I recall some questions about general virology, morphology, ultra-structure of viruses, classification, cultivation, what general methods of laboratory diagnosis of viral infection. During this lecture, I want to connect with you because some questions you remember from previous semester and during life. But you know the answer to some questions.
I want to start from definition. What is virus? Virus is a non-living microorganism.
It's a small, obligating, transcellular parasite which by definition contains either RNA or DNA. Never mind. Around nucleocase...
It's... protein for protection from non-operable conditions and for protection of genetic material. Genital properties of viruses non-cellular, a-cellular.
What cellular microorganism you remember? Bacteria, it's a cellular. Prokaryotes. Protozoa, it's a cellular microorganism. Fungi, cellular microorganism.
viruses, non-cellular. Smallest infection agent from 20 to 200, 300, 400 nanometers. If you remember E.
coli, it's a bacteria, one micrometer, it's 1000 nanometers. viruses from 20 to 3 or 4 nanometers. And for examination of viruses we can use only electron microscope. Light microscope in the biological laboratory is present, but in the light microscope we cannot see morphology, we cannot see the structure of virus. on the electron microscope.
Basic structure consists of protein shell capsid surrounding nucleic acid core, DNA or RNA. Only DNA or RNA and one of the classification of viruses, the RNA viruses and DNA viruses. Examples of RNA viruses influenza virus, coronavirus, paramyxovirus like measles, mumps.
DNA viruses, for example, it's adenovirus or hepatitis B virus or herpesvirus. Viruses are parasites that genetically replicate only in living cells and not the extracellular environment. Viruses are the worst with great variability in their structure and in result mutation, sometimes now life, and you remember pandemic of COVID-19, it's a bad example. because you know that it's a conclusion. Influenza virus and result mutation, new subtypes of influenza virus type 1 and the cost division of pandemias.
Size compared to E. coli bacteria, 1,000 nanometers compared. red blood cell you can see the size of viruses, rhinovirus 30 nanometers, picorna viruses like enteroviruses or poliovirus the smallest viruses, adenovirus 90 nanometers but we know that some viruses three four hundred nanometers like varicella virus bacteriophage remember what is bacteriophage viruses infect cells animal, human, plant cells, and some viruses can infect bacteria. And this virus is bacteriophages. The size of bacteriophage can be different.
Bacteriophage to 25 nanometers or bacteriophages 20-30 nanometers. Virion, what different virus and virion? In the broad sense, we can use the word virus, and the virus intracellular or extracellular, but in the narrow sense, if we talk about complete particle of virus, we...
all this microorganism virion, extracellular. In this case, the virion ready to infect other cells. RNA or DNA around nucleic acid, capsid. Capsid or protein shell or cord that include the nucleic acid genome.
For protection, nucleic acid. from an unpreparable condition. Capsid consists from capsomers, morphologic unit on the surface of icosahedral virus particles.
Enveloped in lipid-containing membrane that surrounds some virus particle. Enveloped virus and result reproduction with some small particles. pieces of human cell membrane. Cellular membrane is the part of the envelope, part of the complete virion.
Nucleococcus capsid, the protein nucleic acid complex. Nucleic acid and capsid, nucleococcus. It's a simple, naked, non-enveloped virus.
consists from only nucleocapsid. Complex virions include nucleocapsid and surrounding enveloped naked virus or non-enveloped virus nucleic acid, DNA or RNA and around the capsid protein shell it's a simple virus adenovirus, picornaviruses. enteroviruses, polioviruses. It's a non-enveloped virus. Enveloped virus with super capsid or lipid enveloped.
Lipid enveloped is a part of membrane or host cell, human or animal cell. We study medical microbiology, we talk about human cell stuff. Classification of viruses by types of nucleic acid, two types, DNA or RNA viruses. Different types of capsid symmetry, helical type of symmetry, and if you remember history, the first discovered virus, tobacco mosaic virus. with helical type of symmetry.
Ebola virus. Ebola virus is a cause of hemorrhagic fever. This helical type of virus.
Polyhedral virus or icosahedral type of symmetry. Example adenoviruses. Adenovirus is a cause of hemorrhagic fever. of infection of respiratory tract, conjunctivitis, or infection of gastrointestinal tract. Complex viruses.
