Skip to main content
PMC home page
Elsevier - PMC COVID-19 Collection logoLink to Elsevier - PMC COVID-19 Collection
. 2020 Nov 6;291:198222. doi: 10.1016/j.virusres.2020.198222

Deletion in the C-terminal region of the envelope glycoprotein in some of the Indian SARS-CoV-2 genome

Ballamoole Krishna Kumar a, Anusha Rohit b, Kattapuni Suresh Prithvisagar a, Praveen Rai a, Indrani Karunasagar a, Iddya Karunasagar c,*
PMCID: PMC7645280  PMID: 33166565

Highlights

  • •

    First observation on the extensive deletion of amino acid residues in the C-terminal region of the E protein in some of the SARS-CoV-2 sequenced from the India. .

  • •

    The deletion is outside the primer binding region of RTqPCR targeting E gene used in India in isolates from various states except Odisha, which had deletion in primer binding region.

  • •

    Characteristic in-frame deletion in the E protein map to the homopentameric interface and PDZ binding motif (PBM) present in the C-terminal region of E protein.

  • •

    The isolates with deletions belonged to different clades.

Keywords: COVID-19, SARS-CoV-2, Viral assembly, Genome analysis, E protein

Abstract

The envelope glycoprotein (E) is the smallest structural component of SARS-CoVs; plays an essential role in the viral replication starting from envelope formation to assembly. The in silico analysis of 2086 whole genome sequences from India performed in this study provides the first observation on the extensive deletion of amino acid residues in the C-terminal region of the envelope glycoprotein in 34 Indian SARS-CoV-2 genomes. These amino acid deletions map to the homopentameric interface and PDZ binding motif (PBM) present in the C-terminal region of E protein as well as immediately after the reverse primer binding region as per Charité protocol in 26 of these genomes, hence, their detection through RT-qPCR may not be hampered and therefore E gene-based RT-qPCR would still detect these isolates. Eight genomes from the State of Odisha had deletion even in the primer binding site. It is possible that the deletions in the C-terminal region of E protein of these genomes are a result of adapting to a newer geographical area and host. The information on the clinical status was available only for 9 out of 34 cases and these were asymptomatic. However, further studies are indispensable to understand the functional consequences of amino acid deletion in the C terminal region of SARS-CoV-2 envelope protein in the viral pathogenesis and host adaptation.

The coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 become a pandemic affecting over 200 countries, causing more than 33.8 million cases and associated with over 1.01 million deaths worldwide. The disease spreads mostly through droplets released when an infected person coughs or speaks or sneezes, and the disease spreads rapidly among contacts. SARS-CoV-2 is an enveloped, single-stranded positive-sense RNA virus belonging to the genus β-coronavirus (Lu et al., 2020; Malik et al., 2020). Similar to SARS-CoV and MERS-CoV, the 29.9 kb genome of SARS-CoV-2 encodes four major structural proteins - spike (S), envelope (E), membrane (M), as well as nucleocapsid (N) protein, 16 non-structural proteins (nsp1–16), and five to eight accessory proteins (Wu et al., 2020). Based on the currently available pieces of evidence, it's noteworthy to mention that the severity of COVID-19 differs significantly within populations and geographical locations. Episodes of asymptomatic infection were also reported in more than 80 % of the tested positive COVID-19 cases in India (Acharya and Porwal, 2020). Genomic data on Indian isolates of SARS-CoV-2 is coming from different laboratories, and interim analysis shows the introduction of this virus to India from multiple sources such as China, Europe, USA, Canada and the Middle East (Potdar et al., 2020; Singh and Sharma, 2020; Somasundaram et al., 2020). Analysis of 361 genomes of SARS-CoV-2 from India revealed that there were 5 clusters, 4 of these being known clades identified by Nextstrain: A2a, A3, B, and B4. 62 % of the genomes belonged to A2a clade, but 29 % belonged to a distinct cluster designated clade I/A3i, not reported outside India (Banu et al., 2020). It has been suggested that the evolution of Clade I/A3i is primarily determined by changes in the structural proteins, N and E, while the evolution in globally predominant A2a clade is determined by changes in Spike (S) and Membrane (M) proteins. Since E gene is the target for amplification in Reverse Transcription Real-Time PCR (RT-qPCR) used for diagnostic purposes in India (Alagarasu et al., 2020), we analyzed the sequence of E genes to see if variations affected the primer binding sites.

