1. SARS-CoV-2 mutant spectra reveal differences between COVID-19 severity categories
- Author
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Martínez-González, Brenda, Soria, María Eugenia, Vázquez-Sirvent, Lucía, Ferrer-Orta, Cristina, Lobo-Vega, Rebeca, Mínguez, Pablo, Fuente, Lorena de la, Llorens, Carlos, Soriano, Beatriz, Ramos-Ruíz, Ricardo, Cortón, Marta, López-Rodríguez, Rosario, García-Crespo, Carlos, Somovilla, Pilar, Durán-Pastor, Antoni, Gallego, Isabel, Ávila, Ana Isabel de, Delgado, Soledad, Morán, Federico, López-Galíndez, Cecilio, Gómez, Jordi, Enjuanes Sánchez, Luis, Salar-Vidal, Llanos, Esteban-Muñoz, Mario, Esteban, Jaime, Fernández-Roblas, Ricardo, Gadea, Ignacio, Ayuso, Carmen, Ruíz-Hornillos, Javier, Verdaguer, Núria, Domingo, Esteban, Perales, Celia, Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación (España), Consejo Superior de Investigaciones Científicas (España), Fundació La Marató de TV3, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Comunidad de Madrid, European Commission, Centro de Investigación Biomédica en Red Enfermedades Hepáticas y Digestivas (España), Fundación Ramón Areces, Banco Santander, Ministerio de Sanidad y Consumo (España), and Ministerio de Economía y Competitividad (España)
- Abstract
Trabajo presentado en el XVI Congreso Nacional de Virología, celebrado en Málaga (España) del 06 al 09 de septiembre de 2022., RNA virus populations are composed of complex mixtures of genomes that are termed mutant spectra. SARS-CoV-2 replicates as a viral quasispecies, and mutations that are detected at low frequencies in a host can be dominant in subsequent variants. We have studied mutant spectrum complexities of SARS-CoV-2 populations derived from thirty nasopharyngeal swabs of patients infected during the first wave (April 2020) in the Hospital Universitario Fundación Jiménez Díaz. The patients were classified according to the COVID-19 severity in mild (non-hospitalized), moderate (hospitalized) and exitus (hospitalized with ICU admission and who passed away due to COVID-19). Using ultra-deep sequencing technologies (MiSeq, Illumina), we have examined four amplicons of the nsp12 (polymerase)-coding region and two amplicons of the spike-coding region. Ultra-deep sequencing data were analyzed with different cut-off frequency for mutation detection. Average number of different point mutations, mutations per haplotype and several diversity indices were significantly higher in SARS-CoV-2 isolated from patients who developed mild disease. A feature that we noted in the SARS-CoV-2 mutant spectra from diagnostic samples is the remarkable absence of mutations at intermediate frequencies, and an overwhelming abundance of mutations at frequencies lower than 10%. Thus, the decrease of the cut-off frequency for mutation detection from 0.5% to 0.1% revealed an increasement (50- to 100 fold) in the number of different mutations. The significantly higher frequency of mutations in virus from patients displaying mild than moderate or severe disease was maintained with the 0.1% cut- off frequency. To evaluate whether the frequency repertoire of amino acid substitutions differed between SARS-CoV-2 and the well characterized hepatitis C virus (HCV), we performed a comparative study of mutant spectra from infected patients using the same bioinformatics pipelines. HCV did not show the deficit of intermediate frequency substitutions that was observed with SARS-CoV-2. This difference was maintained when two functionally equivalent proteins, the corresponding viral polymerases, were compared. In conclusion, SARS-CoV-2 mutant spectra are rich reservoirs of mutants, whose complexity is not uniform among clinical isolates. Virus from patients who developed mild disease may be a source of new variants that may acquire epidemiological relevance., This work was supported by Instituto de Salud Carlos III, Spanish Ministry of Science and In-novation (COVID-19 Research Call COV20/00181), and co-financed by European Development Regional Fund ‘A way to achieve Europe’. The work was also supported by grants CSIC-COV19-014 from Consejo Superior de Investigaciones Científicas (CSIC), project 525/C/2021 from Fundació La Marató de TV3, PID2020-113888RB-I00 from Ministerio de Ciencia e Innovación, BFU2017-91384-EXP from Ministerio de Ciencia, Innovación y Universidades (MCIU), PI18/00210 and PI21/00139 from Instituto de Salud Carlos III, and S2018/BAA-4370 (PLATESA2 from Comunidad de Madrid/FEDER). C.P., M.C., and P.M. are supported by the Miguel Servet programme of the Instituto de Salud Carlos III (CPII19/00001, CPII17/00006, and CP16/00116, respectively) co-financed by the European Regional Development Fund (ERDF). CIBERehd (Centro de Investi-gación en Red de Enfermedades Hepáticas y Digestivas) is funded by Instituto de Salud Carlos III. Institutional grants from the Fundación Ramón Areces and Banco Santander to the CBMSO are also acknowledged. The team at CBMSO belongs to the Global Virus Network (GVN). B.M.-G. is supported by predoctoral contract PFIS FI19/00119 from Instituto de Salud Carlos III (Ministerio de Sanidad y Consumo) cofinanced by Fondo Social Europeo (FSE). R.L.-V. is supported by predoctoral contract PEJD-2019-PRE/BMD-16414 from Comunidad de Madrid. C.G.-C. is sup-ported by predoctoral contract PRE2018-083422 from MCIU. BS was supported by a predoctoral research fellowship (Doctorados Industriales, DI-17-09134) from Spanish MINECO.
- Published
- 2022