Metagenomic Investigation of Idiopathic Meningoencephalomyelitis in Dogs.

BACKGROUND: Meningoencephalomyelitis of unknown origin (MUO) is a common and life-threatening neuroinflammatory disease in dogs. Features of the disease are suggestive of an underlying immune-mediated process, but the association of this disease with a pathogen is still unknown. HYPOTHESIS/OBJECTIVES: To search for candidate etiologic agent associated with cases if MUO using next generation metagenomic sequencing. ANIMALS: Twenty-two dogs diagnosed with either MUO (11/22; 10 CSF and 3 brain), or noninflammatory CNS diseases inconsistent with MUO (11/22; 11 CSF and 2 brain) that served as negative controls. METHODS: A case control study was performed by identifying MUO and non-MUO cases. Samples were blindly processed and then unblinded for comparative analyses. Inclusion criteria for MUO cases included consistent MRI lesions and inflammatory CSF with a negative PCR panel for infectious agents or histopathologic diagnosis. Dogs with glucocorticoid therapy within 2 weeks of sample collection were excluded. Fresh-frozen cerebrospinal fluid (CSF; 21) and brain (5) samples were collected and RNA and DNA were extracted separately for shotgun metagenomic sequencing. Known positive samples were used as controls to validate our sequencing and analysis pipelines and to establish limits of detection. Sequencing results were analyzed at a nucleotide and protein level for broad comparison to known infectious organisms. RESULTS: No candidate etiologic agents were identified in dogs with MUO. CONCLUSIONS AND CLINICAL IMPORTANCE: These results support but do not prove the hypothesis that MUO is not associated with infectious agents and might be an autoimmune disease.

Detection and prevalence of boid inclusion body disease in collections of boas and pythons using immunological assays.

Inclusion body disease (IBD) of boas and pythons is characterized by the intracytoplasmic accumulation of an antigenic 68 kDa viral protein IBDP, more recently known as the nucleoprotein (NP) of the reptarenaviruses. Blood samples of 131 captive boas and pythons (53 boa constrictors, Boa constrictor; 35 rainbow boas, Epicrates cenchria; 22 ball pythons, Python regius; 5 carpet pythons, Morelia spilota; 6 Burmese pythons, Python bivittatus; 4 Jamaican boas, Epicrates subflavus; 5 anacondas, Eunectes spp.; and 1 green tree python, Morelia viridis) were obtained from 28 collections in the USA. Diagnosis of IBD was initially made by the identification of eosinophilic intracytoplasmic inclusion bodies in hematoxylin and eosin (HE) stained blood films and isolated peripheral white blood cells (PWBC). The overall prevalence of IBD in study snakes was 25/131 or 19% (95% CI = 12.4%, 25.8%) with boa constrictors being more commonly infected (22/53 or 41.5%; 95% CI = 28.2%, 54.8%) than other species in this study. Of the 22 IBD positive boa constrictors, 87% were clinically healthy, 13% had various signs of chronic illness, and none showed signs of central nervous system disease. Using a validated monoclonal anti-NP antibody, NP was confirmed within the isolated PWBC by immunohistochemical staining and Western blots. The presence of reptarenaviruses within blood samples of 27 boa constrictors and three rainbow boas was also assessed by PCR. Among boa constrictors, very good agreements were shown between the observation of inclusion bodies (by HE stain) and the presence of NP (by immunohistochemistry, kappa = 0.92; and Western blots, kappa = 0.89), or the presence of reptarenaviruses (by PCR; kappa = 0.92).

Polar bear encephalitis: establishment of a comprehensive next-generation pathogen analysis pipeline for captive and free-living wildlife.

This report describes three possibly related incidences of encephalitis, two of them lethal, in captive polar bears (Ursus maritimus). Standard diagnostic methods failed to identify pathogens in any of these cases. A comprehensive, three-stage diagnostic 'pipeline' employing both standard serological methods and new DNA microarray and next generation sequencing-based diagnostics was developed, in part as a consequence of this initial failure. This pipeline approach illustrates the strengths, weaknesses and limitations of these tools in determining pathogen caused deaths in non-model organisms such as wildlife species and why the use of a limited number of diagnostic tools may fail to uncover important wildlife pathogens.