New World camelids are sentinels for the presence of Borna disease virus

Borna disease (BD), a frequently fatal neurologic disorder caused by Borna disease virus 1 (BoDV-1), has been observed for decades in horses, sheep, and other mammals in certain regions of Europe.

The bicoloured white-toothed shrew (Crocidura leucodon) was identified as a persistently infected species involved in virus transmission.

Recently, BoDV-1 attracted attention as a cause of fatal encephalitis in humans.

Here, we report investigations on BoDV-1-infected llamas from a farm in a BD endemic area of Switzerland, and alpacas from holdings in a region of Germany where BD was last seen in the 1960s but not thereafter.

All New World camelids showed apathy and abnormal behaviour, necessitating euthanasia.

Histologically, severe non-suppurative meningoencephalitis with neuronal Joest-Degen inclusion bodies was observed.

BoDV-1 was confirmed by immunohistology, RT-qPCR, and sequencing in selected animals.

Analysis of the llama herd over 20 years showed that losses due to clinically suspected BD increased within the last decade.

BoDV-1 whole-genome sequences from one Swiss llama and one German alpaca and-for comparison-from one Swiss horse and one German shrew were established.

They represent the first published whole-genome sequences of BoDV-1 clusters 1B and 3, respectively.

Our analysis suggests that New World camelids may have a role as a sentinel species for BoDV-1 infection, even when symptomatic cases are lacking in other animal species.