Infectious bursal disease virus: case report and experimental studies in vaccinated and unvaccinated SPF chickens and commercial broiler chicks

Abstract

IBDV Gm 11 (Simbios eleven-molecular group) has been detected since 1997 in many farms of commercial broilers and layers causing high mortality (2 to 15%) and severe macro and microscopic damage in cloacal bursae, spleen, thymus, kidney and liver. Five serial passages of 2050/97-Gm 11 IBDV sample by CAM route in SPF chicken's embryonated eggs did not elicit increased embryo mortality. High mortality (100%) of 21 day-old SPF leghorn chickens and severe bursal and splenic lesions were seen from 24 up to 48 hours after eye-drop inoculation of 2050/97 strain (50 mL of 10-2 dilution of 10% bursae homogenate). Mortality was not detected when vaccinated SPF and broiler chickens were inoculated. One dead bird was found among ten challenged unvaccinated broilers. Variations in the intensity of cloacal bursae injury and spleen response were found between unvaccinated and vaccinated broiler chickens. IBDV antibodies were detected by ELISA test in almost all vaccinated SPF chickens before challenge while low number of commercial vaccinated and unvaccinated broilers were serologically positive (0 to 3 birds in 18). Increasing IBDV antibody titers were detected after challenge with 2050/97 strain and highest GMTs were found in broilers. It was concluded that 2050/97 strain is a highly virulent IBDV and SPF leghorn chickens immunized with BV8 intermediate vaccine strain were resistant to the challenge. Increasing susceptibility was found from experimental groups of unvaccinated broilers to vaccinated broilers and to unvaccinated SPF birds. It is discussed that passive immunity was involved in the rate of protection of challenged unvaccinated broiler and in the immune response impairment after vaccination of broilers chicks. The use of a constant virus suspension with known potency to challenge the experimental birds was suitable to evaluate vaccination efficacy. Evaluation of bursal and splenic responses at early and delayed time after challenge were useful to estimate vaccination efficacy and field interactions

A Comparative Study of Pathology and Host Immune Response Induced by Very Virulent Infectious Bursal Disease Virus in Experimentally Infected Chickens of Aseel and White Leghorn Breeds

“…Focal areas of hemorrhage were also encountered ( Figure 2 d). In a previous study [ 43 ], a similar increase in germinal centers in vaccinated birds, and splenic necrosis in nonvaccinated IBDV-infected birds was observed.…”

Morphology of the chicken sleep and its changes during vaccination

“…Також у вакцинованих курчат відмічали зменшення індексу органів імунного захисту, зокрема селезінки (Guralska, 2015). Подібні зміни також в своїх дослідженнях спостерігали Scanavini Neto et al (2004). Rautenschlein et al (2005), Thomrongsuwannakij et al (2021) висловлюють думку, що перш ніж застосовувати певні вакцини проти інфекційних захворювань необхідно вивчити імунний статус курчат, небезпеку виникнення спалахів хвороби.…”

Characterization of field infectious bursal disease viruses in Zambia: evidence of co-circulation of multiple genotypes with predominance of very virulent strains

“…The pathogenicity and pathology of vvIBDVs isolated in Europe, Asia, North and South America have been studied under experimental conditions (Scanavini et al, 2004;Williams & Davison, 2005;Jackwood et al, 2016;Prabhu et al, 2017). However, under both experimental and natural conditions, such studies on vvIBDV strains detected in Africa have not been well investigated as most studies have focused on the molecular epidemiology of the disease.…”