Prevalence and molecular characterization of gumboro virus in chicken farms in Ismailia

Abstract EN

Infectious bursal disease (IBD, Gumboro disease) is a worldwide immunosuppressive disease of chickens in their first weeks of life.

IBD is one of the most economically important diseases that affects commercially produced chickens.

Vaccination programmes with inactivated and live attenuated viruses have been used to prevent IBD.

Some of the vaccines may not induce full protection against the very virulent IBDV strains and antigenic variants.

In this study, 20 farms were represented for a prevalence study of the disease in Ismailia governorate, Egypt (IBDV-Ismailia-isolate-2014).

Isolates from bursal samples of commercial broiler farms exhibiting some clinical and postmortem signs with poor performance were used for Reverse transcription (RT)-polymerase chain reaction (PCR) assay.

RT-PCR was used to amplify a 620-bp product within the hypervariable region of the IBDV VP2 gene.

Three farms out of 20 (15 %) were positive.

The positive samples were subjected for nucleotide sequence analysis (265 nucleotide in hyper variable region of VP2).

Nucleotide and amino acid sequence analysis and blast indicated that Ismailia isolateshave close relationships between the previously isolated Egyptian IBDVs and they are clustered together (with 99-100% identity) while other classic attenuated vaccine strains (Bursavac and Bursine) were grouped in another group (with 92.45 % and 91.32 %.

identity respectively).

This result guides us to review the vaccination programs against IBDV in Egypt and better selection of vaccines that canimprove the immune response against the infection.