Comparative Study of the Immune Response Induced by an Argentinian Classical Strain of IBDV in Two Chicken Breeds

Abstract

The hybrid chicken Negra INTA, which originated at the National Institute of Agricultural Technology (INTA), is the product of the cross between Barred Plymouth Rock females and Rhode Island Red males, and it is used as a laying hen for egg consumption. It has been characterized by productive parameters, but the characterization from an immunological perspective has not been done yet. Infectious bursal disease virus (IBDV) causes a highly contagious viral disease that affects the bursa of Fabricius. Although most chickens are regularly vaccinated against IBDV, this virus still generates negative impacts on production with significant economic losses. The aim of the present work was to compare the immune responses of the Negra INTA hybrid and the White Leghorn layer line to the infection with a field isolate of IBDV. Four-week-old chickens were infected with a single dose of IBDV and at 3, 5, 7, and 30 days postinfection (dpi), bursae were removed, and different parameters were evaluated. Results showed that the reduction of the bursa body (BB) ratio and the histopathological damage were maximum on day 7 postinfection (pi). The viral load was greater in the hybrid Negra INTA at 5 dpi. The humoral immune response between both breeds was similar, although more animals from the commercial line showed higher titers of neutralizing antibodies. Flow cytometry analysis revealed that Bu+ bursal lymphocytes reached a minimum at 7 dpi. Meanwhile, T cell infiltration measured by the percentage of CD3+, CD4+, and CD8+ cells in the bursa was at its maximum at 5 dpi. To our knowledge, this work describes for the first time the pathogenesis and the immune response caused by an Argentinian IBDV isolate in two different chicken lines.

Evasion of maternal antibody protection by an IBDV Argentine variant

“…Figures 2B and 2C show the lesions resulting from infection with isolates G4 and G1. The histologic lesions observed included lymphoid depletion and inflammatory infiltrate, both notable features of IBDV infections ( Jaton et al, 2022 ). Approximately 20% of the G4 MDA group infected with G4 had chickens with both types of lesions in the bursa, whereas the G1 MDA-challenged group had no animals with detectable lesions in this organ.…”

Study of coinfection with local strains of infectious bursal disease virus and infectious bronchitis virus in specific pathogen-free chickens

“…Interestingly, Lupini and colleagues reported similar results when analyzing lymphocyte populations in the spleen, Harderian gland and trachea ( Lupini et al, 2020 ). It has been described that several IBDV isolates produce lymphoid depletion during the first days after infection that could be reversed later ( Kim et al, 1999 ; Jaton et al, 2022 ). Although lymphocyte populations were able to recover after IBDV infection at the evaluated time points, it cannot be stated that the bursa fully recovers its function, which was suggested by the reduced ability of animals in the IBDV/IBV group to produce antibodies against IBV.…”

“…The infectious bursal disease virus [1/chicken/ARG/P33/15 (P33)], belonging to genogroup 4 (GenBank accession number MN313610.1) and the infectious bronchitis virus [AR/13/BA/A13 (A13)], belonging to genogroup I-16 (GenBank accession number MH718950.1), were both isolated from commercial establishments ( Marandino et al, 2019 ; Tomás et al, 2019 ). These viruses were amplified in embryonated White Leghorn SPF eggs and viral stocks, obtained after 5 passages, were kept at −80°C and titrated as previously described ( Jaton et al, 2022 ).…”

“…Mononuclear cells were isolated from bursal and spleen samples and used to study T and B cell populations by flow cytometry as previously described ( Jaton et al, 2022 ). Briefly, bursae were cut into very small pieces and mechanically disrupted by pressing with a syringe plunger, in RPMI 1640.…”