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Rabies is a fatal zoonotic disease endemic in developing countries of Asia and Africa. Recently, the direct rapid immunohistochemical test (DRIT) was recommended by the World Health Organization (WHO) and the World Organization for Animal Health (OIE) as a diagnostic test for rabies. Therefore, a biotinylated polyclonal antibody (pAb) against the rabies lyssavirus (RABV) nucleoprotein was developed using a plasmid cDNA vaccine derived from a challenge virus standard 11 strain. A preliminary evaluation on the efficacy of this reagent in recognizing the Philippine RABV strain was tested using banked canine hippocampal tissue samples with DRIT and the results were compared to dFAT. The effects of acetone and formalin fixation on DRIT were also assessed through immunoreactivity scores of the specimens. Of the 142 samples examined, 104 tested positive and 38 negative using both dFAT and DRIT, showing 100% agreement between the two diagnostic procedures. Moreover, no false positive or false negative results were observed using acetone and formalin fixation. Thus, locally prepared biotinylated pAb from plasmid cDNA can be used for DRIT, especially in resource-limited laboratories in the Philippines. However, these results should be confirmed with a more thorough evaluation of this technique, and the range of detection needs to be further evaluated in a larger panel of animal samples and on other lyssaviruses., Competing Interests: Declaration of Competing Interest The authors have declared no conflicting interests exist with respect to the research, authorship, and/or publication of this article., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The direct fluorescent antibody test (dFAT) on fresh brain tissues is the gold standard for rabies virus antigen detection in dogs. However, this method is laborious and holds a high risk of virus exposure for the experimenter. Skin biopsies are useful for the diagnosis of humans and animals. In mammals, the tactile hair, known as the follicle-sinus complex (FSC), is a specialized touch organ that is abundant in the muzzle skin. Each tactile hair is equipped with more than 2,000 sensory nerve endings. Therefore, this organ is expected to serve as an alternative postmortem diagnostic material. However, the target cells and localization of rabies virus antigen in the FSCs remain to be defined. In the present study, muzzle skins were obtained from 60 rabid dogs diagnosed with rabies by dFAT at the Research Institute of Tropical Medicine in the Philippines. In all dogs, virus antigen was clearly detected in a part of the outer root sheath at the level of the ring sinus of the FSCs, and the majority of cells were positive for the Merkel cell (MC) markers cytokeratin 20 and CAM5.2. Our results suggest that MCs in the FSCs of the muzzle skin are a target for virus replication and could serve as a useful alternative specimen source for diagnosis of rabies., (Copyright © 2016 Elsevier B.V. All rights reserved.)

During rabies virus infections, the minor salivary glands are one of the important organs for virus replication and excretion into the oral cavity. However, details of pathological findings and viral antigen distribution in the minor salivary glands remain poorly understood. In this study, we conducted pathological tests on the tongues of 71 rabid dogs in the Philippines; the minor salivary glands (von Ebner’s glands, lingual glands), circumvallate papilla, autonomic ganglia, and skeletal muscles were evaluated. Inflammatory changes were observed in the von Ebner’s glands of 20/71 dogs, in the circumvallate papilla of 10/71, and in the tongue muscle of 1/71. Conversely, no morphological changes were observed in the lingual glands and autonomic ganglia. Viral antigens were detected via immunohistochemistry-based methods in the cytoplasm of the acinar epithelium in the von Ebner’s glands of all 71 dogs. Virus particles were confirmed in the intercellular canaliculi and acinar lumen via electron microscopy. In the autonomic ganglia, viral antigens were detected in 67/71 rabid dogs. Viral antigens were detected in the taste buds of all 71 dogs, and were distributed mainly in type II and III taste bud cells. In tongue muscle fibers, viral antigens were detected in 11/71 dogs. No virus antigens were detected in lingual glands. These findings suggest that rabies virus descends in the tongue along the glossopharyngeal nerve after proliferation in the brain, and von Ebner’s glands and taste buds are one of the portals of virus excretion into the saliva in rabid dogs. [ABSTRACT FROM AUTHOR]

A solitary mass, 2.5 cm × 2.5 cm × 2.0 cm in size, was found in the subcutis adjacent to the ischial tuberosity of an 8-year-old male German shepherd dog. The excised mass was not encapsulated and the cut surface was solid, grey–white and had multiple red areas suggestive of haemorrhage. Microscopically, the neoplasm was composed of epithelioid cells interspersed with venous vessels of various sizes and irregular bundles of spindle-shaped tumour cells with mucinous stroma. The nuclei showed anisokaryosis and many mitotic figures were noted. Immunohistochemically, the majority of tumour cells were positive for alpha smooth-muscle actin and vimentin, but negative for cytokeratin, desmin, S-100 and factor VIII-related antigen. Ultrastructurally, the tumour cells contained irregular nuclei, few mitochondria, few rough endoplasmic reticulum, cytoplasmic myofilaments of intermediate density, pinocytotic vesicles and distinct basal lamina. Based on these pathological findings, the diagnosis was malignant glomus tumour. [ABSTRACT FROM AUTHOR]