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Rapid Molecular Detection and Differentiation of Influenza Viruses A and B
Published on: January 30, 2017
Detection of influenza C virus but not influenza D virus in Scottish respiratory samples
Donald B Smith1, Eleanor R Gaunt2, Paul Digard2
1Centre for Immunology, Infection and Evolution, University of Edinburgh, Ashworth Laboratories, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, United Kingdom.
Background:
A newly proposed genus of influenza virus (influenza D) is associated with respiratory disease in pigs and cattle. The novel virus is most closely related to human influenza C virus and can infect ferrets but infection has not been reported in humans.
Objectives:
To ascertain if influenza D virus can be detected retrospectively in patient respiratory samples.
Study Design:
3300 human respiratory samples from Edinburgh, Scotland, covering the period 2006-2008, were screened in pools of 10 by RT-PCR using primers capable of detecting both influenza C and D viruses.
Results:
Influenza D was not detected in any sample. Influenza C was present in 6 samples (0.2%), compared with frequencies of 3.3% and 0.9% for influenza A and B viruses from RT-PCR testing of respiratory samples over the same period. Influenza C virus was detected in samples from individuals <2 years or >45 years old, with cases occurring throughout the year. Phylogenetic analysis of nearly complete sequences of all seven segments revealed the presence of multiple, reassortant lineages.
Conclusion:
We were unable to detect viruses related to influenza D virus in human respiratory samples. Influenza C virus was less prevalent than influenza A and B viruses, was associated with mild disease in the young (<2 years) and old (>45 years) and comprised multiple, reassortant lineages. Inclusion of influenza C virus as part of a diagnostic testing panel for respiratory infections would be of limited additional value.
Insights
Influenza D virus was not detected in human respiratory samples. Influenza C virus was found to be less common than influenza A and B, primarily affecting the very young and old.
Area of Science:
- Virology
- Public Health
- Epidemiology
Background:
- A novel genus, influenza D virus, has been identified, primarily affecting swine and cattle.
- This virus shares similarities with human influenza C virus and can infect ferrets, but human cases have not been documented.
Purpose of the Study:
- To investigate the potential presence of influenza D virus in human respiratory samples retrospectively.
- To assess the prevalence and characteristics of influenza C virus in the human population.
Main Methods:
- Screening of 3300 human respiratory samples (2006-2008) using RT-PCR with primers for influenza C and D viruses.
- Phylogenetic analysis of detected influenza C virus segments.
Main Results:
- Influenza D virus was not detected in any of the human samples.
- Influenza C virus was detected in 0.2% of samples, significantly less than influenza A and B.
- Influenza C virus cases occurred in individuals under 2 or over 45 years old, with year-round circulation and multiple reassortant lineages identified.
Conclusions:
- The study did not find evidence of influenza D virus in the tested human respiratory samples.
- Influenza C virus is less prevalent than other human influenza types and is associated with mild illness in specific age groups.
- Routine inclusion of influenza C virus in diagnostic panels for respiratory infections may offer limited additional benefit.
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