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ABSTRACT Canine distemper causes demyelinating leucoencephalitis, like human multiple sclerosis. The encephalic microenvironment, including the extracellular matrix, is an important key factor of this lesion, already described in multiple sclerosis but not proved in canine distemper. Thereby, the aim of this work is to characterize the extracellular matrix in the encephalon of dogs with canine distemper. Samples of cortex and cerebellum of 14 naturally infected dogs with canine distemper virus were collected after being sent for necropsy in the Animal Pathology Laboratory of the Veterinary Hospital of Uberlândia Federal University. The samples were processed as routine, stained with Hematoxylin and Eosin (H.E), Masson Trichrome (MT), Periodic Acid-Schiff (PAS) and Reticulin, and then described. Areas of demyelination and necrosis were quantified in percentage of stain. The TM samples showed blue stain around vessels and meninge, which indicates a higher deposition of collagen in lesioned areas. At necrotic areas, reticulin stain pointed to a disorganization in the vascular wall and PAS-stained pink granules in macrophages. We conclude that the extracellular matrix seems to participate in the pathogeny of canine distemper. More research should be done to better detail the involvement of these molecules in the course of this disease.
RESUMO A cinomose canina, assim como a esclerose múltipla, provoca leucoencefalite desmeilinizante. O microambiente encefálico, incluindo a matriz extracelular, atua como fator adjuvante na esclerose múltipla, porém não há comprovação do mesmo na cinomose canina. Portanto o objetivo neste trabalho é caracterizar a matriz extracelular do encéfalo de cães com cinomose canina. Foram coletados fragmentos de córtex frontal e cerebelo de 14 cães naturalmente infectados com cinomose canina encaminhados para necropsia no Laboratório de Patologia Animal do Hospital Veterinário da Universidade Federal de Uberlândia. Os fragmentos foram processados rotineiramente, corados com Hematoxilina e Eosina (H.E.), Tricrômico de Masson (TM), Ácido-Periódico de Schiff (PAS) e Reticulina e então foram descritas. As áreas com desmielinização e/ou necrose também foram quantificadas. A coloração de TM evidenciou marcação azulada em vasos e meninge, indicando maior deposição de fibras colágenas nas lesões. Nas áreas de necrose notou-se parede vascular desorganizada, a partir da reticulina, além de pigmentos róseos em macrófagos corados com PAS. Conclui-se que a matriz extracelular aparenta participar na patogenia da cinomose. Outros estudos são necessários para maiores detalhes da ação dessas moléculas na patogenia da cinomose canina.
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The present case is the first description of a co-infection with canine distemper virus (CDV) and canine adenovirus type 1 (CAdV-1) in a free-living hoary fox pup from Brazil. The animal was found and rescued with poor body condition, dehydration, incoordination, ataxia, excessive vocalization, and "blue eyes" phenomenon. Despite the efforts, euthanasia was elected due to worsening clinical signs and poor prognosis. Pathologic examination revealed a mild, acute, random, necrotizing hepatitis, acute bronchopneumonia, hydrocephalus, corneal edema with epithelium degeneration, and acidophilic intracytoplasmatic inclusion bodies in different epithelial cells types with rare syncytial. Through immunohistochemistry, CDV antigen was observed in the tongue, trachea, lungs, liver, spleen, stomach, intestine and urinary bladder. Adenovirus antigen was identified in the nucleus of scattered hepatocytes. Polymerase chain reaction and sequencing demonstrated high similarity with CAdV-1 and wild-type strain of CDV close related to Brazilian viral lineages isolated from domestic dogs. Disease surveillance in wildlife animals is essential to assess possible conservation threats and consider the implementation of mitigation or control measures.
