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virology test 1
| Question | Answer |
|---|---|
| what are the four properties of viruses? | 1) small size - filterable infectious agent 2) obligate, intracellular parasites 3) 2 basic components - nucleic acid genome and protein coat 4) viral genome (DNA or RNA) |
| viruses are the only entity that can have an RNA genome. T/F | true |
| agents that can pass through filters that trap most known bacteria. | virus |
| Use of ______ ________to visualize viruses | electron microscope |
| • Viruses are small and have diverse________ | shapes |
| Viruses are small enough to pass through 200 micron filters, but bacteria cannot. | |
| Still small, but bigger than typical viruses; not filterable; infect amoeba; some even infected by smaller viruses | Giruses - giant viruses |
| viruses are Obligate, intracellular parasites must grow within living cells dependent on cells to supply energy and means of ______ and ________ synthesis, i.e. dependent on cell _______, _________, and cellular ________ | DNA and protein; mitochondria, ribosomes, cellular enzymes |
| ♣ To protect that nucleic acid genome from cell to cell and person to person | protein coat (capsid) |
| subunits of the capsid are called | capsomeres |
| some viruses have an ________ - lipid bilayer | envelope |
| ______ genomes may be single stranded, double stranded, or circular | DNA |
| ______ genomes may be positive or negative, segmented, or double stranded segmented | RNA |
| what are the 6 DNA viruses? | Parvoviridae, papovaviridae(papillomaviruses), herpesviridae, adenoviridae, poxviridae, hepadnaviridae |
| consequences of viral properties: viruses must use host cell _______ to synthesize their components; viruses must________ any required processes not provided by the cell | processes ; encode |
| consequences of viral properties ; do not replicate by division; they are just_________ – put together; components are made in the cell and the components come together to make a virus | assembled |
| viruses cannot be cultured on artificial media such as_______ plates, they require cells to grow viruses are not susceptible to_______ | agar; antibiotics (have a whole different biochemistry than bacteria) |
| what are the 3 things that viruses are classified under? | virus size and morphology; DNA or RNA genome; replication strategies |
| Why is it important to have a basic understanding of the structure and molecular properties of viruses? (6) | viral diagnosis, treatment of viral diseases, prevention of viral diseases, disease transmission, viral epidemiology, pathology |
| detection of viral antigens/ nucleic acid in tissue, serology | viral diagnosis |
| Antiviral agents work at specific sites of viral replication | treatment |
| Viral vaccine target specific components of viruses- viral antigens, envelope glycoproteins | prevention |
| enveloped viruses vs non-enveloped viruses | disease transmission |
| i.e., influenza pandemics influenced by genetic reassortment – genetic shift and drift | viral epidemiology |
| DNA viruses vs RNA viruses, nuclear vs cytoplasmic viral inclusions | pathology |
| Two Basic Types of Viral Shapes (Symmetry) | icosahedral (more stable) and helical symmetry |
| All helical viruses have: what? | an RNA genome an envelope |
| derived from cell plasma membrane composed of membrane materials- lipid, protein, glycoproteins | viral envelope |
| can a virus make an envelope? | no |
| o Virus has envelope - how does it have to be transmitted? | TO CLOSE PERSON TO PERSON CONTACT OR BLOOD ; the envelope makes it very labile |
| viral envelope is environmentally_______- sensitive to acid, detergents, drying, heat, cannot survive GI tract | labile |
| poxvirus has an envelope but the morphology is neither icosahedral nor helical, but is_________ | complex |
| Some, but not all, icosahedral viruses have an________ | envelope |
| envelope________ are targets for immune responses and vaccine components | antigens |
| most abundant biological entity on earth | bacteriophages |
| ______ viruses are ALWAYS the exception for type of symmetry | Poxes - complex |
| why do bacteriophages play an important ecological role? | recycle carbon and organic matter so that new life can be generated |
| Since their discovery in 1915, bacteriophages have played an important role in our understanding of ______ ______ and ________ | molecular biology and genetics. |
