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DNA Viruses - Coggle Diagram
DNA Viruses
Poxviridae
- enveloped, but persists in environment in scabs
- one of the few DNA viruses that replicate in cytoplasm instead of nucleus
- lesions attack epithelium (found in skin and mucosa) = epitheliotropic
- can see cytoplasmic inclusion bodies
- infection provides lifelong immunity
- encode all the enzymes necessary for replication
Capripoxvirus (Sheep & Goat Poxvirus & Lumpy skin disease virus)
- REPORTABLE
- not found in canada
- clinical signs: lesions (little pustules) on skin and mucous membranes, fever, lymphadenitis, viral pneumonia
- vaccine available
- vaccine & recovery from infection = lifelong immunity
Fowlpox virus (dry and wet form)
- affects chickens and turkeys
- pathogenesis dry form: infected by mosquito bites chicken/turkey -> cutaneous form -> skin lesions (dry pox)
- pathogenesis wet form: infection via droplets -> diptheric form -> wet pox with exudate on mucosa of larynx and mouth
- vaccine available
Bovine Papular Stomatitis Virus (Parapoxvirus)
- little clinical importance
- causes papular and erosive lesions on mouth and teats of cows
- zoonotic
Orf Virus
- affects sheep, goats, llamas, alpacas
- clinical signs: lesions at junction of lips, buccal mucosa, feet/coronary bands, teat lesions
- zoonotic
Parvoviridae
- non enveloped -> stable in environment
- replicate in nucleus of host cells
- targets actively dividing cells (a lot of hematopoietic cells) -> will often see leukopenia
Canine Parvovirus (CPV)
- target: rapidly dividing cells (hematopoietic), gut epithelial cells
- released after replication via cell lysis
- pathogenesis: fecal oral route -> replicates in lymph nodes, thymus, tonsil -> infects intestinal crypt epithelial cells -> hemorrhagic diarrhea, vomiting, anorexia, lymphopenia, dehydration, depression, nasal discharge, myocarditis if infected in utero or when less than 2 weeks old
- mortality higher in pups (6 wks - 6 months old)
- diagnosis: SNAP test using fecal sample (antigen in feces), PCR
- treatment: fluid, electrolytes and antibiotics to prevent secondary bacterial infection
- vaccine works well
- post mortem will find severe hemorrhagic necrosis and enteritis of small intestine (including peyer's patches), hemorrhage in lymph nodes (multifocal) and hemorrhage of thymus (diffuse)
- virus shed in feces within 4-5 days of exposure (before clinical signs) and up to 10 days after clinical recovery
Feline Panleukemia Virus (FPV)
- target: intestinal epithelial cells and rapidly dividing cells
- clinical signs: SEVERE and prolonged leukopenia, diarrhea, vomiting, dehydration, anorexia, fever, cerebellar hypoplasia if infected last 2 wks in utero or first 2 weeks of life
- pathogenesis: same as canine parvovirus
- diagnosis: PCR, antigen detection in feces with ELISA
- treatment: no effective treatment, can give antibiotics to prevent secondary bacterial infections
- vaccine works well
- antigenically very similar to canine parvovirus
Porcine Parvovirus (PPV)
- antigenically different from CPV and FPV
- clinical signs: SMEDI (stillbirth, mummification, embryonic deaths, infertility)
Circoviridae
- replicates in nucleus
- non-enveloped -> stable in environment
- DNA is circular (circo)
-
Porcine Circovirus Associated Disease = Post-weaning multisystemic wasting syndrom
- clinical signs: gradual wasting away, stops growing, pale, anemic, jaundice, diarrhea, inguinal lymphadenopathy, lymphoid depletion
Beak and Feather Disease Virus
- clinical signs: necrotic or abnormally formed feathers
- most birds die from secondary infections after getting this virus
Herpesviridae
- enveloped (won't last long in environment)
- latency common! animal will recover from acute infection and then it remains dormant in their body. Reactivated during times of stress/winter time
Alphaherpesvirinae
- infects epithelial cells