The envelope (E) protein of SARS-CoV is the smallest structural component plays an essential role in the viral replication starting from envelope formation, to assembly (Schoeman and Fielding, 2019). Studies have reported that mutation or deletions in the E protein significantly affects the viral maturation, incompetent viral progeny leading to reduced viral titer upon infection (Cohen et al., 2011; Schoeman and Fielding, 2019). In this study nucleotide sequence of E genes from Indian isolates were examined to see if there are any changes in primer binding sites. Further, in silico analysis of the Indian SARS-CoV-2 E proteins were performed to investigate the amino acid composition, domains involved in the pathogenicity to obtain better insight into the epidemiology and pathogenicity of Indian SARS-CoV-2.

E gene nucleotide and protein sequences available for the 2086 Indian SARS-CoV-2 genome as of Sep 11th 2020 and Reference sequence were downloaded from the GISAID as well as NCBI virus database and aligned using Geneious Prime. These genome sequences were derived from both illumina sequencing technology with coverage of more than 47 X (47X-764 X) and ARTIC Network Primal Scheme on MinION with coverage of more than 673 X (673 X- 4600X) (Table 1 ). The detailed information on the sequences used and their metadata is given in Supplementary Table S1. As the success of PCR based molecular diagnostics mainly depends on the efficient primers and/or probes to specifically amplify the target gene, any genetic variations, especially in the 3' primer or probe binding regions, can result in potential mismatches and false-negative results. The primer/probes described in Charite-E protocols (WHO, 2020) were mapped to the multiple sequence alignment of E gene to see if there are any changes in primer binding sites (data not shown).

Table 1.

Patient characteristics of the COVID-19 cases used for the genome analysis of SARS-CoV-2.

