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SP1 Virology > Lecture 13/14 3/21/24 > Flashcards

Lecture 13/14 3/21/24 Flashcards

1
Q

What are the characteristics of avian influenza?

A

-type A influenza virus
-8 gene segments
-18 HA subtypes
-11 NA subtypes
-viral reassortment allows for the recombination of HA and NA subtypes

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2
Q

What are the general characteristics of avian influenza transmission?

A

-low path. AI naturally found in wild birds
-not normally found in chickens and turkeys, unless transmitted from wild birds
-can cause serious disease outbreaks if established in chickens/turkeys

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3
Q

What are the characteristics of localized AI infections?

A

-mild to moderate disease
-intestinal disease in wild ducks/shorebirds and poultry
-resp. disease in humans, swine, horses, poultry, domestic ducks, seals, mink
-typically low path.

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4
Q

What are the characteristics of systemic AI infections?

A

-high mortality
-chickens, turkeys, and other gallinaceous birds
-can infect other mammals, but rare
-typically high path.

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5
Q

Which HA subtypes are subtypes of HPAI?

A

H5 and H7

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6
Q

What are the characteristics of AI in poultry?

A

-LPAI can mutate in HPAI
-HA must be cleaved into HA1 and HA2 to be infectious
-LPAI requires trypsin-like proteases for cleavage, which are only found in cells at mucosal surfaces
-HPAI has additional basic cleavage site that allows for use of ubiquitous proteases
-HA cleavage site is clinical virulence factor

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7
Q

What are the characteristics of the immune response against AI?

A

-antibody and cell mediated immune responses both contribute to protection
-Ab against HA protein is best correlate of protection
-antibodies are not cross-protective to other HA types
-vaccine must match field strain HA to provide good protection

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8
Q

What are the characteristics of AI vaccines?

A

-can help eradicate outbreaks
-significant reduction of virus shedding
-do not provide sterilizing immunity

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9
Q

What strategy is used in the US to control AI?

A

-massive and rapid cull response program
-infected flocks are euthanized
-viral detection/RT-PCR and serologic surveillance
-quarantine/movement controls/biosecurity
-NO VACCINE USE

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10
Q

How is AI reported?

A

-USDA approved testing of suspected cases done at NAHLN labs
-samples screened via PCR for AI; positive samples tested again for H5 and H7
-samples suspected to be HPAI are retested by NVSL

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11
Q

What is the importance of AI as a zoonotic pathogen?

A

-LPAI and HPAI can both cause severe disease in humans
-HPAI has yet to have human-to-human transmission
-human mortality in HPAI cases is greater than 50%

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12
Q

What are the characteristics of newcastle disease virus?

A

-hardy despite envelope bc chicken houses are humid
-hemagglutinates chicken RBCs
-has low, moderate, and very virulent forms
-reportable
-US is free of disease

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13
Q

How is newcastle disease virus transmitted?

A

-aerosol
-direct contact
-fecal-oral
-fomite

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14
Q

What are the clinical signs of newcastle disease?

A

-sudden death
-resp. signs
-green, watery diarrhea
-depression/drooped wings
-muscle tremors
-opisthotonos/circling/paralysis
-drop in egg production/thin-shelled eggs
-swelling of tissues around eyes/waddle/neck
-increased mortality

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15
Q

How is newcastle disease diagnosed?

A

-RT-PCR to amplify matrix gene
-more specific RT-PCR for fusion protein if first PCR is positive

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16
Q

How is newcastle disease controlled?

A

-vaccination
-good flock management/all-in, all-out
-backyard flock restrictions

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17
Q

What are the characteristics of infectious bronchitis virus?

A

-pathotypes include respiratory, egg production losses, and renal disease
-many serotypes
-reportable

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18
Q

What are the clinical signs of infectious bronchitis virus?

A

-coughing
-nasal discharge
-conjunctivitis
-rales
-airsacculitis
-secondary bact. infections
-swollen, pale kidneys w/ distended ureters
-urates in kidneys/nephritis

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19
Q

What is the reproductive pathology associated with infectious bronchitis virus?

A

-cystic oviducts
-ovarian regression
-drop in egg production
-misshapen eggs with abnormal shells

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20
Q

How is infectious bronchitis virus diagnosed?

A

RT-PCR with serotype specific primers on samples from trachea, kidneys, cecal tonsils, repro. tract

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21
Q

How is infectious bronchitis virus controlled?

A

vaccines; however, vx is usually serotype-specific

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22
Q

What are the characteristics of infectious laryngotracheitis?

A

-gallid alphaherpesvirus 1
-upper resp. tract infection
-highly contagious with high mortality
-reportable
-latency and carriers possible

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23
Q

What are the clinical signs of infectious laryngotracheitis?

A

-severe dyspnea
-coughing
-rales
-nasal/ocular discharge
-tracheitis
-conjunctivitis
-extension of neck
-gasping
-rattling
-bloody, mucoid exudate
-drop in egg production

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24
Q

How is infectious laryngotracheitis diagnosed?

