Antibody Responses to SARS-CoV-2 mRNA Vaccines Are Detectable in Saliva

The approved Pfizer and Moderna mRNA vaccines are well known to induce serum antibody responses to the SARS-CoV-2 Spike (S)-protein. However, their abilities to elicit mucosal immune responses have not been reported. Saliva antibodies represent mucosal responses that may be relevant to how mRNA vaccines prevent oral and nasal SARS-CoV-2 transmission. Here, we describe the outcome of a cross-sectional study on a healthcare worker cohort (WELCOME-NYPH), in which we assessed whether IgM, IgG, and IgA antibodies to the S-protein and its receptor-binding domain (RBD) were present in serum and saliva samples. Anti-S-protein IgG was detected in 14/31 and 66/66 of saliva samples from uninfected participants after vaccine doses-1 and -2, respectively. IgA antibodies to the S-protein were present in 40/66 saliva samples after dose 2. Anti-S-protein IgG was present in every serum sample from recipients of 2 vaccine doses. Vaccine-induced antibodies against the RBD were also frequently present in saliva and sera. These findings may help our understanding of whether and how vaccines may impede SARS-CoV-2 transmission, including to oral cavity target cells.

Postconvalescent SARS-CoV-2 IgG and Neutralizing Antibodies are Elevated in Individuals with Poor Metabolic Health

PURPOSE

Comorbidities making up metabolic syndrome (MetS), such as obesity, type 2 diabetes, and chronic cardiovascular disease can lead to increased risk of coronavirus disease-2019 (COVID-19) with a higher morbidity and mortality. SARS-CoV-2 antibodies are higher in severely or critically ill COVID-19 patients, but studies have not focused on levels in convalescent patients with MetS, which this study aimed to assess.

METHODS

This retrospective study focused on adult convalescent outpatients with SARS-CoV-2 positive serology during the COVID-19 pandemic at NewYork Presbyterian/Weill Cornell. Data collected for descriptive and correlative analysis included SARS-COV-2 immunoglobin G (IgG) levels and history of MetS comorbidities from April 17, 2020 to May 20, 2020. Additional data, including SARS-CoV-2 IgG levels, body mass index (BMI), hemoglobin A1c (HbA1c) and lipid levels were collected and analyzed for a second cohort from May 21, 2020 to June 21, 2020. SARS-CoV-2 neutralizing antibodies were measured in a subset of the study cohort.

RESULTS

SARS-CoV-2 IgG levels were significantly higher in convalescent individuals with MetS comorbidities. When adjusted for age, sex, race, and time duration from symptom onset to testing, increased SARS-CoV-2 IgG levels remained significantly associated with obesity (P < 0.0001). SARS-CoV-2 IgG levels were significantly higher in patients with HbA1c ≥6.5% compared to those with HbA1c <5.7% (P = 0.0197) and remained significant on multivariable analysis (P = 0.0104). A positive correlation was noted between BMI and antibody levels [95% confidence interval: 0.37 (0.20-0.52) P < 0.0001]. Neutralizing antibody titers were higher in COVID-19 individuals with BMI ≥ 30 (P = 0.0055).

CONCLUSION

Postconvalescent SARS-CoV-2 IgG and neutralizing antibodies are elevated in obese patients, and a positive correlation exists between BMI and antibody levels.

Antibody responses to SARS-CoV-2 mRNA vaccines are detectable in saliva

Vaccines are critical for curtailing the COVID-19 pandemic (1, 2). In the USA, two highly protective mRNA vaccines are available: BNT162b2 from Pfizer/BioNTech and mRNA-1273 from Moderna (3, 4). These vaccines induce antibodies to the SARS-CoV-2 S-protein, including neutralizing antibodies (NAbs) predominantly directed against the Receptor Binding Domain (RBD) (1-4). Serum NAbs are induced at modest levels within ~1 week of the first dose, but their titers are strongly boosted by a second dose at 3 (BNT162b2) or 4 weeks (mRNA-1273) (3, 4). SARS-CoV-2 is most commonly transmitted nasally or orally and infects cells in the mucosae of the respiratory and to some extent also the gastrointestinal tract (5). Although serum NAbs may be a correlate of protection against COVID-19, mucosal antibodies might directly prevent or limit virus acquisition by the nasal, oral and conjunctival routes (5). Whether the mRNA vaccines induce mucosal immunity has not been studied. Here, we report that antibodies to the S-protein and its RBD are present in saliva samples from mRNA-vaccinated healthcare workers (HCW). Within 1-2 weeks after their second dose, 37/37 and 8/8 recipients of the Pfizer and Moderna vaccines, respectively, had S-protein IgG antibodies in their saliva, while IgA was detected in a substantial proportion. These observations may be relevant to vaccine-mediated protection from SARS-CoV-2 infection and disease.

