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95 Cards in this Set

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Name three general ways viral diseases are diagnosed.
Through direct demonstration (EM), Isolation, Serology
Name an example of a virus that cannot be cultured
HPV
Do all viruses evoke an immune response?
Yes
Viral Hemagglutination is a serological diagnosis test. Explain how it works.
If a sample has a high titter of viruses, if you expose RBC to the sample, viral antigens will bind to ligands on the RBC surface and will cause RBC's to agglutinate.
Specifically, you can take a sample of unknown virus and extract their antigens and place them on an antigen carrying particle, like latex (this improves shelf life) and expose it to a possible antibody. If they stick, you know the type of virus because you know the antibody that stuck to it. You will know they got stuck because when RBC are exposed to the antigen-antibody solution, they will not agglutinate because the antigens have already been neutralized by the antibody.
Do all viruses evoke an immune response?
Yes.
Viral Hemagglutination is a serological diagnosis test. Explain how it works.
Specifically, you can take a sample of unknown virus and extract their antigens and place them on an antigen carrying particle, like latex (this improves shelf life) and expose it to a possible antibody. If they stick, you know the type of virus because you know the antibody that stuck to it. You will know they got stuck because when RBC are exposed to the antigen-antibody solution, they will not agglutinate because the antigens have already been neutralized by the antibody.
Serological tests must be performed under optimized conditions.
True, serology is the interaction between antibody and antigen, and things like pH, concentrations, alotted time, all affect their reaction.
Define prozone, zone of equivalence, and postzone.
Prozone = when antibody is in excess in a serology test. Zone of Equivalence = when concentrations of antibody and antigen are equal; Postzone = when antigen is in excess in a serology test.
Agglutiantion of RBC in a hemagglutination test means what?
That the tested antibodies are not specific to the virus because they did not attach. The virus does not correspond to the tested antibody.
Describe Direct Immunofluorescence
Desribe Indirectimmunofluorescence (IFA)
Descrbie ELISA
Enzyme-linked immunosorbant assay
Describe RIA
Radio-immunoassay, uses radioactive iodine and machine to measure radioactive emission
Describe detection of viral genome using Dot-Blot Hybridization
Place nucleic acid from sample in wells. Treat with fluorescent complimentary sequence of the viral sequence sought after. Wash. If the sample nucleic acid fluoresces, then there is viral nucleic acid.
Viral genome is also detected by PCR
True, primers used are those complimentary only to the viral sequence sought after so that amplification will only occur if the right viral genome is present.
Describe IgM and IgG tests to detect infection
Isolate IgM (if recent infection) or IgG (if past infection) and expose to a sample of hypothesized virus. If they cling to the virus, then that virus caused the infection in the patient.
Western, Northern, and Southern Blots
Separates protein, RNA, DNA, respectively, and treats with antibodies. Washed, and clinged antibodies are visualized with a dye. It's like doing an IFA on protein, RNA, DNA instead of on cultured infected cells
Describe Viral Neutralization
Describe Complement Fixation
Describe Immunogold tracking
Immunohistochemistry is the general term for which two laboratory tests?
Direct Immunofluorescnece and IFA
What virus causes infections that are asymptomatic in children, but can have stuffy nose, cough, gastroenteritis, can cause pneumonia in older children and adults, is strongly associated with conjunctivitis and keratoconjuntivitis, can also casue pharyngitis, is highly infective, epidimics in spring and summer in children, no treatment, prophylaxis of "live" oral virus - feared to cause cancer; 7 human serotypes (A through G).
Adenovirus (mastadenovirus = mammals, aviadenovirus = birds)
Adenovirus is said to be shed intermittently. Why?
It can become latent, in the adenoids, and if latent, will not be shed while in latency, so shedding will be intermittently.
Hemorrhageic cysts of the bladder, intussusception, and necrotizing enterocolitis are all possible complications fo infections of what virus?
Adenovirus
Describe Replication of Coronavirus
SS (+) RNA which will replicate in the cytoplasm. Penetration is mediated by peplomer protein on envelope. After replication, viruses will get their envelope from the ER.
What sets rhinovirus apart from other picornaviridae?
It can withstand lower pH and temperatures - an adaptation to replicating in upper-respiratory epithelia and mucosa.
Rhinovirus can inhibit host cell protein production
true.
Rhinovirus immediately translates its genome in the cytoplasm (b/c it's SS (+) RNA) into one large protein that gets multiple cleaves
True.
Rhinovirus replicates its SS RNA using a DS RNA intermediate
True.
