ABSTRACT
OBJECTIVE: Chicken infectious anemia virus (CIAV) is an economically important emerging infection of poultry as it causes immunosuppression and reduces egg production. Although it is worldwide distributed and first reported (single case) in Bangladesh in 2002, no epidemiological and serological investigations have been conducted. The current study aimed to conduct a serological investigation on the prevalence of CIAV infection in broiler breeder and layer farms in some selected areas of Bangladesh. MATERIALS AND METHODS: A total number of 460 sera samples were randomly collected from unvaccinated broiler breeder and layer flocks, of which 276 were from 11 broiler breeder farms and 184 from 12 layer farms. The sera samples were subjected to a commercially available enzyme-linked immunosorbent assay kit to observe antibodies induced by CIAV. RESULTS: Results demonstrated that the overall prevalence of CIAV was 83.6% among a total of 460 samples. In broiler breeder birds, the prevalence was 89.9%, whereas it was 78.3% in layer birds. A higher number of female birds was found to be seropositive than male birds. However, chickens of all age groups were found to be susceptible to the virus. CONCLUSIONS: These results indicate the presence of CIAV in Bangladesh, which may be the sequel of naturally occurring either vertical or horizontal infection in all bird flocks tested without clinical symptoms of the disease. A further epidemiological investigation will be required, followed by molecular isolation and characterization of the virus for suitable vaccine candidate selection and/or preparation.
ABSTRACT
Background: Duck viral enteritis, commonly known as duck plague (DP), is an acute and contagious fatal disease in ducks, geese, and swans caused by the DP virus (DPV). It poses a serious threat to the growth of duck farming in the Haor (wetland) areas of Bangladesh. Aim: This study aimed to detect the circulating DPV by molecular characterization, followed by phylogenetic analysis, targeting the UL30 gene in infected ducks from five Haor districts in Bangladesh and to observe the variation in the genome sequence between the field virus and vaccine strain of DPV. Methods: A total of 150 samples (liver, 50; intestine, 50; and oropharyngeal tissue, 50) were collected from DP-suspected sick/dead ducks from 50 affected farms in Kishoreganj, Netrokona, B. Baria, Habiganj, and Sunamganj districts in Bangladesh. For the identification of DPV in collected samples, polymerase chain reaction (PCR) was utilized. Nucleotide sequences of the amplified UL30 gene were compared with those of other DPV strains available in GenBank. Results: Of the 150 samples, 90 (60%) were found to be positive for DPV, as confirmed by PCR. Organ-wise prevalence was higher in the liver (72%), followed by the intestine (64%) and oropharyngeal tissue (44%). Regarding areas, the highest and lowest prevalence in the liver and intestine was observed in Habiganj and B. Baria, respectively, whereas the highest and lowest prevalence in the oropharyngeal tissue was observed in B. Baria and Habiganj, respectively. Two isolates, BAU/KA/DPV(B1)/2014 from Kishoreganj and BAU/KA/DPV(B4)/2014 from Sunamganj were sequenced, and phylogenetic analysis revealed that these isolates are evolutionarily closely related to Chinese isolates of DPV. Additionally, the isolates of DPV BAU/KA/DPV(B1)/2014 and BAU/KA/DPV(B4)/2014 showed the highest (98%) similarity to each other. The nucleotide sequence of the isolate BAU/KA/DPV(B1)/2014 exhibited higher nucleotide variability (246 nucleotides) than that of the vaccine strain (accession no. EU082088), which may affect protein function and additional drug sensitivity. Conclusion: Based on the findings of the molecular study, it can be assumed that the Bangladeshi isolates and all Chinese isolates of DPV may have a common ancestry.
