Micro Final (-) RNA Viruses – Flashcards
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| What does positive strand mean? |
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| Viral genome functions as mRNA |
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| What does negative strand mean? |
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| Negative RNA genome is a TEMPLATE for mRNA |
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| What is the structure of Rhabdoviruses |
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| Rhabdo= ROD in Greek- these are BULLET-SHAPED viruses, with a Negative Sense RNA strand, ENVELOPED, helical |
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| What virus is BULLET SHAPED? |
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| Rhabdoviruses |
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| How does one typically get rabies? |
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| Bite of a rabid animal; inoculation of intact mucous membranes; aerosolization (though bites are most common) |
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| How does rabies promote its own spread? |
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| Hypersalivation with heaps of virus in the saliva combined with PROMOTING AGGRESSIVE BEHAVIOR |
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| Where does rabies spread to in the body? |
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| Directly to peripheral nerves by binding the nicotinic Ach Receptor OR indirectly into the muscle at the site of inoculation |
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| How does the rabies virus travel? |
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| RETROGRADE AXOPLASMIC TRANSPORT to dorsal root ganglion and spinal cord |
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| What virus travels via RETROGRADE AXOPLASMIC TRANSPORT? |
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| Rabies |
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| Where does the rabies virus go after brain infection? |
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| Highly innervated sites like skin, salivary glands, retina, cornea, nasal mucosa- FATAL |
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| What is the principle vector of rabies worldwide? What are the minor animal vectors? |
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| DOGS; raccoons, skunks, bats, foxes |
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| What are the classic neurological symptoms of rabies? |
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| Hydrophobia, seizures, disorientation, hallucination, paralysis, confusion, delerium |
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| What virus causes HYDROPHOBIA? |
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| Rabies |
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| What is the laboratory presentation of rabies on microscopy? |
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| NEGRI BODIES- cytoplasmic inclusions where viral assembly occurs |
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| Infection from what virus will cause NEGRI BODIES on microscopy? |
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| Rabies |
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| What is the course of treatment if rabies infection is suspected? |
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| 1 dose of human rabies immunoglobulin (HRIG) 5 doses of rabies vaccine |
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| What are the characteristics of filoviridae? |
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| Filamentous, ENVELOPED, Negative Sense RNA Virus- helical nucleocapsid endemic in Africa -Ebola and Marburg |
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| What are the main sites of tissue damage in Ebola, and what is the end result of the infection? |
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| Parenchyma of liver, spleen, LN and lungs -WIDESPREAD HEMORRHAGE THAT CAUSES EDEMA AND SHOCK |
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| How is Ebola transmitted? |
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| Airborne to animals; direct contact with blood and other secretions |
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| What are some "fascinating facts" about Marburg Virus? |
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| Exposure to African Green Monkeys imported for research and to prepare polio vaccine |
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| What are the characteristics of bunyaviridae? |
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| Segmented, ENVELOPED, Negative Sense RNA Viruses- helical -Hanta, Nairo, Phlebo, Bunya ZOONOTIC |
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| How is Hantavirus spread? |
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| Rodent born |
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| What is the vector for most Bunyaviridae? |
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| Mosquitos- can cause encephalitis |
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| Because bunyaviruses are injected directly into blood via mosquitos, how does this effect their pathogenesis? |
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| Primary viremia which spreads to target organs including CNS, liver, kidney, and vascular endothelium |
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| What are the neural and CNS complications of bunyavirus infection? |
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| Neuronal or glial cell damage, cerebral edema leading to encephalitis |
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| What is the hallmark symptom of Hantavirus infection? |
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| MASSIVE PULMONARY EDEMA (Hantavirus Pulmonary Syndrom HPS) |
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| What virus causes MASSIVE PULMONARY EDEMA? |
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| Hantavirus |
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| What are the clinical symptoms of Hantavirus infection? |
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| Hantavirus Pulmonary Syndrome (massive pulmonary edema); hemorrhagic tissue destruction and lethal complications; FUNCTIONAL IMPAIRMENT OF VASCULAR ENDOTHELIUM; significant leg cramping and pain |
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| What virus causes FUNCTIONAL IMPAIRMENT OF VASCULAR ENDOTHELIUM? |
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| Hantavirus |
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| What is the vector for bunyaviruses and where do they breed? |
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| Aedes; water treeholes and discarded trees |
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| How are humans infected by Hantavirus? |
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| Close contact with rodents or droppings |
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| What are the symptoms of Hantavirus? |
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| Non-specific presentation with short febrile prodrome lasting 3-5 days -fever, myalgia, headache, chills, dizziness, non-productive cough, nausea, vomiting SHORTNESS OF BREATH, TACHYPNEA, TACHYCARDIA |
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| What are the symptoms of progressed Hantavirus? |
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| Cardiopulmonary phase- hospitalization is necessary, often with ventilator, to manage TACHYPNEA and TACHYCARDIA |