Testing-on-a-probe biosensors reveal association of early SARS-CoV-2 total antibodies and surrogate neutralizing antibodies with mortality in COVID-19 patients

The association of mortality with the early humoral response to SARS-CoV-2 infection within the first few days after onset of symptoms (DAOS) has not been thoroughly investigated partly due to a lack of sufficiently sensitive antibody testing methods. Here we report two sensitive and automated testing-on-a-probe (TOP) biosensor assays for SARS-CoV-2 viral specific total antibodies (TAb) and surrogate neutralizing antibodies (SNAb), which are suitable for clinical use. The TOP assays employ an RBD-coated quartz probe using a Cy5-Streptavidin-polysacharide conjugate to improve sensitivity and minimize interference. Disposable cartridges containing pre-dispensed reagents require no liquid manipulation or fluidics during testing. The TOP-TAb assay exhibited higher sensitivity in the 0-7 DAOS window than a widely used FDA-EUA assay. The rapid and automated TOP-SNAb correlated well with two well-established SARS-CoV-2 virus neutralization tests. The clinical utility of the TOP assays was demonstrated by evaluating early antibody responses in 120 SARS-CoV-2 RT-PCR positive adult hospitalized patients. Higher TAb and SNAb positivity rates and more robust antibody responses at patient's initial hospital presentation were seen in inpatients who survived COVID-19 than those who died in the hospital. Survival analysis using the Cox Proportional Hazards Model showed that patients who had negative TAb and/or SNAb at initial hospital presentation were at a higher risk of in-hospital mortality. Furthermore, TAb and SNAb levels at presentation were inversely associated with SARS-CoV-2 viral load based on concurrent RT-PCR testing. Overall, the sensitive and automated TAb and SNAb assays allow the detection of early SARS-CoV-2 antibodies which associate with mortality.

Anti-myelin-associated glycoprotein IgM antibody titers in neuropathy associated with macroglobulinemia

Twenty-seven patients with neuropathy and IgM monoclonal gammopathy were tested for antigen specificity of the M-protein and for anti-myelin-associated glycoprotein (MAG) IgM levels by immunoblot. In 16 patients (59.2%) the M-protein reacted with MAG and with cross-reactive glycoconjugates. Anti-MAG IgM titers in these patients ranged between 1:12,800 and 1:100,000. A fainter IgM reactivity with MAG and related glycoconjugates was detected in 3 additional patients with neuropathy, but also in 8 of 24 patients with IgM M-protein without neuropathy (33.3%). This reactivity was not due to the M-protein and corresponded to antibody titers of 1:400 or less in all but 1 patient with a titer of 1:3,200. Low titers of anti-MAG IgM (1:200 or less) were also detected in 17 of 101 control patients without IgM M-proteins (16.8%), while 1 patient with neuropathy of unknown cause had anti-MAG IgMK titers of 1:25,600. In 1 patient with neuropathy and IgM M-protein that was not anti-MAG, the M-protein bound to other antigens in nerve, while in 6, other possible causes or mechanisms for the neuropathy were found. In this study, high titers of anti-MAG IgM antibodies were always associated with neuropathy. The presence of low levels of anti-MAG IgM in a significant proportion of controls suggests that monoclonal expansion of naturally occurring B-cell clones secreting anti-MAG IgM may be responsible for the high incidence of this antigen specificity of the M-protein.

Treatment of patients with neuropathy and anti-MAG IgM M-proteins

Five patients with neuropathy and IgM M-proteins that reacted with myelin-associated glycoprotein (MAG) were treated for 10 to 20 months with cytostatic agents. In 2 patients, a decrease in serum M-protein and in anti-MAG IgM levels coincided with a progressive improvement of neuropathy. No clinical improvement and no decrease of anti-MAG IgM were observed in the other patients. The close relationship between the decrease of anti-MAG M-proteins and clinical improvement in these patients supports the pathogenetic role of the M-protein in the neuropathy.

Studies on anti-myelin antibodies in patients with multiple sclerosis

We studied the CSF and sera from 16 patients with MS to detect IgG antibody activity against normal CNS myelin and some of its proteic and lipidic components. IgG binding to a protein band of the same MW of myelin basic protein was detected by "immunoblot" in the sera and/or CSF of 25% of patients with MS and in none of the controls with OND. No IgG antibody reactivity against other components of CNS myelin was detectable in patients with MS, and immunoabsorption of the CSF of MS patients with CNS myelin did not modify the oligoclonal prophile of CSF IgG. Anti-myelin antibodies do not seem to represent the bulk of oligoclonal IgG in MS patients.