| lecture 2 slide 5 - hershey chase | |
| The majority of bacteriophages contain a _____ and _______ structure. | head and tail |
| what are the 4 basic shapes or symmetries of bacteriophages? | head and tail structure icosahedral helical pleomorphic (shape depends on environmental conditions) |
| bacteriophages are grouped by _______ and _____ _____ _______ | structure; nucleic acid genome |
| what are the 2 replication lifestyles of bacteriophages? | lytic, lysogenic |
| all bacteriophages go through _______ infection, some go through _________ infections | lytic; lysogenic |
| virus infects cell completes life cycle generating new phage kills and lyses cell releasing progeny phage | lytic infection |
| virus infects cell viral genome integrates into the bacterial chromosome establishes a dormant or latent state | lysogeny |
| lecture 2 slide 13 picture | |
| what are the 5 basic steps of lytic infection? lecture 2 slide 15 | attachment, penetration of nucleic acid into host, biosynthesis phage gene expression and genome replication, assembly, release |
| in phage adsorption or attachment, legs have________ for attaching o virus-host interaction is_______ based on if the virus can bind and attach to particular cell | receptors; specific |
| phage attachment happens – causes tail process to release enzyme –________ ♣ enzyme pokes hole in bacterial cell wall ♣ cell wall has peptidoglycan – tough | lysozyme |
| o the tail part has_________ (actin, myosin) that contract like muscles and DNA inserted o when the assembly of this virus takes place, incorporates ATP into it so it can use it for contraction process | proteins |
| attachment (adsorption) causes a_________ change, resulting in contraction of the tail sheath and penetration of the bacteriophage tail into the cell. | conformational |
| steps of assembly in order (lecture 2 slide 21) | copy of genomic DNA is "reeled into" a preassembled icosahedral head, tail is assembled, final assembly of head and tail |
| in the phage release process of lytic infection, phage enzymes________ (break) bonds in the peptidoglycan of the bacterial cell wall, allowing the viruses to be released. | hydrolyze |
| what is different in lysogenic infection compared to lytic infection life cycle? | when the phage penetrates the cell wall, the genome does not go through biosynthesis; it is incorporated into the host chromosome and will be replicated with the host chromosome until the virus is induced |
| Lysogenic bacteriophages infect their hosts but do not kill them. T or F | true |
| in a lysogenic infection, The integrated bacteriophage genome is called a_________. | prophage |
| The viral DNA replicates every time the cell copies its chromosomal DNA during cell division in lysogenic infection. T or F | true |
| __________Conditions Influence the Phage Life Cycle | Environmental |
| environmental conditions are favorable for bacterial and phage growth (i.e. optimal temperature and sufficient nutrients). | lytic infection |
| environmental conditions are NOT favorable for bacterial and phage growth. | lysogeny |
| A type of lysogeny also occurs in human viruses: Latency – what two?) | herpesviruses retroviruses (HIV |
| the transfer of genes and genetic traits from one bacteria to another | genetic exchange |
| Genetic exchange in bacteria may result in: increased_________ transfer of _______ ________ evasion of ______ ______ _______ | pathogenicity; antibiotic resistance; host immune defenses |
| o Genetic exchange is good for bacteria because allows them to________ and change | evolve |
| 3 modes of genetic exchange in bacteria | transformation, conjugation, transduction |
| _________- uptake of naked DNA (genes) through cell wall into bacteria __________- uptake of DNA through sex pili ________- genetic exchange mediated by a virus | Transformation; Conjugation; Transduction |
| what are the Two modes of genetic exchange by phage transduction | generalized and specialized |
| in _______ transduction, during lytic infection, a small piece of bacterial DNA is packaged into a phage particle and transferred into a recipient cell any chromosomal gene can be transferred | generalized ; lecture 2 slide 32 |
| specialized transduction depends on _________ | lysogeny |
| in _______ transduction, during lysogeny phage DNA integrates into host chromosome; upon induction, prophage exits incorrectly and takes along adjacent host DNA genes, which get incorporated into recipient cell | specialized |
