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Olfactory receptors are the largest group of orphan G protein-coupled receptors with an infinitely small number of agonists identified out of thousands of odorants. The de-orphaning of olfactory receptor (OR) is complicated by its combinatorial odorant coding and thus requires large scale odorant and receptor screening and establishing receptor-specific odorant profiles. Here, we report on the stable reconstitution of OR-specific signaling in HeLa/Olf cells via G protein ␣olf and adenylyl cyclase type-III to the Ca 2؉ influx-mediating olfactory cyclic nucleotide-gated CNGA2 channel. We demonstrate the central role of G␣olf in odorant-specific signaling out of OR. The employment of the non-typical G protein ␣15 dramatically altered the odorant specificities of 3 of 7 receptors that had been characterized previously by different groups. We further show for two OR that an odorant may be an agonist or antagonist, depending on the G protein used. HeLa/Olf cells proved suitable for high-throughput screening in fluorescenceimaging plate reader experiments, resulting in the deorphaning of two new OR for the odorant (؊)citronellal from an expression library of 93 receptors. To demonstrate the G protein dependence of its odorant response pattern, we screened the most sensitive (؊)citronellal receptor Olfr43 versus 94 odorants simultaneously in the presence of G␣15 or G␣olf. We finally established an EC 50 -ranking odorant profile for Olfr43 in HeLa/Olf cells. In summary, we conclude that, in heterologous systems, odorants may function as agonists or antagonists, depending on the G protein used. HeLa/Olf cells provide an olfactory model system for functional expression and de-orphaning of OR.

Anti-SARS-CoV-2 mRNA vaccine in patients with rheumatoid arthritisLong-term vaccine-induced immunity is crucial for controlling the COVID-19 pandemic. Vaccination against COVID-19 is recommended for patients with rheumatic diseases, but a paucity of data are available regarding COVID-19 vaccines in patients with rheumatoid arthritis. Because patients receiving immunosuppressive treatment were excluded from the phase 3 clinical trials, 1,2 it is not clear whether disease-modifying anti-rheumatic drug (DMARD) treatment should be continued before and after vaccination. In addition, some published reports are limited to follow-up after a single vaccine dose. [3][4][5] Here we report 53 consecutive patients with rheumatoid arthritis on DMARDs and 20 healthy controls (appendix p 1) who were eligible for vaccination according to the Swiss federal regulations and were enrolled in the RECOVER study, a non-randomised, prospective, observational trial. The RECOVER study was approved by the Ethical Committee of St Gallen, Switzerland, and written consent was obtained from all patients before inclusion. The vaccination itself was not part of the study. Nine patients received two doses of the mRNA-1273 vaccine (Moderna), all others received two doses of the BNT162b2 vaccine (Pfizer-BioNTech). Serum samples were collected at baseline, 3 weeks after the first vaccination, and 2 weeks after the second vaccination. Quantitative antibody testing was done using the Roche Elecsys Anti-SARS-CoV-2 spike subunit 1 (S1) assay that measures antibodies to SARS-CoV-2 spike protein 1 (range 0•4-2500 U/mL) and to SARS-CoV-2 nucleoprotein. This assay was used because it can distinguish between people who develop an anti-S1 response after vaccination or after natural infection, when typically antibodies to both S1 and nucleoprotein are generated. The threshold for this anti-SARS-CoV-2 S1 assay that might correspond to neutralisation of viral infectivity is still being discussed, but a cutoff level of 133 U/mL has been proposed. 6 A lower cutoff level of >15 U/mL has been suggested, 7 emphasising the need to establish formal cutoff levels of anti-SARS-CoV-2 antibody titres associated with protection against SARS-CoV-2 infection and severe disease.Intervals between the first and second vaccine dose and the intervals between vaccination and serum

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