Molecular characterization of Pakistani field isolates of infectious bursal disease virus.
The reverse transcriptase-polymerase chain reaction followed by restriction fragment length polymorphism (RT-PCR/RFLP) technique was used to identify and characterize Pakistani field isolates of infectious bursal disease virus (IBDV). These isolates have caused heavy losses to the poultry industry (mortality up to 60%) during the period between 1999 and 2005. Ten samples (five local isolates and five commercial vaccines) were examined for IBDV. Nine samples were positive for IBDV as evidenced by the amplification of the 743-bp region of the VP2 gene by RT-PCR. The RT-PCR products were subjected to restriction enzyme digestion with BstNI, MboI, and SspI. The RFLP profiles of all samples on digestion with the MboI enzyme yielded a fragment size of 229 and 362 bp except for vaccine strain Bursine Plus, which yielded a profile of 229 and 480 bp. However, digestion with BstNI yielded two distinct RFLP patterns. The first profile was detected in field isolates ML-1/SPVC/2001 and NP2/SPVC/2002 with four fragments of 119, 154, 172, and 209 bp, resembling RFLP profiles of molecular group 4 isolates. NL-3/SPVC/2003, NK-4/SPVC/2004, and NPK-5/SPVC/2005 generated a different RFLP profile with fragments of 119, 172, and 424 bp, resembling the profiles of molecular group 6 isolates. However, all the field and vaccine strains showed the absence of SspI restriction sites in their genome. It can be concluded that the Pakistani isolates can be grouped in molecular groups 4 and 6 of IBDV.
Lone
Nazir Ahmed
NA
Department of Microbiology, University of Karachi, Karachi 75270, Pakistan.
Rehmani
Shafqat Fatima
SF
Kazmi
Shahana Urooj
SU
Muzaffar
Rana
R
Khan
Taseer Ahmed
TA
Khan
Adnan
A
Khan
Shakeel Ahmed
SA
Ahmed
Ayaz
A
D000818:Animals; D018175:Birnaviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D002645:Chickens; D007243:Infectious bursal disease virus / Q000235:genetics / Q000302:isolation & purification*; D010154:Pakistan / Q000453:epidemiology; D011201:Poultry Diseases / Q000453:epidemiology / Q000821:virology*