| in specialized transduction, only chromosomal genes_________ to prophage will be transferred | adjacent; lecture 2 slide 34 |
| occurs when a lysogenized bacteriophage increases the pathogenicity of a bacteria | lysogenic conversion |
| what are some bacterial diseases that become pathogenic from lysogenic conversion of bacteriophages? | diptheria, cholera, scarlet fever |
| o________ – bacteria build up in body ♣ heart valves, knee implant, hip implant o problems in medicine o many antibiotics can’t get to them well | BIOFILM |
| Bacteria protected in_______ are often not sensitive to antibiotics- causes treatment problems | biofilms |
| beneficial bacteriophage in biofilm is what? | Bacteriophages may be useful to control bacterial biofilms by killing antibiotic resistant bacteria on medical devices. |
| Bacteriophages are a potential therapeutic against ______ ________bacteria | antibiotic resistant - Staph infection |
| look at advantages and disadvantages of phage therapy - lecture 2 slide 49 | |
| bacteriophages o Can make a normally non pathogenic bacteria very pathogenic by a process called_______ ________ | lysogenic conversion |
| Bacteriophages Are a Threat to _______ and ________Industries; 1%–10% of dairy product fermentation batches are lost to bacteriophage infection.often because the raw starting materials are contaminated with undetectable numbers of bacteriophages | Fermentation and Pharmaceutical |
| used in clean rooms of cheese, meat, and poultry processing plants to inhibit growth of Listeria on products such as lunch meat and hot dogs | LISTEX P100 |
| a cocktail of 6 Listeria bacteriophages in the form of an application spray | LISTEX P100 |
| _______is a foodborne illness caused bacterium Listeria monocytogenes. contaminated lettuce may cause outbreaks of GI disease occurs in pregnant women (miscarriage, stillbirth, premature delivery), newborns, and people with weakened immune systems. | Listeriosis |
| Due to their smaller________, viruses have limited capacity to synthesize all of the products needed to replicate. | genomes |
| viral replication largely depends on using cellular biosynthesis machinery including:what 3 things? | DNA synthesis enzymes, transcription factors, translation factors |
| what is the problem with antivirals? | o Problem with antivirals – the virus is using the same biochemistry of our cells and so to find antiviral agent have to find something that will affect target of virus but won’t be toxic to eukaryotic cell. NOT EASY |
| eukaryotic cells ribosomes vs prokaryotic cells | eukaryotic - 80S (60S and 40S) prokaryotic - 70S (50 AND 30) |
| eukaryotic cells have a defined _________ and ______; prokaryotes do not | nucleus; mitochondria |
| what direction is DNA synthesized? | 1 direction - 5' to 3' |
| all DNA replication has to be initiated by a ________ | primer |
| DNA unwinding proteins | helicase and single stranded binding proteins |
| ________ fragments solve lagging strand problems | okazaki |
| DNA replication of eukaryotic genomes is complex and involves many replication proteins and enzymes By contrast, viral genomes are much smaller and DNA replication is less complex | |
| viruses and eukaryotic cells both have to do gene expression. T or F | true |
| transcription in the cell _______; translation in the cell _________ | nucleus; cytoplasm |
| in transcription, o an enzyme called a _____________ will copy DNA into a mRNA strand | DNA dependent RNA polymerase |
| 3 steps of transcription | initiation, elongation, termination |
| ________ and _________ are added to the RNA. This processing helps to stabilize the RNA. | Poly A tail and mRNA cap; so exonuclease can't digest it |
| viruses will add 5' cap and 3' poly A tail and splice out introns in transcription. T or F | true |
| ________ viruses are king of splicing | adeno |
| coding sequence of gene starting with ATG start site and ending with stop sites | open reading frame |
| review slides 20-23 lecture 2 | |
| o_________ happen in virus from a sloppy copying which leads to change in protein which leads to virus mutants – no one does it better than the AIDs virus | Mutations; o Mutations in DNA = mutations in RNA = mutations in protein |
| LOOK AND UNDERSTAND ALL PARTS OF ONE STEP GROWTH CURVE | |
| what are the stages in a one step growth curve | attachment and penetration, eclipse, maturation, release |
