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Flashcards in Virology Deck (153)
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Poxvirus transmission

Resistant in environment (despite envelope)-->
Transmit via abraded skin, respiratory route (droplets), mechanical (fomites, insects, etc.)


Genus Capripoxvirus spp.

sheep pox
lumpy skin disease
goat pox
(all serologically identical)


Genus Caprivirus Epidemiology

endemic in SE Europe, Middle East, Africa, Asia
Generalized disease
Can spread between sheep/goats/cattle but often remain in respective host sp.
Mortality up to 50% in indigenous breeds, up to 100% in European breeds


Genus Caprivirus Pathogenesis and clinical signs

Infection by abrasion, aerosols, mechanical--> replicates locally in skin/lungs--> regional lymph nodes--> viremia-->shed from skin lesions and nasal/ocular discharge
Incubation ~ 1 week--> fever, edema of eyelids, conjunctivitis, nasal discharge, skin lesions, lung consolidation/hemorrhage


Genus Avipoxvirus spp., modes of transmission

Fowlpox virus, other avian poxviruses
Mechanical transmission by mosquitoes, aerosol transmission


Orf virus (scabby mouth, contagious ecthyma)
Transmission, pathogenesis, maintenance in population

= contagious pustular dermatitis (worldwide)
Transmitted by direct/indirect contact (abrasions)- infectious in scab for months
Epitheliotropic- proliferates locally in epidermal keratinocytes--> wart-like lesions near lips, muzzle, feet, genitalia, teats
Primarily in young sheep, maintained by chronic carriers


Myxoma virus epidemiology and pathogenesis

Myxomatosis = poxvirus disease of rabbits
Benign fibromas in American wild rabbits, severely degenerative in European species
Mechanical transmission by mosquitoes and fleas (not contagious)-->listless and febrile--> often death w/in 48 hours (survivors have sub-Q gelatinous swellings)
Mortality rate ~99% in wild rabbits w/ virulent strain


African swine fever (asfarviridae) epidemiology, pathogenesis

Infects Suidae and soft ticks
Persistent tick infection--> 1) sylvatic cycle- viremia in juvenile warthogs (little-no dz in African breeds)
--> 2) domestic cycle- up to 100% mortality due to diffuse hemorrhage from platelet damage and complement activation, fever (European breeds)
Persists in meat for months-->pigs can become infected from carcass of dead infected pigs
No neutralizing Ab made, no vaccine, risk of international spread in pig products


Herpesvirus epidemiology/pathogenesis

Labile (enveloped)--> spread by close or mucosal contact (e.g. droplets)
Lifelong latent infection in neural or lymphatic tissue with continuous or periodic shedding (reactivated in times of stress)
Copies DNA in infected neurons, no viral gene expression except latency associated transcripts (LATs- inhibit apoptosis)
Can be shed while sub-clinical or recrudescent (reemerging clinical signs)


Bovine Herpesvirus 1 (infectious bovine rhinotracheitis)
Pathogenesis, clinical signs

Respiratory infection by aerosol route--> viremia (dissemination)--> rhinotracheitis, vulvovaginitis, balanoposthitis (virus shed in semen), conjunctivitis, abortion, enteritis, nasal discharge, hyperemic nasal mucosa, dyspnea, coughing, focal areas of epithelial necrosis and inflammation
Recovery 5-10 days
Intensive environments (e.g. feedlots) morbidity ~100%


Bovine herpesvirus 2

Bovine mammillitis virus/ pseudo-lumpy skin disease virus
2 forms:
Mammillitis (localized lesions on teats)
Generalized nodules and necrosis


Bovine herpesvirus 5

Bovine encephalitis virus
direct neural spread via trigeminal nerve from nasopharynx--> fatal meningoencephalitis in calves


Equine herpesvirus 1
epidemiology, pathogenesis

Most important viral cause of horse abortion worldwide
Infection via respiratory tract--> respiratory and neural dz--> viremia and systemic infection--> endothelium of endometrial vasculature--> vasculitis--> infarction--> abortion
Aborting mare infectious for 1-2 days from reproductive tract, 2 weeks from respiratory tract
Minimize risk by keeping pregnant mares separate from other horses and in small groups by foaling date
Reduce latent infection risk by minimizing stress


Equine Herpesvirus 4

Equine rhinopneumonitis- similar to EHV1 but only acute respiratory dz
nasal discharge and lymphadenopathy in foals (esp. weanlings and yearlings)
Only ELISA can differentiate EHV1/EHV4


Equine Herpesvirus 3

Equine coital exanthema
Veneral alphavirus
Lifelong latently infected carriers
Spread by mucosal contact


Feline Herpesvirus 1
clinical signs and prevention

Feline rhinotracheitis
Acute respiratory dz (similar signs to calicivirus)- nasal/ocular discharge, sneezing, dyspnea, oral ulcers
Lifelong latent carriers
Inactivated and live attenuated vaccines available
Live vaccine can cross placenta in pregnant queens


Gallid Herpesvirus 1
Clinical signs

Infectious laryngotracheitis (young chickens)
Acute respiratory dz- nasal/ocular discharge, sneezing, dyspnea, gasping/coughing
Often hemorrhagic exudate w/ diphtheritic pseudo-membrane occluding trachea