Complex viruses consist from two types of symmetry, helical and ticosidral. Bacteriophage, one of the type of bacteriophages in the complex. the hetaicosidal type of symmetry, neocatical type of symmetry.
And enveloped spherical viruses, enveloped spherical but Inside can be helical capsid. Just a minute. Next.
The nucleic acid can be single-stranded or double-stranded. Whereas family name have the suffix viridae, for example, herpesviridae family. the genus name creates a suffix virus, coronavirus, for example. The Baltimore classification of viruses and every lecture and every practical classes, we talk about different types, different groups by this classification.
And during practical classes, we talk about different types of reproduction and what different of reproduction double-stranded DNA from RNA viruses single-stranded positive or negative double-stranded or single-stranded RNA waste reproduction in the cytoplasm or the nucleus or cytoplasm and nucleus what it's I think it will be but if during it practical classes, for example, different types of viruses and talk about different reproduction of nuclear cases. Now, seven groups by Baltimore. The first group, smallpox virus with double-stranded DNA. Group two, positive single-stranded DNA. DNA like parvoviruses.
Group 3 double-stranded RNA rotaviruses. Group 4 positive single-stranded RNA coronaviruses. Group 5 negative single-stranded RNA measles virus. Group 6 positive single-stranded RNA with enzyme reviews transcript. days it's a example retroviruses HIV group 7 double-stranded DNA with enzyme reverse transcriptase hepatitis V virus what different naked viruses from enveloped viruses Naked viruses consist from nucleocapsid, RNA or DNA, and around nucleic acid present protein shell.
The non-enveloped or naked viruses less susceptible to disinfectant. Naked viruses more virulent viruses. Naked viruses resistant to heat and drainage, resistant to some disinfectant, resistant to some more resistant, compared to enveloped viruses, to some antimicrobial chemicals. Both examples are adenovirus, poliovirus, and hepatitis A virus, the picornavirus.
Complex or enveloped viruses consist from nucleocapsid, nucleocaesid and around protein layer and around present enveloped viruses, complex viruses, less virulent but more dangerous viruses. It's enveloped viruses. for now, HIV, influenza, coronaviruses, enveloped viruses. Enveloped viruses, lipid layer and this type of virus is more sensitive, more susceptible to disinfectant.
The part of enveloped consists from cell membrane of host cell human cells Some viruses present enzymes. Some viruses lack enzymes for reproduction and use enzymes of host cell. But some viruses with enzymes.
And what types of enzymes can be? Polymerase. What function of polymerase synthesizes new DNA or RNA?
Replycase. The function of replicase copy RNA from RNA to RNA, viral RNA or RNA in the matrix for synthesizes of proteins. Reverse transcriptase, HIV, retroviruses.
The function of reverse transcriptase synthesizes DNA from RNA. Transcription, the classic rules in genetics. Transcription, the classic rules in genetics.
DNA to RNA from RNA protein. Transcriptions process synthesizes of RNA from DNA from RNA to protein. It's a translation DNA RNA the process transcription vice versa with reverse transcriptase from RNA into DNA. retroviruses, HIV, it's RNA virus and one of the stage of reproduction synthesizes DNA from RNA. And lysozyme.
You remember from immunology our cell of immune system produce lysozyme. Lysozyme present in the tears and this alignment the breast milk and the function of lysozyme destroy cell wall cell wall of bacteria the non-specific immune response uh for protection from gram positive first of all bacteria yes it's because mechanism of lysozyme like a non-specific factor of immune response destroy cell wall peptide or glycan What viruses produce lysozyme? What do you think? You can answer in the chat. Lysozyme.
What different human cells from bacterial cells? Human cells, no, first of all, human cells, so karyotic cells, you remember, red blood cells, prokaryotic cells. And what main different absent cell wall? Membrane.
Bacteria with cell wall and what virus produce lysozyme for good connection with this cellular and future for reproduction. It's bacteriophage. Bacteriophage produce lysozyme and because this enzyme help to attachment to the surface of the bacteria. Next question about viral replication.
A virus must undergo the process of replication to create new infection virions that are able to infect other cells of the body or subsequent host. What reproduction of viruses? If you remember from previous semester, different from reproduction of bacteria, from reproduction of eukaryotic cells, bacteria multiply, I see, breakdown, the peptide glycine, bacteria cell wall, yeah, thank you. And the reproduction of viruses without host cell, impossible.
