S:D614G and S:H655Y are gateway mutations that act epistatically to promote SARS-CoV-2 variant fitness

Abstract/Summary SARS-CoV-2 variants bearing complex combinations of mutations that confer increased transmissibility, COVID-19 severity, and immune escape, were first detected after S:D614G had gone to fixation, and likely originated during persistent infection of immunocompromised hosts. To test the hypothesis that S:D614G facilitated emergence of such variants, S:D614G was reverted to the ancestral sequence in the context of sequential Spike sequences from an immunocompromised individual, and within each of the major SARS-CoV-2 variants of concern. In all cases, infectivity of the S:D614G revertants was severely compromised. The infectivity of atypical SARS-CoV-2 lineages that propagated in the absence of S:D614G was found to be dependent upon either S:Q613H or S:H655Y. Notably, Gamma and Omicron variants possess both S:D614G and S:H655Y, each of which contributed to infectivity of these variants. Among sarbecoviruses, S:Q613H, S:D614G, and S:H655Y are only detected in SARS-CoV-2, which is also distinguished by a polybasic S1/S2 cleavage site. Genetic and biochemical experiments here showed that S:Q613H, S:D614G, and S:H655Y each stabilize Spike on virions, and that they are dispensable in the absence of S1/S2 cleavage, consistent with selection of these mutations by the S1/S2 cleavage site. CryoEM revealed that either S:D614G or S:H655Y shift the Spike receptor binding domain (RBD) towards the open conformation required for ACE2-binding and therefore on pathway for infection. Consistent with this, an smFRET reporter for RBD conformation showed that both S:D614G and S:H655Y spontaneously adopt the conformation that ACE2 induces in the parental Spike. Data from these orthogonal experiments demonstrate that S:D614G and S:H655Y are convergent adaptations to the polybasic S1/S2 cleavage site which stabilize S1 on the virion in the open RBD conformation and act epistatically to promote the fitness of variants bearing complex combinations of clinically significant mutations.Abstract Figure <jats:fig id="ufig1" position="float" orientation="portrait" fig-type="figure"><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="535005v2_ufig1" position="float" orientation="portrait" /></jats:fig>Highlights <jats:list list-type="bullet">S:D614G is ubiquitous among SARS-CoV-2 B-lineage Spikes and is required for infectivity of the main Variants of ConcernIn an example of convergent evolution, SARS-CoV-2 A lineage viruses maintained transmission chains in the absence of S:D614G, but were instead dependent upon S:Q613H or S:H655YS:D614G and S:H655Y are both adaptations to the polybasic S1/S2 cleavage siteIncreased infectivity of S:D614G and S:H655Y is associated with a more open RBD conformation and increased steady-state levels of virion-associated S1.

Medienart:

Preprint

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

bioRxiv.org - (2023) vom: 26. Apr. Zur Gesamtaufnahme - year:2023

Sprache:

Englisch

Beteiligte Personen:

Yurkovetskiy, Leonid [VerfasserIn]
Egri, Shawn [VerfasserIn]
Kurhade, Chaitanya [VerfasserIn]
Diaz-Salinas, Marco A. [VerfasserIn]
Jaimes, Javier A. [VerfasserIn]
Nyalile, Thomas [VerfasserIn]
Xie, Xuping [VerfasserIn]
Choudhary, Manish C. [VerfasserIn]
Dauphin, Ann [VerfasserIn]
Li, Jonathan Z. [VerfasserIn]
Munro, James B. [VerfasserIn]
Shi, Pei-Yong [VerfasserIn]
Shen, Kuang [VerfasserIn]
Luban, Jeremy [VerfasserIn]

Links:

Volltext [kostenfrei]

Themen:

570
Biology

doi:

10.1101/2023.03.30.535005

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

XBI039126307