Isolation,full-genome Characterization And Pathogenicity Of A Novel Tembusu Virus Isolated From Goslings

Tembusu virus is an acute,highly contagious and high infection rate infectious disease pathogen that mainly affects waterfowl.Since its discovery in our country in 2010,it has gradually spread to most areas of the country in recent years.After the onset,it will show production performance,causing the practitioners in the waterfowl breeding industry to experience severe economic losses and psychological pressure.In 2019,we aseptically collected disease material of an infected goose suspected of being infected with Tembusu virus at a goose farm in Anhui,and confirmed that it was infected with Tembusu virus through RT-PCR identification.After 48 hours of inoculation of the diseased material to the filtrate of BHK-21 cells,the cells began to die.The virus solution was continued to be passaged,and RT-PCR was performed during this period.Each generation of the virus solution could detect TMUV.The results showed that the isolated virus strain was TMUV.Named as AQ-19 strain.Twenty-five 5-day-old goslings were randomly divided into 3 groups.Among them,0.5m L(TCID₅₀=10^-4/0.1m L)was injected into the leg muscles to inoculate the TMUV AQ-19 strain,the TMUV AH-F10 strain,and the cell supernatant of uninfected virus.Supernatant.Goslings of the AQ-19 strain challenge group showed mild clinical symptoms after the challenge,with green and brown loose feces,and poor mental state;then they developed mental depression,unstable walking and other neurological symptoms;even some goslings appeared Unsteady standing,tremors of the head and neck,reflexed horns,and finally died.The necropsy of the AQ-19 strain infection group showed pericardial effusion,which showed light yellow transparent liquid,myocardial hypertrophy and soft,pale myocardium,and blood vessel flushing;liver was enlarged,showing khaki,congestion,lung hemorrhage,anemia;Cerebral edema;enlarged spleen;enlarged pancreas.Experiments have shown that the AQ-19 strain can infect goslings.Compared with the AH-F10 strain,it is more pathogenic for young geese.Thirty healthy 3-week-old ICR mice were randomly divided into 6 groups and inoculated by intracranial injection of 30μL of AQ-19 strain and AH-F10strain each,and intraperitoneal injection of 300μL.AQ-19 strain and 5 AH-F10 strain viruses were inoculated with the supernatant of cells that were not infected with the virus in the same way.Animal experiments showed that mice in the AQ-19 intracranial challenge group suffered from mental depression after the challenge,followed by neurological symptoms such as depression,unstable walking,purulent secretions in the eyes,and tremor and paralysis of the hind limbs in the later period.Experiments have shown that the AQ-19 strain can infect mice,and is more pathogenic to mice than the duck-derived AH-F10 strain.In summary,a highly pathogenic goose-origin Tembusu virus AQ-19 was isolated.Completed the observation of the pathogenicity of the AQ-19 strain on goslings and mice,which will provide a theoretical basis for better research on the pathogenic mechanism and prevention of Tembusu virus in the future,and strengthen the discovery and follow-up of clinical cases.The research on the pathogenicity of Tembusu virus is of great significance to the prevention and control of Tembusu virus.