Mutational Profile of SARS-CoV-2 Spike Protein in Brazilian isolates

doi:10.21203/rs.3.rs-402349/v1

Download PDF

Short Report

Mutational Profile of SARS-CoV-2 Spike Protein in Brazilian isolates

https://doi.org/10.21203/rs.3.rs-402349/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this older preprint version

Read the latest preprint version →

Due to the essential role of S protein in early steps of SARS-CoV-2 replication, high antigenicity and surface exposure the spike protein has been recognized as the most promising molecular target for neutralizing antibodies, diagnostic methods, vaccines, and antiviral drugs development to control the COVID-19. In this study we analyzed the most predominant mutations in S protein of Brazilian isolates and predicted the effect of these amino acids alterations to protein conformation. A total of 2869 sequences were obtained from GISAID for five regions of Brazilian territory (Midwest, North, Northeast, South and Southeast) according to exclusion criteria. Prediction effects of the amino acids substitutions on the structure dynamics of spike protein indicated a positive ΔΔG value for seven mutations and negative for three mutations. These seven mutations also had positive values of ΔΔSVib which is associated to reduction of molecular flexibility of spike protein allowing for adaptative convergent evolution principles to take place. These lineages which are circulating in Brazil, which based on structure-based prediction of protein stability, maybe are changing in different conformational states affecting infectivity and our results point to an increased stability and reduced flexibility of the P1 variant of concern. The advance of infections and re-infections require continuous genomic surveillance studies in order to characterize emerging mutations and monitoring of vaccines efficacy thus considering structural data and dynamics in the observed phenotypes.

Structural Biology

Structure dynamics

Adaptative evolution

Convergent adaptative evolution

Molecular dynamics

SARS-CoV-2

Coronaviruses (CoVs) consists of a wide group of enveloped viruses from Coronaviridae family which transmit respiratory, enteric, liver and neurological diseases in several avian and mammalian species (Woo et al., 2009). Human coronaviruses (hCoVs) infections were associated to mild diseases until the global emergence of Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS-CoV) coronaviruses in 2002 and 2012, respectively (Drosten et al., 2003; Nassar et al., 2018; Peret et al., 2003; Zaki et al., 2012). In late December 2019, several cases of pneumonia of unknown origin were reported in Wuhan (China) and in January 2020 the causal agent was defined as the severe acute respiratory syndrome (SARS-CoV 2) (Wu et al., 2020). SARS-CoV-2 infections spread rapidly worldwide, and the World Health Organization declared a pandemic status for the disease caused by SARS-CoV-2 infection (COVID-19) which currently has more than 130 million confirmed cases with global distribution (WHO, 2021).

SARS-CoV-2 genome is a (+) ssRNA of approximately 30 kb which encodes for nonstructural proteins (NSPs) from two open reading frames 1a and 1b (ORF1a and ORF1b) that is cleaved into individual nonstructural proteins (NSPs). Subgenomic RNAs (sgRNAs) are synthesized from negative-sense RNA intermediates and subsequently sgRNA is translated into four structural proteins such as spike (S), envelope (E), membrane (M) and nucleocapside (N) (Dongwan et al., 2020). In addition, six accessories proteins are encoded by ORF3a, ORF6, ORF7a, ORF7b, and ORF8 genes (Khailany et al., 2020; Li et al., 2005; Oostra et al., 2007).

The Spike (S) protein is a conserved, transmembrane class I fusion, glycoprotein that mediates CoVs entry into host cells (Du et al., 2009; Lan et al., 2020). This protein forms homotrimers in the mature viral surface and comprises two functional subunits denominated S1 and S2, which are responsible for binding into cell receptor such as angiotensin-converting enzyme 2 (ACE-2) and for fusion of viral and cellular membranes, respectively (Walls et al., 2020). Due to the essential role of S protein in early steps of viral replication, high antigenicity and surface exposure the spike protein has been recognized as the most promising molecular target for neutralizing antibodies, diagnostic methods, vaccines, and antiviral drugs development (Moura et al., 2021; Suryadevara et al., 2021; Townsend et al., 2021).

Studies on the evolutionary dynamics of structural proteins of SARS-CoV-2 are useful for development of novel vaccines, diagnostic tests and therapeutic strategies. It has been observed that several amino acids substitutions in the S protein had affected virulence properties worldwide. In this study we analyzed the most predominant mutations in S protein of Brazilian isolates and predicted the effect of these amino acids alterations to protein conformation.

