In relation to the recent outbreak of IHN in Denmark, the EURL has observed unsatisfactory performances of the RT-qPCR protocols currently recommended in the diagnostic manual on the EURL website.
Both recommended methods, the validated RT-qPCR described in the publication by Purcell et al., 2013 (two-steps method) and Cuenca et al., 2020 (one-step method), have shown low sensitivity detecting the IHNV variant present in Denmark in May 2021. Conversely, the isolation of the virus on cell culture has not shown challenges.
Download letter with further clarifications and recommendations send from the EURL to the NRL's
A temporary amendment of the manual will be formulated on the EURL website, until an RT-qPCR method is fully validated to detect all variants of IHNV.