Substitutions in Spike and Nucleocapsid proteins of SARS-CoV-2 circulating in Colombia
Authors: Franco-Muñoz Carlos , Álvarez-Díaz Diego A. , Laiton-Donato Katherine , Wiesner Magdalena , Escandón Patricia , Usme-Ciro José A. , Franco-Sierra Nicolás D. , Flórez-Sánchez Astrid C. , Gómez-Rangel Sergio , Rodríguez-Calderon Luz D. , Barbosa-Ramirez Juliana , Ospitia-Baez Erika , Walteros Diana M. , Ospina-Martinez Martha L. , Mercado-Reyes Marcela 
Published: June 2020

AbstractIntroductionSARS-CoV-2 is a new member of the genusBetacoronavirus, responsible for the COVID-19 pandemics. The virus crossed the species barrier and established in the human population due to its ability to exploit the ACE receptor for virus entry, which is present and abundant in several tissues, including the lung and respiratory tract, gastrointestinal tract and hearth. Virus interaction with the cellular receptor is mediated by the surface protein, known as Spike. Another structural protein of major importance in the Nucleocapsid, directly interacting with the viral RNA to form the ribonucleocapsid, considered a multifunctional protein, and being the target of the most molecular diagnostics assays.ObjectiveTo describe the frequency of substitutions in spike and nucleocapsid proteins of SARS-CoV-2 circulating in Colombia and evaluate the frequency of these substitutions in SARS-CoV-2 sequences from other countries of South America.Materials and methodsSamples of 43 patients were included for viral RNA detection by real-time RT-PCR using the Charité-Berlin protocol for the amplification of the SARS-CoV-2 E and RdRp genes. Genome sequences were obtained through the Oxford Nanopore and Illumina MiSeq technologies, following the artic.network “nCoV-2019 sequencing protocol”. Available genomes were consulted from GISAID, GenBank, and Genome sequence archive (GSA) and a total of 371 genomes sequences from South America were included. The genome sequences were aligned with the Muscle tool using the MEGA X software. Substitution matrices of the Colombian sequences respect to the reference genome (NC_045512) at the nucleotide and amino acid levels were generated for the spike and nucleocapsid gene.Resultssubstitution D614G in the amino acid sequence of spike protein was found in 86.7% of the Colombian sequences; substitutions G181V and D936Y in 2.3%, respectively. Five substitutions were found in the nucleocapsid protein, with substitution R203K and G204R being the most frequent (13.95 %) in Colombia. The substitutions D614G in Spike and R203K-G204R in nucleocapsid have a frequency of 83% and 28% respectively in sequences from South America.ConclusionNon-synonymous substitutions were found in the spike and nucleocapsid proteins in Colombian genomes, the most frequent being D614G in Spike and R203K-G204R in nucleocapsid. These substitutions are frequent in the genomes reported for other South American countries. It is necessary to continue with genomic surveillance of the changes in Spike and Nucleocapsid proteins during the SARS-CoV-2 pandemic in Colombia and South America, even more considering that these proteins are the most commonly used antigen in serological tests.HighlightsThe spike and nucleocapsid proteins of SARS-CoV-2 circulating in Colombia and South-American countries have similar patterns of non-synonymous substitutionsSubstitutions D614G in Spike and R203K-G204R in Nucleocapsid are the most frequent in Colombia and South-American countries