Evaluation of "Caterina assay": An Alternative Tool to the Commercialized Kits Used for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Identification.

Germano Orrù,Giorgio Carlo Steri,Ferdinando Coghe,Alessandra Scano,Simonetta Santus,Sara Fais,Riccardo Cappai,Mauro Giovanni Carta,Miriam Loddo,Maria Laura Ferrando

doi:10.3390/pathogens10030325

Germano Orrù, Giorgio Carlo Steri + Show 8 more

Open Access

https://doi.org/10.3390/pathogens10030325

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Abstract

Here we describe the first molecular test developed in the early stage of the pandemic to diagnose the first cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Sardinian patients in February–March 2020, when diagnostic certified methodology had not yet been adopted by clinical microbiology laboratories. The “Caterina assay” is a SYBR®Green real-time reverse-transcription polymerase chain reaction (rRT-PCR), designed to detect the nucleocapsid phosphoprotein (N) gene that exhibits high discriminative variation RNA sequence among bat and human coronaviruses. The molecular method was applied to detect SARS-CoV-2 in nasal swabs collected from 2110 suspected cases. The study article describes the first molecular test developed in the early stage of the declared pandemic to identify the coronavirus disease 2019 (COVID-19) in Sardinian patients in February–March 2020, when a diagnostic certified methodology had not yet been adopted by clinical microbiology laboratories. The assay presented high specificity and sensitivity (with a detection limit ≥50 viral genomes/μL). No false-positives were detected, as confirmed by the comparison with two certified commercial kits. Although other validated molecular methods are currently in use, the Caterina assay still represents a valid and low-cost detection procedure that could be applied in countries with limited economic resources.

Highlights

The current pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1], poses serious problems in different fields of medical practice [2,3]
The methods for the specific detection of SARS-CoV-2 were based on real-time reversetranscription polymerase chain reaction, most of them to reveal the genetic material through the use of multiple primers and hydrolysis probes designed on RNA sequences of one or more reference (i.e., TaqMan probe) [11]
PCR primers were designed on the nucleotide sequence of SARS-CoV-2 Wu-Hu-1 accession number MN908947.3, which was posted for the first time in the open access Virological website on 11 January 2020 and available in Global Initiative on Sharing lll Influenza Data (GISAID, https://www.gisaid. org/ accessed on 20 January 2020) (Figure 1A)

Summary

Introduction

The current pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [1], poses serious problems in different fields of medical practice [2,3]. The main gene targets used in COVID-19 diagnosis by main health organizations are related to N (nucleocapsid phosphoprotein, N1, N2 and N3 amplicons, Centers for Disease Control and Prevention (CDC) [12] and N2 amplicon WHO [13]), E (envelope protein, E amplicon, WHO [13,14]) and ORF-1ab (RdRP gene, ab polyprotein) RNA region [13,15,16,17]

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