Isolation And Identification Of Avian Influenza Virus H9N2 Subtype ZZ1 Strain And Research Of Immunology

Avian Influenza virus by the Division are sticky, influenza virus type A influenza virus (Avian Influenza Viruses, AIV) caused an acute, highly contagious diseases.Hemagglutinin(HA) and Neuraminidase(NA) of influenza viruses are easy to have antigenic drift and antigenic shift,and new pathogenic subtype which is able to infect humans can be formed by such viral mutations. Genetic reassembly which always happens in H5N1 subtype accelerates the threat of avian influenza A viruses to human being.According to the pathogenicity,Pathogenic avian influenza be divided into highly pathogenic avian influenza(HPAI) and low pathogenic avian influenza(LPAI),generally.Highly pathogenic avian influenza is a devastating blow on the poultry industry, and low pathogenic avian influenza is often complicated by secondary infection or other bacterial or viral diseases, which may caused the death of a large number of chickens. at the same time ,AI constitutes a serious threat to the public health of human beings.Vaccine means the most important measure to combat Avian influenza outbreak for a long time,But, because of high frequency variation of avian influenza virus antigen, which resulted in the effective prevention and control difficult.Because of broad area, large quantity of birds, frequent circulation of poultry product, it is difficult to remove completely from the external environment after once the bird flu happened, The antigenic drift and antigenic shift of AIV makes it be possible that low virulence influenza shift to HPAI, and which makes potential menace to the avian industry in our country.At present in our country, multi-subtype avian influenza virus (AIV) has been isolated from many areas,and low-pathogenic avian influenza has occurred from time to time, which to result in China's poultry industry suffered heavy financial losses. In recent years, avian inflenza still occur from time to time after routine immunization program in some farms of Henan Province, which result in serious economic losses, and caused great public health risk . Objective This study was conducted to identify the exact cause of the disease, and to provide scientific data for the control of avian influenza. In this study, isolation of pathogen and study on some biological characteristics was performed in several farms by routine methods and molecular biological methods.Trachea, kidney, and lung samples collected from suspect AI outbreaks were made to suspensions which were inoculated into the allantoic of SPF embryo. The third passage virus produced gross lesions to chicken embryos,and allantoic fluid can agglutinate a 1% suspension of fowl erythrocytes. The allantoic fluid neutralize by ND positive serum and inoculated 9-day-old chick embryo, the collection allantoic fluid can still agglutinate 1% suspension of fowl erythrocytes.Physical and chemical characteristics of the pilot showed that the allantoic fluid of fat, such as solvent detergent inactivated more sensitive, formalin, ether could undermine its infectious, and it is intolerance to heat, strong acid strong base.Strain isolated was Named A/Chicken/henan/ZZ1/06, referred to as strain ZZ1. Allantoic fluid sent to the Harbin Veterinary Research Institute to identify avian influenza subtypes.The result showed that which belonged to H9 subtype strain. NA gene primers were synthesized and the objective fragment was amplified with by RT-PCR.The NA gene order was sequenced and analysis of genetic evolution.Antigen? were prepared comprise Inactivation ZZ1 strain. were inoculated into SPF chickens and Roman chinckens.Antibody levels of H9 subtype AI were measured weekly.The results showed that vaccination with Inactivation ZZ1 strain inactivated Antigen, not only had higher antibody levels ,but also resistance to the challenges with ZZ1 strain,which showed that the Inactivation ZZ1 strain have good immunogenicity.