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| What are the 4 Arenaviridae, and what do they cause? |
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| LCMV- Lymphocytic Choriomeningitis Virus Lassa, Junin, and Machupo all cause Hemorrhagic Fever |
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| What is the structure of the Reoviruses? |
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| DOUBLE-STRANDED NAKED RNA- reovirus, rotavirus, Colorado Tick Fever Virus |
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| How is rotavirus transmitted, and what does it cause? |
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| Fecal-oral; gastroenteritis without blood or pus |
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| How is reovirus transmitted, and what does it cause? |
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| Fecal-oral AND respiratory; common cold, gastroenteritis |
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| How is Colorado Tick Fever Virus spread, and what does it cause? |
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| Ticks- virus infects erythroid precursors; Flu-like illness, biphasic fever, conjunctivitis, possible rash |
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| What virus causes BIPHASIC FEVER and CONJUNCTIVITIS? |
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| Colorado Tick Fever Virus |
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| What are the 3 viruses in the orthomyxoviridae family? |
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| INFLUENZA A, B, and C |
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| Which influenza virus can be found in animals and humans, and which can be found only in humans? |
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| INFLUENZA A- ANIMALS AND HUMANS (Shift can only happen in A) INFLUENZA B- ONLY HUMANS |
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| Which influenza virus can undergo SHIFT? |
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| Influenza A |
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| What type of viral change causes EPIDEMICS in influenza? |
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| Antigenic DRIFT |
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| What type of viral change causes PANDEMICS in influenza? |
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| Antigenic SHIFT |
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| What is the structure of the orthomyxoviridae? |
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| Negative Stranded ENVELOPED RNA viruses- 8 SEGMENT Genome |
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| What is Hemagglutinin (HA)? |
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| On the influenza viral envelope- responsible for entry of virus into cells -BINDS TO N-ACETYLNEURAMIC ACID (SIALIC ACID) ON THE CELL SURFACE |
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| What part of influenza binds to sialic acid on the host cell surface? |
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| Hemagglutinin (HA) |
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| What virus has hemagglutinin and what does it bind to? |
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| Influenza; Sialic Acid |
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| What is Neuraminidase (NA)? |
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| On the influenza viral envelope- liquifies mucous in the respiratory tract to allow the virus easy access to epithelial cells -REMOVES SIALIC ACID from proteins in virus and infected cells |
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| What part of the influenza virus does the new class of flu drugs block the function of? |
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| Neuraminidase- prevents ACCESS |
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| What do the nomenclature designations of H and N stand for? |
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| Hemagglutinin and Neuraminidase |
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| How many antigenically different flu vaccines are included in the main flu vaccine? |
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| 3 |
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| What is antigenic shift? |
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| The sudden replacement of one flu subtype that has been around for decades with a brand new subtype- -always involves the HA subtype, but only sometimes the NA subtype |
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| What flu subtype is ALWAYS involved in antigenic SHIFT? |
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| HA |
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| How does antigenic shift occur? |
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| Only in Type A influenza virus (because they infect animals as well as humans); REASSORTMENT OF VIRAL RNA SEGMENTS WHEN THERE IS COINFECTION WITH 2 DIFFERENT INFLUENZA SUBTYPES (must have all 8 genome segments together) |
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| What is it called when cells are coinfected with two different influenza subtypes and the RNA segments are reassorted to make a new virus? |
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| ANTIGENIC SHIFT |
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| What must happen to the viral genome in antigenic shift? |
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| ALL 8 PIECES OF THE GENOME MUST BE ASSEMEBLED (FROM 2 DIFFERENT SOURCES) |
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| What is antigenic drift and what types of influenza viruses can use it? |
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| Mutations in RNA; both types A and B can drift -small changes in the amino acid sequence of HA and NA |
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| What is the term for small changes in the amino acid sequence of HA and NA in influenza? |
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| Antigenic Drift |
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| What does antigenic drift allow for in a population? |
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| Drift in HA allows the virus to circumvent existing immunity in a segment of the population each year |
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| How many antigenic sites on HA are recognized by antibodies, and what happens to these sites during antigenic drift? |
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| 4 sites; gradual AA sequence changes occur to allow the virus to avoid antibody recognition |
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| What is the consequence of destruction of ciliated epithelium in viral infections? |
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| Like Influenza- the cilia don't work, so stuff doesn't get cleared as well, and it creates a chain reaction with secondary BACTERIAL INFECTIONS |
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| How is the influenza virus spread? |
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| Respiratory Droplets |
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| What cells are infected by influenza virus? |
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| Ciliated columnar epithelium |
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| How does influenza enter ciliated epithelium? |
