| Avian paramyxoviruses(Avian paramyxoviruses)is a kind of virus that is widespread in various birds.Avian paramyxovirus is one of the important pathogens that infects birds around the world,and has caused huge economic losses to the poultry farming industry on a global scale.However,the most widely studied is Newcastle Disease Virus(APMV-1),while the related research on other serotype viruses is limited.Avian paramyxovirus belongs to the Paramyxovirus family and the subfamily of mumps virus.According to the latest virological classification,avian paramyxoviruses are now divided into three species,namely the genus Metapneumovirus(APMV-2,-5,-6,-7,-8,-10,-11,-14,-15,-20,-21),Orthoavulavirus(APMV-1,-9,-12,-13,-16,-17,-18,),and Paraavulavirus(APMV-3,-4).The continuous emergence of new viruses and the mutation of the original serotype viruses prompt us to strengthen the monitoring of avian paramyxovirus in wild birds and poultry.The complete monitoring system of avian paramyxovirus didn’t establish in China,and limited analytical epidemiological data can only be obtained from scattered reports,which has become one of the bottlenecks hindering the prevention and control of avian paramyxovirus in China.Therefore,the establishment of a complete avian paramyxovirus monitoring network in China is very important for virus prevention,control and early warning.Migratory birds are considered to be the natural reservoir of avian paramyxovirus and the gene pool of genetic diversity.Many migratory birds do not show clinical symptoms after infection.Avian paramyxovirus is transmitted to other areas through migration.During the transmission process,the probability of mutations in the viral genome is greatly increased,which may cause the virus to mutate and produce new highly pathogenic strains.Therefore,migratory birds play an important role in the continued existence,evolution and continuous spread of avian paramyxovirus.Through the active monitoring of avian paramyxovirus in migratory birds,we can understand the status of migratory birds carrying avian paramyxovirus and its genetic variation,and then clarify the distribution relationship between migratory birds and avian paramyxovirus,which can provide early warning of the cross-border transmission and spread of the virus.The instructions of avian paramyxovirus provide a scientific basis for the early warning,prevention and control,which is great significance.For this purpose,this research carried out the following research contents:1.From 2014 to 2020,we set up 10 monitoring points nationwide,collected 11041 samples of wild birds and poultry,and isolated 118 APMV strains,with a virus isolation rate of 1.08%.According to the results of PCR identification,7 strains were APMV-13,and the virus isolation rate was 0.063%.This is the first time that the APMV-13 strain has been isolated in China,and all the strains are from birds of Anseriformes.2.The high-throughput sequencing results showed that APMV-13/Wild goose/China/Hubei/2015/V93-1 has a full-length genome of 16158 nt and a GC content of 42.6%.Among the APMV-13 strains that have been published,the sequence isolated in China is the longest.3.Analysis of the sequence comparison results showed that the type 13 strains which isolated in China had genetic mutations in the HN protein and the 5’end.The results of genetic evolution analysis showed that the type 13 isolates in China and Kazakhstan isolates have a close genetic relationship and high homology.4.On the basis of genetic evolution analysis,perform evolutionary genetic analysis on the isolated strains.The results show that APMV-12 and APMV-13 have a common ancestor,the most recent common ancestors of HN and F genes originated in1950.8 and 1964.5,respectively.The evolution rates are 4.5x10-3 s/s/s/y and 1.314 x10-3 s/s/y,respectively.The results of genealogical analysis of genealogy showed that the APMV-13 transmission event was inferred to be Kazakhstan→China through software calculations.The results of genetic evolution analysis showed that the type 13 strain of Kazakhstan was earlier than the type 13 strain isolated from China in this study,which is basically consistent with the predicted occurrence.However,due to the lack of early surveillance data of avian paramyxovirus in neighboring countries of China,the transmission route of other pathogens is still unclear.This still requires further system monitoring to obtain data for analysis.5.The weight of the poultry infected with APMV-13 virus decreased and returned to normal,and the mortality rate was less than 30%.The virus could always be detected in the lungs of the experimental poultry,and the tissue tropism of the virus in different hosts was different.The virus was detected in brain tissue.The above research results suggested that the virus can replicate and multiply in the host after infecting the host,with low pathogenicity,and the virus cannot be transmitted by direct contact and air transmission between poultry,and the epidemic risk is low.However,pigeons are highly susceptible to APMV-13 virus,and attention should be paid to avoid economic losses to the breeding industry.In this study,the migration routes and living habits of migratory birds passing through China were studied and analyzed,and monitoring points for migratory birds and poultry were set up in different regions,and a multi-angle,all-round dynamic monitoring network for avian paramyxovirus was constructed to grasped initially the prevalence of avian paramyxovirus in China.Through high-throughput sequencing and other corresponding technique,a comprehensive analysis of the gene structure of the pathogen is carried out,and it confirmed whether the relevant sites of the virus gene have mutated,and there is a potential risk of virulence of the virus have changed.Based on the prediction of the origin and spread of the virus,the possible source of emerging avian paramyxovirus in China is inferred.Our research provides a new kind of guidance and countermeasures for China which response to the cross-border transmission of avian paramyxovirus and the import of emerging viruses,which has a significant demonstration effect. |
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