| why are there two lines on a one step growht curve | intracellular and extracellular |
| ________period is the time it takes for a virus to complete its replication cycle to generate new virus particles within a cell. | Eclipse |
| The end of the________ period indicates the time it takes to______ infectious virus from the cell for infection of other cells. | maturation; release |
| The________ indicates the amount of new virus generated. | yield |
| the one step growth curves for different viruses are the same or different | different |
| steps for virus replication | attachment, penetration, uncoating, biosynthesis, assembly, matuation, release |
| virus from the protein capsid and release of viral nucleic acid into the cell | uncoating |
| of virus to the host cell receptor on cell membrane | attachment |
| transcription of the viral genome into messenger RNA translation of viral mRNA into viral proteins, including viral enzymes replication of viral DNA or RNA genome into progeny nucleic acids | biosynthesis |
| _________of virions into infectious virus including addition of viral envelope for some viruses. | Maturation |
| Viruses attach to_______ on host cells | receptors |
| o Attachment and absorption is VERY________; depends on specific receptors on virus capsid/envelope interacting with receptors on host cell | specific |
| o Some viruses are________-specific ♣ Viruses that infect humans and only humans; cows and only cows etc. | species |
| some viruses May be specific regarding cell _____ or ______ | type or tissue |
| Viral _____ ______ or _______ refer to the type of cells that a virus infect. | host range or tropism |
| a viruse _______ with the cell membrane | fuses |
| the ability of a virus to get into the cell | virus penetarion |
| what are the 2 ways of penetration by enveloped viruses? | receptor fusion and endocytosis |
| fuse their envelope with the cell membrane and the capsid gets released into the cell | receptor fusion |
| ♣ Virus is engulfed by cell membrane and the virus capsid can get out of endosome | endocytosis |
| Penetration of a naked (non-enveloped) virus by_________ in clathrin- coated pits | endocytosis |
| During________, the viral capsid is broken down by cellular enzymes and the virus nucleic acid is released into the cell cytoplasm or nucleus. | uncoating |
| After______, viral particles are not seen in infected cells by electron microscopy. | uncoating |
| why does eclipse period go to 0 on the one step growth cruve | o During eclipse phase, there is viral DNA/RNA there but no infectious virus particles there and that is why it goes to 0 there |
| Viral Gene Expression Transcription of viral genes- viral mRNA Translation of viral mRNA into proteins- structural – capsid, envelope proteins nonstructural - enzymes Replication of the viral DNA or RNA genome | viral biosynthesis |
| DNA virus replication and virion assembly occurs in the cell _______- where cellular DNA replication enzymes are located.* except poxviruses | nucleus |
| DNA viruses induce ______ _______ in infected cells. | intranuclear inclusions |
| these are USE FOR DIAGNOSIS OF dsDNA VIRUSES | intranuclear inclusions |
| o First genes expressed are going to be the _____ ______ genes ♣ Transcripts made and bind to ribosomes in cytoplasm and make proteins –_______ proteins | immediate early; regulatory |
| Regulatory proteins made from immediate early gene expression turn on next set of genes - _______ genes | early |
| o Early gene products are used in _____ _______ | genome replication and just ohter proteins |
| late gene products make _____ ______ | capside and envelope ; structural |
| turned on by early; ♣______ genes – structural; made last and make capsids and glycoproteins | Late |
| o Viral nucleic acid synthesis occurs during this time on the one step growth curve / viral replication | eclipse period |
| • During the early stage of DNA virus gene expression Enzymes involved in ______ _________ are produced | DNA replication |
| • Poxviruses are large DNA viruses that replicate entirely within the host cell________; and induce inclusions here | cytoplasm |
| • Hepatitis B is DNA virus but goes through______ intermediate step in its replication cycle and utilized reverse transcriptase | RNA |
| Viral RNA replication in cell________ with ________ inclusions in infected cells (except influenza) | cytoplasm; intracytoplasmic |