Coronavirus uses peplomers to attach and penetrate to the host cell. What does rhinovirus use?
Intercellular ICAM-1
Explain Hemadsorption
This test is used when the viruses causes no CPE. When RBC's are introdued to infected cells, the infected cells will bind the RBC. Adsorption of this kind indicates an infection, and for this reason, hemadsorpion is commonly used to double-check what is thought to be negative result from a lack of CPE.
Trypsin can be used to dislodge individual cells the monolayer culture.
True.
How are antibodies obtained for diagnostic tests?
From the Monoclonal technique - mice are vaccinated, to induce the production of specific antibody. Then treated chemically to fuse splenic cells and make them produce the antibody. Splenic cells that are producing antibodies are selected for in selective medium. Antibody is isolated. Mono because only one kind of antibody results from each selective media.
What do you isolate for Immunohistochemistry?
Virus
What do you isolate for ELISA and RIA?
Virus, just as IFA
What do you isolate from the serum with a Complement Fixation test?
antibody
What do you isolate from a viral neutralization test?
antibody
What do you isolate from a radial hemaloysis test?
antibody
Explain Radial Hemaloysis Test?
Test well suited for epidemiological studies, including Influenza and rubella. Involves placing sample serum in a agarose-gell well, and the virus-infected RBC in the agarose gel. Complement poured over everything. Overnight, antibodies will spread, and if specific to the proposed virus, a complex will form, binding the lytic complement, and sparring the RBC. No zone of lysis indicates a positive infection with that kind of virus. If the virus is not specific to the isolate antibody, the complex will not form, complement will not bind, and it will be free to lyse the RBC.
What is FACS
Fluorescent-Activated Cell-Sorter
Dot Blot Hybridization and PCR are used to detect the presence of viral genome. Give an example of an infection type where this type of test is useful.
HPV because these are yet to be grown in lab. For a papsmear, sample tissue is collected and its cells are lysed to release its nucleic acid. A probe specifically designed to attach to HPV nucleic acid is introduced. It has attached to it a marker enzyme, Horse-raddish peroxidase. The system is washed. Substrate for horse-radish persoxidase is added, and if the enzyme is present because of viral nucleic acid presence, a precipitate will form. A precipitate means there is an infection. This is considered a simple test because there was no isolation of any kind. Hemadsorption could have been performed to look for the infection, but hemadsorption is not specific, so you wouldn't know whether you actually have HPV, or if its something else.
Which of the following is able to survive longer: Adenovirus, Coronavirus, Rhinovirus, Influenza?
Adenovirus and Rhinovirus because these are enveloped, and Rhinovirus and Coronavirus are not
He protein in which virus allows for release?
Coronavirus
A patient comes in with a cough, stuffy nose, pharyngitis, no fever, gastroenteritis, what viral infection might they have?
Adenovirus
A patient comes in with runny nose, gastroenteritis, no cough, fever, no sore throat
Coronavirus
A patient comes in with sore throat, sneezing, coughing, malaise, headache, some gastroenteritis - what virus infection might this be?
Rhinovirus.
Treatment for ifluenza includes...?
Amantadine, prevents viral uncoating by attacking the M2 ion channel protein; Zanamivir, prevents viral release by inhibiting neuraminidase action
Influenza is helical, (-) SS RNA, and enveloped
true.
Describe Replication of Influenza
HA attaches to the sialic acid of host cell. Invagination: virus gets in endosomes. pH in endosome allows for an HA change that makes the virus release from the endosome. M2 ion channel protein then allows protons to enter through the envelope, allowing for uncoating as the influx of protons destroys the M1 protein lining. The 8 exposed (-) RNA strands are transported to the nucleus where they will replicate, unlike most RNA viruses. Influenza will then use its endonuclease to cleave and steal normal cellular mRNA's 5'-methyl guanosine cap and other nucleotides to use them as the primer for replicate the (-) RNA to (+) RNA. In doing the stealing, it has also inhibited the synthesis of the host cell's normal proteins, which will eventually kill the host cell. Of the 8 translated RNA's, now (+), six will be translated into structural proteins, two will be converted to mRNA through splicing and will go onto to form non-structural proteins. Influenza does not make the most out of splicing, like Adenoviruses do, they only use it for two of the eight RNA strands. The virus assembles in the PM, where it gets it's HA and NA. NA will cleave the siacilic acid from the viral envelope as it buds off to help release and that it does not attach to the cell it just came out of.
What property of Influenza kills the host cell?
