The SARS-CoV-2 Virus-Host Interaction Antibody Sampler Kit provides an economical means of detecting key viral and host proteins involved in SARS-CoV-2 infection of human host cells. The kit includes enough antibodies to perform two western blot experiments with each primary antibody.
Specificity / Sensitivity
Each antibody in the SARS-CoV-2 Virus-Host Interaction Antibody Sampler Kit detects endogenous levels of its target protein. For viral proteins, endogenous expression is defined as levels of target protein present in host cells following infection with the SARS-CoV-2 virus. SARS-CoV-2 Spike Protein (S1) (E5S3V) Rabbit mAb and SARS-CoV-2 Spike Protein (RBD) (E7B3E) Rabbit mAb detect both the full-length SARS-CoV-2 spike protein and the S1 fragment (containing the receptor-binding domain) generated by furin cleavage. Cleaved SARS-CoV-2 Spike Protein (Ser686) Antibody specifically detects the S2 fragment of SARS-CoV-2 spike protein only after cleavage at the S1/S2 junction. The antibodies targeting SARS-CoV-2 proteins do not detect orthologous spike proteins from SARS or MERS coronaviruses. Neuropilin-1 (D62C6) Rabbit mAb detects endogenous levels of total neuropilin-1 protein, but also detects an 80 kDa protein of unknown identity.
Source / Purification
Monoclonal antibodies are produced by immunizing animals with synthetic peptides corresponding to residues surrounding Ala254 of human EMMPRIN protein, Asp201 of human ACE2 protein, and Ser459 of SARS-CoV-2 spike protein, with a recombinant protein corresponding to the S1 domain of the SARS-CoV-2 spike protein, and with a GST-fusion protein corresponding to residues of mouse neuropilin-1 protein. Polyclonal antibodies are produced by immunizing animals with synthetic peptides corresponding to the amino terminus (Ser668) of the SARS-CoV-2 spike protein S2 domain, Pro229 of human cathepsin L, and Ala237 of human furin protein.
The cause of the COVID-19 pandemic is a novel and highly pathogenic coronavirus, termed SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2). SARS-CoV-2 is a member of the Coronaviridae family of viruses (1). The SARS-CoV-2 virion is comprised of four key structural proteins: spike (S), envelope (E), membrane (M), and nucleocapsid (N) (2). Coronavirus spike proteins are class I fusion proteins and harbor an ectodomain, a transmembrane domain, and an intracellular tail (3,4). The highly glycosylated ectodomain projects from the viral envelope surface and facilitates attachment and fusion with the host cell membrane. The ectodomain can be further subdivided into the receptor-binding domain (RBD) S1 and membrane-fusion (S2) subunits, which are produced upon proteolysis by host proteases. S1 and S2 subunits are reassociated after cleavage, assembling into crown-like homotrimers (2,4).
The SARS-CoV-2 spike protein contains a novel tetrabasic "furin cleavage site" (FCS) at the S1/S2 junction. Research studies suggest this site is cleaved by proprotein convertases (e.g., furin) or lysosomal proteases (e.g., cathepsin L) (5,6). S1/S2 cleavage elicits a confirmational change in the spike protein that positions elements of the trimeric RBD in an exposed "up" position, priming it for interaction with host receptor proteins. Cleavage can occur at multiple steps of the viral lifecycle, including during viral packaging, or upon contact of the intact virion with the host cell surface. This novel cleavage event has been suggested to contribute to the high infectivity rate of the SARS-CoV-2 virus (7).
The SARS-CoV-2 virus has been shown to utilize the angiotensin-converting enzyme 2 (ACE2) protein as its primary receptor for cellular entry (8). However, research studies have suggested that other cell surface proteins may serve as receptors or co-receptors for SARS-CoV-2. These include neuropilin-1 (NPN1), a single-pass transmembrane receptor that can function as part of a semaphorin receptor complex, and as a vascular endothelial growth factor (VEGF) receptor (9), and Basigin/EMMPRIN (CD147), a type I integral membrane receptor belonging to the immunoglobulin superfamily (10).