| Since cells cannot replicate RNA, viruses must encode an ____ ______ _____ _________ (transcriptase) | RNA dependent RNA polymerase |
| Viral transcriptases do not have ___________ability so RNA viruses are more prone to mutation (resistance to antiviral drugs and vaccines) | proof-reading |
| RNA viruses have________: | polarity |
| viral RNA genome directly serves as messenger RNA (mRNA) for translation into viral proteins synthesizes viral encoded transcriptase | + polarity RNA viruses |
| what is the most important enzyme that RNA viruses need to have in their genome? | transcriptase so they can copy their genome |
| what is one of the first proteins made by a positive polarity RNA virus? | viral transcriptase |
| Positive polarity RNA viruses must synthesize a complementary______ RNA strand. | negative |
| what does the complementary negative RNA strand do for a positive polarity virus? | used as a template to generate more + strand RNA. |
| • + RNA replication o negative strand is an________ and be copied by transcriptase into another + strand | intermediate |
| cannot bind to ribosomes viral RNA genome cannot serve as mRNA | negative polarity RNA viruses |
| what is unique about the negative polarity RNA virus? | viral RNA transcriptase must be included within virion capsid |
| -RNA virus- entry and uncoating, transcriptase copies genomic RNA into complementary ______ which can be used: as mRNA for making viral transcriptase and other viral proteins as a template to copy into new –RNA for inclusion into progeny viruses | +RNA |
| Retroviruses like HIV are RNA Viruses that use a______ Intermediate to Replicate; viral reverse transcriptase copies the viral RNA genome into DNA which is integrated into the host cell chromosome | DNA |
| lecture 3-5 slide 81 | |
| which mutate or evolve more rapidy - RNA or DNA viruses? | RNA - RNA polymerases lack proofreading ability |
| occurs when an appropriate concentration of virus proteins and genomic nucleic acids are reached and localized at specific sites within the infected cell | viral assembly |
| o If it is enveloped =_______ will occur and virus will pick up an envelope from host cell plasma membrane | maturation |
| Newly formed viruses are released from the cell into the outside environment | virus release |
| what are the 5 Possible Outcomes of Virus Infection | abortive, lytic, persistent, latent, transformation (oncogenesis) |
| virus cannot complete its replication cycle no infectious virus produced | abortive infection |
| o dog licks you, you cant get canine parvo virus – it will go through______ infection | abortive |
| virus completes replication cycle kills cell may cause acute disease | lytic infection - more typical |
| virus replication continues generating infectious virus cell is not killed measles virus | persistent |
| virus establishes a dormant infection (no active replication) may reactivate at a later time herpesviruses, HIV | latent infection |
| virus does not kill cell, but rather induces cell growth- cancer papillomavirus, retroviruses | transformation (oncogenesis) |
| Any of the 7 stages of the virus life cycle can be targeted for_______ intervention: | antiviral |
| • A virus attaches and penetrates a host cell. The virus comletes its replication cycle and releases infectious virus. The host cell is not killed. This is an example of | persistent infection |
| an infectious agent that causes illness or disease virus, fungus, bacteria, protozoa | pathogen |
| the ability of a virus to cause disease a genetic trait of the virus viruses can exert a range of disease severity | pathogenic |
| the degree of pathogenicity of a virus as indicated by disease severity and the ability to invade tissues of the host a genetic trait of the virus | virulence |
| molecules produced by viruses that contribute to pathogenicity i.e, some viruses produce factors that help them evade host defenses | virulence factors |
| the lack of pathogenicity or ability to cause disease (attenuated) | avirulent |
| The pathogenicity a virus may vary depending on_____ conditions. | host |
| Name a condition in which a normally avirulent virus is highly pathogenic. | person is immunosuppressed - case where normally avirulent virus could cause some damage |
| Name a condition in which a normally virulent virus is NOT highly pathogenic. | person is vaccinated; a person who is a carrier (chicken pox) |
