Analysis of the upper respiratory tract microbiota in mild and severe COVID19 patients
16S rRNA SequencingRNA was extracted using QIAamp Viral RNA Mini Kit (250) (Qiagen) according to the manufacturers protocol. 16S library preparation and sequencing were done according to Illumina protocol (16S Metagenomic Sequencing Library Preparation). Briefly, extracted RNA was amplified using standard 16S rRNA gene primers, complementary to V3-V4 region and containing 5-illumina adapter sequences. In the next step individual amplicons were PCR indexed and pooled. DNA libraries were sequenced on a MiSeq instrument (Illumina, San Diego, CA, USA) using Miseq reagent kit v3 (Illumina, San Diego, CA, USA).