A total of 2869 sequences were obtained from GISAID for five regions of Brazilian territory (Midwest, North, Northeast, South and Southeast) according to exclusion criteria. Southeast region showed the highest number of RNA sequences available on GISAID (1122; 39.1%), followed by North (644; 22.4 %), Northeast (533; 18.62%), South (436; 15.2%), and Midwest (134; 4.7%). The states of Sao Paulo (SP), Rio de Janeiro (RJ) and Rio Grande do Sul (RS) had the highest number of sequences (533, 485 and 324, respectively). In addition, at least one mutation was detected in 94.9% of genomes (2722 of 2869).

The SARS-CoV-2 genome sequences from Brazil revealed the most prevalent variants belongs to the clade GR (2457/2722; 90.3%), G (119/2722; 4.4%) and GH (23/2722; 0.8%). The G clade genomes, including GH and GR sub-clusters, are predominant in Europe specially United Kingdom, Portugal and Russia (Mercatelli and Giorgi, 2020; Resende et al., 2020). The L genome, which is related to the SARS-CoV-2 reference genome, were only detect in two genomes sample from The State of Bahia.

Amino-acid mutation frequency of spike proteins were analyzed, and the top ten sequences are described in Table 1. A total of 208 amino acid positions substitutions found in the S protein sequences. The subunits S1 and S2 presented with 114 and 85 substitutions, respectively. Most of these amino acid substitutions were D614G, V1176F and E484K. Among the deletions an overall 139 mutations were detected in nine amino acids: Y144 (50/139), H69(40/139), V70 (36/139), V143(4/139), G142 (4/139), L141(3/139), R190 (1/139) and L189 (1/139).

Prediction of effect of the amino acids substitutions on the structure dynamics of spike protein indicated a positive ΔΔG value for seven mutations and negative for three mutations, as described in Table 2. The most prevalent mutations in Brazil (D614G, V1176F and E484K) and H655Y showed higher ΔΔG value indicating a great stabilizing effect on structural dynamics of the S protein. These seven mutations also had positive values of ΔΔSVib which is associated to reduction of molecular flexibility of spike protein.

The rapid spread of SARS-CoV-2 worldwide has been associated to a large number of genomic mutations leading the emergence of new lineages. Currently, Brazil reported more than 12 million of SARS-CoV-2 infections and have been considerate the epicenter of COVID-19 pandemic. Thus, the investigation of the mutational spectra of Brazilian isolates of SARS-CoV-2 are important tools comprehension of virulence, drugs and vaccines efficacy of emerging lineages.

The subunit S1 of the S protein (14–685 residues) plays an essential role in the transmission and pathogenesis of COVID-19 involving the binding of the virus to the host cellular angiotensin-converting enzyme (ACE-2) in host cell-surface. In this study, we found a high number of amino acid substitution in S1 in comparison to S2 subunit (114 versus 85). The D614G mutation occurs in SD2 domain of S1 subunit and have been classified under the G clade. Since the emergence of COVID-19 pandemic several studies have reported the critical role of D614G in the increase of infectivity, transmissibility, and mortality rate of SARS-CoV-2 worldwide (Mahmoudi Gomari et al., 2021; Mohammad et al., 2021; Plante et al., 2020). In addition, the global prevalent mutation D614G is related to immune system evasion process. Our data indicated D614G is the dominant form among Brazilian isolates containing at least one mutation (2645/2722; 97%).

The V1176F was found in 52% of the SARS-CoV-2 isolated sequences evaluated herein. As opposed to D614G, the V1176F mutation occurs in the subunit S2 of S protein (686–1273 residues) which mediates fusion of viral and host cell membranes leading to the release of SARS-CoV-2 genome into host cell. Despite no antigenic effect has yet been reported to V1176F, this variation along with D614G have been positively correlated to increased severity and mortality rates in Saudi-Arabia and South America, including Brazil (Farkas et al., 2020).