The principle, What mean principal reproduction of virus? It's injection of nucleic acid, RNA or DNA and the change, the factory like the source of energy, source of enzymes, source of ribosomes for synthesizes proteins and this cellular host cell the factory for reproduction of virus. Virus lack energy, lack enzymes, lack some components for synthesizing new nucleic acid. like genetic material.
For synthesis, protein component of capseed. For synthesis, component of enveloped. Enveloped is a part of the eukaryotic human cells.
We talk about human viruses. And change this cellular. Genetic level for synthesizers for reproduction different parts, different components of viruses. Viruses are host specific. The human resistant to viruses of plant.
The human resistant to bacteria of age. What do you think? Why? As my group we talk about this moment why human resistant to viral infections of plant or fish or bacteria of age because in the our cells absent receptors absent connection Impossible connection, impossible the first stages of infection process.
You remember, infection process start from connection. And only foreign particles, foreign microorganisms can be cause divergence of infection process and infection disease. Host-specific and viruses, some viruses specific.
Different structure, yes, different structure of viruses. Some viruses, broad spectrum, broad spectrum, if we talk about spectrum, broad spectrum, the first-minded spectrum of antibiotics, yes. I mean the spectrum and specific to... macro-organism, human and animal. You know rabies virus.
Rabies virus infect animal but sometimes it can infect human too and reproduction of rabies virus in the different cells of our human cell and the muscle cell, the neural cell. We talk about hepatitis B virus in the narrow spectrum. cells of liver hepatocytes sensitive to hepatitis B virus narrow spectrum.
Their replication and relationship between virus and cellular and you can see example of replication of bacteriophage but for Human viruses can be the same lytic cycle and lysogenic cycle. Lytic cycle and result reproduction of virus will be lysis of host cell. During lysogenic cycle, during one of the stage of reproduction, DNA of provirus can integrate into DNA of host cell. And Carinobacterium diphtheria, Clostridium botulinum produce exotoxin and non-toxigenic strain can be toxigenic and result lysogenic conversion and result transduction. It's a relationship, lysogenic cycle relationship between bacteriophage and host cell.
What would stages of reproduction? Purple, apple, red. Seven stages. The first stage attachment, the second penetration, uncoating, replication, assembly, maturation and release. The main seven stages of reproduction for different viruses depend on nucleic acid.
It depends on the structure of the virus, whether it is a naked or an enveloped virus. There can be some examples in the different stages of reproduction. And we start from attachment. Attachment, the binding of the virus to the host cell.
The virion recognizes specific cell surface molecules and interacts with specific receptor sites on the surface. of the susceptible host cell. Absent receptor, absent connection, absent infection process and infection disease impossible.
Susceptible cells determine the type of viral tropism like hepatotropism, enterotropism or neurotropism, some viruses with broad spectrum, some viruses with narrow spectrum. And you can see the cells surface receptor. for attachment of human viruses for rhinoviruses intracellular adhesion molecule for polio virus polio virus receptor CD 155 of human immunodeficiency HIV connect with CD4 receptor and to core receptors CCR5 and CXCR4.
And some people in the world resistant to human immunodeficiency virus because these people with mutation of CCR5. And result this mutation in possible complete connection Virus and membrane of CD4 cells, T lymphocytes, the main high concentration of CD4 receptors. Impossible connection, impossible attachment and these people resistant, no sensitive, immune to HIV. It's a small person. Influenza A virus, salic acid, epithelium cells of respiratory tract.
Measles virus, CD46, CD150. Hepatoplasmic virus, paroxysulfate, nectin, HVM receptor. Dengue virus, disease in receptor. Hepatitis B virus, sodium trocholate receptor.
and human papillomavirus, the parane surface and the integrin receptor. Connection of surface antigens of viruses with receptors of sensitive cells. Always occur via receptors attachment and And some small different attachments in the first stage of reproduction are enveloped viruses and naked viruses. Enveloped viruses, like influenza viruses, use spikes located on the enveloped. Naked viruses and attachments of naked viruses are small fibers of the cornet or the icosahedron.
like rhinovirus or adenovirus. The second stage. Engulfment or penetration. Penetration results in crossing the plasmid membrane of the virus. In contrast to virus attachment, penetration requires energy.
