Fatal tick-borne encephalitis virus infection in Dalmatian puppy-dogs after putative vector independent transmission

Abstract

In a retrospective metatranscriptomics study, we identified tick-borne encephalitis virus (TBEV) to be the causative agent for a fatal non-suppurative meningoencephalitis in a three-week-old Dalmatian puppy in Switzerland. Further investigations showed that the two other littermates with similar signs and pathological lesions were also positive for TBEV. By using an unbiased approach of combining high-throughput sequencing (HTS) and bioinformatics we were able to solve the etiology and discover an unusual case of TBEV in three young puppies. Based on our findings, we suggest that a vector-independent transmission of TBEV occurred and that most likely an intrauterine infection led to the severe and fulminant disease of the entire litter. We were able to demonstrate the presence of TBEV RNA by in situ hybridization (ISH) in the brain of all three puppies. Furthermore, we were able to detect TBEV by RT-qPCR in total RNA extracted from formalin-fixed and paraffin embedded (FFPE) blocks containing multiple peripheral organs. Overall, our findings shed light on alternative vector-independent transmission routes of TBEV infections in dogs and encourage veterinary practitioners to consider TBEV as an important differential diagnosis in neurological cases in dogs.

Keywords:

• Tick-borne encephalitis virus
• puppies
• metatranscriptomics
• high-throughput sequencing

Acknowledgements

The authors would like to thank Dr. Lisa Goldinger from the animal clinic tezet AG for referring the cases to the Institute of Veterinary Pathology of the Vetsuisse Faculty Zurich. Furthermore, we would like to thank the Next Generation Sequencing Platform of the University of Bern for performing the high-throughput sequencing experiments. A special thanks goes to Elsbeth Keller-Gautschi and Camille Monney for their excellent technical support.

Authors contributions

Clinical examinations were performed by S.E. Pathological examinations were conducted by C.B, G.R, P.G, M.H and A.O. The cases were referred by M.H and further data was collected by K.D. The writing of the manuscript was carried out by K.D and T.S. All authors read and approved the submitted version.

Disclosure statement

The authors reported no potential conflict of interest.

Ethical statement

No ethical approval was required for this study as it was non-interventional and based on archived animal tissues that have been collected in the framework of diagnostic pathological examinations. Written informed consent to conduct and publish this study was provided by the dog’s owner.

Data availability statement

Raw sequencing reads generated and analysed are available at the National Center for Biotechnical Information (NCBI) sequence read archive under the Accession Number PRJNA1014446. The genome of TBEV-EU-Switzerland-2019-Thurgau is available at NCBI GenBank under the Accession Number OR523238.

Additional information

Funding

This project was partially funded by the Albert-Heim-Foundation, project number 154.