| able to be spread to other people | transmissable |
| capable of being transmitted from one person to another | contagious |
| what is an example of Some viruses may be more transmissible (contagious) than others. | chicken pox - highly contagious HIV - not highly contagious by casual contact |
| lecture 6,7 slide 14 | |
| the incidence of disease | morbidity |
| the incidence of death | mortality |
| The rhinovirus (common cold) virus has_____ morbidity, and _____mortality. The smallpox virus had______ morbidity and_____ mortality. | high; low; high; high |
| 5 sites of viral entry into the body? | respiratory tract, GI tract, urogenital tract, conjunctiva (eyes), skin |
| most common route of viral infection | upper respiratory tract |
| particles including viruses are trapped within mucus ciliated cells move trapped particles upward particles are removed by coughing | viral entry through the upper respiratory tract |
| Some more pathogenic upper tract viruses and can withstand the natural upper defenses (ciliated cells) and can get into_____ _____ ______ and reach bronchioles and alveoli | lower respiratory tract |
| ______ and _______ may remove viruses in the lower respiratory tract | macrophages and antibodies |
| example of upper respiratory tract viral infection vs example of lower respiratory viral infection | upper - common cold; rhinovirus lower - bronchitis and pneumonia - influenzxa |
| example of o Some viruses enter respiratory tract but spread through body and cause symptoms else where | chicken pox - breathe in and causes rash |
| o Virus is swallowed, has to get through the stomach – natural barrier for pathogens for its high acidity and churning | gastrointestinal tract |
| Viruses must pass through the acid environment of the_______ to infect cells of the small intestine. | stomach |
| major world-wide cause of disease and death 38 million pediatric cases and 2 million deaths per year 300 deaths per year in U.S. children- rotaviruses adults- noroviruses | acute viral gastroenteritis |
| viruses shed in the feces from an infected person contaminated food or water are ingested by another person viruses infect the GI tract- shedding of virus in feces cycle repeats | oral-fecal route of viral transmission |
| o Papilloma virus – doesn’t lytically kill the cells but transforms cells – lose growth properties and causes ______ | warts |
| natural defenst to viral infections in the eyes | tears; they have lytic enzymes that help guard against pathogens |
| the white part of the eye | conjunctiva |
| infection of the cornea | keratitis |
| infection of the conjunctiva | conjunctivitis - pinkeye |
| infection of cornea and conjunctiva | keratoconjunctivitis |
| o skin is pretty impermeable to infectious agents, but if you have a_______ in the skin – gives virus access through break in the skin | break; cuts, insect bites, animal bites, needle sticks |
| • A virus that causes acute gastroenteritis most likely o Can withstand the _____ ____ of the stomach o These viruses will be without an_____ Won’t have______ symmetry because if it does it has to have an envelope | acidic pH; envelope; helical |
| o Infect, get into blood stream, if that person donates blood that virus can be passed onto recipient | viruses that enter through blood stream |
| solid transplants- kidney, liver bone marrow transplants cytomegalovirus, HIV, hepatitis B, rabies | viruses that enter through transplants |
| Infections generated by a physician e.g., surgical procedures using contaminated equipment/tools. Creutzfeld-Jocob Disease (prion disease) | iatrogenic induction |
| Virus infection stays at or near the site of entry. common cold rhinovirus infects upper respiratory system and remains there until disease is resolved- does not progress to the lower respiratory tract | localized infection |
| Virus initiates infection at one site and then spreads throughout the body. chickenpox varicella-zoster virus (VZV) infects respiratory tract and then spreads through the blood causing skin rash | systemic infection |
| 2 mechanisms of viral spread of pathogenesis | localized and systemic |
| localized or systemic? warts (papilloma) papillomavirus (HPV) infects skin and causes wart- does not spread to other tissues. | localized |
| what are the two ways a systemic infection virus is spread? | viremia and nervous sytem |
| the presence of virus in the blood | viremia |
