Lecture 13/14 3/21/24 Flashcards
What are the characteristics of avian influenza?
-type A influenza virus
-8 gene segments
-18 HA subtypes
-11 NA subtypes
-viral reassortment allows for the recombination of HA and NA subtypes
What are the general characteristics of avian influenza transmission?
-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
What are the characteristics of localized AI infections?
-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.
What are the characteristics of systemic AI infections?
-high mortality
-chickens, turkeys, and other gallinaceous birds
-can infect other mammals, but rare
-typically high path.
Which HA subtypes are subtypes of HPAI?
H5 and H7
What are the characteristics of AI in poultry?
-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
What are the characteristics of the immune response against AI?
-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
What are the characteristics of AI vaccines?
-can help eradicate outbreaks
-significant reduction of virus shedding
-do not provide sterilizing immunity
What strategy is used in the US to control AI?
-massive and rapid cull response program
-infected flocks are euthanized
-viral detection/RT-PCR and serologic surveillance
-quarantine/movement controls/biosecurity
-NO VACCINE USE
How is AI reported?
-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
What is the importance of AI as a zoonotic pathogen?
-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%
What are the characteristics of newcastle disease virus?
-hardy despite envelope bc chicken houses are humid
-hemagglutinates chicken RBCs
-has low, moderate, and very virulent forms
-reportable
-US is free of disease
How is newcastle disease virus transmitted?
-aerosol
-direct contact
-fecal-oral
-fomite
What are the clinical signs of newcastle disease?
-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
How is newcastle disease diagnosed?
-RT-PCR to amplify matrix gene
-more specific RT-PCR for fusion protein if first PCR is positive
How is newcastle disease controlled?
-vaccination
-good flock management/all-in, all-out
-backyard flock restrictions
What are the characteristics of infectious bronchitis virus?
-pathotypes include respiratory, egg production losses, and renal disease
-many serotypes
-reportable
What are the clinical signs of infectious bronchitis virus?
-coughing
-nasal discharge
-conjunctivitis
-rales
-airsacculitis
-secondary bact. infections
-swollen, pale kidneys w/ distended ureters
-urates in kidneys/nephritis
What is the reproductive pathology associated with infectious bronchitis virus?
-cystic oviducts
-ovarian regression
-drop in egg production
-misshapen eggs with abnormal shells
How is infectious bronchitis virus diagnosed?
RT-PCR with serotype specific primers on samples from trachea, kidneys, cecal tonsils, repro. tract
How is infectious bronchitis virus controlled?
vaccines; however, vx is usually serotype-specific
What are the characteristics of infectious laryngotracheitis?
-gallid alphaherpesvirus 1
-upper resp. tract infection
-highly contagious with high mortality
-reportable
-latency and carriers possible
What are the clinical signs of infectious laryngotracheitis?
-severe dyspnea
-coughing
-rales
-nasal/ocular discharge
-tracheitis
-conjunctivitis
-extension of neck
-gasping
-rattling
-bloody, mucoid exudate
-drop in egg production
How is infectious laryngotracheitis diagnosed?
-clinical signs
-histopath.
-qPCR
How is infectious laryngotracheitis controlled?
-good biosecurity
-elimination of carriers
-zone vaccination
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
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
How is swollen head syndrome diagnosed?
-RT-PCR on nares and trachea samples
-additional RT-PCR to subtype
How is swollen head syndrome controlled?
-good biosecurity
-vx is not available in the US
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
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
How is infectious bursal disease virus diagnosed?
-bursa of Fabricius collected for diagnostics
-histopath.
-RT-PCR
-sequencing
How is infectious bursal disease virus controlled?
-vaccination of breeder stock
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
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
How is chicken infectious anemia virus diagnosed?
-PCR
-histopath.
-must be distinguished from Marek’s
How is chicken infectious anemia virus controlled?
-natural exposure
-vaccines
-greater than 95% of birds must be exposed/vaccinated
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
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
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
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
How is MDV controlled?
-vaccination
-biosecurity
-genetic resistance
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
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
How is ALV diagnosed?
-clinical signs/gross path./histopath.
-IHC
-qPCR
-serology
-gross and microscopic path. to distinguish from MDV
How is ALV controlled?
-breeding flocks without disease/eradication
-NO treatment or vx
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
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
What are the characteristics of fowlpox?
-cutaneous and diphtheric disease
-affects all ages
-horizontal, mechanical, and mosquito transmission
-not contagious to humans
How is fowlpox diagnosed?
-clinical signs
-histopath
-viral isolation and PCR
Which samples are used for fowlpox?
-oro-nasal swabs for diphtheric form
-scrapes or biopsies of cutaneous lesions for cutaneous form
How is fowlpox controlled?
-mosquito/pest control methods
-vaccination
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
How is avian encephalomyelitis diagnosed?
-clinical signs and history
-histopath./RT-PCR/viral isolation using CNS, pancreas, or duodenum samples
-ELISA
How is avian encephalomyelitis controlled?
live vaccination
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
How are avian reoviruses diagnosed?
-RT-PCR of tendon or synovial fluid
-ELISA, but not definitive
How are avian reoviruses controlled?
-vaccination
-immune response is serotype specific
