ReVir

An infectious disease spread among nearly all reindeer at in a small, isolated herd in Norway in autumn 22. They had no contact with other reindeer or animals after the last introduction of a bull 3 years ago. Clinical signs included lethargy, enlarged lymph nodes, wounds around the eyes (picture eye) that progressed with varying degrees of crusts, and similar lesions around vulva and penis, and in the nostrils. Necropsies showed enlarged lymph nodes, swollen livers and spleens and fibrinopurulent crusts on the eyelids and around vulva and anal opening. Very similar lesions are also reported from reindeer herds in Sweden with increasing prevalence over the last years (pers. comm. Rockström, Swedish Reindeer Health Advisory Service, SRHAS).

The efficient spread of disease in the small, Norwegian herd, the increasing prevalence in Sweden and the clinical signs indicate this may be an emerging virus causing a transmissible, systemic, serious disease in reindeer. Investigations for reindeer pathogens in samples from Swedish reindeer yielded negative results. Bacteriology and parasitology, and investigations for reindeer alphaherpesvirus CvHV2 DNA, gammaherpesvirus DNA and antibodies and ovine herpesvirus-2 DNA on samples from UiT-reindeer yielded negative results.

There is extensive contact between Norwegian and Swedish reindeer and disease challenges are often shared. The clinical presentation in UiT- and Swedish reindeer is very similar, and so is the lack of isolation of known pathogens. It is hence likely that the same, unknown virus caused the disease outbreaks.

Samples from necropsied and live Norwegian and Swedish reindeer with disease have already been secured. Enrichment of virus nucleic acid, based on degradation of host nucleic acids with nucleases will be performed. Samples will be sequenced on a large scale on the NextSeq (Illumina) and on a MinION (Oxford Nanopore), with an optimized protocol, to generate long reads. This combination of a large amount of short reads with low error-rate (NextSeq) with longer reads (Minion), will increase the quality of the final sequence and increase the likelihood of agent identification. Bioinformatic analysis will be based on host subtraction before de novo assembly and mapping. A draft genome will enable identification and characterization of the pathogen.

The results will be communicated orally to The Norwegian Food Safety Authority, UiT and reindeer herders, and internally at NVI (Tellus/Workplace). A popular science article will be written in Reindriftsnytt. A scientific paper will be submitted to a peer reviewed journal.