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| HA binds to sialic acid receptors and the virus is phagocytized |
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| What is the effect of M2 protein in influenza infection? |
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| The endosome pH drops to 5.5 because the M2 protein acts as an ion channel in the virus envelope; nucleocapsids are released into the cytoplasm |
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| What viral infection is characterized by ABRUPT ONSET of fever? |
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| Influenza |
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| What is the progression of symptoms in influenza infection? |
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| Abrupt onset of fever; Headache (severe RETROORBITAL pain), myalgia, sore throat, and non-productive cough; 4th day- respiratory symptoms predominate (pharyngitis, laryngitis, and tracheobronchitis); Cough and malaise may last 1-2 weeks after other symptoms TOTAL DURATION= ABOUT 1 WEEK |
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| What causes the systemic symptoms in influenza infection? |
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| Cell damage initiates acute inflammatory response, and systemic symptoms are due to the release of inflammatory mediators |
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| In what setting is influenza diagnosis particularly important? |
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| Nursing homes |
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| What do rapid influenza tests not differentiate? |
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| Between influenza A and B |
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| What should not be given to children or adolescents as a treatment for the flu? |
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| Aspirin: can cause Reye's syndrome- similar to chicken pox |
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| What antiviral treatments are used against the flu in severe cases? |
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| Amantadine and Rimantadine: specific activity against TYPE A viruses- they interfere with viral uncoding -can be used prophylactically, and are best given within 48 hours |
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| How do Neurominidase Inhibitors work? |
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| Inhibit influenza A and B neurominidase- the drugs are ANALOGS OF SIALIC ACID, so they block the active site of Neuraminidase -Prevent viral infection of uninfected cells TAMIFLU and RELENZA -most effective in the first few days |
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| What type of vaccine is available for influenza? |
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| Inactivated (killed) or live attenuated- usually given in the late fall before the flu season starts -Both Type A and Type B vaccines are given concomitantly |
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| What two subtypes of Type A influenza are still circulating currently? |
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| H3N2 and H1N1- both are included in vaccine |
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| What is picked each year for the trivalent vaccine? |
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| One H3N2, one H1N1, and one type B strain -chosen as the strains most likely to be prevalent in the upcoming winter |
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| What is special about the Paramyxoviridae (measles, etc.) in terms of their action on cells? |
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| The can induce cell to cell fusion forming a SYNCYTIA- giant, multinucleated cells |
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| What Negative Sense RNA viral family causes cells to form SYNCYTIA? |
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| Paramyxoviridae, like measles, parainfluenza, RSV FUSION PROTEIN IN THE ENVELOPE |
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| Name four viruses in the paramyxoviridae family: |
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| Measles, parainfluenza, mumps, and RSV |
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| What virus causes measles, and what are its symptoms? |
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| Morbillivirus; rash, high fever, cough, conjunctivitis, coryza (symptoms of a head cold) |
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| What is the pathogenesis of measles? |
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| Cell fusion, formation of giant cells- virus passes directly from cell to cell and escapes antibody recognition |
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| How is measles transmitted? |
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| Respiratory droplets |
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| Where does measles replicate, and where does it spread? |
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| Respiratory tract; spreads to lymphatics and causes viremia |
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| What are some possible sites of infection due to measles? |
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| Conjunctiva, respiratory tract, urinary tract, small blood vessels, lymphatics, and CNS |
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| What is the sneaky thing about the spread of measles? |
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| It can be spread in respiratory secretions before AND after the onset of symptoms. |
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| What virus can be spread in respiratory secretions both before AND after the onset of symptoms? |
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| Measles |
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| What is the difference in timeframe between German Measles and regular Measles? |
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| German Measles= RUBELLA= 3 days Measles Measles= RUBEOLA= Full Week |
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| What is roseola? |
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| Caused by Herpes 6- FEVER GOES AWAY, THEN RASH APPEARS |
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| What are the 3C's of measles? |
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| Cough, conjunctivitis, and coryza (runny nose) |
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| What are Koplick spots, and in what viral infection do they occur? |
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| Look like small grains of sand that appear on buccal mucosa, conjunctiva, or vagina- Associated with MEASLES |
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| What is the relationship between Koplick Spots and the rash in measles? |
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| Spots appear before the rash |
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| What characterizes the rash in measles? |
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| 12-24 hours after the appearance of Koplick spots, the measles rash begins BELOW THE EARS and spreads all over the body MACULOPAPULAR RASH -FEVER IS HIGHEST ON THE DAY OF THE RASH |
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| Where does the measles rash start? |
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| Below the ears, spreads to entire body |
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| What virus causes a maculopapular rash that starts BELOW THE EARS, and the presence of which marks the day that the fever is highest and patient is sickest? |
