Putative Novel Serotypes '33' and '35' in Clinically Healthy Small Ruminants in Mongolia Expand the Group of Atypical BTV.

Bernd Hoffmann,Erdene-Ochir Tseren-Ochir,Christina Ries,Martin Beer,Tumenjargal Sharav

doi:10.3390/v13010042

Bernd Hoffmann, Erdene-Ochir Tseren-Ochir + Show 3 more

Open Access

https://doi.org/10.3390/v13010042

Copy DOI

Abstract

Between 2015 and 2018, we identified the presence of three so-far-unknown Bluetongue virus (BTV) strains (BTV-MNG1/2018, BTV-MNG2/2016, and BTV-MNG3/2016) circulating in clinical healthy sheep and goats in Mongolia. Virus isolation from EDTA blood samples of BTV-MNG1/2018 and BTV-MNG3/2016 was successful on the mammalian cell line BSR using blood collected from surveillance. After experimental inoculation of goats with BTV-MNG2/2016 positive blood as inoculum, we observed viraemia in one goat and with the EDTA blood of the experimental inoculation, the propagation of BTV-MNG2/2016 in cell culture was successful on mammalian cell line BSR as well. However, virus isolation experiments for BTV-MNG2/2016 on KC cells were unsuccessful. Furthermore, we generated the complete coding sequence of all three novel Mongolian strains. For atypical BTV, serotyping via the traditional serum neutralization assay is not trivial. We therefore sorted the ‘putative novel atypical serotypes’ according to their segment-2 sequence identities and their time point of sampling. Hence, the BTV-MNG1/2018 isolate forms the ‘putative novel atypical serotype’ 33, the BTV-MNG3/2016 the ‘putative novel atypical serotype’ 35, whereas the BTV-MNG2/2016 strain belongs to the same putative novel atypical serotype ‘30’ as BTV-XJ1407 from China.

Highlights

Accepted: 25 December 2020The vector-transmitted Bluetongue virus (BTV) is the prototype virus of the genusOrbivirus, family Reoviridae, and can cause a systemic haemorrhagic fever, the bluetongue disease, especially in sheep [1,2,3]
We present the discovery of three novel BTV strains in Mongolia, BTV-MNG1/
The three Mongolian strains were found to circulate in clinically healthy sheep and goats, which is characteristic of atypical BTV in general [14,36,43]

Summary

Introduction

Family Reoviridae, and can cause a systemic haemorrhagic fever, the bluetongue disease, especially in sheep [1,2,3]. The virus neutralization tests (VNT) have been recognised as the reference method for serotype identification and 24 classical BTV serotypes and three atypical BTV serotypes could be serologically defined [2,6,7,8]. The VP2 (Seg-2) as the most variant BTV protein is part of the outer capsid layer and was identified to play the major role in serum neutralization and serotype specificity [2,9,10]. The identification of the serotype plays an essential part in disease control, as commercially available BTV vaccines on the market induce serotype-specific protection. Two putative novel serotypes—BTV-XJ1407 from China [13] and BTV-X ITL2015 from Italy [14]—were

Methods

Results

Conclusion