WledgmentsWe thank Felix Gut, Silvia Paoletta, and Jens Carlsson for reading and critically commenting on the manuscript.Author ContributionsConceived and designed the experiments: PK AS KAJ. Performed the experiments: PK KP ZG ACM. Analyzed the data: PK ACM KAJ. Wrote the paper: PK ACM AS KAJ.In Silico Screening for A1AR Antagonists
Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) infection in humans results in Acute Respiratory Distress Syndrome (ARDS) in 20?0 of patients with 10 mortality [1]. Passive antibody therapy has been successfully used to treat patients infected with SARS-CoV [2?], and to confer protection against lethal challenge in experimental animals [5]. Reemergence of SARS in humans remains a credible health threat because of the animal reservoirs [6?]. As of now, there is no effective treatment for SARS. However, since virus titer peaks 10 days post-infection [1,10], post-exposure treatment that is effective against a broad spectrum of viral variants remains a viable option. Many of the reported HmAbs against SARS-CoV fail to neutralize all of the clinical isolates [11?3]. Therefore, there is a need for a clinically usable therapy against SARS-CoV infection. The Spike (S) glycoprotein plays an essential role in receptor binding and membrane fusion critical for the virus entry, and contains epitopes that elicit neutralizing Abs [14?7]. The SARSCoV S protein consists of two functional domains, S1 (amino acids 12?80) and S2 
(amino acids 681?255) [18]. The receptor binding domain (RBD) (amino acids 318?10) contained within the S1 domain is required for binding to ACE-2 receptor on thecell surface and is thought to contain the majority of neutralizing epitopes [14,19,20]. Co-crystallization of the RBD and human ACE-2 identified the receptor binding motif (RBM) (amino acids 424?94) in direct contact with ACE2 [18]. The S2 domain contains the fusion peptide followed by two conserved heptad repeats (i.e. HR1 and HR2), which upon order Imazamox cleavage by cathepsin-L associate to form a fusion core [15,18,21?3], and facilitate fusion with the cell membrane required for the virus entry [24]. Synthetic HR2 peptides as well as HR2 specific antibodies have been shown to block SARS-CoV infection [25?7]. The RBD shows high rates of mutation which allows the virus to escape neutralization by Abs without losing its ability to infect cells [13,28]. In contrast, the S2 domain is highly conserved among different clinical isolates of the SARS-CoV [29,30], and thus raise the possibility that Abs against this region may confer better protection against a broad spectrum of clinical isolates. Previously, using 842-07-9 Xenomouse (mouse immunoglobulin genes were replaced by human immunoglobulin genes) immunized with SARS-CoV Urbani strain S protein ectodomain, we produced a panel of 19 neutralizing HmAbs and found that they all bound to the S1 region of the S protein [19]. We found that 18 HmAbs bound to RBD and neutralized the virus by blocking virus binding to the ACE-2 receptor, while one 
HmAb (4D4) neutralized theSARS-CoV Neutralization by Human Antibodiesvirus by inhibiting a post-binding event [11]. In this study, we describe neutralizing HmAbs that specifically bind to S2 region and found that these HmAbs, unlike S1 specific HmAbs, were better able to neutralize a broader range of surrogate clinical isolates.Materials and Methods Construction of Expression Plasmids for SARS-CoV 12-510 S1-IgG and Full Length Spike (S) Protein MutantsThe expression pla.WledgmentsWe thank Felix Gut, Silvia Paoletta, and Jens Carlsson for reading and critically commenting on the manuscript.Author ContributionsConceived and designed the experiments: PK AS KAJ. Performed the experiments: PK KP ZG ACM. Analyzed the data: PK ACM KAJ. Wrote the paper: PK ACM AS KAJ.In Silico Screening for A1AR Antagonists
Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) infection in humans results in Acute Respiratory Distress Syndrome (ARDS) in 20?0 of patients with 10 mortality [1]. Passive antibody therapy has been successfully used to treat patients infected with SARS-CoV [2?], and to confer protection against lethal challenge in experimental animals [5]. Reemergence of SARS in humans remains a credible health threat because of the animal reservoirs [6?]. As of now, there is no effective treatment for SARS. However, since virus titer peaks 10 days post-infection [1,10], post-exposure treatment that is effective against a broad spectrum of viral variants remains a viable option. Many of the reported HmAbs against SARS-CoV fail to neutralize all of the clinical isolates [11?3]. Therefore, there is a need for a clinically usable therapy against SARS-CoV infection. The Spike (S) glycoprotein plays an essential role in receptor binding and membrane fusion critical for the virus entry, and contains epitopes that elicit neutralizing Abs [14?7]. The SARSCoV S protein consists of two functional domains, S1 (amino acids 12?80) and S2 (amino acids 681?255) [18]. The receptor binding domain (RBD) (amino acids 318?10) contained within the S1 domain is required for binding to ACE-2 receptor on thecell surface and is thought to contain the majority of neutralizing epitopes [14,19,20]. Co-crystallization of the RBD and human ACE-2 identified the receptor binding motif (RBM) (amino acids 424?94) in direct contact with ACE2 [18]. The S2 domain contains the fusion peptide followed by two conserved heptad repeats (i.e. HR1 and HR2), which upon cleavage by cathepsin-L associate to form a fusion core [15,18,21?3], and facilitate fusion with the cell membrane required for the virus entry [24]. Synthetic HR2 peptides as well as HR2 specific antibodies have been shown to block SARS-CoV infection [25?7]. The RBD shows high rates of mutation which allows the virus to escape neutralization by Abs without losing its ability to infect cells [13,28]. In contrast, the S2 domain is highly conserved among different clinical isolates of the SARS-CoV [29,30], and thus raise the possibility that Abs against this region may confer better protection against a broad spectrum of clinical isolates. Previously, using Xenomouse (mouse immunoglobulin genes were replaced by human immunoglobulin genes) immunized with SARS-CoV Urbani strain S protein ectodomain, we produced a panel of 19 neutralizing HmAbs and found that they all bound to the S1 region of the S protein [19]. We found that 18 HmAbs bound to RBD and neutralized the virus by blocking virus binding to the ACE-2 receptor, while one HmAb (4D4) neutralized theSARS-CoV Neutralization by Human Antibodiesvirus by inhibiting a post-binding event [11]. In this study, we describe neutralizing HmAbs that specifically bind to S2 region and found that these HmAbs, unlike S1 specific HmAbs, were better able to neutralize a broader range of surrogate clinical isolates.Materials and Methods Construction of Expression Plasmids for SARS-CoV 12-510 S1-IgG and Full Length Spike (S) Protein MutantsThe expression pla.
