鸭瘟病毒野毒株的分离鉴定和疫苗免疫试验OA

To determine whether the outbreak in Cherry Valley breeder ducks in a farm in Jiangsu Province in January 2024 was related to a variant of duck plague virus,tissues from the liver,spleen,intestine,esophagus,and trachea of dead ducks were collected for virus isolation and culture.The isolated strain was subjected to PCR amplification based on the unique long region 2(UL2)gene and long open reading frame 5(LORF5)gene,as well as animal regression experiments,virulence determination,and vaccine immunization evaluation.The results showed that one duck plague virus strain was successfully isolated and designated QL240109.The UL2 gene fragment length of this strain was consistent with that of the attenuated strain,whereas the LORF5 gene fragment length was consistent with that of the virulent strain.Animal regression experiments demonstrated that the isolated strain was highly lethal to susceptible Cherry Valley ducks.Virulence determination indicated that the strain had lower virulence than the classical Chinese virulent strain CVCC AV1221.Vaccine efficacy evaluation revealed that the duck plague live vaccine provided 75％-100％ protection against the isolated strain.These findings suggest that,compared with the attenuated vaccine strain and classical virulent strains in China,the isolated strain underwent genomic variation,exhibited strong lethality but lower virulence than classical virulent strains,and could still be effectively controlled by duck plague live vaccines.The results provide a reference for the prevention and control of this mutant strain of duck plague virus in duck farms.