Cellular DNA quantification in respiratory samples for the normalization of viral load

a real need?

Research output: Contribution to journalArticle

Abstract

Background: Respiratory tract infections have an enormous social economic impact, with high incidence of hospitalization and high costs. Adequate specimen collection is the first crucial step for the correct diagnosis of viral respiratory infections. Objectives: The present retrospective study aimed: i) to verify the cell yield obtained from sampling the nasal respiratory tract using mid-turbinate flocked swabs; ii) to evaluate the normalization of viral load, based on cell number; and iii) to compare the kinetics of viral infection obtained with normalized vs non-normalized viral load. Study design: The number of cells were quantified by real-time PCR in residual extract of nasal swabs tested for respiratory viruses detection and stored at −80 °C in a universal transport medium (UTM™). Results: A total of 513 virus-positive and 226 virus-negative samples were analyzed. Overall, a median of 4.42 log10 β2-microgolubin DNA copy number/ml of UTM (range 1.17–7.26) was detected. A significantly higher number of cells was observed in virus-positive as compared to virus-negative samples (4.75 vs 3.76; p < 0.001). Viral loads expressed as log10 RNA copies/ml of UTM and log10 RNA copies/median number of cells were compared in virus-positive samples and a strict correlation (r = 0.89, p < 0.001) and agreement (R2 = 0.82) were observed. In addition, infection kinetics were compared using the two methods with a follow-up series of eight episodes of viral infection and the mean difference was -0.57 log10 (range −1.99 to 0.40). Conclusions: The normalization of viral load using cellular load compliments the validation of real-time PCR results in the diagnosis of respiratory viruses but is not strictly needed.

Original languageEnglish
Pages (from-to)6-10
Number of pages5
JournalJournal of Clinical Virology
Volume107
DOIs
Publication statusPublished - Oct 1 2018

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Viral Load
Viruses
DNA
Virus Diseases
Cell Count
Nose
Respiratory Tract Infections
Real-Time Polymerase Chain Reaction
RNA
Specimen Handling
Turbinates
Respiratory System
Hospitalization
Retrospective Studies
Economics
Costs and Cost Analysis
Incidence
Infection

Keywords

  • Cell number
  • Flocked mid-turbinate nasal swabs
  • Quantification
  • Respiratory viruses
  • Viral load

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases

Cite this

@article{d5991cf6ed5f462790936364d13965ac,
title = "Cellular DNA quantification in respiratory samples for the normalization of viral load: a real need?",
abstract = "Background: Respiratory tract infections have an enormous social economic impact, with high incidence of hospitalization and high costs. Adequate specimen collection is the first crucial step for the correct diagnosis of viral respiratory infections. Objectives: The present retrospective study aimed: i) to verify the cell yield obtained from sampling the nasal respiratory tract using mid-turbinate flocked swabs; ii) to evaluate the normalization of viral load, based on cell number; and iii) to compare the kinetics of viral infection obtained with normalized vs non-normalized viral load. Study design: The number of cells were quantified by real-time PCR in residual extract of nasal swabs tested for respiratory viruses detection and stored at −80 °C in a universal transport medium (UTM™). Results: A total of 513 virus-positive and 226 virus-negative samples were analyzed. Overall, a median of 4.42 log10 β2-microgolubin DNA copy number/ml of UTM™ (range 1.17–7.26) was detected. A significantly higher number of cells was observed in virus-positive as compared to virus-negative samples (4.75 vs 3.76; p < 0.001). Viral loads expressed as log10 RNA copies/ml of UTM™ and log10 RNA copies/median number of cells were compared in virus-positive samples and a strict correlation (r = 0.89, p < 0.001) and agreement (R2 = 0.82) were observed. In addition, infection kinetics were compared using the two methods with a follow-up series of eight episodes of viral infection and the mean difference was -0.57 log10 (range −1.99 to 0.40). Conclusions: The normalization of viral load using cellular load compliments the validation of real-time PCR results in the diagnosis of respiratory viruses but is not strictly needed.",
keywords = "Cell number, Flocked mid-turbinate nasal swabs, Quantification, Respiratory viruses, Viral load",
author = "Antonio Piralla and Federica Giardina and Francesca Rovida and Giulia Campanini and Fausto Baldanti",
year = "2018",
month = "10",
day = "1",
doi = "10.1016/j.jcv.2018.07.010",
language = "English",
volume = "107",
pages = "6--10",
journal = "Journal of Clinical Virology",
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TY - JOUR

T1 - Cellular DNA quantification in respiratory samples for the normalization of viral load

T2 - a real need?

