Isolation And Identification Of Avian Paramyxovirus Type 1 From Chicken And Duck And Virulence Valuation

Avian paramyxovirus type 1(APMV-1) has been one of the most devastating pathogens of poultry industry, which mainly causes Newcastle disease in chicken, APMV-1 infections in goose, APMV-1 infections in pigeon, etc. In recent years, the host range of APMV-1 has a tendency to be enlarging, and it has been reported that some biological characteristics including the virulence and its associated genes, pathogenicity and immunogenicity among the APMV-1 isolates from different poultry species are not fully identical. Therefore, it is very necessary to study the main biological characteristics for approach the mechanism of evolution, infection and spread of viruses, and the epidemiology of disease in the field.The isolation and identification of APMV-1 were performed on the different cases of suspected APMV-1 infections of chicken and duck in Guangxi, and the virulence of the isolates was evaluated by the classical pathogenicity tests e.g. mean death time (MDT) and intracerebral pathogenicity index (ICPI) for Newcastle disease virus (NDV). The results showed that the isolates GXD070035, GXD070036 (duck origin) and GXcn, GXx (chicken origin) are identified as APMV-1 by haemagglutination test (HA), haemagglutination inhibition test (HI) with the monoclonal antibodies and a reverse-transcription polymerase chain reaction (RT-PCR) based NDV rapid differential diagnostic technique developed in the laboratory. The MDTs and the ICPI values of isolates GXD070035 and GXD070036 were 79.20h, 85.80 and 1.53, 1.34 respectively, with the characteristic of mesogenic viruses; while the MDTs and ICPI values of isolates GXcn, GXcx were 41.60h, 51.40h and 1.81, 1.69 respectively, with the characteristic of velogenic viruses. The results of pathotyping are identical with the epidemiological characters in the field for all the isolates.The results of the study demonstrated that there is difference on biological characteristics among APMV-1 isolates of different host origins and further studies such as the molecular mechanism of the difference and its significances in the epidemiology of the disease in the field are necessary.