Adaptation and validation of an influenza a subtyping panel for detection of H1pdm09, H3 and H5 on a high-throughput RT-qPCR system

Why this matters for everyday health

Bird flu headlines can sound distant—about chickens, ducks, or dairy cows on the other side of the world. But when animal flu viruses jump into people, they can spark the next pandemic. This study describes a new laboratory test that can very quickly sort out which major influenza A strains are infecting patients, including the worrisome H5 bird flu. Faster, more reliable testing helps health authorities spot dangerous new strains early, giving doctors and public health teams more time to respond.

New worries from birds, cows, and people

Influenza A is not one single virus, but a moving family of related strains that circulate in humans, birds, and other animals. Two types, known as H1N1 and H3N2, cause the usual seasonal flu in people. Others, especially H5 viruses from birds, only sometimes infect humans but can be far more lethal and have pandemic potential. Recently, a highly pathogenic H5N1 variant has spread widely in birds and surprisingly also in dairy cattle, with dozens of confirmed human infections. Most human cases have been mild, but a few severe infections and signs of adaptation to human cells have raised global concern. Against this backdrop, being able to rapidly tell which influenza A subtype is present in a patient becomes critical for surveillance and early warning.

Building a faster flu-typing test

The researchers set out to adapt an existing molecular test so it could run on a fully automated, high-throughput machine widely used in diagnostic labs (the Roche cobas 5800/6800/8800 systems). Their goal was a single test panel that would do two things at once: confirm that influenza A virus is present and distinguish between the common human H1N1pdm09 and H3N2 strains and the H5 subtype of concern. The test relies on RT-qPCR, a method that detects and amplifies tiny amounts of viral genetic material. The team selected and modified published genetic target regions so that the test would recognize a broad range of current virus variants while avoiding unrelated microbes. They then combined these targets into a multiplex format, meaning several viral signals can be measured from the same patient sample in one automated run.

Checking accuracy in the computer and the lab

Before running patient samples, the group tested their design in silico by comparing the chosen genetic targets to tens of thousands of virus sequences stored in public databases. This screening showed that the test should match at least 99 percent of known H1N1pdm09, H3N2, and general influenza A sequences, and nearly all H5 variants linked to bird and cattle outbreaks, with little risk of confusing them with other flu types. Next, they measured how small an amount of virus the assay could reliably detect, using well-characterized reference samples quantified by digital PCR. The detection limits were low enough to catch clinically relevant infections, and the response of the assay remained linear over a wide range of viral loads, meaning its signal tracked smoothly with the amount of virus present.

Putting the test to work in real samples

The new panel was then challenged with a broad set of materials: reference RNA from multiple H5 bird flu strains, standardized external quality samples, and a large collection of clinical swabs from patients with influenza A. The pan-influenza A signal and subtype calls matched expected results in all reference and external quality samples, and there were no false positives in samples containing other respiratory viruses, bacteria, or fungi. When compared head-to-head with an established commercial flu typing test, the new assay showed strong agreement but actually identified additional H1N1pdm09 infections that the older test missed, likely because newer virus lineages have mutated away from the older test’s target sites. In a full year of hospital use, the panel successfully assigned a subtype to about 96 percent of influenza A–positive patient samples.

What this means for future outbreaks

From a lay perspective, the bottom line is that this study delivers a practical, scalable tool that helps laboratories around the world keep closer watch on dangerous flu strains, especially H5N1. By plugging into a high-throughput, fully automated system, the new test can process hundreds to thousands of samples per day with minimal hands-on time and at relatively low cost. That makes it suitable not only for routine flu season diagnostics but also for surge testing during outbreaks. While the assay will need periodic updates as the virus evolves—and may later be expanded to other emerging strains like H7 or H9—it already offers a faster, more reliable way to flag concerning influenza A infections in humans, helping health systems react earlier and potentially interrupt chains of transmission before they grow into something much larger.

Citation: Giersch, K., Nörz, D., Grunwald, M. et al. Adaptation and validation of an influenza a subtyping panel for detection of H1pdm09, H3 and H5 on a high-throughput RT-qPCR system. Sci Rep 16, 12888 (2026). https://doi.org/10.1038/s41598-026-45563-5

Keywords: influenza A, H5N1 bird flu, PCR diagnostics, viral surveillance, zoonotic infections