What are virologists busy with the new crown epidemic sweeping the globe?

Source: Back to Park ID: Fanpu2019 Author Li Qingchao (Shandong Normal University) Most people's impressions of biological research are basically derived from sci-fi movies: scientists in trouble, human catastrophes, heroes save the planet.
2020, disaster really came, the new crown epidemic swept the world, virologists are busy with what? Fighting the epidemic, what's the only secret of virologists? Can a virus cause a disease, and can a virus cure a disease? Today's article will take you to the study and application of viruses.
viruses are a class of important pathogens that cause human diseases.
people have been trying to deal with them long before they know what a virus is.
Chinese began using human pox to prevent smallpox in the Ming Dynasty, and in 1798, British doctor Jenner invented the use of bovine pox as a vaccine to prevent smallpox.
1885, French scientist Pasteur invented the rabies vaccine.
1892, humans discovered the first virus, the tobacco leaf virus, which is smaller than bacteria and can make plants sick.
discovered the first human virus, the yellow fever virus, transmitted by mosquitoes, in 1901.
1911 discovered the Lowe's sarcoma virus, which can cause chicken tumors (Figure 1).
later, the understanding of the virus became more and more profound, and viral research became a separate discipline: virology (Figure 2).
, unlike the average person's imagination, virology research involves the development and use of viruses in addition to answering basic scientific questions, preventing and treating viral diseases.
all three functions are inseparable from the most important virus research tools: the reverse genetic operating system.
this system, can be said to be the virologist's "poison door cheat."
first step: The first step in viral research is virus detection.
detection of known viruses, mainly used in medical diagnosis and epidemiological investigation, the main detection methods are symptom diagnosis, immunology detection, nucleic acid testing and some clotting experiments and other specific reactions detection.
for unknown viruses, it is necessary to isolate, culture, identify the process to find, and finally through the electron microscope to directly observe the virus.
but ultimately to sequence the virus's genome by means of sequencing.
this is because the genome sequence of a virus is its core component, and capturing the genome sequence of the virus is equivalent to finding the virus.
the rapid development of today's technology, researchers using deep sequencing technology (Figure 3) makes it easy to spot a large number of new viruses.
for patients suspected of being infected with unknown pathogens, we can sample, extract nucleic acids, build libraries, and sequence them in depth. After
sequencing, the sequence of pathogens in it is found by means of biological information, and the identification results are given.
zoomin: "Poison" door secret found the virus, how to carry out research next? Next, let's introduce the most important research tool used by virologists: the reverse genetic operating system.
01, Genetics and Reverse Genetics In order to understand reverse genetics, you need to understand genetics first.
look at organisms, we can find structural and functional features, such as hair, skin, pupil color, which is called profiling, also known as phenotypes.
phenotypes are determined by the genome of organisms, and the entire genetic mix of the individual is collectively called genotype (Figure 4).
genotype determines phetype, which reflects genotype.
people didn't know the nature of genetics at first, so they started with phenotypes to study genetics.
Mendel used peas and morgans to study genetics using fruit flies, looking for genetic patterns and targeting phenotypes by pea red flowers, white flowers, or fruit flies, and white eyes.
therefore, classic genetics is from phenotypes to study genotypes, this is positive genetics.
in forward genetics, it is necessary to screen mutants with special phenotypes by means of natural mutations or mutagenics, and then locate which gene determines the phenotype and study the function of the gene.
in reverse genetics, scientists get an unknown gene that can actively alter or change its expression (overexpression, low expression, or knockout not expressive), then observe what phenotype changes caused by gene mutations or changes in gene expression, and compare it with phenotypes of wild (normal genotypes that are not artificially altered) to speculate on the function of the gene.
, therefore, reverse genetics studies the function of genes by altering genotypes and observing the results of phenotype changes (Figure 5).
02, the necessary condition of reverse genetics is genetic engineering technology based on the concept, we can easily see that in reverse genetics, the need for a specific nucleic acid sequence modification, and this modification of the technology, in fact, we understand the structure and function of the genetic material of DNA, the development of a variety of genetic engineering tools enzymeor or genetic engineering means, can be achieved.
genetic engineering is a technology that uses biotechnology to directly manipulate the genes of organisms and alter the genetic composition of cells.
therefore, the idea of reverse genetics appears later than the idea of classical genetics.
DNA is the genetic material of cell organisms, it is more stable than RNA, and most genetically engineered tool enzymes are targeted at DNA, so the transformation of genetic material is mainly done on DNA.
we do genetic material modification, mainly on plasmids (Figure 6), because plasmids are free DNA that can be independently copied outside the genome and is easily amplification able to be done in bacteria or yeast.
(learn more about plasmids: What is plasmid? From biological weapons to genetically modified foods, the genomes of infectious clones are usually small, so we can assemble a double-linked DNA copy of the virus genome into a plasmid.
send these plasmid DNA with a viral sequence, or RNA produced by plasmid-directed transcription, a process called "transfection" -- that directs cell factories to produce viral proteins, replicate new viral genomes, and assemble releases to produce infectious viral particles. the genome of
viruses can be DNA or RNA.
DNA virus genomes can be amplified, cut and then directly connected to plasmids, while RNA viruses need to guide the reverse transcription process of synthetic DNA, converted into DNA, and then connected to the plasmids.
these plasmids that carry a sequence of viral genomes that can produce infectious virus particles are called "infectious cloning."
a constructed infectious clone is transfected into cells, or transcribed into RNA and then transfected cells, new viruses can be produced (Figure 7).
