Viral culture and immunofluorescence for the detection of SARS-CoV-2 infectivity in RT-PCR positive respiratory samples.
COVID-19
Infectivity
SARS-CoV-2
VERO E6 cells
Viral culture
Viral isolation
Journal
Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology
ISSN: 1873-5967
Titre abrégé: J Clin Virol
Pays: Netherlands
ID NLM: 9815671
Informations de publication
Date de publication:
07 2022
07 2022
Historique:
received:
30
11
2021
revised:
06
02
2022
accepted:
20
04
2022
pubmed:
7
5
2022
medline:
15
6
2022
entrez:
6
5
2022
Statut:
ppublish
Résumé
Knowing how long SARS-CoV-2-positive individuals can remain infective is crucial for the design of infection prevention and control strategies. Viral culture is the gold standard for detecting an active-replicative virus and evaluating its infectious potential. To assess the correlation of SARS-CoV-2 infectivity with the number of days from symptom onset and the Ct value, using culture as a reference method. Also, to describe a detailed protocol for SARS-CoV-2 culture and immunofluorescence confirmation based on our experience with other respiratory viruses. 100 consecutive respiratory samples positive for SARS-CoV-2 by RT-PCR from different subjects were inoculated into VERO E6 cells. Viral isolation was successful in 58% of samples. The median number of days from symptom onset for culture-positive samples was 2, and 15 for culture-negative samples. Six positive cultures were obtained in patients ≥14 days after symptom onset, all of whom were immunocompromised or with severe COVID-19. The mean Ct value was 12.64 units higher in culture-negative than in culture-positive samples. The probability of successfully isolating SARS-CoV-2 in samples with a Ct value <22 was 100%, decreasing to 3.1% when >27. Our findings show a significant positive correlation between the probability of isolating SARS-CoV-2 in culture, fewer days of symptoms and a lower RT-PCR Ct value. SARS-CoV-2 infectivity lasts no more than 14 days from symptom onset in immunocompetent individuals. In contrast, in immunocompromised patients or those with severe COVID-19 infectivity may remain after 14 days. Ct value <22 always indicates infectivity.
Sections du résumé
BACKGROUND
Knowing how long SARS-CoV-2-positive individuals can remain infective is crucial for the design of infection prevention and control strategies. Viral culture is the gold standard for detecting an active-replicative virus and evaluating its infectious potential.
OBJECTIVE
To assess the correlation of SARS-CoV-2 infectivity with the number of days from symptom onset and the Ct value, using culture as a reference method. Also, to describe a detailed protocol for SARS-CoV-2 culture and immunofluorescence confirmation based on our experience with other respiratory viruses.
STUDY DESIGN
100 consecutive respiratory samples positive for SARS-CoV-2 by RT-PCR from different subjects were inoculated into VERO E6 cells.
RESULTS
Viral isolation was successful in 58% of samples. The median number of days from symptom onset for culture-positive samples was 2, and 15 for culture-negative samples. Six positive cultures were obtained in patients ≥14 days after symptom onset, all of whom were immunocompromised or with severe COVID-19. The mean Ct value was 12.64 units higher in culture-negative than in culture-positive samples. The probability of successfully isolating SARS-CoV-2 in samples with a Ct value <22 was 100%, decreasing to 3.1% when >27.
CONCLUSIONS
Our findings show a significant positive correlation between the probability of isolating SARS-CoV-2 in culture, fewer days of symptoms and a lower RT-PCR Ct value. SARS-CoV-2 infectivity lasts no more than 14 days from symptom onset in immunocompetent individuals. In contrast, in immunocompromised patients or those with severe COVID-19 infectivity may remain after 14 days. Ct value <22 always indicates infectivity.
Identifiants
pubmed: 35523105
pii: S1386-6532(22)00100-7
doi: 10.1016/j.jcv.2022.105167
pmc: PMC9046102
pii:
doi:
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
105167Informations de copyright
Copyright © 2022 Elsevier B.V. All rights reserved.
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