| • Viremia spreads virus to _____ _____; skin, lungs, liver, brain | target organs |
| o Experimentally one can use_______ infection to experimentally show how a virus can spread through viremia – virus getting in the blood | mousepox |
| mousepox infection - Following initial infection in the_______, the virus spreads by _____ _____ to the spleen and liver where viral replication occurs. _____ _______ spreads the virus throughout the body causing skin rash. | footpad; primary viremia; Secondary viremia |
| in chicken pox pathogenesis, Following initial infection in the _____ _______, the virus spreads by _____ _______ to the spleen and liver where viral replication occurs. ______ _______ spreads the virus throughout the body causing skin rash. | respiratory tract; primary viremia; Secondary viremia |
| in chicken pox pathogenesis, VZV establishes _____ ______ in sensory nerve ganglia. Later in life, VZV may reactivate and go into lytic infection to cause shingles (skin rash). | latent infection; |
| if someone has a latent infection of VZV, would you be able to see the virus with an electron microscope? | no; it is latent |
| example of viral spread by the nervous system | rabies pathogenesis |
| o Person bit by rabid dog on the leg; infects the muscle and skin tissues of the leg; virus replicates and attaches to _____ ______ in the leg and the virus will infect the nerve and progress up to the spinal cord to the brain | sensory nerves; |
| in systemic infection through nervous system, o Might take weeks for the virus to make the progression from the sensory nerves to the brain so there is time to vaccinate a person who has been bit by a rabid animal | |
| The_______ is a protective interface between the mother and developing fetus exchange of nutrients, gas, waste products share blood supply | placenta |
| 3 types of virus transmission to fetus or newborn | transplacental, perinatal, postnatal |
| virus crosses the placenta to infect the fetus may cause cause death (abortion) or congenital malformations human cytomegalovirus, rubella virus, Zika virus? | transplacental virus infection |
| occurs during childbirth viruses present in mother’s blood or vaginal secretions infect baby herpes simplex type 2 | perinatal virus infection |
| occurs after birth newborn is infected through infected breast milk cytomegalovirus, rubella | posnatal virus infection |
| 5 types of virus diseases | acute infection; acute infections followed by a persistent or latent infection; chronic infections with continuous virus shedding; slow infections; oncogenic infections |
| what type of virus disease? acute disease symptoms self-limited- infections last only a relatively short time, virus eliminated usually no lasting effects common cold | acute infection |
| what type of virus disease? acute disease symptoms- usually resolve within two weeks virus establishes persistent or latent infection, virus not eliminated herpesviruses, HIV | acute infection followed by persistent or latent infection |
| what type of virus disease? acute disease symptoms resolve virus continues to be produced for at least six months over time, chronic infection and inflammation results in disease hepatitis B and C | chronic infection |
| what type of virus disease? the time between initial virus infection and disease symptoms (incubation period) may be several years AIDS, Creutzfeldt-Jakob disease | slow infection |
| what type of virus disease? some viruses may induce host cells to divide out of control causing tumors and cancers papillomaviruses, RNA tumor viruses | oncogenic infection |
| 3 main mechanisms for oncogenesis | activate cell growth-stimulating genes suppress normal cell-growth breaking mechanisms prevent apoptosis (programmed cell death) |
| disease progression steps? 4 | incubation, prodromal, period of illness, convalescence |
| the time between initial virus infection and the onset of symptoms the infected person may feel OK, but could be contagious (able to transmit infectious virus to another person) | incubation period; may differ for viruses |
| the first appearance of mild or nonspecific symptoms of illness coughing, sneezing, malaise, fever often precedes more specific or serious disease symptoms | prodromal period |
| the time period when a person experiences defined disease symptoms usually contagious | period of illness |
| the recovery period after an illness ends person no longer has acute symptoms the person may feel better, but could still be contagious | convalescence |
