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BEIJING, Apr. 26, 2020 /PRNewswire=KYODO JBN/--

Exclusive Interview with Virologist, Associate Professor, Dr. Kitazato Kaio

from Nagasaki University

A news report by Science and Technology Daily:

The COVID-19 has swept more than 200 countries and regions, which causes an

increasing number of infected cases day by day.

Dr. Kitazato Kaio, Associate Professor from Nagasaki University in Japan, is

quite concerned about this pandemic. In an interview with the Science and

Technology Daily reporter, he made a detailed analysis in terms of virus

transmission characteristics, the scientific and long-term nature of virus

traceability, the achievements made by Chinese scientists, and called for a

global joint-operation.

The transmission characteristics of novel coronavirus and main causes of global

pandemic

Dr.Kitazato Kaio concluded that, based on many research reports from all over

the world, this new coronavirus has several new salient features compared with

the previously discovered SARS-CoV and MERS-CoV.

First, the spike protein (S protein) of the novel coronavirus is the surface

envelope protein responsible for the virus particles entry into their infected

cells, which is the human angiotensin converting enzyme 2 (ACE2) binding

protein. The S protein of the novel coronavirus binds to its cell receptor ACE2

with an affinity that is 10 to 20 times higher than that of the SARS-CoV S

protein. The high affinity of the S protein to the receptor shows that the

virus particles have a strong attachment to the cells and it is easy to infect

the cells.

Like the infectious enveloped virus, such as influenza virus, the novel

coronavirus has the characteristics of protease dependence in the infection

process of invading infected cells. The S protein itself is a precursor protein

and has no cell fusion activity. It is only cleaved into two protein fragments

S1 and S2 by the protease of the host cell. After the exposure of fusion

peptide (FP) responsible for cell membrane fusion in S2 fragment, the S protein

is activated and the virus particles can fuse with the infected cell membrane,

invades the cell, and completes its infection process.

The second characteristic of the novel coronavirus is that its S protein has a

furin protease cleavage site between S1 and S2 which do not exist in SARS-CoV

or MERS-CoV. The furin protease is a ubiquitous protease in human cells. When

the novel coronavirus particles are assembled and released from infected human

cells, the S protein of the virus has been cleaved into the activated state of

S1 and S2 by the furin protease in the cells. And its virus particles have

already had a strong cell infection and fusion membrane activity, which makes

the infection efficiency of the new coronavirus nearly 1,000 times higher than

SARS-CoV.

Finally, the structural characteristics of the novel coronavirus S protein

determine its ability to infect cells and replicate rapidly. Therefore, the

person who is infected can release a large number of highly infectious virus

particles in the early stage of infection before the systemic symptoms appear.

Stronger infectivity than influenza virus is the main reason why the novel

coronavirus can be pandemic in the world.

Virus searching is a very serious scientific issue, which needs to be supported

by clear scientific evidence

Dr. Kitazato Kaio said that coronavirus can be classified into four genera:

Alpha, Beta, Gamma, and Delta. Gamma, and Delta mainly infect birds, while

Alpha and Beta mainly infect mammals. The novel coronavirus is classified as

Beta group. The natural host is likely to orginate from bats. It has also been

reported that similar viruses have been found in pangolins, snakes and other

wild animals.

Currently, the route of infection remains a question to the public. The novel

coronavirus infects people through the intermediate hosts or just directly

infect people from the natural reservoir, which are both under rigorous

research. So, virus searching, seeking for intermediate hosts, and research on

the transmission of viruses to people are the important steps to completely cut

off the spread of the virus.

This is a very serious scientific issue, which needs to be supported by solid

scientific evidence. The solution to this crisis requires the joint efforts of

scientists from all over the world.

Screening of serum antibodies in patients with suspected influenza cases may

provide clues to search the virus origin

Dr. Kitazato Kaio believes that the continuous plague records in human history

indicate that new viruses could invade people from other organisms. With the

emergence of the new virus, it is impossible to effectively prevent the

infection through the immune system due to the reason that the human body does

not have specific immunity. The virus will continue to spread and replicate its

"off-springs" in the crowd. Only until the majority of people are immune to it

can we successfully contain the development of the pandemic.

The most effective way for humans to deal with the infection of emerging

viruses is to research and develop vaccines. Before achieving the goal of herd

immunity, everyone is susceptible to the virus and no one can stay out of the

possible infection.

The immune system has a memory function for the infection of pathogens that

invade the body. With the current technology, as long as the antibodies in the

blood are detected, it is possible to screen out the past infected experience

of various pathogens.

If the serum antibodies of clinically suspected influenza cases and other

patients are widely screened in the future, it will help to provide clues for

finding the source of novel coronavirus infections.

Chinese scientists guard well against new challenges

In the early stage of the epidemic, Chinese doctors and scientists efficiently

isolated the virus in the shortest time and analysed the whole genome sequence

of the virus. In addition, China has been timely releasing information on

COVID-19 to the rest of the world since the onset of the epidemic, making the

international community informed about the emergence of the COVID-19.

This fully demonstrates the professional performance and the sense of

responsibility of Chinese scientists to the public health, and lays a solid

foundation for the public to face new challenges together.

In addition, in order to quickly contain the spread of the epidemic, the

Chinese government took strict and comprehensive prevention and control

measures including city lockdowns to contain the virus and protect its

citizens. These efforts and sacrifices of China have won precious time for the

world to jointly fight the epidemic, and are highly appreciated by the World

Health Organization (WHO) and relevant experts from various countries.

"Joint Global Operation" is essential to successfully contain the COVID-19

When COVID-19 occurs at the early stage, countries around the world should have

been vigilant with all kinds of preparedness. However, some politicians failed

to take positive measures to prevent the spread of the pandemic in their own

countries, which led to spread across the world. They made dangerous attempts

to politicize COVID-19, casting a shadow on our joint fight against our common

enemy.

The novel coronavirus pandemic, regarded as a once-in-a-century global

challenge, is extracting a huge cost in terms of human lives and health, and

posing challenges to political, economic and national management system.

COVID-19 poses a huge threat to human life and health. The pandemic does not

distinguish the country, race, gender, age and social status. All countries

should join hands to fight against COVID-19 with our global wisdom and

scientific strength when confronted with our common enemy. Only with solidarity

and by cooperation can the international community prevail over the pandemic

and safeguard the common homeland of humanity.

Dr. Kitazato Kaio reminds that the COVID-19 may break out again at any time

before widespread vaccination. Human community should actively make back-up

plans to deal with such possible outbreaks without affecting the normal

development of society.

SOURCE: Science and Technology Daily