Differentiation of Indian isolates of chicken anaemia virus by polymerase chain reaction-restriction enzyme analysis
*Central Avian Research Institute, Izatnagar - 243 122, Bareilly (U.P.)
Study was carried to find out the differences among the Indian isolates of chicken anaemia virus (CAV) by polymerase chain reaction (PCR) - restriction enzyme (RE) analysis. The RE analysis of the 454 bp PCR products of the CAV genome region (819–1272 bp) generated from six field virus isolates from different geographical regions of the country (A-Uttar Pradesh, B-Haryana, C-Himachal Pradesh, D-Maharashtra, E-Tamil Nadu and F-Maharashtra) was carried out using six different restriction endonuclease enzymes viz., Hae III, Hind III, Mbo I, Nci I, Rsa I and Sty I. Digestion of amplicons of the five field isolates A, B, D, E and F with all the restriction enzymes revealed similar pattern with that of published sequence of CAV strain (Cux-1 isolate). Whereas, isolate-C revealed a different pattern with Hae III, Rsa I and Sty I RE enzymes. Digestion with Hae III enzyme yielded four fragments with similar pattern with five field isolates viz., A, B, D, E and F whereas only three fragments were observed with the isolate-C. Rsa I restriction pattern was identical in the five field isolates with two cutting sites, whereas isolate-C also had two cutting sites but at different position. Digestion with Sty I yielded two fragments with same pattern in five isolates but DNA of isolate-C was not digested. Hind III, Mbo I and Nci I enzymes did not reveal any differences among the isolates. The enzymes Rsa I and Sty I seem to have been used for the first time for the RE analysis of CAV-DNA. In conclusion, RE analysis revealed one of the isolates (CAV-C from Himachal Pradesh) to be different from other isolates. These findings can be of importance for future molecular epidemiological investigations to distinguish different CAVs circulating in the poultry flocks of the country. However, the existence of difference between the isolates can be further analysed in detail by nucleotide sequencing.