Standardizing the influenza neuraminidase inhibition assay among United States public health laboratories conducting virological surveillance

Authors

M. Okomo-Adhiambo, Centers for Disease Control and Prevention (CDC), Atlanta, GA
V.P. Mishin, Centers for Disease Control and Prevention (CDC), Atlanta, GA
K. Sleeman, Centers for Disease Control and Prevention (CDC), Atlanta, GA
E. Saguar, California Department of Public Health (CDPH), Richmond, CA
H. Guevara, California Department of Public Health (CDPH), Richmond, CA
E. Reisdorf, Wisconsin State Laboratory of Hygiene (WSLH), Madison, WI
R.H. Griesser, Wisconsin State Laboratory of Hygiene (WSLH), Madison, WI
K.J. Spackman, Unified State Laboratories: Public Health (USLPH), Taylorsville, UT
M. Mendenhall, Unified State Laboratories: Public Health (USLPH), Taylorsville, UT
M.P. Carlos, Maryland Department of Health and Mental Hygiene (MD DHMH) Laboratories Administration, Baltimore, MD
B. Healey, Maryland Department of Health and Mental Hygiene (MD DHMH) Laboratories Administration, Baltimore, MD
K. St. George, New York State Department of Health (NYSDOH), Albany, NY
J. Laplante, New York State Department of Health (NYSDOH), Albany, NY
T. Aden, Association of Public Health Laboratories (APHL), Silver Spring, MD
S. Chester, Association of Public Health Laboratories (APHL), Silver Spring, MD
X. Xu, Centers for Disease Control and Prevention (CDC), Atlanta, GA
L.V. Gubareva, Centers for Disease Control and Prevention (CDC), Atlanta, GAFollow

Date of this Version

2016

Citation

Antiviral Research 128 (2016) 28-35

Comments

U.S. Government Work

Abstract

Background: Monitoring influenza virus susceptibility to neuraminidase (NA) inhibitors (NAIs) is vital for detecting drug-resistant variants, and is primarily assessed using NA inhibition (NI) assays, supplemented by NA sequence analysis. However, differences in NI testing methodologies between surveillance laboratories results in variability of 50% inhibitory concentration (IC₅₀) values, which impacts data sharing, reporting and interpretation. In 2011, the Centers for Disease Control and Prevention (CDC), in collaboration with the Association for Public Health Laboratories (APHL) spearheaded efforts to standardize fluorescence-based NI assay testing in the United States (U.S.), with the goal of achieving consistency of IC₅₀ data.

Methods: For the standardization process, three participating state public health laboratories (PHLs), designated as National Surveillance Reference Centers for Influenza (NSRC-Is), assessed the NAI susceptibility of the 2011-12 CDC reference virus panel using stepwise procedures, with support from the CDC reference laboratory. Next, the NSRC-Is assessed the NAI susceptibility of season 2011-12 U.S. influenza surveillance isolates (n = 940), with a large subset (n = 742) tested in parallel by CDC. Subsequently, U.S. influenza surveillance isolates (n = 9629) circulating during the next three influenza seasons (2012-15), were independently tested by the three NSRC-Is (n = 7331) and CDC (n = 2298).

Results: The NI assay IC₅₀s generated by respective NSRC-Is using viruses and drugs prepared by CDC were similar to those obtained with viruses and drugs prepared in-house, and were uniform between laboratories. IC₅₀s for U.S. surveillance isolates tested during four consecutive influenza seasons (2011-15) were consistent from season to season, within and between laboratories.

Conclusion: These results show that the NI assay is robust enough to be standardized, marking the first time IC₅₀ data have been normalized across multiple laboratories, and used for U.S. national NAI susceptibility surveillance.