Once the eight negative sense RNA segments enter the host nucleus, Influenza will cleave cellular mRNA's from their 5'-methyl guanine caps, and other nucleotides, to use them as the primer to replicate its RNA. In stealing these from cellular mRNA, the host cell cannot synthesize its own protein necessary for survival, and it will eventually die.
Explain Antigenic Drift.
Drift is less drastic than shift. Drift arises within Influenza B as normal mutation rate of HA and NA and gives rise to localized epidemics.
Explain Antigenic Shift
Shift occurs only in Influenza A (genomically, B can't undergo this for some reason). Shift occurs from reassortment between strains of different species. The only way to get reassortment with B is to have a human A in a human host already in infected with B. Otherwise, reassortment can occur in any animal between two different species strains of Influenza A.
A patient comes in with a fever, but claims he had no sore throat or runny nose. What virus may have caused his condition?
Influenza.
Is there coughing in Influenza?
Usually not, if there is, it will be a dry non productive cough.
If it takes a month for a patient to recover from the common cold, what viral infection did they most likely have?
Unless they are immunosuppressed, they were more likely not be have been infected by common cold viruses, but by Influenza, which usually has a longer convalescnece period
Influenza infection of the lower respiratory tract tract can lead to what condition?
Viral pneumonia
In some cases, the myocitis experienced during the flu systems, arising from systemic spread, can also lead to myocarditis and pericarditis.
True.
Influenza's destruction of the mucociliary elevator can lead to secondary bacterial infections like pneumonia.
True.
Which class of antiviral would be more effective on H5N1?
H5N1 has developed resistance to amantadine from illegal widespread use in Chinese poultry. That means than any other drug that inhibits uncoating will also not work. The only other class of drug is Oseltamivir (Tamiflu) which acts by inhibiting NA, thus viral release. Amantadine, however, was a much more effective drug.
Is corona virus enveloped?
Yes, composed of three types of proteins: matrix protein, HE (similar to Influenza's NA, not HA), and peplomers (which are similar to Influenza's HA)
Is rhinovirus enveloped?
No, a rarity for RNA viruses
Is adenovirus enveloped?
No, it is resistant to detergent and mild chlorine, that's why children get commonly infected in Spring in public pools with pharyngitis and conjunctivitis.
What is the transmission route for rhinovirus?
Aerosol, direct contact, fomites. Not fecal-oral because it does not cause gastroenteritis.
Of what polarity are the nucleic acids of viruses that cause upper respiratory and eye infections?
Of the studied, two of three are (+) SS RNA (Coronavirus and Rhinovirus), Adenovirus is DS DNA. Rhinvorus does has a DS RNA intermediate though, during replication.
Complications with Influenza due to antigen hypersensitivity include what two (out of four)?
Reye's Syndrome (usually in children, exacerbated by aspirin; has a genetic component; characterized by destruction of fats on liver and other viscera which leads to metabolic problems which can result in encephalopathy, commonly called acute metabolic encephalopathy) and Guillan Barre's Syndrome - an autoimmune attack on peripheral nerves' myelin sheath - commonly reffered to as French Polio.
What can IgA, IgG, and IgM do?
IgA provides immune protection from colostrum, and is also found in mucus membranes. IgG gives long-term immunity. IgM gives initial immunity to a systemic infection (does not cross placenta). IgG can cross the placenta.
Alphaherpes infects a broad, or a narrow, range of cells?
broad, think of the systemic infection of VZV.
Alphaherpesvirus has a short, or a long, reproductive cyle?
short, remmber HSV and VZV are commonly latent, and localized infections don't last for more than two weeks.
Betaherpesviruses have a short, or a long, reproductive cycle?
Long, remember that betaherpesviruses include cytomegallovirus, one that causes CMV mononucleosis, a disease whose convalescence can last for months (hence, deductively, it has a long reproductive cycle).
Gammaherpesviruses have a wide, or narrow, range of host cells?
Narrow, EBV mononucleosis tends to infect lymphocytes.
Herpesviruses are said to have a trilaminar envelope. What are the three layers?
The lipid bilayer, tegument (matrix proteins), and inner core
In order to fight any herpesvirus, the body must employ both antibodies and cell-mediated immunity. Why is this so?
Antibodies alone cannot fight a viral infection when the virus is hidden in cells and not reproducing (i.e. latent, as all herpesviruses can). During latency then, only CMI can combat the virus by noticing antigenic changes on the surface of cells.
What is the symmetry of herpesviruses?
Icosahedral
Do all herpesviruses replicate and assemble in the nucleus?
