Acute infectious bursal disease in poultry: A review

Abstract

This review is focused on the acute form of infectious bursal disease (IBD) caused by very virulent IBD virus (vvIBDV). First described in Europe about 10 years ago, this new form of the disease has rapidly spread all over the world, causing dramatic losses; after a decade, it still represents a considerable threat to the poultry industry. Emergence of the acute forms of the disease has drastically changed the epidemiology of IBD. Although their origin is still under investigation, vvIBDVs have spread all over the world in a very explosive but conserved manner. This raises the question of the origin of vvIBDVs, of the possible existence of reservoirs and of the possible emergence of new, distinct lineages in the future. While it has become clear that amino acids within the variable region of virus protein VP2 account for the molecular basis of antigenic variation, no definite hot spot that determines pathogenicity has been identified. Fingerprints of VP2 on vvIBDVs have to be considered more as common evolutionary markers than as virulence markers. The search for such markers is in progress. Pathogenesis of the disease is still poorly understood, and cytokines might play a crucial role in the onset of the disease and in the development of immunosuppression. Mechanisms such as apoptosis and necrosis have been described in lymphoid organs and are involved in the severity of the disease. Macrophages, especially, could play a specific role in the acute phase. Classical serotype 1 vaccines still induce good protection, but the actual problem for control of the disease has became the interference of maternally derived antibody in the establishment of the vaccination schedule. The development of safe vaccines that could either transmit a high passive immunity which could protect broilers during the whole growing period or prime an immune response before or at hatching in the presence of passive immunity might be established in the near future. In this context, recombinant vaccines and virus-neutralizing factor technology might have an advantage over other approaches.

Modelling the evolution of HIV‐1 virulence in response to imperfect therapy and prophylaxis

“…In addition to conventional resistance mechanisms (e.g., efflux pumps to thwart drugs or antigenic variation to escape vaccine‐induced immunity), experiments have shown that parasite virulence can evolve in response to—and mitigate the effects of—medical interventions, as exemplified by Marek's disease virus in response to vaccines (Read et al., 2015), and rodent malaria parasites in response to drugs (Schneider et al., 2012) and vaccines (Barclay et al., 2012). The extent of this kind of evolution in nonexperimental systems is poorly understood, but there is some evidence of vaccine‐driven virulence evolution in parasites of humans (pertussis, Mooi et al., 2009), cats (feline calicivirus, Radford, Dawson, Coyne, Porter, & Gaskell, 2006) and poultry (Marek's disease virus, Nair, 2005; avian infectious bursal disease virus, van den Berg, 2000). Through the development of general theory, Gandon, Mackinnon, Nee, and Read (2001) formalized the prediction that imperfectly effective, or “leaky” vaccines can drive virulence evolution.…”

Relationship between Virus Replication and Apoptosis Events in IgM + Cells from Chicken Spleen and Bursa of Fabricius Infected with Malaysia Strain of Very Virulent Infectious Bursal Disease Virus

“…Infectious bursal disease virus caused immosuppression in chickens, especially between the ages of 3 to 6 weeks [1]. This virus belongs to the Avibirnavirus genus in the Birnaviridae family with bi-segments genomes, namely segment A and B [6].…”

“…IBDV serotype 1 normally targeted the IgM bearing B cells in the chicken bursa of Fabricius. Infection resulted in depletion of B cells and subsequently destruction of the bursa which leaded to immunosuppression of the bird [1]. It was postulated that the depletion of cells in the bursa was due to apoptosis [1] and evidence showed apoptosis in lymphoid tissues of embryo and young chickens after being infected with vvIBDV strains [8,20].…”

Exploration of the in vitro cytotoxic and antiviral activities of different medicinal plants against infectious bursal disease (IBD) virus

“…IBD is an acute and contagious disease also known as Gumboro disease and has gained socio-economic importance at the international level [1]. IBD affects young chicks from 3-6 weeks of age [2] and based on the virulence IBD has been categorized into three categories i.e., a) mild b) virulent and c) very virulent.…”