Astrovirus-Associated Polioencephalomyelitis in an Alpaca

Abstract

An 8-year-old alpaca was admitted to the emergency service of the Clinic for Ruminants in Bern due to a reduced general condition and progressive neurological signs. Despite supportive treatment, its condition deteriorated and the animal had to be euthanized. Histopathological analysis revealed a severe non-suppurative polioencephalomyelitis with neuronal necrosis, most likely of viral origin. We detected abundant neuronal labelling with antibodies directed against two different epitopes of Bovine Astrovirus CH13/NeuroS1 (BoAstV-CH13/NeuroS1), which is a common viral agent associated with non-suppurative encephalitis in Swiss cattle. These findings were further verified by detection of viral RNA by use of in-situ hybridization and real-time RT-PCR. Next generation sequencing revealed that the detected virus genome had a pairwise identity of 98.9% to the genome of BoAstV-CH13/NeuroS1. To our knowledge, this is the first report of an astrovirus-associated polioencephalomyelitis in an alpaca. These results point to the possibility of an interspecies transmission of BoAstV-CH13/NeuroS1.

Neurotropic Astroviruses in Animals

“…Occasionally, the inflammation also involves the meninges (meningitis). This pattern of lesions was observed in all affected species [ 10 , 11 , 20 , 21 , 22 , 23 , 24 ] and is typical for virus-induced encephalitis [ 25 ]. Inclusion bodies have not been reported.…”

“…Cell tropism appears to be variable between different NT-AstV. In human cases, viral protein and viral RNA were detected in astrocytes [ 11 ] and neurons [ 30 ], while in ruminants and pigs, mainly neurons and only occasionally glial cells were affected ( Figure 2 B,C) [ 21 , 24 , 26 , 31 ].…”

“…Very recently (2020), the first reported case of astrovirus-associated encephalitis in an alpaca was reported [ 24 ]. The alpaca was eight years old and presented to the Clinic for Ruminants at the University of Bern because of a decreased general condition, anorexia, reduced gastrointestinal peristalsis and neurological signs (e.g., ataxia, intermittent tremor and absence of menace response in the left eye).…”

Beyond the Gastrointestinal Tract: The Emerging and Diverse Tissue Tropisms of Astroviruses

“…The identification of an astrovirus strain in brain tissue from a human patient with encephalitis in 2010 opened a new frontier on the spectrum of astrovirus-associated diseases, leading to reinvigorated interest in the pathogenicity of these viruses [84]. Subsequently, astroviruses have been associated with neurological diseases in other mammals including cattle, pigs, mink, muskox, sheep, and alpaca [3,85,86]. Currently, the prevalence of astrovirus-associated neurological diseases remains unknown.…”

“…Other neurological diseases have been attributed to astroviruses in sheep, muskox, and alpaca [85,86,120,124,125]. Given the frequency that astroviruses are detected from animals, there could be a greater burden of astrovirus-associated neurological diseases than what has been previously appreciated.…”