Sl. No Accession No. (NCBI/GISAID) Isolate name Sequencing Technology Coverage Geographical Location Age Gender Patient status
1. NC_045512 - WU Wuhan-Hu-1 Illumina NA China/Wuhan NA NA Ref. seq.
2. MT012098 - KL SARS-CoV-2/human/IND/29/2020 Illumina NA India/Kerala NA NA NA
3. EPI_ISL_428482 hCoV-19/India/nimh-0182/2020 Oxford nanopore technology MinION 1,900x India/Karnataka 26 Male NA
4. EPI_ISL_436447 hCoV-19/India/KA-NCDC-4055/2020 Oxford nanopore technology MinION 1,294.84x India/Karnataka 18 Male NA
5. EPI_ISL_428485 hCoV-19/India/KA-nimh-0834/2020 Oxford nanopore technology MinION 700x India/Karnataka 32 Male Asymptomatic
6. EPI_ISL_486405 hCoV-19/India/KA-nimh-14709/2020 Oxford nanopore technology MinION NA India/Karnataka 34 Male Asymptomatic
7. EPI_ISL_516078 hCoV-19/India/KA-nimh-1600/2020 Oxford nanopore technology MinION 1814.56x India/Karnataka 21 Female Released
8. EPI_ISL_428484 hCoV-19/India/KA-nimh-0351/2020 Oxford nanopore technology MinION 1200x India/Karnataka 55 Male NA
9. EPI_ISL_486402 hCoV-19/India/KA-nimh-11076/2020 Oxford nanopore technology MinION NA India/Karnataka 30 Female Asymptomatic
10. EPI_ISL_428480 hCoV-19/India/KA-nimh-0116/2020 Oxford nanopore technology MinION 900x India/Karnataka 28 Female NA
11. EPI_ISL_436139 hCoV-19/India/KA-nimh-3970/2020 Oxford nanopore technology MinION NA India/Karnataka 20 Male Symptomatic
12. EPI_ISL_436140 hCoV-19/India/KA-nimh-4376/2020 Oxford nanopore technology MinION NA India/Karnataka 52 Female Asymptomatic
13. EPI_ISL_436138 hCoV-19/India/KA-nimh-3952/2020 Oxford nanopore technology MinION NA India/Karnataka 38 Male Asymptomatic
14. EPI_ISL_428481 hCoV-19/India/KA-nimh-0130/2020 Oxford nanopore technology MinION 3000x India/Karnataka 55 Male NA
15. EPI_ISL_428487 hCoV-19/India/KA-nimh-1071/2020 Oxford nanopore technology MinION 1600x India/Karnataka 25 Male NA
16. EPI_ISL_428486 hCoV-19/India/KA-nimh-0996/2020 Oxford nanopore technology MinION 2000X India/Karnataka 43 Male NA
17. EPI_ISL_428483 hCoV-19/India/KA-nimh-0318/2020 Oxford nanopore technology MinION 4600x India/Karnataka 19 Male NA
18. EPI_ISL_516077 hCoV-19/India/KA-nimh-1453/2020 Oxford nanopore technology MinION 1000.31x India/Karnataka 23 Male Released
19. EPI_ISL_515948 hCoV-19/India/KA-nimh-11074/2020 Oxford nanopore technology MinION 1,510x (average) India/Karnataka 10 Male Released
20. EPI_ISL_515953 hCoV-19/India/KA-nimh-12171/2020 Oxford nanopore technology MinION 726x (average) India/Karnataka 35 Female Released
21. EPI_ISL_436156 hCoV-19/India/KA-nimh-1596/2020 Oxford nanopore technology MinION NA India/Karnataka 55 Female Asymptomatic
22. EPI_ISL_436141 hCoV-19/India/KA-nimh-4378/2020 Oxford nanopore technology MinION NA India/Karnataka 27 Female Asymptomatic
23. EPI_ISL_436137 hCoV-19/India/KA-nimh-2873/2020 Oxford nanopore technology MinION NA India/Karnataka 28 Female Asymptomatic
24. EPI_ISL_436157 hCoV-19/India/KA-nimh-1598/2020 Oxford nanopore technology MinION NA India/Karnataka 50 Female Asymptomatic
25. EPI_ISL_428479 hCoV-19/India/KA-nimh-0113/2020 Oxford nanopore technology MinION 3000x India/Karnataka 68 Male NA
26. EPI_ISL_528426 hCoV-19/India/MH-IGIB-D2/2020 Oxford nanopore technology MinION NA India/Maharashtra 24 Female NA
27. EPI_ISL_436438 hCoV-19/India/MH-NCDC-3835/2020 Oxford nanopore technology MinION 1,467.2x India/Maharashtra NA Male NA
28. EPI_ISL_436446 hCoV-19/India/MH-NCDC-3985/2020 Oxford nanopore technology MinION 673.53x India/Maharashtra 25 Male NA
29. EPI_ISL_436442 hCoV-19/India/MH-NCDC-3950/2020 Oxford nanopore technology MinION 1,345.3x India/Maharashtra 31 Male NA
30. EPI_ISL_436437 hCoV-19/India/DL-NCDC-3831/2020 Oxford nanopore technology MinION 1,531.56x India/Delhi 56 Male NA
31. EPI_ISL_436443 hCoV-19/India/MP-NCDC-3961/2020 Oxford nanopore technology MinION 1,346.03x India/Madhya Pradesh 33 Male NA
32. EPI_ISL_455773 hCoV-19/India/OR-RMRC22/2020 Illumina 179x India/Odisha 29 Male NA
33. EPI_ISL_463046 hCoV-19/India/OR-ILSCV16495/2020 Illumina 355x India/Odisha 37 Male NA
34. EPI_ISL_463080 hCoV-19/India/OR-ILSCV20598/2020 Illumina 403x India/Odisha 58 Male NA
35. EPI_ISL_463091 hCoV-19/India/OR-ILSCV27412/2020 Illumina 47x India/Odisha 20 Female NA
36. EPI_ISL_463048 hCoV-19/India/OR-ILSCV16508/2020 Illumina 275x India/Odisha 35 Male NA
37. EPI_ISL_463021 hCoV-19/India/OR-ILSCV13695/2020 Illumina 764x India/Odisha 29 Male NA
38. EPI_ISL_463041 hCoV-19/India/OR-ILSCV15937/2020 Illumina 638x India/Odisha 50 Male NA
39. EPI_ISL_463093 hCoV-19/India/OR-ILSCV28955/2020 Illumina 84x India/Odisha 55 Male NA
Open in a new tab

NA = Not Available.

