Effectiveness of Live Vaccines in Controlling Gumboro Disease in Poultry

Live immunocomplex vaccines are considered one of the most effective ways to combat Gumboro disease in birds, despite the emergence of new variant strains of the virus. They not only promote the formation of cellular and humoral immunity but also become active from the first days after vaccination, competing with pathogenic strains for attachment sites in the cells.

This is reported by AgroReview

Impact of G2 Virus Variants on Bird Immunity

According to research, Gumboro virus variants from the G2 genogroup, particularly those isolated in China, can infect young chicks at an early age, even in the presence of maternal antibodies transferred from immunized parents. This often leads to damage to the bursa in chicks, resulting in significant lesions after hatching. Such an immune response is often accompanied by immunosuppression, as the damaged bursa is no longer capable of regeneration and normal functioning, complicating the body’s defense against disease.

Chinese studies have confirmed that the new G2 variant can damage the bursa of Fabricius even in immunized chickens that already have antibodies—such as those obtained through the use of various vaccines against highly virulent strains. Analyses of the reactivity of monoclonal antibodies and cross-neutralization have shown significant antigenic mismatch between this new strain and traditional highly virulent viruses.

Challenges and Prospects of Vaccination Based on Virus Competition

Research conducted in 2022 demonstrated that simultaneous infection of chicks with a highly virulent strain and G2 variants reduces mortality and tissue damage. This is related to the so-called principle of competitive competition between viruses for the receptors of bursal cells—a mechanism underlying the action of immunocomplex vaccines. Thus, the use of vaccines based on this principle may reduce the negative impact of highly virulent strains and enhance the protection of young birds.