The Virome of Waterbuffalos in Switzerland (2013 - 2016)

Doctoral Thesis of Julia Lechmann

In the last two decades, the population of waterbuffaloes in Switzerland steadily increased and meanwhile it is counting over 1200 animals distributed over 75 farms. While being the most important all-purpose life-stock animals in Asia, buffaloes in Switzerland are mainly kept for beef and dairy production, for example mozzarella cheese. The import and the increasing number of exotic animals in Switzerland goes along with an increased risk of introduction and distribution of novel pathogenic agents such as viruses, bacteria and protozoa. Transmission of these newly introduced agents to our native animals and also to humans may cause severe illness. On the other hand, water buffaloes may succumb to illness when getting in contact with native pathogens that are relatively harmless for native species. In order to obtain more information on the virome of Swiss water buffaloes, i.e. the spectrum of viruses present, blood samples of 48 water buffaloes and of contact animals (26 small ruminants) from three Swiss farms were analysed by a wide range of routine diagnostic means as well as by next generation sequencing (NGS). In summary, we found single waterbuffaloes positive in ELISA or PCR for viruses of bovine origin such as bovine herpesvirus 6 (BoHV-6), bovine herpesvirus 2 (BoHV-2), bovine viral diarrhea virus (BVDV), and the arbovirus bluetongue virus (BTV), but there was no indication for virus transmission from or to small ruminants. While virome analysis by NGS supported these findings, it additionally showed that the blood samples of more than half of the animals from one single farm were positive for a small circular DNA virus of the Gemycircularvirus family. Members of this recently detected virus family have mainly been found in environmental samples but have also been described in bovine serum and human cerebrospinal liquid. Further analysis is necessary to shed light on the significance of GyCV in humans and animals.

Cover Illustration: Two waterbuffaloes enjoying a Swiss alpine lake (Hinterburgerseeli, Axalp)