The analysis revealed that none of the E gene sequences analysed had variations in the primer/probe binding regions except in 8 out of 168 sequences from the State of Odisha where reverse primer binding found to be abolished. Hence such strains may be negative for E gene in RT PCR. This may explain observations from some diagnostic laboratories in India using GeneXpert and Trunat systems that occasional samples can be negative for E gene but positive for N gene or ORF1 gene (Rohit et al., unpublished observations). SARS-CoV-2 E protein has 75 amino acid residues with a predicted molecular weight of 8.3 kDa and has an N-terminal cytoplasmic segment and C-terminal non-cytoplasmic region separated by a hydrophobic transmembrane domain (aa 12-aa 35) as predicted using XtalPred Server (http://xtalpred.godziklab.org/) InterPro Scan search (http://www.ebi.ac.uk/interpro/). Multiple sequence alignment revealed that amino acid residues of E proteins are highly conserved in all the sequences except that there was a characteristic in-frame deletion of 25–55 amino acid residues in the E protein C-terminal region of the 34 SARS-CoV-2 genomes available from Karnataka (20/128), Maharashtra (4/325), Delhi (1/121), Madhya Pradesh (1/41) and Odisha (8/168) (Fig. 1 ). These amino acid deletions map to the homopentameric interface and PDZ binding motif (PBM) present in the C-terminal region as well as immediately after the reverse primer binding region as per Charité protocol (WHO, 2020) in 26 genomes (except the ones from the State of Odisha discussed above), hence, their detection through RT-qPCR may not be hampered and therefore E gene based RT-qPCR would still detect these isolates. Among them, 9 individuals were asymptomatic (Table 1) and the clinical condition of other individuals was not available in the GISAID database. When we analyzed the patient data for these cases, none of them had a travel history to COVID-19 infected countries; hence their exact source of the contract cannot be adequately traced. We also examined the lineage of these sequences using the methodology of Pattabiraman et al. (2020) and as indicated in Table S1, of the 34 sequences with E gene deletions, 15 belonged to 19A, one belonged to 19B, 4 belonged to 20A and 20B each and remaining sequences could not be categorised into any of the clades defined by Nextstrain. Our data suggests that C-terminal deletion in the E-gene of SARS-CoV-2 was spread across different lineages and this deletion event would have occurred independently in different lineages and geographical locations.

Fig. 1.

Fig. 1

Open in a new tab

Representative image showing the amino acid residues and domains in the envelope (E) protein of SARS-CoV-2. Homopentameric interface region and PDZ binding domains are indicated with star marks coloured in blue and orange. The location of N-glycosylation sites are marked with a straight line (Inline graphic) at the top of the residue. The predicted antigenic determinant regions are highlighted in the box.

Further, sequential B cell epitopes on the E protein was predicted using BepiPred-2.0 (http://www.cbs.dtu.dk/services/BepiPred/index.php). This showed the presence of highly conserved antigenic determinant regions in the N-terminal region (SEET) and C-terminal region (YVYSRVKNLNSSRVP) of E protein (Fig. 1). It is also important to highlight that; we were unable to map the C terminal antigenic determinant region in those 34 isolates of SARS-CoV-2 E proteins as there was a deletion of 25–55 amino acid residues in its C-terminal region. Based on PROSITE analyses (https://prosite.expasy.org/), it was predicted that SARS-CoV-2 E protein has two N-glycosylation sites at N48 and N66 but lacking in all 34 isolates of SARS-CoV-2 which had an extensive deletion/gaps in C-terminal region amino acid residues. Recent study of Sun et al. (2020) reported 12 bp deletions in the E gene of SARS-CoV-2 genome at the position of 26320–26331 and mutant strain had higher spike protein compared to wildtype without any difference in viral titer. In SARS-CoV, PDZ binding motif of E protein is considered to be the major determinant of virulence and known to participate in interactions with several host proteins like syntenin and PALS1 during viral infection (Jimenez-Guardeño et al., 2014; Teoh et al., 2010). SARS-CoVs lacking PBM domain of E protein have abrogated expression of inflammatory cytokines and were attenuated, causing the least damage to lungs without the mortality of the infected animal (Jimenez-Guardeño et al., 2014). DeDiego et al. (2008) showed that elimination of SARS-CoV E protein has the deleterious effect of viral replication where it grew about 100-fold lower compared to the wild type virus in lung cells of the infected mice. In many coronaviruses, E protein is targeted towards the Golgi complex, where it participates in viral assembly and budding. Studies have shown that Golgi complex targeting information is located in the C-terminal region of the E protein and therefore, either truncation of C-terminal region or mutation of conserved amino acid residues in the C-terminal would disrupt the Golgi complex targeting the region of the SARS-CoV E protein leading to crippled viral maturation and incompetent viral progeny (Cohen et al., 2011). It has also been shown that the deletion of N-glycosylation sites in the envelope protein of many viruses had a significant consequence on infectivity potential and antibody-mediated neutralization by the host immune system. It was also observed that mutation of the glycosylation site at N66 resulted in the formation of oligomers of E protein with higher molecular weight, thereby affecting the functionality of E protein in the viral replication (Liao et al., 2006; Schoeman and Fielding, 2019).

