Document Detail

High-throughput detection method for influenza virus.
MedLine Citation:
PMID:  22331038     Owner:  NLM     Status:  MEDLINE    
Influenza virus is a respiratory pathogen that causes a high degree of morbidity and mortality every year in multiple parts of the world. Therefore, precise diagnosis of the infecting strain and rapid high-throughput screening of vast numbers of clinical samples is paramount to control the spread of pandemic infections. Current clinical diagnoses of influenza infections are based on serologic testing, polymerase chain reaction, direct specimen immunofluorescence and cell culture (1,2). Here, we report the development of a novel diagnostic technique used to detect live influenza viruses. We used the mouse-adapted human A/PR/8/34 (PR8, H1N1) virus (3) to test the efficacy of this technique using MDCK cells (4). MDCK cells (10(4) or 5 x 10(3) per well) were cultured in 96- or 384-well plates, infected with PR8 and viral proteins were detected using anti-M2 followed by an IR dye-conjugated secondary antibody. M2 (5) and hemagglutinin (1) are two major marker proteins used in many different diagnostic assays. Employing IR-dye-conjugated secondary antibodies minimized the autofluorescence associated with other fluorescent dyes. The use of anti-M2 antibody allowed us to use the antigen-specific fluorescence intensity as a direct metric of viral quantity. To enumerate the fluorescence intensity, we used the LI-COR Odyssey-based IR scanner. This system uses two channel laser-based IR detections to identify fluorophores and differentiate them from background noise. The first channel excites at 680 nm and emits at 700 nm to help quantify the background. The second channel detects fluorophores that excite at 780 nm and emit at 800 nm. Scanning of PR8-infected MDCK cells in the IR scanner indicated a viral titer-dependent bright fluorescence. A positive correlation of fluorescence intensity to virus titer starting from 10(2)-10(5) PFU could be consistently observed. Minimal but detectable positivity consistently seen with 10(2)-10(3) PFU PR8 viral titers demonstrated the high sensitivity of the near-IR dyes. The signal-to-noise ratio was determined by comparing the mock-infected or isotype antibody-treated MDCK cells. Using the fluorescence intensities from 96- or 384-well plate formats, we constructed standard titration curves. In these calculations, the first variable is the viral titer while the second variable is the fluorescence intensity. Therefore, we used the exponential distribution to generate a curve-fit to determine the polynomial relationship between the viral titers and fluorescence intensities. Collectively, we conclude that IR dye-based protein detection system can help diagnose infecting viral strains and precisely enumerate the titer of the infecting pathogens.
Pawan Kumar; Allison E Bartoszek; Thomas M Moran; Jack Gorski; Sanjib Bhattacharyya; Jose F Navidad; Monica S Thakar; Subramaniam Malarkannan
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Video-Audio Media     Date:  2012-02-04
Journal Detail:
Title:  Journal of visualized experiments : JoVE     Volume:  -     ISSN:  1940-087X     ISO Abbreviation:  J Vis Exp     Publication Date:  2012  
Date Detail:
Created Date:  2012-02-14     Completed Date:  2012-05-21     Revised Date:  2014-02-04    
Medline Journal Info:
Nlm Unique ID:  101313252     Medline TA:  J Vis Exp     Country:  United States    
Other Details:
Languages:  eng     Pagination:  -     Citation Subset:  IM    
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MeSH Terms
Bronchoalveolar Lavage Fluid / virology
Cell Line
High-Throughput Screening Assays / methods*
Influenza A Virus, H1N1 Subtype / isolation & purification*
Influenza, Human / virology
Mice, Inbred C57BL
Orthomyxoviridae Infections / virology
Grant Support
N01-HHSN26600500032C//PHS HHS; R01 A1064826-01//PHS HHS; U19 AI062627-01/AI/NIAID NIH HHS

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