Avian Influenza: Mixed Infections and Missing Viruses

A high prevalence and diversity of avian influenza (AI) viruses were detected in a population of wild mallards sampled during summer 2011 in California, providing an opportunity to compare results obtained before and after virus culture. We tested cloacal swab samples prior to culture by matrix real...

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Main Authors: David E. Wentworth, Vivien G. Dugan, Xudong Lin, Seth Schobel, Magdalena Plancarte, Terra R. Kelly, LeAnn L. Lindsay, Walter M. Boyce
Format: Article
Language:English
Published: MDPI AG 2013-08-01
Series:Viruses
Subjects:
Online Access:http://www.mdpi.com/1999-4915/5/8/1964
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author David E. Wentworth
Vivien G. Dugan
Xudong Lin
Seth Schobel
Magdalena Plancarte
Terra R. Kelly
LeAnn L. Lindsay
Walter M. Boyce
author_facet David E. Wentworth
Vivien G. Dugan
Xudong Lin
Seth Schobel
Magdalena Plancarte
Terra R. Kelly
LeAnn L. Lindsay
Walter M. Boyce
author_sort David E. Wentworth
collection DOAJ
description A high prevalence and diversity of avian influenza (AI) viruses were detected in a population of wild mallards sampled during summer 2011 in California, providing an opportunity to compare results obtained before and after virus culture. We tested cloacal swab samples prior to culture by matrix real-time PCR, and by amplifying and sequencing a 640bp portion of the hemagglutinin (HA) gene. Each sample was also inoculated into embryonated chicken eggs, and full genome sequences were determined for cultured viruses. While low matrix Ct values were a good predictor of virus isolation from eggs, samples with high or undetectable Ct values also yielded isolates. Furthermore, a single passage in eggs altered the occurrence and detection of viral strains, and mixed infections (different HA subtypes) were detected less frequently after culture. There is no gold standard or perfect reference comparison for surveillance of unknown viruses, and true negatives are difficult to distinguish from false negatives. This study showed that sequencing samples prior to culture increases the detection of mixed infections and enhances the identification of viral strains and sequences that may have changed or even disappeared during culture.
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spelling doaj.art-5d4ecfb7399a42e1b835bc83100eeee12022-12-22T01:19:09ZengMDPI AGViruses1999-49152013-08-01581964197710.3390/v5081964Avian Influenza: Mixed Infections and Missing VirusesDavid E. WentworthVivien G. DuganXudong LinSeth SchobelMagdalena PlancarteTerra R. KellyLeAnn L. LindsayWalter M. BoyceA high prevalence and diversity of avian influenza (AI) viruses were detected in a population of wild mallards sampled during summer 2011 in California, providing an opportunity to compare results obtained before and after virus culture. We tested cloacal swab samples prior to culture by matrix real-time PCR, and by amplifying and sequencing a 640bp portion of the hemagglutinin (HA) gene. Each sample was also inoculated into embryonated chicken eggs, and full genome sequences were determined for cultured viruses. While low matrix Ct values were a good predictor of virus isolation from eggs, samples with high or undetectable Ct values also yielded isolates. Furthermore, a single passage in eggs altered the occurrence and detection of viral strains, and mixed infections (different HA subtypes) were detected less frequently after culture. There is no gold standard or perfect reference comparison for surveillance of unknown viruses, and true negatives are difficult to distinguish from false negatives. This study showed that sequencing samples prior to culture increases the detection of mixed infections and enhances the identification of viral strains and sequences that may have changed or even disappeared during culture.http://www.mdpi.com/1999-4915/5/8/1964avian influenzasurveillancehemagglutininvirus isolationembryonated chicken eggsequencinggenome
spellingShingle David E. Wentworth
Vivien G. Dugan
Xudong Lin
Seth Schobel
Magdalena Plancarte
Terra R. Kelly
LeAnn L. Lindsay
Walter M. Boyce
Avian Influenza: Mixed Infections and Missing Viruses
Viruses
avian influenza
surveillance
hemagglutinin
virus isolation
embryonated chicken egg
sequencing
genome
title Avian Influenza: Mixed Infections and Missing Viruses
title_full Avian Influenza: Mixed Infections and Missing Viruses
title_fullStr Avian Influenza: Mixed Infections and Missing Viruses
title_full_unstemmed Avian Influenza: Mixed Infections and Missing Viruses
title_short Avian Influenza: Mixed Infections and Missing Viruses
title_sort avian influenza mixed infections and missing viruses
topic avian influenza
surveillance
hemagglutinin
virus isolation
embryonated chicken egg
sequencing
genome
url http://www.mdpi.com/1999-4915/5/8/1964
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AT sethschobel avianinfluenzamixedinfectionsandmissingviruses
AT magdalenaplancarte avianinfluenzamixedinfectionsandmissingviruses
AT terrarkelly avianinfluenzamixedinfectionsandmissingviruses
AT leannllindsay avianinfluenzamixedinfectionsandmissingviruses
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