04, reverse genetic operating system mentioned earlier, the idea of reverse genetic research is to change the gene sequence, from the genotype to study phenotypes, and then study gene function.
is the same for viruses: building infectious clones, genetically engineering them, transferring the modified infectious clones into cells, and then using these new viruses to infect cells or hosts, and observing the virus's replication, host symptoms and other phenotypes, you can study the function of virus-related genes (Figure 8).
such a system, which we call the reverse genetic operating system of viruses.
take the recently released new crown virus reverse genetic operating system as an example: it is used to obtain infectious cloning using yeast.
, the new coronavirus genome RNA obtains DNA fragments by reverse transcription and amplification, or directly synthesizes the DNA version of the virus, and then recombines in yeast to synthesize the synthetic cloned plasmids, extracts the plasmids, and transcribes the synthetic RNA, RNA transfected cells to produce the new coronavirus (Figure 9).
whether it's for research, vaccines or treatments, to make viruses, we all need to make plasmids, and in the process, we'll use genetic engineering tools such as enzyme cut sites, screening markers, and necessary plasmid fragments.
at the same time, our virus sequence is obtained from natural viruses, design and manufacturing infectious cloning process, will certainly follow the existing theoretical model and design ideas, even from the beginning of the artificial synthesis of a new virus, will also be in the password sub-use frequency, etc. , leaving artificial traces.
therefore, whether a virus is synthetic is easy to identify. The reverse genetic operating system of the applied virus in the
virology research is a very important tool in the field of virology and related life sciences, which can be used for basic research, the function of various genes in viruses, can also be used for vaccine development, and can also use the virus as a vector, loaded with different gene sequences for other life science research.
, with the development of life science, the future of viral vectors for cell therapy, gene therapy and cancer treatment is brighter.
01, basic research applied virology ideas and tools in the basic research of biology is widely used.
the current virus vector is widely used in gene overexpression, knockout, knockout, animal model transformation and other aspects.
take the use of pseudovirus in virology (Figure 10): We can use the basic methodof reverse genetic operating system to make fake virus particles, so that the false virus particles containing the virus on the envelope protein, can be used to simulate the antigen, neutralization and early infection process of virus particles;
because of the good safety, with the help of fake virus particles, we can study some dangerous viruses in laboratories with relatively low biosecurity levels.
02, vaccine development and production of each of us have been vaccinated, we can touch the scar on their arm, that is the injection card seed left behind.
vaccine prevents disease by stimulating the body to produce acquired immune protection.
according to the components of the vaccine, can be divided into inactivated vaccines, weak lysis, toxins, subunit vaccines, recombinant proteins or peptide vaccines, as well as viral vector vaccines, DNA or RNA vaccines.
vaccine needs to meet two conditions at the same time: both to stimulate the body to produce effective immune protection, but also without causing disease.
the vaccination process, like a military training of the immune system: training the immune system without damaging the body.
and so-called immunity, in fact, is the body in the next encounter with the pathogen can quickly eliminate pathogens, let people (or animals) do not become ill.
we look at an example of a reverse genetic operating system making a vaccine (Figure 11).
we know that the flu will mutate frequently, and the virus strain that is circulating every year may be different, and the immune system does not know it after changing the armor.
so we have to produce a new flu vaccine based on the strain of the virus that was prevalent that year.
this time we will use the reverse genetic operating system: (1) we detect the epidemic strong strain from the clinic, get its antigen coding sequence, (2) through genetic engineering, the antigen part of the coding sequence recombined into the vaccine weak strain infected cloning;
the most effective way to prevent viral diseases is to develop vaccines.
in order to prevent and control the new coronavirus outbreak, researchers around the world are working hard to develop a new coronavirus vaccine, China's Chen Wei academician team developed a new recombinant coronavirus vaccine (Ad5-nCoV) has entered Phase II clinical trials.
according to the name, the vaccine uses adenovirus, adenovirus is a dna virus without a membrane, we can cause disease in adenovirus genes and some unrelated genes removed, and then recombined the introduction of new coronavirus antigen expression genes, the production of a deanovirus vector-based coronavirus vaccine.
adenovirus vector is characterized by high efficiency, high titer (titer refers to the concentration of the virus), low pathogenicity, and will not integrate into the host cell chromosome, is a commonly used virus vector.
researchers at home and abroad have also used strategies such as inactivated vaccines, subunit vaccines, pseudoviral particles, pox virus vector vaccines and nanoparticle vaccines to develop vaccines (Figure 12).
, the nanoparticle vaccine is a nanoparticle consisting of viral antigens and self-assembled protein components.
03, viruses can also treat viruses or viral vectors can also be used in phage therapy, cell therapy, gene therapy, as well as cancer treatment and prevention.
because of the discovery and application of various antibiotics, bacteria to human health harm greatly reduced, but, antibiotic abuse brought the problem of bacterial resistance, some of these bacteria have multi-antibiotic resistance, we call superbugs, superbug infection is very dangerous, and in medicine is very difficult, and phages can infect bacteria virus, so the use of phages to treat drug-resistant bacteria infection as one of the ideas of treatment of bacterial infection.
2015, a university of California scientist couple on a trip to Egypt, her husband Tom Patterson infected with superbugs, died in danger, and later recovered using phage therapy (Figure 13).
https://cancer is a serious threat to human health, and certain viruses can cause tumors to dissolve, which we call tumor-soluble viruses.
lysoma viruses contain adenoviruses, pox viruses, Virus A, Newcastle virus, herpes simplex virus-1, measles virus, etc. (Figure 14).
these viruses have been modified to be used in cancer treatment: on the one hand, they do not cause disease, but they can kill tumor cells on the other. there are various mechanisms for treating tumors
tumor-soluble viruses, such as destroying tumor blood vessels, cutting off the source of tumor nutrition, killing tumor cells directly, or inducing a cellular immune response to tumors.
the body's immune system is like an army that can resist the invasion of foreign pathogens, while also identifying and eliminating abnormal "renegade" cells, and there are.