AU - Piralla, Antonio

AU - Giardina, Federica

AU - Rovida, Francesca

AU - Campanini, Giulia

AU - Baldanti, Fausto

PY - 2018/10/1

Y1 - 2018/10/1

N2 - Background: Respiratory tract infections have an enormous social economic impact, with high incidence of hospitalization and high costs. Adequate specimen collection is the first crucial step for the correct diagnosis of viral respiratory infections. Objectives: The present retrospective study aimed: i) to verify the cell yield obtained from sampling the nasal respiratory tract using mid-turbinate flocked swabs; ii) to evaluate the normalization of viral load, based on cell number; and iii) to compare the kinetics of viral infection obtained with normalized vs non-normalized viral load. Study design: The number of cells were quantified by real-time PCR in residual extract of nasal swabs tested for respiratory viruses detection and stored at −80 °C in a universal transport medium (UTM™). Results: A total of 513 virus-positive and 226 virus-negative samples were analyzed. Overall, a median of 4.42 log10 β2-microgolubin DNA copy number/ml of UTM™ (range 1.17–7.26) was detected. A significantly higher number of cells was observed in virus-positive as compared to virus-negative samples (4.75 vs 3.76; p < 0.001). Viral loads expressed as log10 RNA copies/ml of UTM™ and log10 RNA copies/median number of cells were compared in virus-positive samples and a strict correlation (r = 0.89, p < 0.001) and agreement (R2 = 0.82) were observed. In addition, infection kinetics were compared using the two methods with a follow-up series of eight episodes of viral infection and the mean difference was -0.57 log10 (range −1.99 to 0.40). Conclusions: The normalization of viral load using cellular load compliments the validation of real-time PCR results in the diagnosis of respiratory viruses but is not strictly needed.

AB - Background: Respiratory tract infections have an enormous social economic impact, with high incidence of hospitalization and high costs. Adequate specimen collection is the first crucial step for the correct diagnosis of viral respiratory infections. Objectives: The present retrospective study aimed: i) to verify the cell yield obtained from sampling the nasal respiratory tract using mid-turbinate flocked swabs; ii) to evaluate the normalization of viral load, based on cell number; and iii) to compare the kinetics of viral infection obtained with normalized vs non-normalized viral load. Study design: The number of cells were quantified by real-time PCR in residual extract of nasal swabs tested for respiratory viruses detection and stored at −80 °C in a universal transport medium (UTM™). Results: A total of 513 virus-positive and 226 virus-negative samples were analyzed. Overall, a median of 4.42 log10 β2-microgolubin DNA copy number/ml of UTM™ (range 1.17–7.26) was detected. A significantly higher number of cells was observed in virus-positive as compared to virus-negative samples (4.75 vs 3.76; p < 0.001). Viral loads expressed as log10 RNA copies/ml of UTM™ and log10 RNA copies/median number of cells were compared in virus-positive samples and a strict correlation (r = 0.89, p < 0.001) and agreement (R2 = 0.82) were observed. In addition, infection kinetics were compared using the two methods with a follow-up series of eight episodes of viral infection and the mean difference was -0.57 log10 (range −1.99 to 0.40). Conclusions: The normalization of viral load using cellular load compliments the validation of real-time PCR results in the diagnosis of respiratory viruses but is not strictly needed.

KW - Cell number

KW - Flocked mid-turbinate nasal swabs

KW - Quantification

KW - Respiratory viruses

KW - Viral load

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DO - 10.1016/j.jcv.2018.07.010

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JF - Journal of Clinical Virology

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