| Canine distemper(CD)is a highly contagious disease caused by Canine distemper virus(CDV),which is distributed all over the world.The disease is highly infectious and has a high incidence.It is more likely to cause secondary infection of other viruses and bacteria.The mortality rate of secondary infection is as high as 80%.Canine animal is the main host of canine distemper.Canine distemper can easily be carried and spread by many canine animals such as dogs and foxes,and a large-scale outbreak of canine distemper can occurred.The eastern part of Heilongjiang Province has many rivers and high vegetation coverage.It is a good place for wildlife breeding and habitat,and has rich wildlife resources.The outbreak of canine distemper can easily threaten the health of local wildlife populations.In order to systematically understand the biological safety risk of canine distemper in this area.Firstly,this study explored the high-risk distribution of canine distemper in the eastern part of Heilongjiang Province.And find out the relationship between various environmental factors and canine distemper through MaxEnt model.Secondly,the spatial and temporal dynamics of canine distemper H gene was studied to analyze the transmission and evolution characteristics of canine distemper.Finally,Fox semen was sampled randomly in the eastern part of Heilongjiang Province in 2018.Epidemiological investigation was carried out through virus metagenomics analysis to assess the risk of canine distemper epidemic in this area.The main results are as follows:1.The main environmental factors affecting the distribution of canine distemper susceptible wildlife in the eastern part of Heilongjiang Province are the ratio of day-night temperature difference to annual temperature difference(bio3)of 60.1%,the highest temperature in November(tmax11)of 21.8%and the precipitation in November(pre11)of 18.1%,among which bio3 has the greatest impact on the distribution of canine distemper susceptible wildlife.According to MaxEnt prediction results,the distribution situation gradually decreases from east to west and from north to south,with the eastern part of Jiamusi area having the highest probability of distribution;2.The main environmental factors affecting the distribution of canine distemper in eastern Heilongjiang Province are the hottest monthly maximum temperature(bio5)of 58.3%,January precipitation(prec1)of 28.8%and August maximum temperature(tmax8)of 12.9%,among which bio5 has the greatest impact on the distribution.According to MaxEnt's prediction results,the distribution decreases gradually from west to East and from south to north,and Mudanjiang area having the highest probability of distribution;3.By overlapping the suitability distribution map of susceptible wildlife and the risk map of canine distemper distribution in eastern Heilongjiang Province,the high-risk distribution areas of canine distemper in eastern Heilongjiang Province were studied.The results showed that the high risk area of canine distemper was located in the central part of the eastern part of Heilongjiang Province.4.The global data set of H gene canine distemper was used to analyze the molecular evolution by Bayesian Markov Monte Carlo method.The results show that the United States is the origin of canine distemper,which started a worldwide outbreak after its ntroduce to Europe in 1933.The two channels of canine distemper virus spreading to China are Europe-China and the United States-China;Analysis two major genotypes of canine distemper virus in China(type 1 and 11)shows that Guizhou is the origin of canine distemper.It was introduced to Beijing in 1964,and then began to spread further throughout the country.The analysis of transmission probability between hosts showed that canines were the main source of infection from susceptible hosts.5.The viruses in the library were obtained by Miseq high-throughput sequencing and bioinformatics technology,and the composition of virus family in fox semen was also analyzed.The results showed that there were 24 viruses contains 13 families in the two libraries:Small RNA Viridae(52.18%),Smacoviridae(18.64%),Parvoviridae(5.56%),Genomoviridae(5.3%),Picobimaviridae(4.69%),Circoviridae(4.34%),Ascoviridae(3.82%),Poxviridae(2.3%),Baculoviridae(1.55%),Herpesviridae(0.73%),unclassified virus family(0.4%),Retroviridae(0.38%)and Anelloviridae(0.12%).The virus species composition of low-risk library Foxl is similar to that of high-risk library Fox2,but the number of virus sequences detected is quite different.The number of virus sequences detected by high-risk library Fox2 is significantly higher than that of low-risk library Foxl.No canine distemper virus was detected in these two libraries,indicating that the biological safety of foxes is reliable,but it does not exclude the risk of canine distemper in the eastern part of Heilongjiang Province. |
PDF Full Text Request