Lot is contributed by the host cell, not the virus, the energy from the host cell. Virion is taken up inside the cell via receptor-mediated endocytosis uptake of the ingest virus with an endosome. And second variant of penetration can be fusion of the virion envelope with the plasma membrane of the host cell. We can see two different types of endocytosis, for example, hepatitis virus.
and fusion of example mumps virus. After specific attachment to host cell engulfment and result formation of virus and vesicle in the cytoplasm, vesicle enveloped and capsic break down. Free DNA present in the cytoplasm of host cell. In result fusion and some viruses produce some viruses with F protein and the function of this F protein surface antigen and the function of this F protein fusion. The second type of penetration is the host membrane and formation of receptor spike complex.
And during this variant... penetration during fusion. Some interesting moment there are some antigens of enveloped present on the membrane of host cell but capseed entered in the cytoplasm. And this is very interesting.
In this moment this cell host cell with new property with a foreign antigen. It will be a signal for immune system I'm infected kill me and you remember the immune response and one of the types of immunity it's a cellular immune response it's a signal for killers because antigen foreign recognized by immune system and killers can be attack infected cell. The next stage is uncoating and the cytoplans after penetration uncoating refer to breakdown or removal the capsid when they release the virus genome in the cell. and the genome replication transcription will take place.
I'm quoting after penetration and two types of penetration. I want to repeat again, it's endocytosis or fusion. The next stage and now... very short information about replication because for different types of viruses with different type of nucleic acid replication, replication of nucleic acid synthesis of proteins, component of capsid or synthesis of new enzymes different during practical process for different groups by Baltimore can be different but what main principle of replication Two important and separate events must occur. Production of structural protein and enzymes of the virus occurs in the cytoplasm of host cell.
The classic example is positive single-stranded RNA viruses. And replication of the viral genome branches. replication, production of structural proteins and enzymes and replication of the new viral genome DNA, mRNA, single-stranded or double-stranded type of viruses. Three examples negative single-stranded RNA Lycotomyxovirus, influenza virus, paramyxovirus like mumps, measles, or para-influenza, rhabdoviruses, costi-vagent of rabies, negative single-stranded RNA, genome complementary to mRNA, and viruses must supply their own RNA polymerase, RNA-depend RNA polymerase. polymerase which form plus mRNA for synthesis new RNA of the nucleic acid genetic material and the matrix for translation in the ribosome of the cytoplasm host cell, it's a matrix for synthesis of proteins, components of viruses.
Positive single-stranded RNA like ... corona viruses, enteroviruses, Coxsackie virus, poliovirus, hepatitis A virus, toga viruses, it's a costevegent of rubella, of flaviviruses. Viral nucleic acids, there is mRNA, no enzymes present, reproduction only in the cytoplasm.
Positive single-stranded RNA retroviruses with reverse transcriptase used for initial synthesis of complementary strains of DNA. One of the stages of reproduction of retroviruses or HIV synthesizes DNA of provirus and integration of DNA of provirus into DNA of host cell T lymphocytes. Next stage is assembly, maturation and release. The processes of assembly, maturation, release are closely linked but all are required to create progeny infection where it is able to continue the cycle infection.
Non-enveloped viruses accumulate, they infect cells, eventually cause lice. and relieve the virus particle, break down assembly maturation and release, break down membrane of host cell and pulverizes host cell. But in velvety virus you remember the first stage attachment and in result fusion, one of the variants of attachment In the result fusion the antigens of enveloped virus present and waiting in new billions of present antigens in the membrane of host cell.
And enveloped viruses material process called budding. Virus specific enveloped glycoprotein are inserted in the cellular membrane and viral nucleocapsid budding. But through the membrane, this modifies site, acquiring and enveloping. Enveloped viruses are not infectious until they have acquired the envelope. Therefore, infection progeny virus typically do not accumulate within the infected cells.
An example of reproduction of HIV type 1 formation. of the connection with CD4 cells. First of all, the T-helpers, T-lymphocyte, but should be present to core receptors, CCR5, CCR4, formation of complex, and after that, budding, fusion, uncoating, reverse transcript.
initiation and synthesis of DNA from RNA of virus. After that the virus present in the nucleus of host cell integration of virus into DNA of host cell and during this stage working next enzyme it integrates with a trans- transcription of mRNA synthesizers and synthesizers of protein or viral particles in the cytoplasm of host cell. Release finding the surface antigens like GP120, weighting the viruses and the lysis of cell Not at this moment, because no reason kill host cell viruses.
