Differential Immunomodulation in Chickens Infected with Classical and Variant IBD Viruses

Critical differences were observed by Ohio State University researchers between chickens infected with classical and variant types of infectious bursal disease (IBD) virus.

21 October 2011

3 minute read

Infectious bursal disease (IBD) is an important immunosuppressive disease of chickens, according to Abdul Rauf and co-authors from Ohio State University. In their paper published recently in Veterinary Research, they explain that the causative agent, infectious bursal disease virus (IBDV), consists of two serotypes, 1 and 2. Serotype 1 consists of classic IBDV (cIBDV) and variant IBDV (vIBDV). The strains vary in antigenicity and pathogenesis.

The goal of the Ohio study was to compare the immunopathogenesis of cIBDV and vIBDV.

Three-week-old specific pathogen-free chickens were inoculated intraocularly with standard challenge strain (STC; cIBDV) and a variant strain Indiana (IN; vIBDV).

The cIBDV produced more pronounced bursal damage, inflammatory response and infiltration of T cells than vIBDV.

There were significant differences in the expression of innate (IFN-α and IFN-β), pro-inflammatory cytokine and mediator (IL-6 and iNOS) in cIBDV- and vIBDV-infected bursas.

The expression of chemokines genes, IL-8 and MIP-a was also higher in cIBDV-infected chickens during the early phase of infection.

The expression of Toll like receptor 3 (TLR3) was down-regulated at post inoculation days (PIDs) 3, 5 and 7 in the bursas of vIBDV-infected chickens, whereas TLR3 was upregulated at PIDs 3 and 5 in cIBDV-infected bursas.

In vIBDV-infected bursa, TLR7 expression was down-regulated at PIDs 3 and 5 and upregulated at PID 7. However, TLR7 was up-regulated at PIDs 3 and 7 in cIBDV-infected bursas.

The expression of MyD88 was down-regulated whereas TRIF gene expression was up-regulated in cIBDV- and vIBDV-infected bursa.

Rauf and co-authors say their findings demonstrate critical differences in bursal lesions, infiltration of T cells, expression of cytokines, chemokines and TLRs in the bursa of cIBDV-and vIBDV-infected chickens.

Reference

Rauf A., M. Khatri, M.V. Murgia, K. Jung and Y.M. Saif. 2011. Differential modulation of cytokine, chemokine and Toll-like receptor expression in chickens infected with classical and variant infectious bursal disease virus. Veterinary Research, 42:85. doi:10.1186/1297-9716-42-85