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.
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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.
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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). |