Yes, they get their envelopes upon budding, however.
Do all herpesviruses eventually kill their host cell?
Yes, in fact, this may be the reason why recurrence decreases with time. They kill the host cell in the same way Influenza is able to sht down the host cell's ability to manufacture its own proteins for survival.
Can all herpesvirues become latent?
Yes, this is trademark of all herpesviruses.
All herpesviruses are known to use a large array of enzymes.
True. In fact, thymidine kinase is one that alphaherpesvirinae has that is used for treatment with the antiviral acyclovir.
Explain the regulation of herpesviruses replication.
Once herpes enters the host cell via the docking proteins B, H, D, C (primarily), the enveloped virus enters the nucleus, where the tegument will activate the activation of the alpha-genes, for early proteins, then these will activate beta-genes, which code for middle proteins, like thymidine kinase, DNA Polymerase, and helicase, and these regulate gamma-genes for they depend on the amount of middle proteins produced. Gamma-genes encode for late proteins (non-structural).
How do herpesviruses gain entrance into the host cell.
By docking to the host cell via docking proteins B, C, D, and H, and then through endocytosis.
Viral Hemagglutination is a serological diagnosis test. Explain how it works.
Specifically, you can take a sample of unknown virus and extract their antigens and place them on an antigen carrying particle, like latex (this improves shelf life) and expose it to a possible antibody. If they stick, you know the type of virus because you know the antibody that stuck to it. You will know they got stuck because when RBC are exposed to the antigen-antibody solution, they will not agglutinate because the antigens have already been neutralized by the antibody.
Serological tests must be performed under optimized conditions.
True, serology is the interaction between antibody and antigen, and things like pH, concentrations, alotted time, all affect their reaction.
Define prozone, zone of equivalence, and postzone.
Prozone = when antibody is in excess in a serology test. Zone of Equivalence = when concentrations of antibody and antigen are equal; Postzone = when antigen is in excess in a serology test.
Agglutiantion of RBC in a hemagglutination test means what?
That the tested antibodies are not specific to the virus because they did not attach. The virus does not correspond to the tested antibody.
Describe the direct method of Immunohistochemistry (Direct Immunofluorescence)
Suceptible cells are cultured and infected. Possibly antibodies are introduced, all tagged differently. System is washed, and look for the antibodies that got stuck - you will thus know the type of virus you have.
Desribe Indirectimmunofluorescence (IFA)
Suceptible cells are cultured and infected. Anibodies are introduced. Washed. Anti-antibodies are introduced. Washed. Wells are that fluoresce have the corresponding virus for the antibody. Adding double anti-body allows for greater sensitivity.
Descrbie ELISA
Enzyme-linked immunosorbant assay
Describe RIA
Radio-immunoassay, uses radioactive iodine and machine to measure radioactive emission
Describe detection of viral genome using Dot-Blot Hybridization
Place nucleic acid from sample in wells. Treat with fluorescent complimentary sequence of the viral sequence sought after. Wash. If the sample nucleic acid fluoresces, then there is viral nucleic acid.
Viral genome is also detected by PCR
True, primers used are those complimentary only to the viral sequence sought after so that amplification will only occur if the right viral genome is present.
Describe IgM and IgG tests to detect infection
Isolate IgM (if recent infection) or IgG (if past infection) and expose to a sample of hypothesized virus. If they cling to the virus, then that virus caused the infection in the patient.
Western (SDS Page), Northern, and Southern Blots
Separates, via gel electophoresis, protein, RNA, DNA, respectively, and treats with antibodies. Washed. Clinged antibodies are visualized with a dye. A this point, it's like doing an IFA on protein, RNA, DNA instead of on cultured infected cells
Describe Viral Neutralization
Isolate antibodies from the serum. Introduced hypothesized possible antigens (delivered on latex particles). Then innoculate suceptible cells. If cells do not develop CPE, then the virus was neutralized, and the test is positive for a certain type of virus.
Describe Complement Fixation
Virus is isolated, and exposed o possible antibody. If the antibodies attach, the erythrocyte-lysing complement will attach as well. When RBC's become exposed, and if complement has not been fixed, RBC's will lyse, and the test is negative. If the well is no murky, no lysing, then the test was positive for the virus related to the used antibody.
Describe Immunogold tracking
Attaching gold particles to antibodies so that when observed through EM, attachment of antibodies is clearly seen as dark patches because gold is electron dense.
Immunohistochemistry is the general term for which two laboratory tests?
Direct Immunofluorescnece and IFA