A

-clinical signs
-histopath.
-qPCR

25
How is infectious laryngotracheitis controlled?
-good biosecurity -elimination of carriers -zone vaccination
26
What are the characteristics of swollen head syndrome/turkey rhinotracheitis?
-four subtypes; subtype C is found in turkeys -considered exotic in US broilers and egg layers -reportable
27
What are the clinical signs of swollen head syndrome?
-inflammation of resp. tract -rales -sneezing with frothy discharge -conjunctivitis -swelling of infraorbital sinuses -submandibular edema -coughing -head shaking
28
How is swollen head syndrome diagnosed?
-RT-PCR on nares and trachea samples -additional RT-PCR to subtype
29
How is swollen head syndrome controlled?
-good biosecurity -vx is not available in the US
30
What are the characteristics of infectious bursal disease virus?
-2 serotypes; serotype 1 causes disease in chickens -highly contagious with a worldwide dist. -100% morbidity, mortality ranges from 5-60% -chickens most susceptible between 3-6 wks of age
31
What are the clinical signs of infectious bursal disease virus?
-hemorrhage, edema, and atrophy of bursa of Fabricius -immunosuppression -vaccine failure -prone to secondary infections -severe prostration -incoordination -watery diarrhea/soiled vent feathers -cloacal inflammation -anorexia/weight loss
32
How is infectious bursal disease virus diagnosed?
-bursa of Fabricius collected for diagnostics -histopath. -RT-PCR -sequencing
33
How is infectious bursal disease virus controlled?
-vaccination of breeder stock
34
What are the characteristics of chicken infectious anemia virus?
-targets hemocytoblasts in bone marrow and T cell precursors in thymus -vertical and horizontal transmission -increased mortality in young chicks -immunosuppression in older chicks/chickens
35
What are the clinical signs of chicken infectious anemia virus?
-anemia -watery/slowly clotting blood -paleness -anorexia/reduced weight gain -lethargy -depression -high mortality due to secondary infections -pale organs and bone marrow -hemorrhages
36
How is chicken infectious anemia virus diagnosed?
-PCR -histopath. -must be distinguished from Marek's
37
How is chicken infectious anemia virus controlled?
-natural exposure -vaccines -greater than 95% of birds must be exposed/vaccinated
38
What are the characteristics of Marek's disease virus?
-immunosuppressive and oncogenic -gallid herpesvirus 2, serotype 1 = virulent -MDV-type 1 causes T cell lymphoma -transmitted through inhalation of poultry dust/dander, upper resp. secretions, and feather follicles -highly contagious
39
What are the steps of MDV pathogenesis?
-early cytolytic: MDV enters resp tract and pulmonary immune cells; disseminates to lymphoid organs -latent: B and T cell transformation; transient immunosuppression -second cytolytic: permanent immunosuppression; T cells continuously infected -proliferative: T cell lymphoma; follicular feather epithelial cells infected
40
What are the clinical signs of MDV?
-neoplasms -enlarged nerves -diffuse or nodular lymphoid tumors -enlarged feather follicles -atrophied bursa of Fabricius -leg paralysis -secondary infections
41
How is MDV diagnosed?
-diagnose tumors, not infection (ubiquitous) -based on enlarged nerves and lymphoid tumors without bursa tumors -IHC of tumors to look for predominant T cell populations or MDV antigens -qPCR
42
How is MDV controlled?
-vaccination -biosecurity -genetic resistance
43
What are the characteristics of avian leukosis and sarcoma viruses?
-exogenous alpharetroviruses with A, B, C, D, and J subgroups -subgroups A and B cause lymphoid leukosis -subgroup J causes myelocytoma -vertical/congenital and horizontal transmission -congenitally infected chickens do not produce neutralizing Abs; viremic for life -more frequent tumor occurrence in congenitally infected -no vx; eliminate through eradication
44
What are the clinical signs of ALV?
-targets bursal-dependent lymphoid system; antibodies produced to virus instead of tumor -inappetence -weakness -diarrhea -dehydration -emaciation -egg production losses -diffuse or nodular lymphoid tumors -myelocytomatosis
45
How is ALV diagnosed?
-clinical signs/gross path./histopath. -IHC -qPCR -serology -gross and microscopic path. to distinguish from MDV
46
How is ALV controlled?
-breeding flocks without disease/eradication -NO treatment or vx
47
What are the characteristics of reticuloendotheliosis virus?
-oncogenic avian retrovirus unrelated to ALV -MDV vaccines may carry REV -causes B and T cell lymphomas -dx requires combo. of gross path., age, clinical signs, IHC, and PCR -no vx; need good biosecurity/management
48
What are the key components to identifying the correct oncogenic virus?
-enlarged nerves and splayed leg presentation is MDV -bursa is more-so affected in ALV -REV is not as ubiquitous -MDV generally seen in chicks as young as 3 wks; ALV in chicks >14 weeks
49
What are the characteristics of fowlpox?
-cutaneous and diphtheric disease -affects all ages -horizontal, mechanical, and mosquito transmission -not contagious to humans
50
How is fowlpox diagnosed?
-clinical signs -histopath -viral isolation and PCR
51
Which samples are used for fowlpox?
-oro-nasal swabs for diphtheric form -scrapes or biopsies of cutaneous lesions for cutaneous form
52
How is fowlpox controlled?
-mosquito/pest control methods -vaccination
53
What are the characteristics of avian encephalomyelitis?
-vertical and horizontal transmission -clinical signs in horizontally-infected chicks around 2-4 wks old -does not cause disease in humans or mammals -morbidity and mortality can exceed 50% in severe outbreaks -paralysis, ataxia, muscular dystrophy in young chickens -no CNS involvement in older chickens; dec. egg production
54
How is avian encephalomyelitis diagnosed?
-clinical signs and history -histopath./RT-PCR/viral isolation using CNS, pancreas, or duodenum samples -ELISA
55
How is avian encephalomyelitis controlled?
live vaccination
56
What are the characteristics of avian reoviruses?
-virulence varies based on virus strain -horizontal and vertical transmission -most infections acquired via ingestion -viremia includes heart, liver, intestine, tendons -causes hydropericardium, edema, heterophilic inflammation, lameness
57
How are avian reoviruses diagnosed?
-RT-PCR of tendon or synovial fluid -ELISA, but not definitive
58
How are avian reoviruses controlled?
-vaccination -immune response is serotype specific

SP1 Virology (22 decks)

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