Up to this point, the variants of concern with most spread of the SARS-CoV-2 worldwide originated in United Kingdom (B.1.1.7), South Africa (B.1.351) and Brazil (P.1 and P.2). These lineages were strongly associated to an increase in transmissibility, mortality and re-infections reports due to the high incidence of E484K, N501Y and K417N mutations in the in RDB domain of S1 subunit of S protein. In this study, we found that mutations E484K, N501Y and K417N have high frequency among Brazilian isolates. According to our data, recent structural studies have described the role of emerging variants containing E484K, N501Y and K417N mutations on alteration of molecular flexibility of S protein mediating the increase the affinity of RBD to ACE2 receptor and facilitating SARS-CoV-2 infection (Khan et al., 2021; Ortuso et al., 2021). The effect of E484K, N501Y and K417N mutations variants in the reduction of neutralizing activity of human convalescent and post-vaccination sera remains unclear (Jangra et al., 2021; Xie et al., 2021).

These events suggest that emerging mutations are associated with independent founding events evaluating to a convergent adaptative evolution of the virus in naive populations, our results are in agreement with stabilizing mutation studies which suggest more rigid structural bodies in natural selection. Hydrogen bonds (H-bonds) and hydrophobic interactions are important specific interactions in the maintenance and stabilization of tridimensional structure of proteins. The increased number of H-bonds (e.g. mutant E484 establish interactions to E488 and E490 residues) and hydrophobic (e.g. mutant F1176 establish interactions to C956 and C957 residues) interactions observed in our experiments are suggestive of more rigid structures and our ΔΔG results are also in agreement with this statement (Figure 1). Actually, more than 12 million positive confirmed cases of SARS-CoV-2 infections in Brazil. There is a lack in genomic monitoring of SARS-CoV-2 in Brazil. Thus, the advance of infections and re-infections require continuous genomic surveillance studies in order to characterize emerging mutations and monitoring of vaccines efficacy.

In order to evaluated genetic variations of the S protein, we retrieved 3,093 genome sequences of SARS-CoV-2 isolated in Brazil available at Global Initiative On Sharing All Influenza Data (GISAID - https://www.gisaid.org) up to March 25, 2021. These sequences belong to infected patients from 26 states in Brazil and 1 Federal District. The search was refined by exclusion of low quality, ambiguous and non-human host RNA sequences through search filters available in GISAID platform. Sequence alignment and amino-acid mutation frequency analysis of S glycoprotein was performed using CoVSurver mutations app (https://www.gisaid.org/epiflu-applications/covsurver-mutations-app/). The complete genome sequence of SARS-CoV-2 hCoV-19/Wuhan/WIV04/2019 was used as a reference.

Single mutational effect on tertiary structure, molecular stability, and flexibility of S protein were predicted by DynaMut server (Rodrigues et al., 2018). Simulations were carried out using the three-dimensional model of SARS-CoV-2 S (PDB 7CWU) selected from Protein Data Bank (PDB). Dynamut server calculated the difference of free energy (ΔΔG) and change in vibrational entropy energy (ΔΔSVib) between wild-type and mutant proteins.

Acknowledgements

This work was supported by grants from National Council for Scientific and Technological Development (CNPq Grant ID 440812/2016-0), Ministry of Health, Coordination for the Improvement of Higher Education Personnel (CAPES Grant ID 88881.130804/2016-01) and the São Paulo Research Foundation (FAPESP Grant ID 17/50333-7) to (CRP).

Author’s contributions

F.R.S.S., C.R.P., project design. M.S.P.A., M.B., H.H.M.C., D.G.R., G.G., G.M.P.M., B.P.C., handle and management biologicals data. F.R.S.S., D.F.L.N., C.R.P., data, and statistical analysis. F.R.S.S., and C.R.P. wrote the manuscript. All authors (F.R.S.S., S.P.A., M.B., H.H.M.C., D.G.R., G.G., G.M.P.M., B.P.C., D.F.L.N., C.R.P.,) reviewed and edited the manuscript.

Additional Information

Dataset of genomes isolates are available in supplemental material

Competing interests

The authors declare no competing interest within the scope of this manuscript.

Dongwan, K., Lee, J.-Y., Yang, J.-S., Kim, J.W., Kim, V.N., Chang, H., 2020. The Architecture of SARS-CoV-2 Transcriptome. Cell 181, 914–921.