| • A patient develops headache, sneezing, chills, malaise, and myalgia (muscle aches). These nonspecific symptoms which appear early in infection occur during the | prodromal period |
| • A pregnant woman is infedcted with the Zika virus. She has no symptoms, but the baby is born with microcephaly. The other probably transmitted the virus to the baby by which transmission? | transplacental |
| very stable in contaminated food, water, persist in environment for long periods of time | naked virus |
| • Transmission depends on________ survival of viruses | environmental |
| ♣ Virus tricks immune system into attacking itself Virus has antigens that cross react with antigens on host cells, immune system respond to viral antigen and host cell antigen and lead to pathology | auto-immune diseases |
| ♣ Natural response to a pathogen o Uncontrolled inflammation can cause disease symptoms o Interferon and cytokine responses; cytokines sometimes cause symptoms – fever, malaise, headache | inflammation |
| __________ complexes can accumulate and have size to them and get trapped in filter apparatus of the kidney – glomerulonephritis | o Antigen-antibody |
| diagnosis of viral diseases - what are some considerations? | clinical symptoms, patient history (other contacts sick, travel), season, |
| ______ diagnosis = first thing to think about= is it infectious disease? What kind – viral, bacterial, etc | presumptive |
| help from clinical lab to ensure presumptive diagnosis | confirmation |
| 5 methods used for laboratory diagnosis of viral diseases | microscopy, cell culture, viral antigen detection, nucleic acid detection, antibody detection |
| o can’t see a virus with a light microscope; what you can see is the________ of a viral disease and pathology associated with it | manifestations |
| cell rounding | cellular necrosis |
| multinucleated cells)- fusion of infected cell membranes | syncytia |
| not usually a standard procedure – requires expensive microscope and technical expertise useful to confirm specific viruses detection of enteric viruses (rotavirus) in stool samples identify unknown viruses or cases of unknown etiology | electron microscopy |
| LOOK AT ADVANTAGES AND DISADVANTAGES OF ALL DIAGNOSITC TOOLS | |
| growth of virus in cell culture specimens derived from patients are added to cell cultures available in the clinical lab | lab diagnosis - viral isolation in cell culture |
| samples derived from skin lesions, sputum, blood, urine, CSF, brain biopsy- transport to lab ASAP some viruses are readily cultured- herpes, adenovirus some viruses cannot be grown in cell culture (hepatitis B) | lab diagnosis - viral isolation in cell culture |
| viral antigen detection in patient specimens or in cell culture immunohistochemistry, immunofluorescence use virus specific monoclonal or polyclonal Ab relatively easy, rapid, sensitive, and specific | lab diagnosis - detection of viral antigens |
| viral antigens are viral _________ | proteins |
| for detection of viral antigens, have to have o specific commercially available_________ that you know react to this infection | antibodies |
| ELISA and immunofluorescence - know how it works; lecture 8 highlight | |
| in situ hybridization polymerase chain reaction (PCR) use virus specific DNA or RNA probes | lab diagnosis - detection of viral nucleic acids |
| o Hybridize a DNA probe specific for this virus and get a color reaction where hybridization occurred | in situ hybridization |
| useful method to detect viral DNA or RNA in a patient extremely sensitive- may detect as little as one viral DNA molecule and amplify several thousand-fold uses virus specific DNA primers | PCR - reverse-transcription PCR (RT-PCR) used to detect viral RNA |
| KNOW STEPS OF PCR LECTURE 8 slide 35 | |
| o Take RNA template and use an enzyme (reverse transcriptase) and copy RNA into DNA then you use standard PCR | RT-PCR |
| o Detecting antibody to a specific virus o Not actually measuring virus itself, measuring immune response to the virus; takes about 7-10 days to build up an antibody response | lab diagnosis - antibody detection |
| patient serum contains antibodies recent viral infection (acute disease): | IgM |
| patient serum contains antibodies re-infection with same virus (acute or convalescent): | IgG |
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jackjack109