| Newcastle disease (ND), one of the most important diseases of poultry, caused by Newcastle disease virus (NDV), also called avian paramyxovirus type 1, is classified as a List A disease by the World Animal Health Organization (Office International des Epizooties, OIE) because it is highly contagious and can causes severe disease and high mortalities in susceptible birds. Newcastle disease virus (NDV) has been placed in the genus Avulavirus, sub-family Paramyxovirinae, family Paramyxoviridae, order Mononegavirales in the current taxonomy, which has a negative-sense, single-stranded RNA genome of 15 kb that contains 6 genes in the order of 3'-NP-P-M-F-HN-L-5', encoding six proteins (nucleoprotein, phosphorprotein, matrix protein, fusion protein, hemagglutinin-neuraminidase protein and large protein respectively).Wild bird are approached as natural hosts of NDV, and NDV are cycling in wild birds. It is necessary to investment and analysis the prevalence, distraction pattern of NDV and the role of migrant birds for transmission of NDV. Therefore, monitoring the molecular epidemiology of distinct originated isolates would illustrate the tendency and variation of NDV, understand the ecological contribution of different birds, which contribute practically for the adjusting of combination control measures for ND.1. Molecular epidemiology of NDV isolated in partial regions of HeiLongjiang province. Cultured by SPF chicken embryo, the results of idenfication showed that these isolate are able to agglutinate chicken red blood cells, which can be inhibited and neutralized by avian Newcastle disease virus (NDV) standard antiserum, but can't be inhibited by avian influenza virus (AIV) standard antiserum (H5 and H9 subtype) and EDS-76 standard antiserum. Full length of F gene was amplified by RT-PCR, then sequenced and analyzed. The isolates were purified thrice by CEF plaquing. The results showed that 14 F genes contained an open reading frame (ORF) in length of 1662nt, coding 533 amino acids, no insertion or deletions were founded. Phylogenetic tree was constructed using F gene nucleotide sequences of these 14 isolates and 23 reference strains from GenBank. The 14 isolates were classified into genotypeâ…¢andâ…¦d. The isolates genotypeâ…¢were vaccine-like strains, which share 99% nucleotides homology with vaccine strains.2. Toxicity Identification of NDV Mallard/China/HLJ363/06. One strain of Newcastle disease virus (named Mallard/China/HLJ363/06) isolated from HeiLongjiang province that without any typical ND symptom was studied. Its MDT, ICPI and IVPI are 50.4,1.83 and 2.24 respectively. The results disclosed that the isolate is virulent strain of Newcastle disease virus.3. The entire genomic sequence of NDV strain Mallard/China/HLJ363/06. In order to obtain the complete genome sequence of NDV CH2000 isolate,9 pairs of primers were designed to amplify the specific gene fragment by RT-PCR and sequenced. The complete genome sequence was analysised by SeqMan. The genomic sequence consists of 15192 nt, which is six nt longer than the published full length genome of the NDV strains LaSota. Which was 6nt longer than the published full length NDV genome of strain Herts/33,Ireland/Ulster/67,LaSota. This additional 6nt motif was located in the non-coding region of NP gene between the corresponding positions 1647nt and 1648nt on the NDV genome of strain LaSota. |
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