Development of a reverse transcription-loop-mediated isothermal amplification assay for the detection of parrot bornavirus 4.

Avian bornavirus (ABV) is the causative agent of proventricular dilatation disease, which is fatal in psittacine birds. ABVs have spread worldwide, and outbreaks have led to mass deaths of captive birds in commercial and breeding facilities. The segregation of infected birds is a countermeasure to prevent ABV spread in aviaries. However, this approach requires a highly sensitive detection method for the screening of infected birds before virus transmission. In this study, we developed a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for the diagnosis of parrot bornavirus 4 (PaBV-4), a dominant ABV genotype. Using this assay, we successfully detected PaBV-4 RNA in cell cultures, brain tissues, and feces. We also developed methods for simple RNA extraction and visual detection without electrophoresis. The sensitivity of the newly established RT-LAMP assay was 100-fold higher than that of the real-time PCR (RT-qPCR) assay. Accordingly, the RT-LAMP assay developed in this study is suitable for the rapid and sensitive diagnosis of PaBV-4 without specialized equipment and will contribute to virus control in aviaries.