The isolation of RNA is a template used in further polymerase chain reaction (PCR) studies to detect the presence of genetic material of viruses that cause respiratory tract infections. For this purpose QIAamp Viral RNA Mini Kit (Qiagen, Hilden, Germany) was used. The kit is designed to isolate RNA from clinical samples. A single elution with the use of elution buffer is sufficient to recover at least 90 % of the viral RNA from the QIAamp column.

The RV15 One Step ACE Detection Kit (Seegene, Seoul, South Korea) is a qualitative in vitro test for the detection of 15 types of respiratory viruses in the aspirates from nasopharynx and nasopharyngeal swabs or samples from bronchopulmonary tree lavage in patients with clinical symptoms. The kit contains a set of reagents due to which it is possible to perform a Multiplex PCR. Simplification of the two-step method results in an increased repeatability of analysis and efficiency of reaction. The kit for determining 15 respiratory viruses in a sample of a clinical material is based on a process of reverse transcription (RT) and amplification of the target DNA by PCR using Dual Priming Oligonucleotide (DPO) primers, which provides freedom in a primer design and PCR optimisation and maximizes PCR specificity and sensitivity by fundamentally blocking non-specific priming. The DPO-based multiplex assay that permits the simultaneous amplification of target sequences of 15 viruses, presented after the amplification reaction, uses e.g., electrophoresis in an agarose gel preceded by nucleic acid isolation (Kim et al. 2013).