Rustrela Virus as Putative Cause of Nonsuppurative Meningoencephalitis in Lions

Abstract

Retrospective investigation of archived tissue samples from 3 lions displaying nonsuppurative meningoencephalitis and vasculitis led to the detection of rustrela virus (RusV). We confirmed RusV antigen and RNA in cortical neurons, axons, astrocytes and Purkinje cells by reverse transcription quantitative PCR, immunohistochemistry, and in situ hybridization.

Keywords: Baumgärtner W; Beer M; Germany; Pfaff F; Puff C; Rubivirus; Rubivirus strelense; Suggested citation for this article: de le Roi M; Wohlsein P; et al. Rustrela virus as putative cause of nonsuppurative meningoencephalitis in lions. Emerg Infect Dis. 2023 May [date cited]. https://doi.org/10.3201/eid2905.230172; lions; meningitis/encephalitis; meningoencephalitis; retrospective study; rustrela virus; viruses.

Figure 1

Histopathologic, immunohistochemical, and in situ hybridization findings in the cerebrum of a lion tested positive for rustrela virus (RusV) by quantitative reverse transcription PCR. A) Histopathologic analysis of cerebral sample from lion 3 indicated lymphohistiocytic meningoencephalitis and vasculitis. B) Immunohistochemistry analysis showed RusV antigen in cortical neurons and their processes. Cytoplasmic granular immunoreactivity is visible (inset). C) In situ hybridization revealed RusV RNA in cortical neurons; we observed cytoplasmic granular-positive signal (inset). Scale bars indicate 50 µm.

Figure 2

Phylogenetic analysis and spatial distribution of rustrela virus infections in Europe. A) Maximum-likelihood phylogenetic tree of partial rustrela virus (RusV) sequences (409 nt, representing genome positions 100–508 of donkey-derived RusV reference genome, GenBank accession no. MN552442.2). Only bootstrap values at major branches are shown in the phylogenetic tree. RusV sequence names are shown in the format host/ISO 1366 code of location (federal, state, country)/animal ID/year. The tree was produced using IQ-TREE version 2.2.0; transition model 2 plus empirical frequency plus gamma 4 with 1,000 bootstrap replicates. Bold text indicates sequences from this study. Scale bar indicates substitutions per site. B) Mapping of the geographic origin of RusV-positive animals in Europe. Colors represent the phylogenetic clades of the sequences. Diamonds represent lions; circles, domestic cats; triangles, other zoo animals; squares, Apodemus spp. rodents. Symbols in gray boxes represent individuals from the same or very close locations. AUT, Austria; BE, Berlin; DEU/GER, Germany; MV, Mecklenburg–Western Pomerania; NI, Lower Saxony; NW, North Rhine–Westphalia; SWE, Sweden.