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Infectious Bursal Disease: Viral infections of the hematopoietic system -…
Infectious Bursal Disease: Viral infections of the hematopoietic system
agent characteristics
avibirnavirus
non-enveloped
heat stable
resistant
down to pH 3
ether
chloroform
2 segments of ds RNA
hence
BIRNA
in genus name
2 serotypes
serotype I
:chicken:
pathogenic
variant strains
recognized from vaccinated birds
rapid bursal atrophy w/o inflammation
persist in thymus
cause immunosuppression regardless of maternal Abs
deleted/altered neutralization site
may cause exceptionally high mortality
serotype II
:turkey: :Chicken:
apathogenic
worldwide distribution
pathogenesis
3-8w old :hatched_chick: most susceptible
transmitted via contaminated feed and water
oral route
very short incubation period
clinical signs appear in 2-3d
targets lymphoid tissues
repilcates in gut macrophages
carry virus to bursa, peripheral organs
replicates in
Bursa of Fabricus
site of hematopoiesis
B cell development
located at cloaca
clinical signs
PE
behavior
anorexia
depression
ruffled feathers
prostration
die
hands-on
hemorrhages on thigh, pectoral mm
test results
necropsy
hemorrhagic bursa
immunosuppression
more pronounced in :hatched_chick: <3w
significantly compromised humoral, local, and cellular immune response
lysis and apoptosis of B cells
supressor T and macrophages have a role
secondary infections
coccidiosis
inclusion body hepatitis
gangrenous dermatitis
salmonellosis
E. coli
infection
vaccination failures
diagnostic tests
IFA
AGID
EM
SN tst
ELISA
virus isolation in emryonated eggs
RT-PCR
in-situ hybridization
prevention
neutralizing Ab response (I am confusion?)
vaccination
types available
attenuated live
100% protection
adaption of IBDV in macrophages
inactivated
recombinant
VP2 Ag + cytokines
VP@ + Newcastle