Drosten, C., Günther, S., Preiser, W., Van der Werf, S., Brodt, H.R., Becker, S., Rabenau, H., Panning, M., Kolesnikova, L., Fouchier, R.A.M., Berger, A., Burguière, A.M., Cinatl, J., Eickmann, M., Escriou, N., Grywna, K., Kramme, S., Manuguerra, J.C., Müller, S., Rickerts, V., Stürmer, M., Vieth, S., Klenk, H.D., Osterhaus, A.D.M.E., Schmitz, H., Doerr, H.W., 2003. Identification of a novel coronavirus in patients with severe acute respiratory syndrome. N. Engl. J. Med. 348, 1967–1976. https://doi.org/10.1056/NEJMoa030747

Du, L., He, Y., Zhou, Y., Liu, S., Zheng, B.J., Jiang, S., 2009. The spike protein of SARS-CoV - A target for vaccine and therapeutic development. Nat. Rev. Microbiol. 7, 226–236. https://doi.org/10.1038/nrmicro2090

Farkas, C., Mella, A., Haigh, J.J., 2020. Large-scale population analysis of SARS-CoV-2 whole genome sequences reveals host-mediated viral evolution with emergence of mutations in the viral Spike protein associated with elevated mortality rates. medRxiv 2020.10.23.20218511. https://doi.org/10.1101/2020.10.23.20218511

Jangra, S., Ye, C., Rathnasinghe, R., Stadlbauer, D., Krammer, F., Simon, V., Martinez-Sobrido, L., Garcia-Sastre, A., Schotsaert, M., 2021. The E484K mutation in the SARS-CoV-2 spike protein reduces but does not abolish neutralizing activity of human convalescent and post-vaccination sera. medRxiv Prepr. Serv. Heal. Sci. https://doi.org/10.1101/2021.01.26.21250543

Khailany, R.A., Safdar, M., Ozaslan, M., 2020. Genomic characterization of a novel SARS-CoV-2. Gene Reports 19, 100682.

Khan, A., Zia, T., Suleman, M., Khan, T., 2021. Higher infectivity of the SARS ‐ CoV ‐ 2 new variants is associated with K417N / T , E484K , and N501Y mutants : An insight from structural data. J. Cell. Physiol. 1–13. https://doi.org/10.1002/jcp.30367

Lan, J., Ge, J., Yu, J., Shan, S., Zhou, H., Fan, S., Zhang, Q., Shi, X., Wang, Q., Zhang, L., Wang, X., 2020. Structure of the SARS-CoV-2 spike receptor-binding domain bound to the ACE2 receptor. Nature 581, 215–220. https://doi.org/10.1038/s41586-020-2180-5

Li, F., Li, W., Farzan, M., Harrison, S.C., 2005. Structure of SARS Coronavirus Spike Receptor-Binding Domain Complexed with Receptor. Science (80-. ). 309, 1864–1868. https://doi.org/10.1177/002205741508100313

Mahmoudi Gomari, M., Rostami, N., Omidi-Ardali, H., Arab, S.S., 2021. Insight into molecular characteristics of SARS-CoV-2 spike protein following D614G point mutation, a molecular dynamics study. J. Biomol. Struct. Dyn. 1–9. https://doi.org/10.1080/07391102.2021.1872418

Mercatelli, D., Giorgi, F.M., 2020. Geographic and Genomic Distribution of SARS-CoV-2 Mutations. Front. Microbiol. 11, 1–13. https://doi.org/10.3389/fmicb.2020.01800

Mohammad, A., Alshawaf, E., Marafie, S.K., Abu-Farha, M., Abubaker, J., Al-Mulla, F., 2021. Higher binding affinity of furin for SARS-CoV-2 spike (S) protein D614G mutant could be associated with higher SARS-CoV-2 infectivity. Int. J. Infect. Dis. 103, 611–616. https://doi.org/10.1016/j.ijid.2020.10.033

Moura, A., Costa, H. da, Correa, V., Lima, A., Lindoso, J., Gaspari, E. De, Hong, M., Cunha-Junior, J., Prudencio, C., 2021. Serological Assessment of COVID-19 Patients in Brazil: Levels, Avidity, and Subclasses of IgG Against RBD. https://doi.org/10.21203/rs.3.rs-131195/v1

Nassar, M.S., Bakhrebah, M.A., Meo, S.A., Alsuabeyl, M.S., Zaher, W.A., 2018. Global seasonal occurrence of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection. Eur. Rev. Med. Pharmacol. Sci. 22, 3913–3918. https://doi.org/10.26355/eurrev-201806-15276

