SARS-CoV-2 receptor binding domain fusion protein efficiently neutralizes virus infection

Abstract

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) is responsible for the COVID-19 pandemic, causing health and economic problems. Currently, as dangerous mutations emerge there is an increased demand for specific treatments for SARS-CoV-2 infected patients. The spike glycoprotein on the virus membrane binds to the angiotensin converting enzyme 2 (ACE2) receptor on host cells through its receptor binding domain (RBD) to mediate virus entry. Thus, blocking this interaction may inhibit viral entry and consequently stop infection. Here, we generated fusion proteins composed of the extracellular portions of ACE2 and RBD fused to the Fc portion of human IgG1 (ACE2-Ig and RBD-Ig, respectively). We demonstrate that ACE2-Ig is enzymatically active and that it can be recognized by the SARS-CoV-2 RBD, independently of its enzymatic activity. We further show that RBD-Ig efficiently inhibits in vitro and in vivo SARS-CoV-2 infection, better than ACE2-Ig. Mechanistically we show that anti-spike antibodies generation, ACE2 enzymatic activity and ACE2 surface expression were not affected by RBD-Ig. Finally, we show that RBD-Ig is more efficient than ACE2-Ig at neutralizing high virus concentration infection. We thus propose that RBD-Ig physically blocks virus infection by binding to ACE2 and that RBD-Ig should be used for the treatment of SARS-CoV-2-infected patients.

Rheumatoid arthritis patients treated with Janus kinase inhibitors show reduced humoral immune responses following BNT162b2 vaccination

“…293T-ACE2 (5 × 10 4 ) cells were seeded in a 96-well plate and stained with 2 μg of RBD-Ig [ 15 ] for 1 h at 4°C. Cells were washed and stained with PE-conjugated goat anti-human IgG (Jackson ImmunoResearch, Cat #109–116-088, 1:200) for 45 min.…”

Infectivity of pseudotyped SARS‐CoV‐2 variants of concern in different human cell types and inhibitory effects of recombinant spike protein and entry‐related cellular factors

“…Recombinant proteins of SARS‐CoV‐2 entry‐related proteins can block SARS‐CoV‐2 infection 14,30 . We examined the inhibitory effects of recombinant S1, RBD, ACE2, Kim‐1, and NRP‐1 proteins on the infection of pseudoviruses of VOCs in Huh‐7 and A549 cells.…”

L-shaped distribution of the relative substitution rate (c/μ) observed for SARS-COV-2's genome, inconsistent with the selectionist theory, the neutral theory and the nearly neutral theory but a near-neutral balanced selection theory: Implication on “neutralist-selectionist” debate

“…In S1, the NTD, RBD and the rest of S1 exhibited four peaks each, with the RBD (e.g., A520S) and the latter portion of S1 (e.g., N658D) exhibiting the highest Ka/Ks substitution sites. Because RBD enables its binding to the host ACE2 cell surface receptor, mediating cell entry, it was targeted by antibody and vaccine therapies can neutralize and prevent cell infection [ [88] , [89] , [90] ]. The mutations in the RBD in response to these therapies has enabled antibody resistance and vaccine escape, as well as enhanced binding affinity to host ACE2 [ 91 , 92 ].…”