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 language | English |
|---|---|
| Pages (from-to) | 6-10 |
| Number of pages | 5 |
| Journal | Journal of Clinical Virology |
| Volume | 107 |
| DOIs | |
| Publication status | Published - Oct 1 2018 |
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Keywords
- Cell number
- Flocked mid-turbinate nasal swabs
- Quantification
- Respiratory viruses
- Viral load
ASJC Scopus subject areas
- Virology
- Infectious Diseases
Cite this
Cellular DNA quantification in respiratory samples for the normalization of viral load : a real need? / Piralla, Antonio; Giardina, Federica; Rovida, Francesca; Campanini, Giulia; Baldanti, Fausto.
In: Journal of Clinical Virology, Vol. 107, 01.10.2018, p. 6-10.Research output: Contribution to journal › Article
}
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
UR - http://www.scopus.com/inward/record.url?scp=85051145921&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85051145921&partnerID=8YFLogxK
U2 - 10.1016/j.jcv.2018.07.010
DO - 10.1016/j.jcv.2018.07.010
M3 - Article
VL - 107
SP - 6
EP - 10
JO - Journal of Clinical Virology
JF - Journal of Clinical Virology
SN - 1386-6532
ER -