کاظم طربی
Molecular epidemiologic survey of infectious bursal disease viruses in broiler farms raised under different vaccination programs
SUMMARY
Over a span of nearly 4 yr, 246 bursal tissue samples were collected from Brazilian commercial
broiler flocks (Gallus gallus) throughout the country and imprinted to sample collection
cards (Flinders Technology Associates (FTA) cards). A total of 75 infectious bursal disease
virus (IBDV) strains was successfully detected from the FTA card imprints and were submitted
for further identification and molecular characterization. Nucleotide and predicted amino acid
sequences of the IBDV surface protein VP2 were used to identify strains of the virus and place
them into phylogenetic groups. The amino acids across the hypervariable region of VP2 in
this study varied, but around half of all positive samples were classified as vaccine virus. The
IBD viruses fell into 3 categories: variant IBDV, classic IBDV (vaccine), and very virulent (vv)
IBDV. The samples were collected according to the 3 different vaccination strategies used in
broilers: vectored vaccine, antigen-antibody complex vaccine, and conventional live vaccine.
The genetic profile and frequency of the strains recovered from the flocks were highly dependent
on the vaccination program. This information helps us gain a better understanding of the
current landscape of IBD in Brazil and provides additional scientific data to support selection
of the most effective vaccination strategies, products, and practices to prevent disease.
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