IBDV
Infectious bursal disease virus (IBDV) causes immunosuppression of the humoral immune system of young chickens. Antibodies produced as a result of an IBDV infection will protect birds from the disease. Thus, control of this disease is achieved by vaccination with live-attenuated viruses. Diagnosis of IBDV is accomplished using assays such as immunofluorescence and antigen capture ELISA, which can detect presence, but not identify serotype, antigenic subtype or virulence of the virus.
|
Vaccine Protection
Protection of chickens from IBD through the use of vaccines is complicated by the presence of two serotypes and several antigenic subtypes of the virus. Vaccination with a given antigenic subtype of IBDV serotype I will not always protect chicks from the disease when the challenge virus is a different antigenic subtype.
Subtypes of IBDV
It is important to identify the IBDV serotype because only serotype I viruses have been found to cause disease in poultry. In general, serotype I viruses have been place into two groups: classic and variant. Differentiation of IBDV strains has been accomplished with restriction enzyme (RE) digestion of RT/PCR products.
|
In one of our studies, the RT/PCR-RE assay differentiated twenty two viruses tested into three functional groups. One molecular group correlated with classic and one with variant antigenic types of IBDV. A third molecular group of viruses was identified which was antigenically related to both classic and variant viruses.
Our lab has used the reverse transcriptase/polymerase chain reaction - restriction fragment length polymorphism (RT/PCR-RFLP) assay with BstN I and Mbo I restriction enzymes. Testing numerous vaccine strains of IBDV resulted in six genetically distinct groups which correlated closely with antigenic subtypes of the viruses (Tables).
|
