Molecular Epidemiological Investigation And Pathogenicity Study Of Pigeon Newcastle Disease Virus In Some Areas Of China In 2021-2022

Newcastle Disease Virus（NDV）has a wide host range and strong transmission ability,and has been prevalent all over the world.Pigeon Newcastle Disease virus is also known as Pigeon paramyxovirus typeⅠ（PPMV-1）.The infection can cause serious respiratory,digestive and nervous system symptoms,and affect the healthy development of pigeon breeding.In order to understand the prevalence of pigeon-derived NDV in China,an epidemiological survey of pigeon-derived NDV was conducted in Anhui,Fujian,Guangdong,Jiangxi,Jiangsu,Yunnan,Ningxia,Guangxi,Henan,Hubei,Sichuan and other 11 provinces from 2021 to 2022,and the genetic and evolutionary characteristics of the NDV were analyzed.First,this study collected 1229 pigeons of the oral cavity and the cloacal swab samples virus isolation,identification,according to the results of a total separation of pigeon NDV strains,31 NDV total separation rate was 2.52%.The results of genetic evolution showed that all the 31 isolates were ClassⅡgene typeⅥ,of which 18 wereⅥ.2.1.1.2.1and 13 wereⅥ.2.1.1.2.2.The genome length of 11 PPMV-1 strains was 15192 nt,and their F protein cleavage site was ¹¹²RRQKR/F¹¹⁷,which indicated that they had the molecular characteristics of typical Newcastle disease virus.Compared with the reference sequence,the 11representative strains had multiple amino acid mutations in glycosylation sites,cysteine residues and neutralization sites related to maintaining protein conformation.The nucleotide identity of the representative strains in the whole genome was 91.6%-99.0%.Finally,in order to further understand the pathogenicity of the representative strain of genotypeⅥNDV on the host,three strains were screened from the above representative strains,namely AH2432/2021 and FJ2168/2021（Ⅵ.2.1.1.2.1）,JS1014/2022（Ⅵ.2.1.1.2.2）,to determine their pathogenicity on the host.The results showed that the ICPI of JS1014/2022 was 1.56,that of FJ2168/2021 was 1.23,and that of AH2432/2021was 1.38,all of which were consistent with the characteristics of strong strains.The fatality rate of JS1014/2022 group was 50%,that of FJ2168/2021 group was 30%,and that of AH2432/2021 group was 20%.Three strains of genotypeⅥNDV representative strains had high viral loads in the lungs,trachea,spleen,kidney and liver after infection.The results showed that the epidemic strain was still highly pathogenic to the host pigeon.In conclusion,this study indicated that the recent isolation rate of pigeon NDV was still at a high level,the prevalent pigeon NDV was characterized by genetic diversity,and the prevalent strain was highly pathogenic to the host pigeon.In this study,we further mastered the epidemic status,genetic evolution characteristics and pathogenicity of pigeon NDV,which provided reference for the comprehensive prevention and control of pigeon NDV.