- latency in sensory ganglia
- rapid, lytic life cycle
Bovine Herpesvirus 1 (BoVH-1)
- REPORTABLE
- causes many diseases in cows: rhinotracheitis, vulvovaginitis, balanoposthitis, conjunctivitis, abortion, enteritis and generalize disease of newborn calves
- life long latent infectioin
- diagnosis: PCR, serology to test for antibodies
- vaccine available
Feline herpesvirus 1 (FHV-1)
- also called feline rhinotracheitis
- clinical signs: acute respiratory infection (very similar to calicivirus -> sneezing, coughing, nasal/ocular discharge, conjunctivitis/keratitis, anorexia, fever, tongue ulcers
- common in homes/shelters with lots of cats
- diagnosis: PCR
- vaccine available
- have to use antivirals otherwise latency will occur
Equine Herpesvirus 1 (EHV-1)
- most important viral cause of abortion in horses
- clinical signs: abortion, respiratory disease, encephalomyelitis
- enzootic (common) in horse populations worldwide
- diagnosis: inclusion bodies in affected tissue (seen with immunohistochemical staining) and PCR
Gallid Herpesvirus 2 (Marek's Disease)
- common and widespread in birds
- infects: lymphocytes (T-cells) and causes cell transformation into T cell lymphoma
- vaccine at hatching or in ovo (inject the egg)
- pathogenesis: aerosol -> respiratory epithelium -> lymphoid tissue -> viremia -> T cell transformation into neoplasia (lymphoma) -> infiltrates different organs/tissues
- 4 different forms depending on where it infiltrates
- classical form = infiltrates around nerves (often sciatic and this leads to paralysis)
- acute form = forms nodules in organs and nerves
- ocular = invades iris
- cutaneous form = affects feather follicles
- diagnosis: PCR targeting the DNA of the virus
- virus will make its way to epithelial cells, spread to the feather follicles, replicate and birds will shed the virus in their dander. Other birds then inhale the virus from the environment
Betaherpesvirinae
- long reproductive cycle
- cause latent infections in secretory glands, lymphoreticular tissues (lymph nodes and spleen) and kidneys
Suid herpesvirus 2
- REPORTABLE
- Also called Inclusion Body Rhinitis
- clinical signs: mucopurulent rhinitis, if sow gets infected during pregnancy, then mummification, still births and neonatal deaths
Gammaherpesvirinae
- establishes latency in lymphocytes
-
Malignant Catarrhal Fever
- fatal disease affecting cows, deer, swine
- wildebeest and sheep are reservoirs (showing persistent subclinical disease)
- affects lymphoid tissue
- clinical signs: lymphadenopathy, CNS signs, fever, depression, leukopenia
Papillomaviridae
- non-enveloped
- pathology is associated with cell transformation (normal cells -> little papillas)
Canine Papillomavirus
- common and self limiting (get from close contact with other animals)
-
Polyomaviridae
- poly = many, oma = tumours
- non-enveloped
- replicates in nucleus
Budgerigar fledgling Disease
- high mortality (sudden death)
- clinical signs: absence of feathers, skin lesions, hemorrhage
Asfarviridae
African Swine Fever
- enveloped
species affected: pigs
host cells infected: monocytes and macrophages
- spread through infected ticks = arbovirus. Ticks are the biological vectors
- pathogenesis: undercooked pork products fed to pigs, movement of wild boars
- clinical signs: severe hemorrhage and high mortality
- Major $$$ impact for farmers
- domestic cycle transmitted between pigs and through ticks. Sylvatic cycle transmitted between wild boars and ticks.
Adenoviridae
- non-enveloped
- replicates in nucleus
- infection is subclinical in most species
- Can cause agglutination of red blood cells
Canine Adenovirus 1 and 2 (Infectious Canine Hepatitis Virus)
- affects dogs
- Adenovirus 1 causes hepatitis and corneal opacity
- Adenovirus 2 causes respiratory disease
- widespread vaccines eradicated disease in many countries
- vaccine provides cross protection against both strains