Molecular and Antigenic Characterization of Bangladeshi Isolates of Infectious Bursal Disease Virus Demonstrate their Similarities with Recent European, Asian and African Very Virulent Strains

Abstract

Three isolates of infectious bursal disease virus (IBDV), obtained from chickens in Bangladesh in 1999 and designated as BD 1/99, BD 2/99 and BD 3/99, were characterized. In an antigen capture enzyme-linked immunosorbent assay using a panel of VP2-specific neutralizing monoclonal antibodies (mAb), all three isolates showed a mAb-binding profile similar to that of very virulent IBDV (vvIBDV) strains. In contrast to the classical virulent strains, they did not react with mAb 3 and mAb 4. Molecular characterization was performed by direct sequencing of a 677-base pair cDNA corresponding to the VP2 variable domain of the polyprotein gene, synthesized by a reverse transcription-polymerase chain reaction. In comparison to the classical virulent strains, the Bangladeshi isolates were found to have five amino acid substitutions in this region. Four of these changes, Pro222Ala, Val256Ile, Leu294Ile and Asn299Ser, were also observed in other vvIBDV strains. The fifth substitution, Glu300Ala, was similar to that in some African strains of IBDV. The results support the observation that antigenically and genetically similar vvIBDV strains, first observed in Europe in the late 1980s, have spread to most parts of the world in a short period of time.

Extensive antigenic changes in an atypical isolate of very virulent infectious bursal disease virus and experimental clinical control of this virus with an antigenically classical live vaccine

“…The 28% mortality induced by isolate 99323 following an experimental 10 4.24 EID 50 challenge in SPF chickens (not significantly different from that induced by strain 89163), the presence in the VP2 protein of 99323 of the four aa found in the typical vvIBDV, and the genetic relatedness between the nt sequences of 99323 and of typical vvIBDVs (as demonstrated by high bootstrap values in the consensus trees) all corroborate the fact that isolate 99323 is indeed a vvIBDV. However in AC-ELISA, the antigenic reactivity of the 99323 isolate was most unusual, as typical vvIBDVs studied until now bound all mAbs but mAbs 3 and 4 (Eterradossi et al, 1997bDi Fabio et al, 1999;Islam et al, 2001). Only three other vvIBDV isolates had been found so far with a modified antigenicity.…”

“…These viruses caused mortality at least twice as high as that induced by the classical serotype 1 viruses (van den Berg et al, 1991;Eterradossi et al, 1992). It has been shown that some Ivorian isolates excepted , the vvIBDV isolates share close genetic relationships in both genome segment A (which encodes IBDV capsid proteins) (Brown et al, 1994) and genome segment B (which encodes virus polymerase) (Islam et al, 2001). Some nucleotide (nt) and the resulting amino acid (aa) changes occurring in segment A have been proposed as the basis for diagnostic tests for the putative vvIBDV, either on an antigenic basis (Eterradossi et al, 1997a,b) or on a molecular basis (Jackwood & Sommer, 1999;.…”

Restriction fragment length polymorphism analysis of the VP2 gene of Australian strains of infectious bursal disease virus

“…Classical IBDV strains have worldwide distribution, with some strains capable of causing low mortalities. Very virulent (vv) IBDV strains can cause high mortalities and have spread from Europe to the Middle East, Asia, Africa and South America (Lin et al, 1993;Etterradossi et al, 1999;Kwon et al, 2000;Zierenberg et al, 2000;Ikuta et al, 2001;Islam et al, 2001;Meir et al, 2001). Antigenic variants are predominantly confined to the US, and are highly immunosuppressiv e but do not induce specific mortalities (Lana et al, 1992;Lasher & Shane, 1994).…”

A field study on the significance of vaccination against infectious bursal disease virus (IBDV) at the optimal time point in broiler flocks with maternally derived IBDV antibodies

“…(Boot et al, 1999); and reverse, 5?-CGC TCG AAG TTR CTC ACC C-3? (Islam et al, 2001). The RT-PCR was performed at the following conditions: RT reaction for 30 min at 528C; denaturation for 30 sec at 958C, 40 cycles with 5 sec at 958C, 10 sec at 578C, and 30 sec at 728C.…”