Advances in Diagnostic Technologies of Major Avian Respiratory Viruses: A Review

Avian respiratory diseases, particularly those induced by the avian influenza virus (AIV), Newcastle disease virus (NDV), infectious bronchitis virus (IBV), and infectious laryngotracheitis virus (ILTV), represent a substantial economic threat to the global poultry industry. Several of these viruses can also transmit across species, posing risks to public health security. Given the challenges posed by similar clinical symptoms from different pathogens, the prevalence of co-infections, and rapid viral mutations, rapid, precise, and highly sensitive diagnostic techniques are imperative for effective disease prevention and control, epidemic surveillance, and epidemiological research. This review provides an overview of molecular and immunological diagnostic techniques for major avian respiratory viruses. All covered technologies are evaluated and compared across key performance metrics: target type, analytical sensitivity, multiplex capacity, turnaround time, point-of-care diagnostic techniques (POCT) suitability and application scenarios. Specifically, the review details real-time quantitative PCR (qPCR) and its multiplex formats, isothermal amplification methods including loop-mediated isothermal amplification (LAMP), recombinase-aided amplification (RAA) and recombinase polymerase amplification (RPA), and innovative CRISPR-Cas-based nucleic acid detection systems. It also examines high-throughput sequencing, microarray technologies, and advanced immunological assays enhanced by nanomaterials, recombinant proteins, and single-domain antibodies. The review further discusses integrated, automated, and portable diagnostic platforms, including microfluidics, and smartphone-assisted systems. Finally, the review outlines future trends in avian diagnostic technologies, providing a practical reference for building more efficient and accessible avian disease surveillance and early warning systems.