| The global spread of the new coronavirus in 2020 has seriously endangered the lives and health of humans,and even animals.In recent years,the more frequent emerging or reemerging pathogens were recorded.The reason for this increase is the increase in pathogenic viruses.Most viruses attach to or reside in the host’s body and spread through contact or air.Naturally,the virus exists in the enverinment for a long time;However,the spillover of the virus from the natural host into a new anima l population may cause serious disease.On the one hand,the new animal population lacks immunity to the emerging virus.On the other hand,the cross-species transmission of the virus may causes the virus gene mutation or recombination,which enhance it’s pathogenicity to new resided animal.The contact between domestic animals and wild animals or the intersection of their living areas may creat the conditions for the transmission of the virus-across species.It is necessary to monitor the pathogens in wild animals and trace viruses existing and behavior.Early finding and timeing conter measures is urgent to prevent the outbreak and spread of viral diseases.Naemorhedus goral is a national level 2 protected wild animal.Naemorhedus goral has been listed as an endangered species by the International Union for Conservation of Nature(IUCN).At the beginning of 2020,the Himalayan subspecies goral in the Baima Snow Mountain National Nature Reserve in Yunnan unnaturally died on a large scale.In this study,17 kinds of viruses that infect Caprinae were selected based on the symptoms of goral death to design primers and establish the molecular detection technique for pathogen screening.Two strains of β-retroviruses have been identified in goral: jaagsiekte sheep retrovirus(JSRV-SL-NG)and enzootic nasal tumor virus(ENTV-2-SL-NG).In comparing and on the full-length genes of Jaagsiekte sheep retrovirus and Enzootic nasal tumor virus that have been documented.The genetic similarity between them is up to 93%,and the genetic similarity between JSRV-SL-NG and ENTV-2-SL-NG is 96.74%.Jaagsiekte sheep retrovirus is the pathogen that causing ovine pμlmonary adenocarcinoma.Wheras,Enzootic nasal tumor virus may cause the enzootic nasal adenocarcinoma.From the documentd literature,it was found the existence of these two viruses in sheep and goats.They can cause respiratory diseases in sheep,Jaagsiekte sheep retrovirus mainly infects sheep’s lung tissues and causes lung epithelial cels to become cancerous and cause tumors.Enzootic nasal tumor virus mainly infects the upper respiratory tract tissue of sheep and causes the upper respiratory tract tissue to become cancerous and produce tumors.Sheep infected with these two viruses will die due to respiratory damage or loss of function.For the first time,we found co-infection of jaagsiekte sheep retrovirus and enzootic nasal tumor virus in wild antelopes that died unnaturally.Further analysis on the ful-length genes of JSRV-SL-NG and ENTV-2-SL-NG showed that: ENTV-2-SL-NG has the highest similarity of 92.35% with the ENTV-2CHN4 gene found in Sichuan yelow goats.JSRV-SL-NG has the highest similarity of92.91% with the en JSRV-3 gene reported on British sheep.The similarity of nucleic acid sequences between these two viruses are not more than 93%.The analysis on gene recombination showed that the ancestors of JSRV-SL-NG and ENTV-2-SL-NG may undergo homologous evolution after gene recombination,which may resulted in a high similarity between the nucleic acid sequences of the two viruses.In detailed,the "gag" gene similarity of the two strains is 93.1%,"pro" gene similarity is 97.3%,"pol" gene similarity is 98.1%,and "env" gene similarity is 85.5%.The amino acids encoded by their "gag,pro,pol,env" genes and other reported JSRV and ENTV showed high mutations.Based on the high conservation of the "pro" gene.In addition,Taq Man probes and primers were designed and verified by using the existed goral samples.Fluorescence quantitative detection methods for ENTV-2-SL-NG and JSRV-SL-NG were furtherly established.The surface membrane protein SU of these two viruses was docked with the viral receptor hyaluronidase 2(Hyal 2)of 10 animals of pigs,mice,buffaloes,goats,humans,sheep,horses,deer,cattle,and dogs.It was deduced the JSRVSL-NG may be more susceptible to buffaloes,goats,horses,deer,and cattle,and ENTV-2-SL-NG may be more susceptible to horses and goats.The Naemorhedus goral is mainly distributed in the southern foothills of the Himalayas.In winter,goral flocks will migrate to low-altitude areas and may contacted with goats or sheep in the same ecological area,Thus the virus have chance to transmit into the goral herd to cause disease.In the Himalayan maountain,the winter climate is dry and cold,with sparse vegetation.The poor living environment of Naemorhedus goral will reduce its immunity and make it easy for pathogens invading.Naemorhedus goral general y gather and breed offspring from November to December each year,the returning infected Naemorhedus goral may carry the pathogen into the flock.Jaagsiekte sheep retrovirus and enzootic nasal tumor virus can spread through the air,It’s more likely to break out in the gathered flock.The epidemic of jaagsiekte sheep retrovirus and enzootic nasal tumor virus in wild social animals has increased the difficulty of wildlife protection.This research relies on the existing knowledge of etiology,virology and epidemiology,Based on the basic knowledge of viruses that have been discovered,Using modern molecular detection technology,the cause of death of goral was found in the dead goral samples of unknown pathogen.This study just found a cause of the massive deaths of Naemorhedus goral.It can provide basic knowledge and technique support for wildlife protection and disease monitoring. |
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