The viruses want to use all components of membrane of host cell in several hours can be analysis of CD4 cells. But the rules of reproduction the same. attachment, penetration, and coating, biosynthesize, maturation, and release.
Maybe questions you have about general characteristics of viruses, classification, reproduction, maybe you can write in the chat. During lecture I can answer this question. during lecture or after lecture date.
No question. Can you hear me? It's okay.
Yes, sir. Okay. The next general characteristic laboratory diagnosis of viral diseases and the main principle of diagnosis is direct examination of specimen, indirect examination, and serological test. Remember, all laboratory diagnosis of infection diseases, there's two branches, detection and finding of pathogen.
antigen or nucleic acid. And the second branch, examination of human and detection of specific immune response, detection of specific antibody. Direct examination of specimen, it's excellent electron microscopy, but it doesn't advantage the low visualization of virus particle detection of unexpected. pathogen discovery of new viruses, maybe discovery of some changes of viruses. What electron microscopy is for scientist laboratory in the life routine of exam laboratory diagnosis we don't use.
Limitation yes expensive required high viral burden in viral recognition and labor intensive. In the light microscope we cannot see virus, but we can see the result multiplication, the result reproduction of virus in the host cell, like detection of the negri body. Negri body and the cytoplasm of the broken ear cell in the cerebral cortex after hematoxylin, as in staining, you can see here. formation of negri-warden in the neural cells.
Direct examination of the specimen is one of my favorite tests, serological test, immunofluorescent test, microscopic but serological test. Direct immunofluorescent test, quick express, and No expensive test. It's easy.
The test for detection of the antigen of influenza virus. Now the pharyngeal swab. We can prepare a smear, treatment of this smear by fluorescent serum.
In 30-40 minutes we can see the result. We can see light and we have conclusion in the specimen of patient present antigen of influenza virus. It's a quick test or ELISA test. One of the ELISA tests is a sandwich test for detection antigen from different test material from patient from different fluid we can detect antigen.
Rapid test strip immunochromatographic test. This test, one of these tests we can use for detection antigen like SARS-CoV-2, COVID-19. From another pharyngeal swab we begin to detect. This test you can see negative, only control line is present. This test is for serological test.
You remember the principle of serological tests, formation of immune complex, complex antigen, antibody. In this test we use protection antigen. Molecular techniques for direct detection of viral genome.
Classic polymerase chain reaction based on the amplification of DNA. We can use real-time PCR or we can use RT-PCR for detection RNA viruses with reverse transcriptase. Remember the function of this enzyme. It's a non-serological test. It's a molecular genetic test, physical test.
In direct examination and cultivation, we cannot use nutrient mediums like mid-peptone broad, mid-peptone agar and other nutrient mediums for cultivation viruses, because viruses obligate intracellular parasites. Without host cell, without live cell, multiple reproduction of viruses is impossible. For cultivation, we can use cell culture. After cultivation, the cell culture, some viruses, not all viruses, but some viruses tend to change morphology of this virus, the cytoplatic effect, CPE. Some viruses, infected cell, can make new properties to adsorb red blood cells.
Awesome. this property of cells we use for indication and identification of virus, confirmation by neutralization, interference or immunofluorescent and other serological tests. Animals disease or death confirmation by neutralization but now laboratory animals we use only in the scientists laboratory very very rare if sent to nativity. methods of cultivation.
About cell culture and different types of cell culture can be primary cell like monkey kidney there are essentially normal cells obtained from freshly killed adult animals. This cell can only be passage once or twice. Semicontinuous cells like human embryonic kidney and skin fibroblasts, there are cells taken from embryonic tissue and may passage up to 50 times. And now in virological laboratory use continuous cells, onco cells, there are tumor cells and 500 passage we can use continuous cells. virus cultivation in the laboratory animals, but I want to repeat only in the scientist laboratory.
Embryonated chick egg, it's a universal model for cultivation of viruses and now the classic Method for cultivation of influenza virus. Every season the scientists prepare a new type of vaccine for prevention of influenza. Because in result of some small mutation, the prognosis of circulation of new viruses, the scientists use for preparing new with small different...
vaccine strain of influenza virus. And chick embryo, it's a model for cultivation, excellent chorion-alantoic membrane inoculation, amniotic inoculation, or yolk sac inoculation, or allantoic inoculation. This method of cultivation obligates intracellular parasites like viruses and some bacteria like lamida and trichetia.
