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his family consists of double-stranded DNA viruses with an  icosahedral nucleocapsid. They have been recovered from many mammalian  and avian species. Many are found in the respiratory tract and  infections are often persistent. Only a small number cause significant  veterinary diseases. 
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Viral Characteristics
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Non-enveloped, viruses with icosahedral symmetry containing a single, linear molecule of double-stranded DNA.
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The capsid consists of capsomeres (called hexons) and 12 vertex capsomeres (called pentons). These are the only viruses with a fiber (the fiber antigen) protruding from each of the 12 pentons (see Fig. 13-1).
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The fiber is the structure of attachment to host cells and is also a type specific hemagglutinin.
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The hexon of mammalian adenoviruses contains a cross-reacting group antigen.
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The fiber antigen attaches to a specific cell receptor and initiates replication.
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The dsDNA encodes approximately 30 proteins. Viral DNA replication,  mRNA transcription and virion assembly occur in the nucleus, utilizing  both host and virus-encoded factors. This results in the formation of  basophilic and / or acidophilic intranuclear inclusions.
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Many adenoviruses agglutinate red cells of various animal species  and some are capable of malignant transformation in tissue culture cell  and oncogenesis when inoculated into laboratory animals.
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They are resistant to trypsin and lipid solvents, and moderately resistant on premises.
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Figure 13-1. Adenoviridae (70 - 90 nm). Note the fiber proteins protruding from the vertices of the 12 pentons. To view click on figure
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Classification
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This family originally consisted of only two genera, Mastadenovirus, which infect mammals, and Aviadenovirus, which infect birds. There are also several as yet unassigned and recently assigned viruses in the family.
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Mastadenovirus
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This genus consists of 20 virus species that infect mammals including  canine, equine, bovine, ovine and porcine adenoviruses. All 20 species  share a common antigen. Important diseases are infectious canine  hepatitis, canine adenovirus 2 infection, and equine adenovirus A  infection.
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Aviadenovirus
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This genus includes the viruses of inclusion body hepatitis, quail  bronchitis, marble spleen disease and a number of adenoviruses of  poultry and birds that are not associated with significant diseases.  Members of the genus share a common antigen.
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Previously Unassigned Adenoviruses
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Included in this category are the viruses that have recently (2002) been placed in the genera Atadenovirus and Siadenovirus. These viruses include the egg drop syndrome virus (Atadenovirus), turkey hemorrhagic enteritis (Siadenovirus), adenoviral splenomegaly of chickens (Atadenovirus) and ovine adenovirus 287 (Atadenovirus; of research interest, but of no disease significance) and some bovine adenovirus types 4 to 8 (Atadenovirus).
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MastadenovirusInfectious Canine HepatitisCause
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Canine adenovirus 1. The DNA sequence of this virus has been determined.
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Occurrence
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Dogs younger than one year of age are most often affected. The virus  also infects wild and captive foxes causing encephalitis, and wolves,  coyotes and bears. Other carnivores may sustain subclinical infections. The disease occurs commonly worldwide, but is uncommon where vaccination  is practiced.
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Transmission
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Infection is by inhalation and ingestion. Spread is by direct and indirect contact.
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Pathogenesis
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The virus replicates initially in tonsils and Peyer’s patches  producing a viremia with secondary localization and replication in the  liver and kidney.
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Clinical & Pathologic Features
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Clinical signs include depression, fever, vomiting, diarrhea, and  discharges from the nose and eyes. Because of a tendency to bleed,  hematomas may be seen in the mouth.
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The principal tissue changes involve the endothelium and hepatic cells.  Damaged endothelium results in widespread petechial hemorrhages. The  liver may be enlarged or normal in size, but usually is mottled because  of focal areas of necrosis.
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Microscopically, the most significant changes are found in the liver,  where centrolobular necrosis is noted and typical adenoviral inclusion  bodies are observed in Kupffer cells and parenchymal cells.
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Circulating immune complexes in the glomeruli may result in  glomerulonephritis. Recovered dogs may develop a transient corneal  opacity ("blue eye") as a result of local immune complex deposition.
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Recovery from infectious canine hepatitis (ICH) results in lasting immunity.
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Diagnosis
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Clinical specimens: liver, spleen, kidney, blood, urine, nasal swabs and paired serum samples.
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Diagnosis of ICH is usually made on the basis of clinical signs and  gross and microscopic lesions including the presence of basophilic  inclusions in hepatocytes, endothelial cells, and Kupffer cells.
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The virus can be demonstrated in frozen liver sections by immunofluorescence.
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The virus can be cultivated in cell cultures of canine origin. The  liver has been reported to be less suitable for virus recovery than  other vital organs.
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A rising titer of antibodies employing hemagglutination inhibition or virus neutralization are supportive of a diagnosis.
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Prevention
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Modified live and killed vaccines  are used, often in combination with parvovirus and canine distemper  antigens. Modified live vaccines induce a longer lasting immunity, but a  small percentage of vaccinated dogs may develop ocular or renal  lesions.
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These core canine vaccines were traditionally administered annually but are now, depending on the type of vaccine, often given less frequently.
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Causes [[Canine Infectious Tracheobronchitis]]
 
Causes [[Canine Infectious Tracheobronchitis]]
  
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