specificity in a real-world clinical setting. For a small group of PCR-positive, we found two lateral flow immunoassay devices with titer sensitivity roughly equal to the ELISA these devices were positive for all PCR-positive patients harboring SARS-CoV-2 neutralizing antibodies. We report on nine lateral flow immunoassays currently available and compare their titer sensitivity in serum to a best-practice enzyme-linked immunosorbent assay (ELISA) and viral neutralization assay. Lateral flow immunoassays for antibody testing have been viewed as a cheap and rapidly deployable method for determining previous infection with SARS-CoV-2 however, these assays have shown unacceptably low sensitivity. In conclusion, Western blot does not seem to be the method of choice for screening purposes in a routine laboratory but can be used as a complement to ELISA for serodiagnosis in patients with disease of short duration.Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), became a pandemic in early 2020. However, the specificity for current disease was not improved by Western blot. Both patients and controls lived in an area endemic for Lyme borreliosis and some ELISA negative but Western blot positive controls were thought to have been previously exposed to Borrelia burgdorferi. Western blot was more sensitive than ELISA, the difference being most pronounced in sera from patients with neurological disease for four weeks or less. ![]() Eight of 44 (18%) controls with meningitis/encephalitis of non-borrelia etiology had positive IgM and/or IgG immunoblots and 4 of 44 (9%) had positive IgM and/or IgG ELISA titers in serum. Fifty-three of 68 (78%) patients with neuroborreliosis had positive IgM and/or IgG immunoblots and 40 of 68 (59%) had positive IgM and/or IgG ELISA titers in serum. The usefulness of Western blot in the serological diagnosis of Lyme borreliosis was evaluated compared with an ELISA using a whole cell sonicate antigen.
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