The SARS-CoV-2 Spike protein has a broad tropism for mammalian ACE2 proteins

Abstract

18SARS-CoV-2 emerged in late 2019, leading to the COVID-19 pandemic that continues to 19 cause significant global mortality in human populations. Given its sequence similarity to CoV, as well as related coronaviruses circulating in bats, SARS-CoV-2 is thought to have 21 originated in Chiroptera species in China. However, whether the virus spread directly to 22 humans or through an intermediate host is currently unclear, as is the potential for this virus 23to infect companion animals, livestock and wildlife that could act as viral reservoirs. Using a 24 combination of surrogate entry assays and live virus we demonstrate that, in addition to human 25 ACE2, the Spike glycoprotein of SARS-CoV-2 has a broad host tropism for mammalian ACE2 26 receptors, despite divergence in the amino acids at the Spike receptor binding site on these 27proteins. Of the twenty-two different hosts we investigated, ACE2 proteins from dog, cat and 28 rabbit were the most permissive to SARS-CoV-2, while bat and bird ACE2 proteins were the 29 least efficiently used receptors. The absence of a significant tropism for any of the three 30 genetically distinct bat ACE2 proteins we examined indicates that SARS-CoV-2 receptor 31 usage likely shifted during zoonotic transmission from bats into people, possibly in an 32 intermediate reservoir. Interestingly, while SARS-CoV-2 pseudoparticle entry was inefficient 33in cells bearing the ACE2 receptor from bats or birds the live virus was still able to enter these 34 cells, albeit with markedly lower efficiency. The apparently broad tropism of SARS-CoV-2 at 35 the point of viral entry confirms the potential risk of infection to a wide range of companion 36 animals, livestock and wildlife. 37 38Introduction 39 40The β-coronavirus SARS-CoV-2 emerged in late 2019, causing a large epidemic of respiratory 41 disease in the Hubei province of China, centred in the city of Wuhan [1]. Subsequent 42 international spread has led to an ongoing global pandemic, currently responsible for 8 million 43 infections and over 435,000 deaths (as of 11 th June 2020, John Hopkins University statistics; 44 https://coronavirus.jhu.edu/map.html). As for SARS-CoV, which emerged in China in late 45 2002, and MERS-CoV, which emerged in Saudi Arabia in 2012, the original animal reservoir 46 of zoonotic coronaviruses is thought to be bats [2]. Spill-over into humans is suspected or 47 proven to be facilitated through an intermediate host, e.g. civets for SARS-CoV [2] or camels 48 for MERS-CoV [3]. For SARS-CoV-2, a bat origin is supported by the 2013 identification of a 49 related coronavirus RaTG13 from Rhinolophus affinis (intermediate horseshoe bat), which is 50 96% identical at the genome level to SARS-CoV-2 [1]. Identifying the animal reservoir of 51 SARS-CoV-2, and any intermediate hosts via which the virus ultimately spread to humans, 52 may help to understand how, where and when this virus spilled over into people. This 53information could be vital in identifying future risk and preventing subsequent outbreaks of 54 both re...

Establishment of replication-competent vesicular stomatitis virus-based recombinant viruses suitable for SARS-CoV-2 entry and neutralization assays

“…Among five non-human cell lines, cells from monkey (Vero) and pig (ST) were susceptible, but cells from hamster (BHK-21), bovine (MDBK), and another porcine cell line (PK15) were resistant. These results were generally consistent with cell tropism profiles determined by wild type SARS-CoV-2, except for PK15 [28][29][30]. Chu et al reported that SARS-CoV-2 could infect and replicate efficiently in PK15 cells measured by quantitative RT-PCR [29].…”

“…Chu et al reported that SARS-CoV-2 could infect and replicate efficiently in PK15 cells measured by quantitative RT-PCR [29]. However, Conceicao et al demonstrated a very low level of SARS-CoV-2 infection in PK15 cells even at a higher MOI [30]. The controversy about the susceptibility of PK15 cells was likely due to differences in testing methods.…”

The Potential Intermediate Hosts for SARS-CoV-2

“…Besides, ACE2 of Rhinolophus ferrumequinum cannot support the entry of SARS-CoV-2 that is a capability of ACE2 of Rhinolophus sinicus in experiments conducted by Tang et al (2020) and Zhou P. et al (2020) . By using pseudotyping particles of SARS-CoV-2 Spike mimics particle entry and quantitative cell-cell fusion assay, Conceicao et al (2020) observed that pangolin-ACE2 sustained higher levels of entry than hACE2. Additionally, they also found dramatic difference in the ability of SARS-CoV-2 Spike to utilize ACE2 among different bat types ( Conceicao et al, 2020 ).…”

“…By using pseudotyping particles of SARS-CoV-2 Spike mimics particle entry and quantitative cell-cell fusion assay, Conceicao et al (2020) observed that pangolin-ACE2 sustained higher levels of entry than hACE2. Additionally, they also found dramatic difference in the ability of SARS-CoV-2 Spike to utilize ACE2 among different bat types ( Conceicao et al, 2020 ). The above results supported the high susceptibility of pangolin, but also indicated that diverse bat types could present different sensitivity.…”

Vaccines for COVID-19

“…SARS‐CoV‐2 has a 10–20 times higher affinity for ACE2 than the related coronavirus SARS‐CoV‐1 [3], which was responsible for the 2002–04 SARS outbreak. SARS‐CoV‐2 is able to bind ACE2 from a wide range of mammalian species [4]. Having bound ACE2, spike protein is cleaved by a host cell surface bound proteinase, either Furin or TMPRSS2, enabling entry of the viral capsid.…”