The in silico analysis performed in this study provides the first observation on the extensive deletion of amino acid residues in the C-terminal region of the envelope glycoprotein in some of the Indian SARS-CoV-2 genomes. It is possible that the deletions in the C-terminal region of E protein of these genomes are a result of adapting to a newer geographical area and host. Sometimes sequencing of samples with low viral titters could lead to assemblies with low coverage and/or spurious gaps in the genome, but this is unlikely in this case since gaps in the same region in 34 isolates from are different geographical location and sequences by different laboratories. It is also possible that these have reduced virulence since nine of the thirty-four individuals from whom isolates were obtained were asymptomatic and clinical information for others were not available. Lack of travel history in the infected individuals suggests that the virus isolates might be circulating in this region for some time. However, further studies are indispensable to understand the functional consequences of amino acid deletion in the C terminal region of SARS-CoV-2 envelope protein in the viral pathogenesis and host adaptation.

Declaration of Competing Interest

The authors report no declarations of interest.

Acknowledgement

The authors are grateful to Nitte (Deemed to be University) for providing computing infrastructure for the execution of this research.We are also very grateful to all the data contributors of the GISAID Initiative and NCBI Virus database.

Footnotes

Appendix A

Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.virusres.2020.198222.

Appendix A. Supplementary data

The following is Supplementary data to this article:

mmc1.xlsx (10.5KB, xlsx)

