According to foreign media reports, a 61-year-old Korean man was diagnosed with Middle East Respiratory Syndrome (MERS) and was treated with isolation after returning to Kuwait. In 2015, MERS caused 36 deaths in South Korea.
The spread of the virus must rely on the media, human activities are one of the ways of viral transmission, and activities such as birds and bats are also the transmission routes of the virus. By capturing the media's activity pathways, can you figure out the course of action of the virus and draw a visual "flight network" for the virus? At the 2018 World Influenza Conference held recently, some scholars reported on relevant research. Through the tracking of migratory birds and poultry, we obtained the transmission route of the virus, and speculated on the "kinship" relationship of the virus world, that is, how to mutate, and then predict the epidemic. outbreak.
Virus comes with migration "timestamp"
“The virus is synchronizing in the process of migration.†Tian Huaiyu, a researcher at the Institute of Global Change and Earth System Science at Beijing Normal University, said that the migration, spread and evolution of the virus family are taking place simultaneously.
The derivation of the virus puts a "time stamp" on the spread of the virus. According to the genetic analysis, the "closeness" of different viruses can be reversed, and the path of their propagation can be reversed. Therefore, the kinship of the virus can be used to judge which path the different "branch" has gone in evolution.
Through the tracking of the popular 2.3.2 branch H5N1 avian influenza virus in recent years, Tian Huaiyu's team found that the virus collected in the East Asian migration zone is highly related; at the same time, the same situation occurs in the migration zone of Central Asia; The above two viruses have kinship at the same time, and the sampling location is also exactly the intersection of these two migratory zones.
For example, the “friend circle†drawn by the virus kinship is highly overlapping with the long-standing migratory band in geography. This is not just a coincidence, the team began to speculate that the spread of the bird flu virus has a specific "flight network."
Migratory bird pathways are consistent with viral gene flow
Due to the spread of avian flu over long distances, the migration of wild birds twice a year can cause rapid spread of the virus. The team began tracking migratory birds to confirm their guess.
“Based on the population size and viability, we have selected four types of wild birds.†Tian Huaiyu said, “We used GPS equipment to record the migration behavior of 56 birds. The current recorded data indicates the speed of migratory birds migration and the epidemic between different countries. The outbreak and the speed of transmission are highly correlated."
At the same time, the team traced the source of the eight segments of the virus separately, using the "timestamp" to give the connection between the locations. "In Asia, virus transmission is not spread randomly, and east-west is rarely transmitted, mainly in north-south direction." Tian Huaiyu said, and the time space for virus transmission is consistent with the migration channel.
More detailed studies have shown that migration time, space, and sequence can best explain the flow of viral gene flow in each group of migratory birds.
The research team constructed 1000 sets of network models based on viral genome sequences and matched migratory bird migration paths. "A considerable part of the model shows that the migration sequence of the virus and the migratory bird migration are quite consistent in time, space and order." Tian Huaiyu said.
However, not all avian influenza virus migrations are highly consistent with migratory bird migration. Tian Huaiyu explained: “Only 20% of the bird flu strains isolated from wild birds have other driving forces to drive the virus.â€
Accurately predict the evolutionary path of viruses
“H7N9 was once considered popular in the Yangtze River Delta and Pearl River Delta regions,†Tian Huaiyu said, but the model predicts that it will spread to the west and north. In 2014, H7N9 was discovered in Xi'an, Shaanxi and other places, confirming the accurate prediction of Tian Huaiyu's team.
“Our poultry flow is divided into three levels, including producers, retailers, and consumers.†Based on the flow chart of poultry trade, the Beijing Normal University team used phylogenetic analysis, geospatial technology, and time series models to analyze bird flu. The spatiotemporal patterns of outbreaks and the effects of vaccines on viral evolution were studied.
"What we capture is often a branch of the virus evolution tree, an instant in the process of derivation." Tian Huaiyu said that in the past research methods, due to the omission of sampling, the sampling point data is not continuous enough to see the virus. All the process of dissemination. Using methods such as phylogenetic analysis, geospatial technology, and time series model, a moment can be used to restore a process by incorporating other factors, and then discover the dynamic mobile network of the virus.
A century ago, the century-old flu, known as the "global century plague," killed 50 million people. The flu is not a common cold, but a serious infectious disease. Humans are also facing the threat and harm of seasonal flu, influenza pandemic and animal flu. Predicting influenza outbreaks has always been an unsolved problem. A new combination of geoinformatics and molecular biology techniques can be used to help humans find out the "flight network" of viruses by studying the propagation vectors and connecting them into networks. ". (Zhang Jiaxing)
Source: Technology Daily
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