Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected at least 180 million people since its identification as the cause of the current COVID-19 pandemic. The rapid pace of vaccine development has resulted in multiple vaccines already in use worldwide. The contemporaneous emergence of SARS-CoV-2 ‘variants of concern’ (VOC) across diverse geographic locales underscores the need to monitor the efficacy of vaccines being administered globally. All WHO designated VOC carry spike (S) polymorphisms thought to enable escape from neutralizing antibodies. Here, we characterize the neutralizing activity of post-Sputnik V vaccination sera against the ensemble of S mutations present in alpha (B.1.1.7) and beta (B.1.351) VOC. Using de novo generated replication-competent vesicular stomatitis virus expressing various SARS-CoV-2-S in place of VSV-G (rcVSV-CoV2-S), coupled with a clonal 293T-ACE2 + TMPRSS2 + cell line optimized for highly efficient S-mediated infection, we determine that only 1 out of 12 post-vaccination serum samples shows effective neutralization (IC90) of rcVSV-CoV2-S: B.1.351 at full serum strength. The same set of sera efficiently neutralize S from B.1.1.7 and exhibit only moderately reduced activity against S carrying the E484K substitution alone. Taken together, our data suggest that control of some emergent SARS-CoV-2 variants may benefit from updated vaccines.

The novel pandemic betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected at least 120 million people since its identification as the cause of a December 2019 viral pneumonia outbreak in Wuhan, China1,2. Despite the unprecedented pace of vaccine development, with six vaccines already in use worldwide, the emergence of SARS-CoV-2 ‘variants of concern’ (VOC) across diverse geographic locales have prompted re-evaluation of strategies to achieve universal vaccination3. All three officially designated VOC carry Spike (S) polymorphisms thought to enable escape from neutralizing antibodies elicited during initial waves of the pandemic4–8. Here, we characterize the biological consequences of the ensemble of S mutations present in VOC lineages B.1.1.7 (501Y.V1) and B.1.351 (501Y.V2). Using a replication-competent EGFP-reporter vesicular stomatitis virus (VSV) system, rcVSV-CoV2-S, which encodes S from SARS coronavirus 2 in place of VSV-G, and coupled with a clonal HEK-293T ACE2 TMPRSS2 cell line optimized for highly efficient S-mediated infection, we determined that only 1 out of 12 serum samples from a cohort of recipients of the Gamaleya Sputnik V Ad26 / Ad5 vaccine showed effective neutralization (IC90) of rcVSV-CoV2-S: B.1.351 at full serum strength. The same set of sera efficiently neutralized S from B.1.1.7 and showed only moderately reduced activity against S carrying the E484K substitution alone. Taken together, our data suggest that control of some emergent SARS-CoV-2 variants may benefit from updated vaccines.

The novel pandemic betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected at least 120 million people since its identification as the cause of a December 2019 viral pneumonia outbreak in Wuhan, China. Despite the unprecedented pace of vaccine development, with six vaccines already in use worldwide, the emergence of SARS-CoV-2 variants of concern (VOC) across diverse geographic locales suggests herd immunity may fail to eliminate the virus. All three officially designated VOC carry Spike (S) polymorphisms thought to enable escape from neutralizing antibodies elicited during initial waves of the pandemic. Here, we characterize the biological consequences of the ensemble of S mutations present in VOC lineages B.1.1.7 (501Y.V1) and B.1.351 (501Y.V2). Using a replication-competent EGFP-reporter vesicular stomatitis virus (VSV) system, rcVSV-CoV2-S, which encodes S from SARS coronavirus 2 in place of VSV-G, coupled with a clonal HEK-293T ACE2 TMPRSS2 cell line optimized for highly efficient S-mediated infection, we determined that 8 out of 12 (75%) of serum samples from 12 recipients of the Russian Sputnik V Ad26 / Ad5 vaccine showed dose response curve slopes indicative of failure to neutralize rcVSV-CoV2-S: B.1.351. The same set of sera efficiently neutralized S from B.1.1.7 and showed only moderately reduced activity against S carrying the E484K substitution alone. Taken together, our data suggest that control of emergent SARS-CoV-2 variants may benefit from updated vaccines.

In the renal proximal tubule (PT), Na+/K+‐ATPase (NKA) is exclusively located in the basolateral domain. Through its classic ATP‐dependent ion‐pumping function, NKA generates the Na+ gradient that drives apical Na+ reabsorption, mostly through Na+/H+ exchanger (NHE3). Accordingly, activation of NKA‐mediated ion transport decreases natriuresis through activation of basolateral (NKA) and apical Na+ reabsorption (NHE3). In contrast, pharmacological evidence suggests that activation of the more recently discovered NKA signaling function triggers a cellular redistribution of NKA and NHE3 that decreases transcellular Na+ flux in cultured PT cells. To obtain genetic evidence of this NKA/Src mechanism in the PT and asses its physiological importance, we used a knockdown and rescue approach in pig renal epithelial cells (LLC‐PK1). Additionally, we genetically targeted NKA α1 in the mouse PT by crossing mice expressing a sodium glucose co‐transporter 2 promoter driven Cre transgene with Floxed NKA α1 mice (PTα1‐/‐). Knockdown of 90% of NKA α1 in PT LLC‐PK1 cells increased transepithelial 22Na flux by 2‐fold, activated NHE3 (50% decrease in inhibitory phosphorylation), and increased basolateral Na+/HCO3‐ cotransporter (NBCe1A) protein content. In the PTα1‐/‐ mouse (4‐month males and females in a 1:1 ratio), 70% decrease in PT NKA α1 expression decreased urine output (0.51±0.14 vs 1.57±0.21 mL/24h in PTα1+/+, p<0.001, n=16) and absolute Na+ excretion (0.14±0.05 vs 0.36±0.05 mmol/24h in PTα1+/+, p<0.05, n=8) by 65%, without histological or functional evidence of renal injury. Those changes were driven by increased PT Na+ reabsorption, as indicated by a 65% decrease in lithium clearance (4‐month males, 1344±220 vs 3932±697 mL/24h in PTα1+/+, p<0.001, n=12) with unchanged GFR. This hyper‐reabsorptive phenotype of PTα1‐/‐ mice was coupled to increased membrane abundance of NHE3 and NBCe1A, and rescued upon crossing with floxed NHE3 mice, consistent a NKA/NHE3‐dependent mechanism. A dismantlement of caveolar NKA/Src receptor complex and intracellular redistribution of pY418Src occurred in knockdown NKA α1 PT cells, and was also observed in the PTα1‐/‐ hypomorphic mouse. Rescue of PT cells with wild‐type but not Src signaling‐null NKA α1 restored NHE3 and NBCe1A to basal levels, indicative of a role for NKA/Src receptor function in the tonic inhibition of Na+ transporters in the PT. Hence, NKA signaling exerts a tonic inhibition on Na+ reabsorption by regulating key apical and basolateral Na+ transporters. This action, which is lifted upon NKA genetic suppression in cells and in vivo, tonically counteracts NKA's ATP‐driven function of basolateral Na+ reabsorption. Strikingly, NKA/Src signaling is not only physiologically relevant, it is functionally dominant over NKA ion‐pumping in the control of PT reabsorption. NKA signaling therefore provides a long sought‐after mechanism for the natriuretic action of endogenous NKA ligands such as cardiotonic steroids.

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