Do you remember? It's an interesting microorganism between viruses and bacteria, but it's by morphology it's bacteria, but for type of reproduction it's like virus between. And for cultivation we can use chick embryo.
After cultivation and cell culture, we can see cytoplatic effect. Morphological changes in cell caused by viral infection cause cytoplastic effect . In light microscope we can see healthy cells before cultivation. You can see monolayer cells, the size of cells the same.
After cultivation some viruses, not all viruses, for example only 30% Influenza virus can produce CPE and this method of cultivation and identification and neutralization test is not a result method. After cultivation can be rounding of cell adenoviruses. Formation of multinucleated giant cells in CTR or CN plus herpesviruses. Formation of plaque cell resaltylizes of cells with lysis of cells plaque formation.
Formation of vacuoles intracytoplasmic inclusion body like or Guarneri body, or Pashen body, intracytoplasmic inclusion body, or influenza virus, or all eye for cytomegalovirus. And CPE we can see in the light microscope. But what will be conclusion in the protocol?
We can see CPE But for identification of virus we use neutralization test with specific antiviral serum. Infected cell with new properties, the properties to hemadsorption. Hemadsorption, adsorption of the red blood cells from the surface of infected cells if the virus with hemagglutinin. Hemagglutinin is a surface antigen for auto-mixer viruses, for influenza virus and for paramyxoviruses, for influenza, mumps, measles and infected cells with new property to hemabsorption. It's method of indication for identification we use neutralization or hemabsorption inhibition test with specific antiviral serum.
Next test is indirect examination of the specimen and the second branch laboratory diagnosis of viral infections examination of the blood serum and detection specific antibody. Detection and change of antibody titrate are important to establish the phase of disease, acute, chronic. convalescent stage during acute infection.
You remember the first type of immunoglobulin IgM production and IgM only during acute infection. Sometimes we can detect total immunoglobulins, or we can not differentiate the ELISA test types of immunoglobulins. we can see the high concentration of antibody.
This concentration can be only during infection disease. But sometimes not enough concentration, we don't know what type of concentration of antibody. After infection disease, after some months or maybe... After vaccination, we use the Perit serum method twice in 10 days.
But this method is only retrospective, and sometimes the level of antibodies is present and can be detected during infection, disease, the patient with symptoms. Sometimes we use treatment, symptomatic treatment. What methods for antibody detection?
Well, classical methods. And I know for students, serological test, it's one of the favorite tests. Yes, it's one of the interesting. And you know my favorite enzyme, Lincoln-Tembuna-Saubernt, I say. And.
immunofluorescent technique. Complement fixation test they can use, but now in practice, no, because it's very difficult. And a lot of components, now we have alternative tests. Hemagglutination inhibition test, this test we use for identification of virus.
And this test we can use for detection, the other side, we can use for detection antibody in the blood serum. In the blood serum present specific antibody, we cannot see agglutination of red blood cells. But for this test, we need the live viruses.
Immunofluorescent test, quick express test for detection. antigen and another technique used for detection antibody, indirect immunofluorescent test. Neutralization test in the blood serum of the patient present antibody can neutralize the virus or after cultivation of virus in the cell culture or cheek embryo we can use neutralization test.
Radium unisex, particle agglutination. or Western blood. What about ELISA and Western blood? ELISA test more sensitive test, Western blood more specific test. For example, HIV laboratory diagnosis first test and ELISA test if the test is positive but sometimes can be false positive we use western blood test western blood test or detection antibody for different antigen of hiv because eliza test for laboratory diagnosis of hiv this test for detection p24 antigen or antibody to p54 24 you Western blood, we use for detection antibody to different antigens of HIV, P17, P24, P120, and antibody to three enzymes.
More specific test. Indirect examination of specimen, and in 10 days, detection of IgM, first immunoglobulin in the blood serum. We can detect late IgG, secondary antigen exposure, or different secondary response from primary response.
The Mario's Caprice, your favorite question, yes. It's the concentration. of IgG and the time of synthesizes of IgG during primary immune response. Hemagglutination inhibition test, inhibition of hemagglutination by antibody from blood serum of the patient.
