Association of Batai Virus Infection and Encephalitis in Harbor Seals, Germany, 2016

Abstract

We isolated Batai virus from the brain of a euthanized, 26-year-old, captive harbor seal with meningoencephalomyelitis in Germany. We provide evidence that this orthobunyavirus can naturally infect the central nervous system of a mammal. The full-genome sequence showed differences from a previously reported virus isolate from a mosquito in Germany.

Keywords: Batai virus; Bunyamwera virus; Germany; Ngari virus; Phoca vitulina; encephalitis; harbor seals; infection; meningitis/encephalitis; orthobunyavirus; viruses; zoonoses.

Figure 1

Histologic analysis and fluorescent in situ hybridization (FISH) of a Batai virus BATV)–infected harbor seal, Germany, 2016. A) Cerebellum showing mild to moderate, perivascularly accentuated, lymphohistiocytic inflammation (hematoxylin and eosin stain; scale bar indicates 200 μm). B) Purkinje cells and neurons of granular cell layer showing intracytoplasmic BATV–specific pink, positive result detected by FISH (fast red stain; scale bar indicates 200 µm). Inset: Higher magnification view of analysis using the QuantiGene ViewRNA ISH Tissue 1-Plex Assay Kit and the QuantiGene ViewRNA Chromogenic Signal Amplification Kit (Affymetrix-Panomics, Santa Clara, CA, USA) (fast red stain; scale bar indicates 20 µm). C) Scattered neurons of spinal cord showing a strong, pink, intracytoplasmic BATV-specific result detected by FISH (fast red stain; scale bar indicates 100 µm). D) Cortical and medullary lymphocytes of pulmonary lymph node showing a mild, pink, intracytoplasmic BATV-specific result detected by FISH (fast red stain; scale bar indicates 20 µm). E). Negative control (incubation without probe) of spinal cord showing no BATV-specific result (fast red stain; scale bar indicates 100 µm).

Figure 2

Bayesian phylogeny trees based on full-genome coding region sequences of small, medium, and large RNA segments of Batai virus and comparison viruses. A) Small RNA segments (69–770 bp). Bunyamwera virus (GenBank accession no. D00353) was used as the outgroup. B) Medium RNA segments (42–4,346 bp). Bunyamwera virus (GenBank accession no. M11852) was used as the outgroup. C) Large RNA segments (49–6,762 bp). Bunyamwera virus (GenBank accession no. X14383) was used as the outgroup. Bold indicates virus isolated in this study. Analysis was performed for 1 million generations and sampled every 100 steps. The first 25% of samples were discarded as burn-in according to MrBayes (11). Hasegawa-Kishino-Yano nucleotide substitution model was selected as best-fit model according to Bayesian information criteria. Numbers at the nodes indicate posterior probabilities percentage. GenBank accession numbers are provided for comparison isolates; accession nos. of the isolated Batai virus strain PV424/DE-2016 are small, MH299972; medium, MH299973; large, MH299974. Scale bars indicate nucleotide substitutions per site.