Nucleotide mutation analyses of isolated lentogenic newcastle disease virus in live bird market.

Abstract

Newcastle Disease (ND) is a major viral disease in Indonesia. It is an RNA virus belongs to Paramyxovirinae. It is well known that RNA virus is easily to mutate. In some cases, this mutation could generate virulence alteration. It is noted that mutation of NDV which has avirulent amino acid sequence on the cleavage site, could mutate to be virulent Newcastle Disease Virus (NDV). It is needed to analyze the nucleotide and amino acid mutations and the effect of those to its virulence. The aim of this study was to analyze nucleotide and amino acid mutations of original isolated Lentogenic Newcastle Disease Virus (NDV). Samples were collected from cloacal swab of native chicken (Gallus gallus domesticus) suspected to be infected by Lentogenic NDV from live bird markets. They were inoculated into embryonated eggs, to isolate the virus. HA and HI assays were conducted to confirm that they were NDV. Positive samples were processed into serial passages in embryonated egg to observe their death time. Samples caused mortality of the embryonated eggs more than 90 hours post infection were suspected as Lentogenic NDV. They were processed to RT-PCR then sequenced. Lentogenic NDV confirmation was done by comparing amino acid at Fusion protein cleavage site of the samples to Lasota/JF950510. Nucleotide and amino acid mutations were analyzed. The result showed that some nucleotide mutations were capable to change sequences of amino acid but the virulence of the samples remained the same to the reference sequence.