References

  1. Acharya R., Porwal A. A vulnerability index for the management of and response to the COVID-19 epidemic in India: an ecological study. Lancet Glob. Health. 2020;8(9):e1142–51. doi: 10.1016/S2214-109X(20)30300-4. 1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Alagarasu K., Choudhary M.L., Lole K.S., Abraham P., Potdar V., Team N.I.C. Evaluation of RdRp & ORF-1b-nsp14-based real-time RT-PCR assays for confirmation of SARS-CoV-2 infection: an observational study. Indian J. Med. Res. 2020;151:483–485. doi: 10.4103/ijmr.IJMR_1256_20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Banu S., Jolly B., Mukherjee P., Singh P., Khan S., Zaveri L., Shambhavi S., Gaur N., Mishra R.K., Scaria V., Sowpati D.T. A distinct phylogenetic cluster of Indian SARS-CoV-2 isolates. bioRxiv. 2020 doi: 10.1101/2020.05.31.126136. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Cohen J.R., Lin L.D., Machamer C.E. Identification of a Golgi complex-targeting signal in the cytoplasmic tail of the severe acute respiratory syndrome coronavirus envelope protein. J. Virol. 2011;85:5794–5803. doi: 10.1128/JVI.00060-11. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. DeDiego M.L., Pewe L., Alvare E., Rejas M.T., Perlman S., Enjuanes L. Pathogenicity of severe acute respiratory coronavirus deletion mutants in hACE-2 transgenic mice. Virology. 2008;376:379–389. doi: 10.1016/j.virol.2008.03.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Jimenez-Guardeño J.M., Nieto-Torres J.L., DeDiego M.L., Regla-Nava J.A., Fernandez-Delgado R., Castaño-Rodriguez C., Enjuanes L. The PDZ-binding motif of severe acute respiratory syndrome coronavirus envelope protein is a determinant of viral pathogenesis. PLoS Pathog. 2014;10 doi: 10.1371/journal.ppat.1004320. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Liao Y., Yuan Q., Torres J., Tam J.P., Liu D.X. Biochemical and functional characterization of the membrane association and membrane permeabilizing activity of the severe acute respiratory syndrome coronavirus envelope protein. Virology. 2006;349:264–275. doi: 10.1016/j.virol.2006.01.028. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Lu R., Zhao X., Li J., Niu P., Yang B., Wu H., Wang W., Song H., Huang B., Zhu N., Bi Y. Genomic characterization and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding. Lancet. 2020;395:565–574. doi: 10.1016/S0140-6736(20)30251-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Malik Y.S., Sircar S., Bhat S., Sharun K., Dhama K., Dadar M., Tiwari R., Chaicumpa W. Emerging novel coronavirus (2019-nCoV)—current scenario, evolutionary perspective based on genome analysis and recent developments. Vet. Q. 2020;40:68–76. doi: 10.1080/01652176.2020.1727993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Pattabiraman C., Habib S., Harsha P.K., Rasheed R., Reddy V., Dinesh P., Damodar T., Hosallimath K., George A.K., Reddy N.V.K., John B., Pattanaik A., Kumar N., Mani R.S., Venkataswamy M.M., Hameed S.K.S., Kumar B.G.P., Desai A., Vasanthapuram R. 2020. Genomic Epidemiology Reveals Multiple Introductions and Spread of SARS-CoV-2 in the Indian State of Karnataka. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Potdar V., Cherian S.S., Deshpande G.R., Ullas P.T., Yadav P.D., Choudhary M.L., Gughe R., Vipat V., Jadhav S., Patil S., Nyayanit D. Genomic analysis of SARS-CoV-2 strains among Indians returning from Italy, Iran & China, & Italian tourists in India. Indian J. Med. Res. 2020;151:255–260. doi: 10.4103/ijmr.IJMR_1058_20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Schoeman D., Fielding B.C. Coronavirus envelope protein: current knowledge. Virol. J. 2019;16:1–22. doi: 10.1186/s12985-019-1182-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Singh S., Sharma B.B. Severe acute respiratory syndrome-coronavirus 2 and novel coronavirus disease 2019: an extraordinary pandemic. Lung India. 2020;37:268–271. doi: 10.4103/lungindia.lungindia_170_20. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Somasundaram K., Mondal M., Lawarde A. Genomics of Indian SARS-CoV-2: implications in genetic diversity, possible origin and spread of virus. medRxiv. 2020 doi: 10.1101/2020.04.25.20079475. Jan 1st. [DOI] [Google Scholar]
  15. Sun Y., Xu F., An Q., Chen C., Yang Z., Lu H., Chen J., Yao P., Jiang J., Zhu H. A SARS-CoV-2 variant with the 12-bp deletion at E gene. Emerg. Microbes Infect. 2020 doi: 10.1080/22221751.2020.1837017. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Teoh K.T., Siu Y.L., Chan W.L., Schlüter M.A., Liu C.J., Peiris J.M., Bruzzone R., Margolis B., Nal B. The SARS coronavirus E protein interacts with PALS1 and alters tight junction formation and epithelial morphogenesis. Mol. Biol. Cell. 2010;201(21):3838–3852. doi: 10.1091/mbc.E10-04-0338. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. WHO . 2020. Diagnostic Detection of 2019-nCoV by Real-Time RT-PCR.https://www.who.int/docs/default-source/coronaviruse/protocol-v2-1.pdf accessed on Jun 6th 2020. Available from: [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Wu A., Peng Y., Huang B., Ding X., Wang X., Niu P., Meng J., Zhu Z., Zhang Z., Wang J., Sheng J. Genome composition and divergence of the novel coronavirus (2019-nCoV) originating in China. Cell Host Microbe. 2020;27:325–328. doi: 10.1016/j.chom.2020.02.001. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

mmc1.xlsx (10.5KB, xlsx)

Articles from Virus Research are provided here courtesy of Elsevier

RESOURCES