Oostra, M., de Haan, C.A.M., Rottier, P.J.M., 2007. The 29-Nucleotide Deletion Present in Human but Not in Animal Severe Acute Respiratory Syndrome Coronaviruses Disrupts the Functional Expression of Open Reading Frame 8. J. Virol. 81, 13876–13888. https://doi.org/10.1128/jvi.01631-07

Ortuso, F., Mercatelli, D., Guzzi, P.H., Giorgi, F.M., 2021. Structural genetics of circulating variants affecting the SARS-CoV-2 spike/human ACE2 complex. J. Biomol. Struct. Dyn. 1–11. https://doi.org/10.1080/07391102.2021.1886175

Peret, T., Ph, D., Emery, S., Tong, S., Ph, D., Urbani, C., Comer, J.A., Ph, D., Lim, W., Rollin, P.E., Dowell, S.F., Ling, A., Humphrey, C.D., Ph, D., Fields, B., Ph, D., Derisi, J., Ph, D., Yang, J., Ph, D., Cox, N., Ph, D., Hughes, J.M., Leduc, J.W., Ph, D., Bellini, W.J., Ph, D., Anderson, L.J., Group, W., 2003. A Novel Coronavirus Associated with Severe Acute Respiratory Syndrome. N. Engl. J. Med. 348, 1953–1966.

Plante, J.A., Liu, Y., Liu, J., Xia, H., Johnson, B.A., Lokugamage, K.G., Zhang, X., Muruato, A.E., Zou, J., Fontes-Garfias, C.R., Mirchandani, D., Scharton, D., Bilello, J.P., Ku, Z., An, Z., Kalveram, B., Freiberg, A.N., Menachery, V.D., Xie, X., Plante, K.S., Weaver, S.C., Shi, P.Y., 2020. Spike mutation D614G alters SARS-CoV-2 fitness. Nature 592. https://doi.org/10.1038/s41586-020-2895-3

Resende, P.C., Delatorre, E., Gräf, T., Mir, D., Motta, F. do C., Appolinario, L.R., da Paixão, A.C.D., Ogrzewalska, M., Caetano, B., dos Santos, M.C., de Almeida Ferreira, J., Santos Junior, E.C., da Silva, S.P., Fernandes, S.B., Vianna, L.A., da Costa Souza, L., Ferro, J.F.G., Nardy, V.B., Croda, J., Oliveira, W.K., Abreu, A., Bello, G., Siqueira, M.M., 2020. Genomic surveillance of SARS-CoV-2 reveals community transmission of a major lineage during the early pandemic phase in Brazil. bioRxiv 2020.06.17.158006. https://doi.org/10.1101/2020.06.17.158006

Rodrigues, C.H.M., Pires, D.E.V., Ascher, D.B., 2018. DynaMut: Predicting the impact of mutations on protein conformation, flexibility and stability. Nucleic Acids Res. 46, W350–W355. https://doi.org/10.1093/nar/gky300

Suryadevara, N., Shrihari, S., Gilchuk, P., VanBlargan, L.A., Binshtein, E., Zost, S.J., Nargi, R.S., Sutton, R.E., Winkler, E.S., Chen, E.C., Fouch, M.E., Davidson, E., Doranz, B.J., Chen, R.E., Shi, P.-Y., Carnahan, R.H., Thackray, L.B., Diamond, M.S., Crowe, J.E.J., 2021. Neutralizing and protective human monoclonal antibodies recognizing the N-terminal domain of the SARS-CoV-2 spike protein. Cell. https://doi.org/10.1016/j.cell.2021.03.029

