SARS‑CoV‑2 Omicron variant escapes monoclonal antibodies

In a current examine revealed on the bioRxiv* preprint server, researchers decide the neutralizing exercise of 4 monoclonal antibodies (mAbs) in opposition to ten strains of the extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which were remoted all through the pandemic.

Study: Omicron variant escapes therapeutic mAbs contrary to eight prior main VOC. Image Credit: ustas7777777 /

Research: Omicron variant escapes therapeutic mAbs opposite to eight prior primary VOC. Picture Credit score: ustas7777777 /


Presently, anti-SARS-CoV-2 mAbs are used to induce lively immunity in opposition to coronavirus illness 2019 (COVID-19) in immunocompromised sufferers who had been unresponsive to the whole vaccine routine. Research have proven that completely different strains of SARS-CoV-2 have variations in susceptibility in direction of mAbs. Furthermore, detailed info relating to mAb-associated neutralization of the SARS-CoV-2 Omicron variant is just not but obtainable.

Concerning the examine

Within the current examine, researchers examined the neutralizing exercise of mAbs reminiscent of bamlanivimab, etesevimab, casirivimab, and imdevimab in opposition to SARS-CoV-2 wild-type (B.1.1), B.1.160, Iota (B.1.526), Mu (B.1.621), Alpha (B.1.1.7), Beta (B.1.351.2), authentic Delta (AY.71), Delta sublineage (AY.4.2), Epsilon (B.1.429), and Omicron (B.1.1.529) strains.

Vero E6 cells had been cultured with out antibiotics in a minimal important medium (MEM) after which used for the neutralization exams of SARS-CoV-2 in MEM progress medium with fetal bovine serum (FBS) and glutamine.

The ten SARS-CoV-2 strains used on this examine had been remoted from SARS-CoV-2-positive nasopharyngeal swabs in cell tradition and saved at -80°C in IHU Méditerranée An infection institute. Later, the supernatant of every pressure was harvested and genotyped utilizing whole-genome next-generation (NGS) sequencing know-how.

Neutralization exams had been carried out by inoculating the viral strains into Vero E6 cells. Two days after viral an infection, the suspension was quantified utilizing reverse transcription-polymerase chain response (RT-PCR) and median tissue tradition infectious dose (TCID50) assay.

All mAbs used within the examine together with etesevimab, bamlavinimab, imdevimab, and casirivimab had been diluted in 1:5 serial dilutions. For the mix of etesevimab + bamlavinimab and casirivimab + imdevimab, the very best focus of the mixtures was examined in opposition to two instances extra etesevimab than bamlavinimab and two instances extra casirivimab than imdevimab mixtures, respectively.

A microneutralization assay was performed by mixing mAb dilutions with every viral pressure. The mAb titer required to acquire 50% neutralization in opposition to SARS-CoV-2 variants was decided utilizing an inverted optical microscope 5 days after viral an infection. Furthermore, mAbs and their mixtures had been examined thrice in opposition to all SARS-CoV-2 variants, besides Omicron, which was examined 4 instances.

Research findings

Bamlavinimab didn’t inhibit the SARS-CoV-2 Mu, Epsilon, Delta, and Beta variants. Etesevimab confirmed 50% neutralization under 5 µg/mL of the SARS-CoV-2 Epsilon, wild-type, and each Delta variants. In etesevimab and bamlanivimab mixtures, important neutralization was detected in opposition to the B.1.160, Iota, and Alpha strains.

Casirivimab confirmed outstanding neutralization in opposition to the B.1.160, wild-type, Alpha, Iota, Epsilon, and each Delta variants of SARS-CoV-2. In distinction, casirivimab didn’t neutralize SARS-CoV-2 Beta and Mu variants.

Imdevimab neutralized all SARS-CoV-2 variants besides Omicron. Nonetheless, imdevimab concentrations required for 50% neutralization of SARS-CoV-2 variants had been greater than that of casirivimab.

The casirivimab + imdevimab mixture confirmed a synergistic impact, particularly in opposition to the Epsilon, AY4.2, and AY.71 variants, with 50% neutralization at 0.03 µg/mL focus. The casirivimab + imdevimab mixture confirmed 50% neutralization at 0.2, 0.4, and 0.7 µg/mL concentrations in opposition to the SARS-CoV-2 Unique, Iota, Alpha, and B.1.160, and Beta variants, respectively.

At a focus of two µg/mL, the casirivimab + imdevimab mixture confirmed 50% neutralization in opposition to the SARS-CoV-2 Mu variant. Nonetheless, not one of the 4 mAbs alone or together exhibited neutralizing capability in opposition to Omicron.


The examine findings counsel that 4 mAbs examined had a decrease inhibitory impact on just lately rising SARS-CoV-2 variants. Nonetheless, their mixture was extremely efficient, notably in opposition to the Delta variant. In distinction, the 4 mAbs mixed or alone had been ineffective in opposition to the Omicron variant.

The current examine underscores the reinforcement of protecting measures in opposition to SARS-CoV-2 Omicron an infection amongst immunocompromised sufferers. Nonetheless, additional research are required to substantiate the ineffectiveness of mAbs in opposition to the Omicron variant.

*Necessary discover

bioRxiv publishes preliminary scientific studies that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information scientific observe/health-related habits, or handled as established info.

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