Molecular epidemiological studies on Newcastle disease in poultry
Abstract
The present study was conducted to detect and characterize newcastle disease virus (ndv) from poultry by molecular techniques. Thirty samples (brain, trachea, lung and allantoic fluid) were collected from different districts of haryana. Six vaccine strains (f1, lasota, r2b and v1) were taken as positive control, whereas the trachea of unvaccinated healthy bird was taken as negative control. Total rna from field samples and vaccine strain was extracted by trizol reagent. Ndv could be detected in eight of the field samples as well as in six vaccine strains by reverse transcription-polymerase chain reaction (rt-pcr) and nested pcr. With primer pair no. 1, a single band of 356 bp and with primer pair no. 2 a band of 216 bp were observed, when analysed on 1.5% aparose gel. Restriction enzyme analysis (re analysis) of five field isolates with bgl i, hha i and taq i revealed that four field isolates were of lentogenic nature while one isolates was of velogenic nature. Sequence analysis of 356 bp pcr product of five field isolate confirmed the observations of restriction enzyme analysis. Four nucleotide and two amino acid substitutions were unique in the velogenic isolates. Phylogenetic analysis revealed divergence of the velogenic isolate from other reported velogenic strains of india, both at nucleotide and amino acid level. All the four lentogenic field isolates were at different place from the f strain both at nucleotide and amino acid level, but in the same lineage with lasota vaccine strain. The present study indicated continuous changes in newcastle disease virus at genomic level in the state of haryana