Characterization of novel monoclonal antibodies against MERS-coronavirus spike protein

Abstract

Middle East Respiratory Syndrome coronavirus (MERS-CoV) causes severe pulmonary infection, with ∼35 % mortality. Spike glycoprotein (S) of MERS-CoV is a key target for vaccines and therapeutics because S mediates viral entry and membrane-fusion to host cells. Here, four different S subunit proteins, receptor-binding domain (RBD; 358-606 aa), S1 (1-751 aa), S2 (752-1296 aa), and SΔTM (1-1296 aa), were generated using the baculoviral system and immunized in mice to develop neutralizing antibodies. We developed 77 hybridomas and selected five neutralizing mAbs by immunization with SΔTM against MERS-CoV EMC/2012 strain S-pseudotyped lentivirus. However, all five monoclonal antibodies (mAb) did not neutralize the pseudotyped V534A mutation. Additionally, one mAb RBD-14F8 did not show neutralizing activity against pseudoviruses with amino acid substitution of L506 F or D509 G (England1 strain, EMC/2012 L506 F, and EMC/2012 D509 G), and RBD-43E4 mAb could not neutralize the pseudotyped I529 T mutation, while three other neutralizing mAbs showed broad neutralizing activity. This implies that the mutation in residue 506-509, 529, and 534 of S is critical to generate neutralization escape variants of MERS-CoV. Interestingly, all five neutralizing mAbs have binding affinity to RBD, although most mAbs generated by RBD did not have neutralizing activity. Additionally, chimeric antibodies of RBD-14F8 and RBD-43E4 with human Fc and light chain showed neutralizing effect against wild type MERS-CoV KOR/KNIH/002, similar to the original mouse mAbs. Thus, our mAbs can be utilized for the identification of specific mutations of MERS-CoV.

COVID-19, an emerging coronavirus infection: advances and prospects in designing and developing vaccines, immunotherapeutics, and therapeutics

“…These mAbs bind to six specific epitope groups interacting with the receptor binding, membrane fusion, and sialic acid-binding sites, which represent the three important entry functions of MERS-CoV S protein. 21,38 Moreover, passive immunization with poorly and potently neutralizing antibodies induces substantial protection in mice subjected to lethal MERS-CoV challenge. Thus, use of these antibodies may represent a novel approach to increase humoral protection against emerging CoVs by targeting various S protein epitopes and functions.…”

Coronaviruses: a paradigm of new emerging zoonotic diseases

“…Recently, Wang and co-workers reported that Remdesivir, a nucleotide analogue prodrug initially developed for the treatment of Ebola and Marburg virus infection, and the anti-malarial drug chloroquine are effective to inhibit 2019-nCoV replication in vitro . Finally, the development and use of neutralizing monoclonal antibodies, as proposed in the case of SARS and MERS, could be envisioned for 2019-nCoV control as well (Kim et al 2019;Goo et al 2020). Many monoclonal antibodies neutralizing SARS-CoV and MERS-CoV infections have been identified, and some of them displayed a potent inhibitory effect in in vitro and in vivo experiments.…”

2019 Novel coronavirus (COVID-19) overview

“…Genomic RNA is encapsulated and polyadenylated, and it encodes various structural and non-structural polypeptide genes (Cui et al 2019;Subissi et al 2014). These polyproteins are split by proteases that exhibit chymotrypsin-like activity (Subissi et al 2014;Goo et al 2020). The resulting complex drives (−) RNA production through both replication and transcription (Jordan et al 2018).…”

“…MERS-CoV can affect human dendritic cells, macrophages and T lymphocytes. This virus can make the antiviral T cell response irregular because of the stimulation of T cell apoptosis, thus causing a collapse of the immune system (Farooq et al 2020;Park et al 2019;Goo et al 2020;Cockrell et al 2016).…”

“…The sensitivity of antibody detection is generally lower than that of molecular methods and is mostly used in retrospective diagnosis (Goo et al 2020;Li et al 2020b). Viral culture is a more time-consuming method compared with the other methods.…”