Elsevier

Journal of Clinical Virology

Volume 97, December 2017, Pages 54-58
Journal of Clinical Virology

The first external quality assessment of isolation and identification of influenza viruses in cell culture in the Asia Pacific region, 2016

https://doi.org/10.1016/j.jcv.2017.10.018Get rights and content

Highlights

  • An external quality assessment (EQA) was developed for influenza virus isolation.

  • National Influenza Centres (NICs) in the Asia Pacific Region performed the EQA.

  • NICs used a variety of techniques to confirm and identify influenza virus isolates.

  • The EQA revealed good proficiency and highlighted the need to improve sensitivity.

Abstract

Background

The isolation and propagation of influenza viruses from clinical specimens are essential tools for comprehensive virologic surveillance. Influenza viruses must be amplified in cell culture for detailed antigenic analysis and for phenotypic assays assessing susceptibility to antiviral drugs or for other assays.

Objectives

To conduct an external quality assessment (EQA) of proficiency for isolation and identification of influenza viruses using cell culture techniques among National Influenza Centres (NICs) in the World Health Organisation (WHO) South East Asia and Western Pacific Regions.

Study design

Twenty-one NICs performed routine influenza virus isolation and identification techniques on a proficiency testing panel comprising 16 samples, containing influenza A or B viruses and negative control samples. One sample was used exclusively to determine their capacity to measure hemagglutination titer and the other 15 samples were used for virus isolation and identification.

Results

All NICs performed influenza virus isolation using Madin Darby canine kidney (MDCK) or MDCK-SIAT-1 cells. If virus growth was detected, the type, subtype and/or lineage of virus present in isolates was determined using immunofluorescence, RT-PCR and/or hemagglutination inhibition (HI) assays. Most participating laboratories could detect influenza virus growth and could identify virus amplified from EQA samples. However, some laboratories failed to isolate and identify viruses from EQA samples that contained lower titres of virus, highlighting issues regarding the sensitivity of influenza virus isolation methods between laboratories.

Conclusion

This first round of EQA was successfully conducted by NICs in the Asia Pacific Region, revealing good proficiency in influenza virus isolation and identification.

Section snippets

Background

Influenza viruses circulate worldwide and represent a continuous threat for human health. The ability to isolate and propagate influenza virus from clinical specimens is essential for ongoing surveillance of circulating virus strains and sharing of viruses. Historically, embryonated chicken eggs have been used to propagate influenza viruses [1], [2] and currently most seasonal influenza vaccines are still produced in this substrate. Mammalian cell culture represents a simple, sensitive and

Objectives

In 2007, WHO initiated an EQA programme for influenza virus subtype A detection by polymerase chain reaction (PCR), following a number of A(H5N1) outbreaks in Asia. The EQA programme has been extended to include seasonal influenza A, influenza B and other non-seasonal influenza A viruses reported in human infections [10]. Most NICs and some additional laboratories in the WHO Western Pacific Region (WPR) and South East Asia Region (SEAR) participate in this EQA programme. Over the years, a

Participating laboratories

19 NICs from 14 countries and areas in the WHO Western Pacific Region (WPR) and 10 NICs from 8 countries and areas in the WHO South East Asian Region (SEAR) were invited to participate in the EQA. Of those invited, 14 NICs from WPR and 7 from SEAR agreed to participate. An EQA panel and questionnaire were dispatched to these laboratories between September and November 2016.

Preparation of EQA panel

The panel for the 2016 EQA of influenza virus isolation and identification comprised 16 samples, containing isolates of

Analysis of VIP-2016-01 using hemagglutination (HA) assay.

HA titers of sample VIP-2016-01 were provided by 17/21 participating laboratories and these were generally within 4-fold of the minimum/maximum HA titers determined at WHO CCRRI (i.e. 32–64 HAU/25ul). One laboratory reported a titer 8-fold lower than the expected minimum HA titer. Participating laboratories used erythrocytes from guinea pig (7/17), human O (5/17), turkey (5/17) or goose (1/17), with one laboratory using both guinea pig and turkey erythrocytes. All laboratories used 0.5–1.0%

Discussion

This study represents the first EQA of influenza virus isolation and identification in cell culture distributed to NIC laboratories in the Asia Pacific Region. Overall, the data confirmed that most of the participating laboratories could detect influenza virus growth and could identify virus amplified from EQA samples. However, some laboratories failed to isolate viruses from EQA samples when they contained low titres of virus, highlighting issues regarding the sensitivity of influenza virus

Competing interests

None declared.

Ethical approval

None required.

Acknowledgements

We acknowledge the following laboratories for their participating in the EQA: PathWest Laboratory Medicine, QEII Medical Centre (Australia);Victorian Infectious Diseases Reference Laboratory (Australia); Institute of Clinical Pathology and Medical Research, Westmead Hospital (Australia); Virology Unit, Institut Pasteur du Cambodge (Cambodia); Centre for Health Protection, Department of Health (Hong Kong Special Administrative Region); National Centre for Laboratory and Epidemiology (Lao

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Cited by (1)

  • A second external quality assessment of isolation and identification of influenza viruses in cell culture in the Asia Pacific region highlights improved performance by participating laboratories

    2021, Journal of Clinical Virology
    Citation Excerpt :

    This study describes the results from the 2019 EQA (panel 3) of influenza virus isolation and identification in cell culture for NIC laboratories in the Asia Pacific Region and compares performance to the results of the first EQA conducted in 2016 (panel 1). A number of NIC laboratories in the Asia Pacific region had difficulty in performing isolation from EQA samples and in identifying influenza viruses in isolates derived from 2016 EQA samples that contained lower amounts of virus, highlighting issues in the sensitivity of influenza virus isolation methods ([4],Fig. 1). In 2019, there was significant improvement in the percentage of laboratories reporting correct results for EQA samples containing low amounts of virus (Fig. 1).

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