Circoviridae, Asfarviridae, Papillomaviridae (Ex2) Flashcards
Circoviridae General Features
- small viruses, nonenveloped, spherical with icosahedral symmetry
- circular single-stranded DNA genomes
- replication in actively dividing cells
- DNA replication in nucleus
Post-Weaning Multisystemic Wasting Syndrome
genus, etiology, host
- circovirus
- caused by porcine circovirus type 2
- pigs
Transmission of PMWS
- fecal-oral route most common
- virus found in all secretions
- vertical transmission in swine
- stable, can survive on fomites
Pathogenesis of PMWS
- characterized by individual to coalescing foci of granulomatous inflammation
- sometimes with prominent botryoid (grape-like) inclusion bodies
- targets cardiomyocytes, hepatocytes, and macrophages during fetal life
- lymphoid depletion and lymphopenia in peripheral blood
Clinical Signs of PMWS
- subclinical most common
- lethargy, weight loss, cough, dyspnea, lymphadenopathy, diarrhea, skin discoloration, tremors
- abortion in transplacental infections
- co-infection can cause severe disease and more pronounced lesions (parvo)
Diagnosis of PMWS
- clinical signs
- samples: blood, tonsils, lymph nodes, etc.
- characteristic histopathology
- serology: most pigs are seropositive so not always effective
- detection of PCV-2 nucleic acids by PCR
What is Porcine Dermatitis and Nephropathy Syndrome?
virus, host, signs
- associated with PCV-2
- sporadic
- in older piglets
- necrotizing skin lesions, necrotizing vasculitis, and nectrotizing and fibrinous glomerulonephritis
What is Chicken Infectious Anemia?
genus, what it is, structure, age
- Gyrovirus
- highly contagious disease of young chickens
- has 12 trumpet-like structures
- older chickens more resistant
Transmission of Chicken Infectious Anemia
- virus shed in feces and feather dander
- inhalation or oral exposure
- vertical through egg
- stable in environment
Pathogenesis of Chicken Infectious Anemia
- replication in hemoctyoblasts of the bone marrow cause anemia
- replication in T cells in thymus and spleen cause immunosuppression
- apoptin protein of the virus induces apoptosis of lymphocytes
- vulnerable to secondary bacterial infections
Clinical Signs of Chicken Infectious Anemia
- anorexia, lethargy, depression, weight loss, pale membranes
- blood may be watery and clot slowly due to thrombocytopenia
- subcutaneous and skeletal hemorrhages
What is the main purpose of vaccination for Chicken Infectious Anemia?
- to protect the progeny of the vaccinated breeders from early infections by means of maternally derived antibodies
- presence of antibodies in breeders reduces vertical and horizontal transmission
General Features of Asfarviridae
- virions are enveloped
- nucleocapsid core surrounded by internal lipid bilayers and icosahedral capsid
- single molecule of linear double stranded DNA
- replication in cytoplasm
African Swine Fever
etiology, host
- only member of Asfarviridae family
- only known DNA arborvirus
- all pigs, domestic and wild
Transmission of African Swine Fever
- vector: soft ticks sylvatic cycle: warthogs and ticks - young pigs develop viremia domestic cycle: domestic pigs - bite of infected tick - direct contact with infected animal - fomites, aerosol, ingestion of infected pork
Pathogenesis of African Swine Fever
- hemorrhages and apoptosis
- leukopenia, lymphopenia, thrombocytopenia
- replication: pharyngeal mucosa, tonsils, endothelial cells, macrophages, megakaryocytes
- p54 protein induces apoptosis
Clinical Signs of African Swine Fever
Peracute: sudden death, high fever, hyperemia
Acute: high fever, anorexia, cyanotic skin, resp distress, vomiting, recumbency, diarrhea, abortion, death
Chronic: emaciation, stunted growth, swollen joints, ulcers, “blackberry jam” spleen
Diagnosis of African Swine Fever
- virus isolation
- hemadsorption
- serology: FAT, immunodiffusion
- PCR
Papillomaviridae General Features
- non-enveloped, spherical, icosahedral
- single molecule of circular double-stranded DNA
- produce papillomas
- species and site specific
- can transform to cancer
Replication of Papillomaviruses
- in squamous epithelium
- infect keratinocytes in basal layer that is exposed through micro-wounds
- genomes replicated with cellular DNA
- after division, one daughter cell migrates from basal layer to outer layers and undergoes differentiation
- virus accumulation most noticeable in stratum granulosum
Bovine Papillomatosis general features and transmission
- warts commonly seen
- all ages susceptible
- horses can get infection after exposure to infected cattle
- transmitted by fomites and sexual transmission
Fibropapilloma
etiology, lesion appearance and location
- Bovine papillomaviruses 1, 2, and 5
- fibrous core covered with stratified squamous epithelium
- small nodules to cauliflower-like
- gray to black in color, rough and spiny
- common on udder and teats, head, neck, and shoulders
- young bulls: on tip of penis
Cutaneous papillomas
etiology and lesions
- Bovine papilloma virus 3
- lesions lack fibrous core
- flat with broad base
- tend to persist
Bracken Fern and Bovine papillomaviruses
- bovine papillomavirus 4 can cause papillomas in alimentary tract
- ingestion of fern can transform the papillomas into invasive carcinomas
- fern contain carcinogens, mutagens, and immunsuppressive chemicals
- papillomaviruses 1 and 2 can also result in enzootic hematuria
Canine Oral Papillomatosis general features
- contagious, self-limiting disease affecting oral cavity of dogs
- warts on lips, buccal mucosa, tongue, palate, and pharynx
- histology: epithelial hyperplasia and cytoplasmic vacuolization
- lesions regress spontaneously
Clinical Signs of Canine Oral Papillomatosis
- halitosis, hemorrhage, hypersalivation, discomfort
- warts may interfere with mastication
- possible secondary bacterial infections
- ocular warts in conjunctiva, cornea, eyelid margins
Equine Sarcoids
what are they, hosts, etiology
- horses, donkeys, and mules 1-6 years old
- locally invasive benign fibroblastic skin tumors
- associated with bovine papillomavirus 1 or 2
- do not metastasize
Equine Sarcoids Transmission
- not confirmed
- flies may be vectors, fomites
- susceptible breeds: arabian, appaloosa, american quarter
- less susceptible: standardbred, thoroughbred
Equine Sarcoids Clinical Signs
- lesions in traumatized areas
- growths bulge under skin
- may be ulcerated