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| Measles |
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| What causes 60% of measles deaths, and what other virus can cause this? |
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| Giant Cell Pneumonia- also caused by chickenpox |
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| What characterizes atypical measles? |
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| Occurs in people that have by vaccinated by inactivated vaccine and have insufficient protection- -ILLNESS BEGINS ABRUPTLY AND IS MORE INTENSE THAN PRIMARY MEASLES |
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| What is Subacute Sclerosing Pan Encephalitis (SSPE) and what virus causes it? |
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| -Extremely serious neurological sequelae of measles-RARE -defective measles virus in the brain acts as a slow virus- it can replicate and spread from cell to cell, but is not released -changes in behavior, muscle jerks, blindness |
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| What is the diagnostic test for Subacute Sclerosing Pan Encephalitis? |
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| High levels of measles Ab in blood and CSF |
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| How is measles diagnosed? |
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| Usually clinical presentation- difficult to isolate and grow, but can be found in secretions, blood, urine, and brain tissue -can LOOK FOR GIANT CELLS -immunofluorescence -Virus-specific IgM when rash is present |
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| What are the symptoms of paramyxovirus parainfluenzae? |
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| Mild, cold-like symptoms, but can cause serious upper respiratory tract disease CAN CAUSE CROUP |
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| What virus can cause CROUP, and what is it? |
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| Parainfluenzae (paramyxovirus); SEAL BARKING COUGH |
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| What virus causes a SEAL BARKING COUGH? |
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| Parainfluenza- this is called Croup |
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| What is the diagnostic for parainfluenza? |
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| Isolated from nasal washings and respiratory secretions- SYNCYTIA can be observed by IF Hemadsorption and hemagglutination |
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| What virus causes acute, benign parotitis? |
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| Mumps |
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| What virus causes painful swelling of the salivary glands? |
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| Mumps |
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| What is acute benign parotitis? |
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| Painful swelling of the salivary glands, as in MUMPS |
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| What type of infection is mumps, and to what cells does it initially spread? |
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| Lytic; upper respiratory tract epithelium |
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| Where in the body does mumps spread? |
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| Via viremia to testes, ovary, pancreas, thyroid, and CNS in 50% of cases |
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| What virus causes orchitis and sterility? |
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| Mumps |
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| What are the reproductive consequences of mumps in males? |
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| Orchitis and sterility |
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| How is mumps spread? |
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| Respiratory droplets- usually in younger people |
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| What are the clinical symptoms of mumps? |
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| BILATERAL parotitis; sudden onset low grade fever, headache, malaise Oral exam reveals redness and swelling of OSTIUM OF STENSON's DUCT |
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| What virus causes redness and swelling of the ostium of Stenson's duct? |
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| Mumps |
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| What are the potential complications of mumps? |
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| CNS involvement (50%); pancreatitis; deafness; orchitis-sterility; death |
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| How is mumps diagnosed? |
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| Virus can be recovered from saliva, urine, pharynx, and CSF -can grow in culture and look for MULTINUCLEATED CELLS -4x increase in specific IgM -Hemagglutination inhibition, ELISA, IF |
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| What is the most frequent cause of fatal respiratory tract infections in infants and young childrean? |
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| Pneumovirus: Respiratory Syncytial Virus |
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| What should you immediately think of in a case with an INFANT THAT HAS VIRAL PNEUMONIA? |
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| Respiratory Syncytial Virus |
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| What does RSV cause in adults? |
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| A cold |
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| Describe the pathogenesis of Respiratory Syncytial Virus: |
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| Upper Respiratory Tract Syncytia Direct viral invasion of respiratory epithelium NECROSIS OF BRONCHI AND BRONCHIOLES LEADING TO MUCUS PLUGS AND FIBRIN which can block airway |
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| What virus leads to mucus plugs and fibrin that can block the airway? |
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| RSV |
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| In what season does RSV almost always occur? |
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| Winter |
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| How is RSV transmitted? |
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| On the hands by fomites, and by respiratory routes; Shed in respiratory secretions for days |
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| What are the symptoms of RSV? |
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| Ranging from common cold to pneumonia RUNNY NOSE Some cases can progress to LRT and cause bronchiolitis in infants; low grade fever, tachypnea, tachycardia and wheezing |
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| What RESPIRATORY virus causes a VERY SERIOUSLY RUNNY RUNNY NOSE? |
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| RSV |
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| How is RSV diagnosed? |
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| Rapid tests |
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| How is RSV treated? |
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| Supportive care, oxygen, IV fluids Ribavirin- can be administered as an inhalant Synagis- Monoclonal Ab against F protein |
