Detection of Infectious Bursal Disease Virus Isolates with Unknown Antigenic Properties by Reverse Genetics

Abstract

Infectious bursal disease virus (IBDV) serotype 1 is the causative agent of a highly contagious immunosuppressive disease of young chickens. In the past, a number of antigenic, as well as pathogenic, subtypes have been described. The determination of the antigenic makeup of circulating strains is of vital interest to the poultry industry because changes in the antigenicity of circulating field strains have an impact on the use of vaccines. To obtain a more comprehensive overview of the relationship between the nucleotide and amino acid sequence and the antigenic makeup of field isolates, a system based on reverse genetics of IBDV was established. Using this approach, a database for field isolates from three different states in the United States (Georgia, Alabama, and Louisiana), consisting of nucleotide sequence, amino acid sequence, and a reaction pattern based on a panel of monoclonal antibodies, was established. The obtained results showed that phylogenic analysis, which is based on the similarity of sequences, would lead to false conclusions regarding a possible antigenic makeup of the particular isolate. Sequences of field samples were divided into three groups: 1) those that grouped with variant strain E/Del sequences but were antigenically different, 2) those that did not group with sequences of E/Del but were similar in their antigenic makeup, and 3) those that did not group with E/Del sequences and were antigenically different. In addition, using the reverse-genetics approach, a number of field isolates showed no reactivity with any of the used monoclonal antibodies, indicating that an unknown, antigenic subtype of IBDV serotype 1 is circulating in the field.

Anin vivoexperimental model to determine antigenic variations among infectious bursal disease viruses

“…The VN titre prior to dilution was 2 14 when 100 TCID 50 of the E/Dellike strain 8903 were used for the VN test. In a separate experiment, the identity of the tissue-culture-adapted 8903 was confirmed by indirect immunofluorescence using the panel of mAbs (10, 57, R63, 67, B69), which resulted in a positive reaction with only R63 and 67 as previously described (Icard et al, 2008). This confirmed the E/Del-like antigenic subtype.…”

“…In addition, an IBDV isolated in Belgium reacted with mAbs 10, R63, 67, and B69, a combination previously not described (Letzel et al, 2007). Furthermore, a new group of viruses was described that did not react with any of the mAbs using a diagnostic reverse genetics system for IBDV (Icard et al, 2008;Durairaj et al, 2011). It is important to keep in mind that virus isolates represent only a snapshot of IBDVs evolving in the field.…”

“…For this purpose, an antigencapture enzyme-linked immunosorbent assay was developed that provided a system for differentiation between different antigenic subtypes of IBDV based on certain reaction patterns using a panel of neutralizing monoclonal antibodies (mAbs; Van der Marel et al, 1990). In-depth analysis of amino acid exchanges causing differences in the antigenicity of IBDV lead to the conclusion that IBDV antigenicity is more complex than expected (Letzel et al, 2007;Icard et al, 2008;Durairaj et al, 2011). It also became clear that amino acid exchanges outside the projection domain might result in antigenic differences (Durairaj et al, 2011).…”

“…It also became clear that amino acid exchanges outside the projection domain might result in antigenic differences (Durairaj et al, 2011). Using this approach, several IBDVs lacking reactivity with any neutralizing mAb and indicating a different antigenic make-up (Icard et al, 2008;Durairaj et al, 2011) were detected and isolated (IBDVn-Var). Attempts to characterize the viruses in cross-neutralization assays in embryonated eggs were subjective since the viruses were not lethal in embryos, as observed with some IBDV strains, and embryo lesions were variable.…”

Protective Vaccination against Infectious Bursal Disease Virus with Whole Recombinant Kluyveromyces lactis Yeast Expressing the Viral VP2 Subunit

“…The cDNA encoding the IBDV D78 VP2 was amplified with the following primer pair on plasmid pD78A [71]: IBDV_AscI_fwd (5′-GGCGCGCCGATGACAAACCTGCAAGATC-3′) containing an AscI site and VP2_NotI_rev (5′-ATAAGAATGCGGCCGCTCACACAGCTATCCTCCTTATG-3′) containing a NotI site. The primer pair used to generate VP2-T2S was IBDV_S:T_AscI_fwd (5′-GGCGCGCCGATGTCTAACCTGCAAGATCAAACCCA-3`) and VP2_NotI_rev.…”