Unique immune and inflammatory cytokine profiles may define long COVID syndrome.

PURPOSE: Long COVID is estimated to occur in 5-10% of individuals after acute SARS-CoV-2 infection. However, the pathophysiology driving the disease process is poorly understood. METHODS: We evaluated urine and plasma inflammatory and immune cytokine profiles in 33 individuals with long COVID compared to 33 who were asymptomatic and recovered, and 34 without prior infection. RESULTS: Mean urinary leukotriene E4 was significantly elevated among individuals with long COVID compared to asymptomatic and recovered individuals (mean difference 774.2 pg/mL; SD 335.7) and individuals without prior SARS-CoV-2 infection (mean difference 503.1 pg/ml; SD 467.7). Plasma chemokine ligand 6 levels were elevated among individuals with long COVID compared to individuals with no prior SARS-CoV-2 infection (mean difference 0.59 units; SD 0.42). We found no significant difference in angiotensin-converting enzyme 2 antibody levels. Plasma tumor necrosis factor receptor-associated factor 2 (TRAF2) levels were reduced among individuals with long COVID compared to individuals who were asymptomatic and recovered (mean difference = 0.6 units, SD 0.46). Similarly, the mean level of Sarcoma Homology 2-B adapter protein 3 was 3.3 units (SD 1.24) among individuals with long COVID, lower than 4.2 units (SD 1.1) among individuals with recovered, asymptomatic COVID. CONCLUSION: Our findings suggest that further studies should be conducted to evaluate the role of leukotriene E4 as a potential biomarker for a diagnostic test. Furthermore, based on reductions in TRAF2, long COVID may be driven in part by impaired TRAF2-dependent immune-mediated inflammation and potentially immune exhaustion.

SARS-CoV-2 Specific IgG Antibodies Persist Over a 12-Month Period in Oral Mucosal Fluid Collected From Previously Infected Individuals.

Background: Developing an understanding of the antibody response, seroprevalence, and seroconversion from natural infection and vaccination against SARS-CoV-2 will give way to a critical epidemiological tool to predict reinfection rates, identify vulnerable communities, and manage future viral outbreaks. To monitor the antibody response on a larger scale, we need an inexpensive, less invasive, and high throughput method. Methods: Here we investigate the use of oral mucosal fluids from individuals recovered from SARS-CoV-2 infection to monitor antibody response and persistence over a 12-month period. For this cohort study, enzyme-linked immunosorbent assays (ELISAs) were used to quantify anti-Spike(S) protein IgG antibodies in participants who had prior SARS-CoV-2 infection and regularly (every 2-4 weeks) provided both serum and oral fluid mucosal fluid samples for longitudinal antibody titer analysis. Results: In our study cohort (n=42) with 17 males and 25 females with an average age of 45.6 +/- 19.3 years, we observed no significant change in oral mucosal fluid IgG levels across the time course of antibody monitoring. In oral mucosal fluids, all the participants who initially had detectable antibodies continued to have detectable antibodies throughout the study. Conclusions: Based on the results presented here, we have shown that oral mucosal fluid-based assays are an effective, less invasive tool for monitoring seroprevalence and seroconversion, which offers an alternative to serum-based assays for understanding the protective ability conferred by the adaptive immune response from viral infection and vaccination against future reinfections.

Detection of SARS-CoV-2 Antibodies in Oral Fluid Obtained Using a Rapid Collection Device.

Current commercially available methods for reliably detecting antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain expensive and inaccessible due to the need for whole-blood collection by highly trained phlebotomists using personal protective equipment (PPE). We have evaluated an antibody detection approach using the OraSure Technologies oral antibody collection device (OACD) and their proprietary SARS-CoV-2 total antibody detection enzyme-linked immunosorbent assay (ELISA). We found that the OraSure test for total antibody detection in oral fluid had comparable sensitivity and specificity to commercially available serum-based ELISAs for SARS-CoV-2 antibody detection while allowing for a more accessible form of specimen collection with the potential for self-collection.

ELISA detection of SARS-CoV-2 antibodies in saliva.

To facilitate containment of the COVID-19 pandemic currently active in the United States and across the world, options for easy, non-invasive antibody testing are required. Here we have adapted a commercially available, serum-based enzyme-linked immunosorbent assay (ELISA) for use with saliva samples, achieving 84.2% sensitivity and 100% specificity in a set of 149 clinical samples. This strategy will enable widespread, affordable testing for patients who experienced this disease, whilst minimizing exposure risk for healthcare workers.