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The use of saliva specimens for detection of influenza A and B viruses by rapid influenza diagnostic tests.

Author(s): Yoon J, Yun SG, Nam J, Choi SH, Lim CS

Publication: J Virol Methods, 2017, Vol. 243, Page 15-19

PubMed ID: 28111058 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared the sensitivity and specificity of influenza diagnosis by real-time qRT-PCR and four commercially available immunoassays of saliva and nasopharyngeal specimens and also compared results between specimen types. Nasopharyngeal and saliva specimens were collected from 385 patients with influenza-like symptoms (body temperature of 37.8°C or higher with one or more respiratory symptoms, including cough or sore throat). Nasopharyngeal specimens were collected with flocked swabs (details not provided) and placed in universal viral transport medium. Saliva specimens were collected into sterile plastic containers. Specimens were stored at 4°C, transported to the laboratory within 24 h of collection, and stored at −80°C until analysis. RNA was extracted from nasopharyngeal specimens in the viral transport medium and from saliva specimens using the QIAamp ViralRNA Mini Kit and influenza A and B viral RNA was detected using an in-house developed, multiplex real-time RT-PCR assay. Specimens were also analyzed using four commercially available immunoassays: Sofia Influenza A + B Fluorescence Immunoassay, ichroma TRIAS Influenza A + B, SD Bioline Influenza Ag, and BinaxNOW Influenza A/B Antigen Kit).

   Summary of Findings:

   The positivity rates of real-time RT-PCR with the nasopharyngeal specimens were significantly higher than those of the saliva specimens for influenza A (94.2% versus 85.0%, P<0.01) and influenza B (93.1% versus 69.0%, P<0.01), but concordance rates between specimen types were 93.5% and 97.1%, respectively. Compared to real-time RT-PCR, the sensitivities of Sofia Influenza A + B Fluorescence Immunoassay, ichroma TRIAS Influenza A + B, SD Bio-line Influenza Ag, and BinaxNOW Influenza A/B Antigen Kit for detection of influenza A virus were 74.2%, 74.2%, 63.3%, and 60.8% for the nasopharyngeal specimens, respectively, and 59.2%, 59.2%, 30.8% and 30.0% for the saliva specimens, respectively. For influenza B, the sensitivities for the nasopharyngeal specimens were 75.9%, 75.9%,75.9%, and 58.6% for Sofia Influenza A + B Fluorescence Immunoassay, ichroma TRIAS Influenza A + B, SD Bio-line Influenza Ag, and BinaxNOW Influenza A/B Antigen Kit, respectively, and were 65.5%, 62.1%, 41.4%, and 31.0% for the saliva specimens, respectively. The sensitivities of immunoassays for both influenza A and B were higher when testing nasopharyngeal specimens than saliva (P<0.01, all) and concordance rates between specimen types varied by assay. The Sofia Influenza A + B Fluorescence Immunoassay and ichroma TRIAS Influenza A + B exhibited moderate agreement for both influenza A (kappa=0.60 and kappa=0.60, respectively) and B (kappa=0.60 and kappa=0.53, respectively), SD Bioline Influenza Ag showed a fair strength of agreement for both influenza A (kappa=0.36) and B (kappa=0.40), while the BinaxNOW Influenza A/B antigen Kit had a fair agreement for influenza A (kappa=0.35), but moderate agreement for influenza B (kappa= 0.41). Compared to real-time RT-PCR results, the specificities of all four immunoassays for detection of influenza A were 100% with nasopharyngeal specimens and ranged from 99.2%-100% with saliva specimens. For detection of influenza B, the specificities of immunoassays with nasopharyngeal specimen were 99.2-99.7% specificities with saliva ranged 98.6%-99.7%. When compared to using nasopharyngeal specimens alone, the inclusion of saliva specimens significantly increased viral detection rate by real-time RT-PCR for influenza A by 6.2% and for influenza B by 7.4% and increased sensitivities of immunoassays from 10.0%-13.3% for influenza A and 10.3%-17.2% for influenza B.

   Biospecimens

   • Cell - Saliva
   • Cell - Nasopharynx

   Preservative Types

   • Frozen

   Diagnoses:

   • Pneumonia/Respiratory Infection

   Platform:

   Analyte	Technology Platform
   RNA	Real-time qRT-PCR
   Protein	Immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Biospecimen location	Nasopharynx Saliva
   Immunoassay Specific	Technology platform	Sofia Influenza A + B Fluorescence Immunoassay ichroma TRIAS Influenza A + B SD Bioline Influenza Ag BinaxNOW Influenza A/B Antigen Kit
   Real-time qRT-PCR Specific	Targeted nucleic acid	Influenza A Influenza B

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