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    Home > Medical News > Latest Medical News > Science: When will the new crown spill over to humans?

    Science: When will the new crown spill over to humans?

    • Last Update: 2021-01-22
    • Source: Internet
    • Author: User
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    Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) and new coronavirus pneumonia (COVID-19) have all been outbreaks for nearly two decades and are caused by different coronavirus strains (CoV). The viruses are thought to have originated in bats and then spread to humans through intermediate hosts. SARS-CoV comes from the wildlife market for beavers, MERS-CoV comes from single-peak camels, but we have not yet determined the direct source of COVID-19 pathogens.
    Recently, Shi Zhengli and Zhou Peng, researchers at
    Wuhan Virus Institute, published a commentary article on the spread of the new coronavirus in the top academic journal Science, entitled "SARS-CoV-2 spillover events", which reviewed and discussed the overflow events of the new coronavirus, direct host traceability, and the effects of virus mutation.
    two authors first mentioned otters. Earlier, on November 10, 2020, Science published online a study by researchers at Rusmus Medical Center in Rotterdam, the Netherlands, and other institutions, virologist Bass B. Oude Munnink et al. have reported in-depth incidents of new coronavirus infections in 16 otter farms and workers working there, 66 of the 97 farmers, workers and their close contacts have been infected with the new coronavirus, and some of the strains of the patients have animal sequence characteristics, providing evidence of the two-way overflow of the new coronavirus between animals and humans in the otter farm.
    in addition to otters, a variety of wild or home-breeding animals may also carry new coronavirus or related viruses. The article mentions that some previous experimental virus infection tests and affinity tests of viral prick proteins and receptors have confirmed that the new coronavirus has a wide range of hosts. After the outbreak of the new crown, some research groups found SARS-related coronavirus in horseshoe bats in China and roller coasters smuggled in South Asia, but genome sequence comparison results show that no direct ancestor of the new crown virus has been found. Home cats, dogs and park tigers have also been found to be able to transmit new coronavirus, but there is also no evidence that they can infect humans. Shi Zhengli and others believe that they are unlikely to be the host of the source of the new coronavirus.
    to date, the World Organization for Animal Health has reported new coronavirus infections on otter farms in eight countries (Netherlands, Denmark, Spain, France, Sweden, Italy, the United States and Greece). In addition to the spread of farm animals to people, frozen food supply chain has also caused great concern.
    several small-scale new crown outbreaks in several Chinese cities are caused by seafood or pork contaminated with the virus overseas, according to a recent article. There is evidence that the new coronavirus can survive for up to three weeks on the surface of meat and frozen food packaging and remains contagious. As a result, meat or virus-contaminated food packaging in infected newly crowned animals may be a source of human infection.
    this has aroused public concern about public health and agriculture in the prevention and control of the new coronavirus. Most animals infected with the new coronavirus do not have significant clinical manifestations and cannot be judged without routine diagnosis. The authors point out that mass culling of farm otters is an effective way to prevent further transmission of the virus, but this does not apply to all livestock (if other species are found to be the host of the new coronavirus). Therefore, for reasons of caution, strict isolation measures should be implemented in poultry farms with high density populations.
    authors also suggest that because the virus can spread from animal to animal, such as otters, to humans, similar control strategies should be implemented in key occupational groups, such as animal keepers, zookeepers, or abattoir workers. However, there is limited evidence of transmission of the new coronavirus between animals and humans other than otters. The scientific community should conduct research on whether other livestock can carry the new coronavirus, whether it can be transmitted to humans, and other relevant factors for virus overflow.
    the problem of viral mutations, the authors write, it is now widely believed that coronavirus tends to evolve rapidly when it jumps to different species. To keep replication error rates low, coronavirus encodes several RNA processing and proofreading enzymes that are thought to improve the fidelity of viral replication. However, viruses tend to reduce this fidelity when adapting to new host species, and the mechanism behind this phenomenon is unclear.
    the coronavirus prickly protein is more prone to mutation because it is the primary key protein of the virus-infected host and therefore faces the strongest selection pressure. Scientists have observed this molecular evolution in the SARS-CoV genome, where the early stages of disease transmission (fruit beavers to humans) are more stressful than later adaptations (between humans).
    authors point out that new coronavirus, which mutates in animals, may increase its pathology and transmission in the population. Five new coronavirus variants were found in otters, of which cluster 5 in Denmark had lower immunogenicity than human neo crown virus in patients with neo-coronary pneumonia because the mutation was located in the prickly protein. Cluster 5 strains infect at least 12 people, but the clinical manifestations, severity and transmission between infected people are similar to other new coronavirus strains that are endemic in humans.
    stressed that there is no evidence that any mutation in the new crown strain of otters can evade the meso-action of antibodies against popular strains in human beings. However, given the possible risk of overflow between humans and certain animals, it is necessary to closely monitor mutations in the viral genome from infected animals and humans, particularly those affecting diagnostic tests, antiviral drugs and vaccine development.
    vaccine will help control COVID-19. However, if the virus continues to overflow from animals, vaccines against current strains may face challenges. In the process of transmission between animals and human species, the virus genome is likely to produce mutations, which raises concerns about whether the current vaccine can prevent new strains in the future.
    authors noted that extensive sequencing of animal and human virus genomes, as well as global data sharing, will be central to monitoring the effects of key mutations in the viral genome on vaccine effectiveness. Laboratory studies should detect whether mutations affect the main characteristics of the virus, including pathogenesis, immunogenicity, and cross-meping. In addition, preparations should be made for the development of new variants of the virus vaccine. In the long run, consideration should also be given to vaccinating animals to avoid the loss of the agricultural economy.
    Shi Zhengli and others also discussed the source of the virus. The genome sequences of coronavirus carried by bats or roller coasters are 90-96% similar to 90-96% of human neo-coronavirus, but whether they are the animal source of the outbreak remains debatable. Evolutionary analysis of bat and pansail virus genomes shows that the virus was further adapted in animal hosts or humans prior to the COVID-19 pandemic. Therefore, animals with high population density may become direct ancestor hosts of the new coronavirus through natural selection and with the applicable new coronavirus subject ACE2.
    controversy is about the source of the new coronavirus. Contact with contaminated, uncooked food may be an important route for the spread of the new coronavirus, given the detection of new coronavirus on the surface of some imported food packaging. In addition, recent studies have detected new coronavirus antibodies in serum samples taken from overseas personnel taken prior to the COVID-19 outbreak, indicating that the new coronavirus had been around for some time before the outbreak was discovered.
    Shi Zhengli and others suggested that samples from otters, other susceptible animals and humans should be reviewed before the outbreak to identify the host of the virus's ancestors and determine when the virus had overflowed to humans.
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