Canine adenovirus 1 pathogenesis

Infectious canine hepatitis (4-9 day incubation)
Contaminated urine/feces--> nasopharynx/mouth/conjunctiva--> tonsil crypts/peyer's patches--> viremia--> vascular endothelial cells--> hemorrhage/necrosis of major organs (esp. liver- inflamm., hepatocellular damage, failure)
--> 1) virus shed in urine/feces/saliva
--> 2) shock--> death
--> 3) Neutralizing Ab response--> recovery


Canine adenovirus 1
clinical presentations, diagnosis, prevention

3 syndromes:
1) peracute dz- 3-4 hours, found dead
2) acute dz- fever, vomiting, dysentery, collapse, petechial gums, icterus, may be fatal
3) mild or inapparent dz

Dx: Ag detection in urine (virus isolation, PCR)
- Ab detection- ELISA, HAI

Prevention: vaccine part of C3 protocol, CAdV2 vaccine cross-protective and safer than CAdV1 (no risk of corneal edema)


Canine adenovirus 2

Infectious canine tracheobronchitis
Localized respiratory dz (part of kennel cough complex)- bronchitis/bronchiolitis
Not systemic, doesn't affect wildlife
Vaccine provides complete homologous protection against CAdV1


Equine adenovirus 1 & 2

EAdV1: found in young horses w/ or w/o respiratory dz
EAdV2: in lymph nodes and feces of foals w/ respiratory disease and diarrhea
Mostly asymptomatic or mild
Could be fatal for Arabian foals with SCID


Family Papillomaviridae pathogenesis

Infections through skin abrasions-->infection of basal cells in squamous epithelium--> clonal proliferation (delayed maturation)--> papilloma formation (finger-like projections)-->viral shedding
Often in young animals, usually regress after several weeks


Bovine papillomavirus
pathogenesis, neoplastic transformation, diagnosis

Transmission via fomites, sexual (venereal warts)--> squamous papilloma in mucocutaneous areas--> fibropapillomas (pedunculated) on udder, teats, head, neck, genitalia--> spontaneous regression after 1-6 months
Neoplastic transformation: BoPV + bracken fern poisoning (enzootic hematuria)--> neoplasia (BoPV2= bladder cancer, BoPV4= alimentary cancer)
- UV + BoPV--> ocular squamous cell carcinoma in lateral esclero-corneal limbus, nictitating membrane, or lower eyelid
Dx: direct observation, histopathology, PCR


Equine sarcoid
Presentations, behavior, treatment

Papillomavirus (BoPV implicated)- most common equid skin tumor
Head, limbs, ventral abdomen of 4+ y.o. horses esp. at site of previous scarring
Locally aggressive but does not metastasize
Transmitted by fomites, possibly flies
Possible presentations: occult, verrucose, nodular, fibroblastic, malevolent, +/- pedunculated
Treatment (excision) ineffective- recurrence common


Feline Panleukemia virus
epidemiology, pathogenesis, clinical signs, prevention

Highly contagious generalized systemic/enteric dz worldwide (1 serotype)
Enters cats (often young as maternal Ab wanes) via oropharynx--> replicates in pharyngeal lymphoid tissue--> viremia--> mitotically active cells (intestinal crypt, bone marrow, fetal cerebellum/retina)--> incubation ~5 days--> bone marrow suppression, GIT signs, cerebellar hypoplasia (in fetus via transplacental transmission)--> shed in saliva, urine, vomit, feces (several weeks)
Inactivated and live vaccines available


Canine parvovirus 2
Epidemiology and prevention

High morbidity and mortality in all Canidae
3 variants (2a, 2b, 2c)
Vaccine protects against all variants but not 100% immunity- part of C3 given @ 6-8 weeks, 14-16 weeks, 1 year, every 3 years


Canine parvovirus 2 pathogenesis

Feco-oral transmission--> pharyngeal lymphoid tissue--> viremia--> replicates in intestinal crypt cells--> hemorrhagic gastroenteritis, vomiting--> virus shed in feces for 3-7 days after infection (persists in environment for months)
Mucosal collapse w/ contraction/fusion of SI villi--> malabsorption, hemorrhage--> dysentery w/ fetid smell (usually enough to make presumptive Dx)


Porcine parvovirus
epidemiology, pathogenesis, diagnosis, prevention

Worldwide reproductive failure, 1 serotype, stable in environment
Infection via oronasal route--> local replication in tonsillar lymphoid tissue--> viremia and transplacental transmission (takes ~15 days to reach fetus)
- <30 days gestation--> resorption
- 30-70 days gest.--> stillbirth & mummification
- >70 days--> stillborn, abnormal, or normal fetus
Dx: infected feti have high virus titer (PCR, HAI)
Prevention: exposing guilt or vaccinating before pregnancy induces immunity


Psittacine beak and feather disease
pathogenesis and clinical signs

Cockatoos, parrots, budgerigars
Replicates in basal epithelial layer--> basophilic intracytoplasmic inclusions, lymphoid depletion--> difficulty feeding and death
Feather changes: stunted pin feathers, bloody/sheathed/fractured adult feathers
Beak/claw deformities: broken, overgrown and shiny, delaminations, palatine necrosis


Porcine circovirus 2

Post-weaning multi systemic wasting syndrome
Progressive dz in 6-week old piglets- weight loss, enlarged lymph nodes, dyspnea