Assuntos
Adenovirus Caninos , Coinfecção , Vírus da Cinomose Canina , Cinomose , Animais , Cães , Raposas , Brasil , Cinomose/patologiaRESUMO
Canine distemper virus (CDV) is a Morbillivirus (Canine morbillivirus) that greatly impacts domestic and wildlife carnivores worldwide. The CDV RNA genome has high genetic variability, evidenced by several lineages that follow a global geographic pattern. The evolutionary trajectories and population dynamics of CDV lineages are still unclear and debatable, particularly in South America, where relatively few sequences are available. We performed phylogenetic and Bayesian analyses using an updated dataset of the highly variable hemagglutinin (H) gene, including seven South American countries. The time to the most recent common ancestor (tMRCA) of the current CDV lineages was dated to the early 1900s in North America. Maximum likelihood and Bayesian maximum clade credibility phylogenies showed similar topologies with two main branches (L1 and L2) corresponding to the NA1 lineage (L1) and the remaining lineages worldwide (L2). The four circulating lineages in South America (EU1/SA1, SA2, SA3, NA4/SA4) arose from independent migration events from North America and Europe. North American strains colonized most northern South American countries via Ecuador and then Colombia and Peru, originating the SA3 and NA4/SA4 lineages during their spread. The entry and expansion in the southern part of South America (Argentina, Brazil, Chile, and Uruguay) occurred through three independent migration events and gave rise to the EU1/SA1 and SA2 lineages. South American lineages have specific combinations of amino acids under positive selection that constitute signatures of taxonomic and evolutionary relevance. Our findings provide a comprehensive scenario for the origin and migration routes of Canine morbillivirus in South America and highlight the importance of phylodynamics in understanding the geographic patterns of modern genetic variability.
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Vírus da Cinomose Canina , Cinomose , Morbillivirus , Animais , Teorema de Bayes , Brasil , Cinomose/epidemiologia , Vírus da Cinomose Canina/genética , Cães , Morbillivirus/genética , Filogenia , América do Sul/epidemiologiaRESUMO
BACKGROUND: Canine distemper virus (CDV), currently termed Canine morbillivirus, is an extremely contagious disease that affects dogs. It is identified as a multiple cell tropism pathogen, and its host range includes a vast array of species. As a member of Mononegavirales, CDV has a negative, single-stranded RNA genome, which encodes eight proteins. MAIN BODY: Regarding the molecular pathogenesis, the hemagglutinin protein (H) plays a crucial role both in the antigenic recognition and the viral interaction with SLAM and nectin-4, the host cells' receptors. These cellular receptors have been studied widely as CDV receptors in vitro in different cellular models. The SLAM receptor is located in lymphoid cells; therefore, the infection of these cells by CDV leads to immunosuppression, the severity of which can lead to variability in the clinical disease with the potential of secondary bacterial infection, up to and including the development of neurological signs in its later stage. CONCLUSION: Improving the understanding of the CDV molecules implicated in the determination of infection, especially the H protein, can help to enhance the biochemical comprehension of the difference between a wide range of CDV variants, their tropism, and different steps in viral infection. The regions of interaction between the viral proteins and the identified host cell receptors have been elucidated to facilitate this understanding. Hence, this review describes the significant molecular and cellular characteristics of CDV that contribute to viral pathogenesis.
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Vírus da Cinomose Canina/genética , Vírus da Cinomose Canina/patogenicidade , Cinomose/virologia , Interações entre Hospedeiro e Microrganismos , Tropismo Viral , Animais , Modelos Animais de Doenças , Vírus da Cinomose Canina/fisiologia , Cães , Hemaglutininas Virais/genética , Especificidade de Hospedeiro , Humanos , Camundongos , Nectinas/genética , Receptores Virais/genética , Membro 1 da Família de Moléculas de Sinalização da Ativação Linfocitária/genética , Proteínas Virais/genética , Zoonoses/virologiaRESUMO
Canine distemper virus (CDV) is a highly contagious disease pathogen which causes disease in the domestic dog and species classified in the Canidae, Procyonidae, Mustelidae, Hyaenidae, Ursidae, Viveridae, Felidae, Tayassuidae, and Cercopithecidae families. A combined strategy that involved the direct sequencing of amplicons from genes coding for nucleocapsid, large polymerase, and hemagglutinin proteins of CDV, as well as the pathological findings and the immunohistochemical detection of viral nucleocapsid protein in diverse tissues, confirmed the participation of CDV in the development of a neurological disease in a southern tamandua (Tamandua tetradactyla) from Midwestern Brazil. Phylogenetic analysis based on the hemagglutinin gene sequences revealed that the strain from this study grouped with isolates from the Europe 1/South America 1 lineage. The specific polymorphisms at the SLAM receptor-binding site of the hemagglutinin gene, previously linked to disease emergence in novel hosts, were not detected in this genome. These findings represent the first description of CDV-induced infection in the Tamandua tetradactyla and extend the distribution of this infection to include members of the family Myrmecophagidae, order Pilosa.