FluChip-8G Insight: HA and NA subtyping of potentially pandemic influenza A viruses in a single assay

BACKGROUND

Global influenza surveillance in humans and animals is a critical component of pandemic preparedness. The FluChip-8G Insight assay was developed to subtype both seasonal and potentially pandemic influenza viruses in a single assay with a same day result. FluChip-8G Insight uses whole gene segment RT-PCR-based amplification to provide robustness against genetic drift and subsequent microarray detection with artificial neural network-based data interpretation.

OBJECTIVES

The objective of this study was to verify and validate the performance of the FluChip-8G Insight assay for the detection and positive identification of human and animal origin non-seasonal influenza A specimens.

METHODS

We evaluated the ability of the FluChip-8G Insight technology to type and HA and NA subtype a sample set consisting of 297 results from 180 unique non-seasonal influenza A strains (49 unique subtypes).

RESULTS

FluChip-8G Insight demonstrated a positive percent agreement ≥93% for 5 targeted HA and 5 targeted NA subtypes except for H9 (88%), and negative percent agreement exceeding 95% for all targeted subtypes.

CONCLUSIONS

The FluChip-8G Insight neural network-based algorithm used for virus identification performed well over a data set of 297 naïve sample results, and can be easily updated to improve performance on emerging strains without changing the underlying assay chemistry.

Validation of alternative potency assays for influenza vaccines requires clinical studies

Readers of this Special Issue of Vaccine are likely unified by a desire to enhance vaccine efficacy and improve vaccine manufacturing efficiency. For influenza vaccines, challenges to achieving those goals are many, and range from improved surveillance to less cumbersome production platforms and more reliable performance verification. Specifically, demand is growing for an alternative vaccine potency assay. Assuming that a replacement potency assay is found to be promising, one question will be: how will it be judged to be accurate? It is generally agreed that any potential replacement for SRID will have to exhibit good correlation with SRID and yield a value within ± 20% of the SRID determined potency. In my opinion, SRID itself has enough limitations that judging alternatives relative to that particular standard will not ensure that the industry as a whole transitions to an improved method. In fact, it could blind us to an assay that may ultimately provide a better predictive measure of vaccine efficacy (or immunogenicity). There is only one way to verify that measured potency is correlated with, and predictive of, measured immunogenicity - test the relationship in clinical studies.