Townsend, A., Rijal, P., Xiao, J., Tan, T.K., Huang, K.-Y.A., Schimanski, L., Huo, J., Gupta, N., Rahikainen, R., Matthews, P.C., Crook, D., Hoosdally, S., Dunachie, S., Barnes, E., Street, T., Conlon, C.P., Frater, J., Arancibia-Cárcamo, C. V, Rudkin, J., Stoesser, N., Karpe, F., Neville, M., Ploeg, R., Oliveira, M., Roberts, D.J., Lamikanra, A.A., Tsang, H.P., Bown, A., Vipond, R., Mentzer, A.J., Knight, J.C., Kwok, A.J., Screaton, G.R., Mongkolsapaya, J., Dejnirattisai, W., Supasa, P., Klenerman, P., Dold, C., Baillie, J.K., Moore, S.C., Openshaw, P.J.M., Semple, M.G., Turtle, L.C.W., Ainsworth, M., Allcock, A., Beer, S., Bibi, S., Skelly, D., Stafford, L., Jeffrey, K., O’Donnell, D., Clutterbuck, E., Espinosa, A., Mendoza, M., Georgiou, D., Lockett, T., Martinez, J., Perez, E., Gallardo Sanchez, V., Scozzafava, G., Sobrinodiaz, A., Thraves, H., Joly, E., 2021. A haemagglutination test for rapid detection of antibodies to SARS-CoV-2. Nat. Commun. 12, 1951. https://doi.org/10.1038/s41467-021-22045-y

Walls, A.C., Park, Y.-J., Tortorici, M.A., Wall, A., McGuire, A.T., Veesler, D., 2020. Structure , Function , and Antigenicity of the SARS-. Cell 180, 281–292.

Woo, P.C.Y., Lau, S.K.P., Huang, Y., Yuen, K.Y., 2009. Coronavirus diversity, phylogeny and interspecies jumping. Exp. Biol. Med. 234, 1117–1127. https://doi.org/10.3181/0903-MR-94

WHO COVID-19 Dashboard. Geneva: World Health Organization, 2020. Available online: https://covid19.who.int/ (last cited: [April 6, 2021]).

Wu, F., Zhao, S., Yu, B., Chen, Y.M., Wang, W., Song, Z.G., Hu, Y., Tao, Z.W., Tian, J.H., Pei, Y.Y., Yuan, M.L., Zhang, Y.L., Dai, F.H., Liu, Y., Wang, Q.M., Zheng, J.J., Xu, L., Holmes, E.C., Zhang, Y.Z., 2020. A new coronavirus associated with human respiratory disease in China. Nature 579, 265–269. https://doi.org/10.1038/s41586-020-2008-3

Xie, X., Liu, Y., Liu, J., Zhang, X., Zou, J., Fontes-Garfias, C.R., Xia, H., Swanson, K.A., Cutler, M., Cooper, D., Menachery, V.D., Weaver, S.C., Dormitzer, P.R., Shi, P.Y., 2021. Neutralization of SARS-CoV-2 spike 69/70 deletion, E484K and N501Y variants by BNT162b2 vaccine-elicited sera. Nat. Med. https://doi.org/10.1038/s41591-021-01270-4

Zaki, A.M., Van Boheemen, S., Bestebroer, T.M., Osterhaus, A.D.M.E., Fouchier, R.A.M., 2012. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N. Engl. J. Med. 367, 1814–1820. https://doi.org/10.1056/NEJMoa1211721

Table 1. Rank of major mutations and the effect on the structural dynamics of spike protein.

Rank	Mutation	Frequency	ΔΔG DynaMut^a	Outcome	ΔΔS_Vib ENCoM^a	Flexibility
1	D614G	2645	1.541	Stabilizing	-0.397	Decrease
2	V1176F	1411	0.730	Stabilizing	-0.080	Decrease
3	E484K	894	1.215	Stabilizing	-1.066	Decrease
4	N501Y	348	-0.325	Destabilizing	4.129	Increase
5	D138Y	310	1.142	Stabilizing	-1.293	Decrease
6	H655Y	309	1.850	Stabilizing	-0.611	Decrease
7	P26S	307	0.392	Stabilizing	-0.602	Decrease
8	L18F	306	-0.575	Destabilizing	0.168	Increase
9	T1027I	306	0.847	Stabilizing	-0.363	Decrease
10	K417T	304	-0.080	Destabilizing	0.047	Increase

^aThe ΔΔG and ΔΔSVib ENCoM values are expressed in kcal.mol^-1and kcal.mol⁻¹.K⁻¹, respectively.

Download PDF

Version 1

posted

You are reading this older preprint version

Read the latest preprint version →

Mutational Profile of SARS-CoV-2 Spike Protein in Brazilian isolates

Status:

Version 1

Abstract

Figures

Introduction

Results

Discussion

Materials And Methods

Declarations

References

Tables

Status:

Version 1