Molecular characterization of infectious bursal disease viruses from Pakistan.
Since the first report of infectious bursal disease in Pakistan in 1987, outbreaks have been common even in vaccinated flocks. Despite appropriate administration of vaccines, concerns arise if the circulating strains are different from the ones used in the vaccine. Here, we sequenced the hypervariable region (HVR) of the VP2 gene of circulating strains of infectious bursal disease virus (IBDV) originating from outbreaks (n = 4) in broiler flocks in Pakistan. Nucleotide sequencing followed by phylogeny and deduced amino acid sequence analysis showed the circulating strains to be very virulent (vv) and identified characteristic residues at position 222 (A), 242 (I), 256 (I), 294 (I) and 299 (S). In addition, a substitution at positions 221 (Q→H) was found to be exclusive to Pakistani strains in our analysis, although a larger dataset is required to confirm this finding. Compared to vaccine strains that are commonly used in Pakistan, substitution mutations were found at key amino acid positions in VP2 that may be responsible for potential changes in neutralization epitopes and vaccine failure.
Quality Operations Laboratory, University of Veterinary and Animal Sciences, Lahore, 54600, Pakistan. shabbirmz@uvas.edu.pk.
Muhammad Zubair
MZ
Shabbir
Bahauddin Zakariya University, Multan, Pakistan.
Muhammad
M
Ali
Livestock and Dairy Development Department, Punjab, Pakistan.
Muhammad
M
Abbas
Roslin Institute, University of Edinburgh, Scotland, UK.
Umer Naveed
UN
Chaudhry
Institute of Pathophysiology and Immunology, Medical University of Graz, Graz, Austria.
Zia-Ur-Rehman
The Pirbright Institute, Woking, Surrey, GU240NF, UK.
Muhammad
M
Munir
D000595:Amino Acid Sequence; D000818:Animals; D018175:Birnaviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics; D002645:Chickens; D004196:Disease Outbreaks; D007243:Infectious bursal disease virus / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010154:Pakistan; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology / Q000821:virology*; D016415:Sequence Alignment
D036022:Capsid Proteins