This test. the excellent test for viruses with surface antigen hemagglutinin like influenza virus and paramyxovirus. Limitation of serological diagnosis for viruses such as rubella and hepatitis A they have clinical symptoms. with the development of antibody and only a retrospective diagnosis.
There are many viruses that often produce clinical disease before the appearance of antibody. There are also viruses that produce clinical disease months or years after seroconversion, like HIV or rabies. HIV can be during a long time, several years, or rabies, one, two years. without clinical manifestation.
Next question, antiviral drugs, mode of action, and what about viral infections? And, you know, about Ukraine now, and Ukraine and from Europe, it's a season of respiratory viral infections. And during this season, a lot of viruses, we don't know which one virus can be caused to which, because more than 100 rhinoviruses, adenoviruses, para...
Influenza viruses, metapneumovirus, coronavirus, now first high temperature and more than 38, and we can see symptoms of corona and influenza. And during one day, we use quick test, immunochromatographic test. Which one?
because we have specific preparations for treatment of influenza virus. We have specific preparation now in Ukraine, I think in Baltimore now, we have specific preparation for treatment of coronavirus. And during the first two days, it's an excellent, it's an optimal time for this preparation, because later the virus will be in the cell.
And and non-effective preparations will be. It's a specific antiviral preparation, like tummy flu. Stop the action of influenza and uriminidase required for antivirus into the cell. Tummy flu, the other side, and repeat influenza virus assembly and body.
It's a specific antiviral preparation. The second variant of antiviral preparation nucleic acid synthesis inhibitors like aciclovir for treatment herpesviral infection and AZT inhibitor reverse transcriptase activity of HIV. Now the people with HIV infection without AIDS, without symptoms, but antiretroviral. antiretroviral therapy.
A lot of 10, 20, 30 years without symptoms can be, and the women can deal with the child, with a healthy child with HIV infection, but antiretroviral therapy. But now renal viral infection, season of viral infection of respiratory tract, we cannot use specific preparations and our immune system produces interferon, one of the type interferon, it's alpha interferon, we use for treatment viral hepatitis. interferon, non-specific factor of immune response, different cells produce antiviral substance.
The last question for today is about types of viral infection and for virus to multiply it must invite host cell, without host cell multiplication, reproduction. I don't like. term multiplication for virus like reproduction and it must take out the host metabolic machinery transformate the host cell the factory for reproduction of virus reproduction of nucleic acid reproduction of component of virion and three types of viral infection for example Acute infection characterized by rapid onset of disease and relatively brief period symptoms, resolution within days, it is usually accompanied by early production of infection virions, and elimination infection by the host immune system. And it's an excellent result during acute infection, it's during several days and can be Two types and during practical classes I want to talk about two these types of viral infection latent and persistent viral infection and in the some books you can see the Latent infection, the variant of persistent and viral infection.
Some book virus worse and some cases the latent and persistent infection different. During practical classes we talked about. But latent virus made asymptomatic host cell for long period. Virus not usually released. And the classic example is herpes virus.
Herpesvirus, varicella zoster virus, cost of agent of chickenpox. Primary infection, the first infection, it's called sore throat. Varicella zoster, sorry, sore throat. Varicella zoster, chickenpox, and this virus present in the latent infection and can be reactivation.
and result decrease of immunity, reactivation and the clinical manifestation like shingles. Persistent viral infection like measles virus may remain within brain cell for many years and cause encephalitis in several years. Or human papillomavirus some types of three types of papillomavirus can lead to cervical cancer, but not all. It's a variant of persistent viral infection.
That's all for today. Tomorrow will be a leg chain flu, paramyxovirus, adenovirus, but now I want to ask what questions do you have? How are you, students? Marisa, how are you?
Oh, thanks for asking. Doing well, thanks. How was your break?
Did you have a nice break? A relaxing holiday? For me? Did you have a relaxing winter break?
No, no, no. No, no, no. Busy?
No, no. Okay, share in summer. Yes.
Okay, student. Thank you. Have a nice day.
See you tomorrow. This presentation now will be in the Google Classroom. Tomorrow lecture again will be from next week where we start to work and will be practical classes.
Maybe the students from group number B, do you have questions? No? Okay. See you.
Have a nice day. Bye bye. You too. Thank you. Bye.
Bye. Bye Jamal.