Data over a period of eleven years was analysed for Infectious Bursal Disease (IBD) virus isolated from chicken samples submit ted to the Regional Veterinary Laboratory at Bukit Tengah, Malaysia (RVLBT) for diagnosis. A total of 247 suspect IBD cases were tested by Virology Section, RVLBT between years of 2006 to 2016. IBD virus has been isolated by using Agar Gel Precipitation Test (AGPT), a bursal homogenate which has been used as an antigen against a known positive antiserum. About 27 cases (11%) from a total of 247 suspect cases in chickens were positive for the presence of IBD. The rate of IBD may be influenced by age of chickens with an increase in the possibility of IBD occurring in chicken older than 3 weeks. Apart from that, both broiler and local chickens are highly susceptible to this disease. Therefore, awareness on the existing IBD cases indicates the importance of strict management procedures, proper management programmes, vaccination and immunisation for chickens in Malaysia.

The objective of this study was to identify the causative agents of hepatitis observed in broiler chickens at processing. Livers of chickens from 16 broiler farms in Saskatchewan with gross lesions of hepatitis were collected at processing. In addition to routine bacterial isolation and histopathological examination, serologic studies for infectious bursal disease virus (IBDV) and Chicken anaemia virus (CAV), calculation of the ratio of the weight of the bursa of Fabricius (BF) to body weight (BBW), and histopathological examination of the BF were done. Of the 264 livers with gross lesions, 83% had multifocal to coalescing necrotizing hepatitis, 16% had perihepatitis, and 1% had hemorrhages. No definitive causative microorganisms were isolated from the hepatic lesions; however, no significant bacterial isolations were made. Bursal atrophy, low BBW ratio, and high titer of antibody against IBDV each correlated with the rate of total condemnations (P = 0.0188, P = 0.0001, and P = 0.0073, respectively). Nucleotide sequencing of IBDV isolated from the BF identified the variant strains Delaware-E and 586. Condemnation because of hepatic lesions was correlated with titer of antibody against IBDV and BBW (P = 0.016 and P = 0.027). The results of this study demonstrate that hepatic lesions in Saskatchewan chickens are not currently caused by a primary bacterial pathogen but are associated with indicators of immunosuppression that is likely due to variant IBDV.

Infectious bursal disease virus (IBDV) is a bi-segmented RNA virus, which belongs to the genus Avibirnavirus of the family Birnaviridae. Two serotypes, 1 and 2, exist in IBDV. The serotype 1 IBDVs are the causative agents of infectious bursal disease (IBD) in chickens worldwide and lead to immunosuppression in young birds. Genome re-assortment has been speculated to occur and contribute to the emergence of new IBDV strains. However, evidence was lacking until recently when two re-assortant viruses were detected in China. In this study, we determined the complete nucleotide sequence of an IBDV, designated KZC-104, from a confirmed natural IBD outbreak in Lusaka, Zambia in 2004. The genome consisted of 3074 and 2651 nucleotides in the coding regions of segments A and B, respectively. Alignment of both nucleotide and deduced amino acid sequences, and phylogenetic analysis revealed that the genome segment A of KZC-104 was derived from a very virulent strain, whereas its segment B was derived from a classical attenuated strain. On BLAST search, the full-length segments A and B sequences showed 98% closest nucleotide homology to the very virulent strain D6948 and 99.8% closest nucleotide homology to the classical attenuated strain D78, respectively. This is a unique IBDV reassortant strain, which has emerged in nature involving segment B of a live attenuated vaccine. This observation provides direct evidence for the involvement of vaccine strains in the emergence of reassortant IBDV in the field. Taken together, these findings suggest an additional risk of using live IBDV vaccines, which may act as genetic donors for genome re-assortment. Further studies are required to investigate the epidemiology and biological characteristics of reassortant strains so that the appropriate and safe IBDV vaccines can be recommended.

Infectious bursal disease virus (IBDV) is a member of the Avibirnavirus genus of the Birnaviridae family which genome consists of two segments (A and B) of double stranded RNA. Segment A gene of KNU08010 isolate, which was isolated from a 15-day-old chicken flock in 2008, was sequenced and compared with other IBDV isolates including SH/92 strain, the first Korean very virulent (vv) IBDV isolate. The amino acid sequences of segment A gene showed that KNU08010 had 99.2% homology with SH92 strain. KNU08010 isolate had specific amino acids A222, I242, I256, I294 and S299 which are highly conserved among vvIBDV strains. Phylogenetic analysis based on the nucleotide sequences of variable region of the VP2 gene of 18 IBDV strains revealed that KNU08010 was grouped with vvIBDVs and was closely related to Korean vvIBDVs isolated from wild birds.

The VP2 full gene of Korean infectious bursal disease virus (IBDV) strain, SH/92, three attenuated vaccine strains, Bur706, Bursine-2 and CEVAC strains, were amplified by reverse transcriptase-polymerase chain reaction and sequenced and compared with published PV2 gene sequences of IBDVs. The VP2 nucleotide sequence similarity between SH/92 and three vaccine stains was 95.6~96.5% whereas the nucleic acid similarity among three vaccine strains was 97.5~98.5%. The amino acid sequence similarity of VP2 of SH/92 compared with three vaccine strains was between 94.4 and 97.6% while the amino acid similarity among three vaccine strains was between 97.4 and 98.4%.

Ever since infectious bursal disease (IBD) was recognised in Nigeria over forty years ago, it continues to pose a threat to poultry production with limited information on the likely role of other avian species especially those raised in close proximity with chickens. For this study, blood samples were obtained from184 unvaccinated apparently healthy birds comprised of Japanese quails (63) andindigenous chickens (60) on smallholdings as well as pigeons (61) in a live-bird market in Osun and Oyo states, southwest Nigeria.Sera from these birds were analysed for IBD virus antibodies using a commercial ELISA kit. Overall, 69 (37.5%) sera were positive for IBDV with 52.8% (65/184) and 6.6% (4/184)from birds on smallholdings and live-bird market, respectively. These findings indicate that these birds were sub-clinically infected and could serve as reservoirs shedding the virus into the environment and perhaps, corroborate the suggestion that the inability to effectively control or eradicate the disease from poultry flocks in Nigeria may be due to limited information on the contributions of other avian species other than chicken in the spread of IBD virus.