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49 Cards in this Set
- Front
- Back
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What do all viruses require? |
They need to get inside the host cell and use the hosts machinery to replicate. They are obligate intracellular parasites |
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What does it mean when they say viruses are obligate intracellular parasites |
- They cannot replicate outside of the host cell - Lack ribosomes for protein sysnthesis - little to no biosynthetic machinery - ALL information for that virus is contained in the genome |
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What do respiratory virus infections cause? |
-Cause about 80% of acute illness that results in a loss of time from work -80% of all respiratory infections are VIRAL -Influenza and pneumonia causes extended absences |
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Do respiratory Viruses have seasonality? |
Yes right now |
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What is the number one respiratory offender? (group? Ciculates as and who do they infect?) |
Influenza -Orthomyxoviridae group - Circulates as three types A,B,C A is naturally found in water fowl and can infect humans, swine, poultry ect B and C only infect humans and never cause pandemics |
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What are the four important thing that make up influenza viral structure and function? |
HA (15 types) - binds to oligosacharides on cell surface containing terminal sialic acids NA (9 types) - cleaves sialic acid groups upon viral exit/entry (tamiflu) M2 - essential for virus uncoating during viral entry PB1,2 and PA - are required for genome replication |
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What do antivirals target and antibodies target? |
Anti virals target many of these proteins however, antibodies specifically target NA and HA |
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What is Antigenic Drift? |
Acquiring point mutations to escape the immune system Small mutations |
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Why is there a new vaccine every year? |
Due to antigenic drift. Small amino acids can change within HA or NA or they can produce minor variations within the same subtype due to lack of proofreading of the RNA polymerase -- This may alter there ability to enter host cells and evade antibody responses. |
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What happens if there are major antigenic changes ? |
There is the potential for a pandemic |
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What are some signs and symptoms for Influenza? Also what is not a primary concern? |
Fever, malaysia, chills, coughing and sneezing for 3-5 days Nausea and Vomiting is not a primary concern but it can occur in kids (20-25%) |
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Where do minor and fatal influenza occur? |
The influenza virus can be minor in young healthy adults but can be fatal in elderly people and those with cardio respiratory diseases. |
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What happened in 1918? (what pandemic, how many people did it kill, how much more lethal than other strains and what was the mortality of the young and healthy?) |
There was a spanish flu pandemic It killed 40-100 million people 50X more lethal than other strains 2.5-5% mortality in the young and healthy (unusual) |
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Why was the Spanish flu so deadly? (what produced the immune response? What causes many of the intense symptoms? What did a lot of people get secondary to the flu? How did it occur?) |
H1 hemagglutinin produced an intense immune response It was the immune response that causes many of the intense symptoms Many individuals got secondary bacterial pneumonia It occurred in two waves, the second being much deadlier (induced intense immune response) |
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What happened in 2009 ? (what was it? Who did it infect? What did it replace? |
The H1N1 human swine influenza - mainly infected young people and pregnant women -Very mild illness -Replaced previous strain |
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What did the human swine influenza not contain? |
It didn't contain PB1 - F2 protein rather it binds to inner mitochondrial membrane and sensitises cells to apoptosis caused inflammation -- which was a significant virulence factor |
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Why was the Human swine influenza not as bad as it could have been? |
- people born before 1975 had cross protection from previous flu outbreaks -Majority of T cell epitopes were similar to past H1N1 -CD8 cytotoxic t cells were good a eliminating infected cells |
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What was the main cause of mortality for H1N1? |
due to high levels of IL-17 |
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Where do epidemics of influenza usually start? |
in the Far East |
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What does seasonality allow in terms of the influenza virus? |
It allows the development of type specific vaccines (usually trivalent) which can effectively prevent widespread mortality |
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When does influenza transmit usually? |
15-25% humidity |
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What is the flu vaccine how is it made? |
Inactivated whole viruses that express many HA antigens Made from 1 chicken egg per vaccine |
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How is the flu vaccine determined? |
by global surveillance of circulating strains |
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What para influenza contain? |
ssRNA enveloped virus posses both hemagglutinin and neurominidase |
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Explain the different types of parainfluenza/paramyxovirus |
Parainfluenza 1 and 3 are closely related and cause acute laryngotracheatis (croup), bronchitis, and pneumonia in young children Parainfluenza 2 causes severe lower respiratory tract disease in children Parainfluenza 4 causes milder illnesses for all ages |
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How do you treat parainfluenza/paramyxcovirus? |
Corticosteroids and epinephrine |
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What parainfluenza induced croup? |
swelling inside the larynx and swollen and sore narrow air way inside the trachea |
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What is respiratory syncytial virus (RSV) (named after, symptoms, and important cause of what...) |
Named for its ability to cause cell fusion (syncytia) Symptoms include bronchiolitis, necrotizing pneumonia, coughing wheezing may become severe leading to hyperinflation and hypoxia Very important cause of respiratory disease in infants |
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When do most outbreaks occur for Respiratory Syncytial Virus? |
in colder weather within localized settings 50% of families can be affected |
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How do you diagnose and treat respiratory syncytial virus? |
diagnosis can be done through rapid viral antigen tests Treatment is provide oxygen and ventilator and if necessary ribavirin. |
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What is Ribavirin? (what does it do and what else is it used for?) |
-Stops the ability of a virus to replicate its genome and it only affects viral RNA synthesis -In addition to helping respiratory syncytial virus it can also be used for hepatitis C infection |
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What does ribavirin mimic? |
It has nucleotide analogues ( mimics A,C,G,T nucleotides) |
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Is there a vaccine availible for respiratory syncytial virus ? |
Trial in 1966 killed two children Infants who were infected had enhanced disease symptoms Formalin killed the virus and changed important parts of the virus required for effectiveness Weak antibody response |
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What is the Adenovirus? (where does it replicate, how is it released, and what does in cause in children under two?) |
It replicates in the nucleus of infected cells It is released by host cell lysis 10% of acute febrile illness in children under two is causes by adenovirus |
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How does the adenovirus bind to a host cell? |
uses extended fibres and knobs to bind to the host cells for entry |
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How is adenovirus spread and what is it capable of? |
it is spread through fecal oral route and aerosols It is capable of latency by integrating the viral genome |
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What are the symptoms of adenovirus? And how many types of adenovirus currently |
common cold, fever, follicular conjunctivitis, gasterienteritis currently there are 35 types of adenovirus |
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How do you treat adenovirus? |
no specific treatment as its usually a mild disease |
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Whats the common cold reffered to as? |
Rhinovirus |
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What is the rhinovirus? (stereotypes and transmission) |
it is a single stranded positive sense RNA virus "ready to go" 108 stereotypes and people remain susceptible throughout life Transmission is through direct contact |
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How is Rhinovirus different than poliovirus? |
they are distinguished by acid lability and optimum replication temperature of 33 degrees |
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What are the symptoms of rhinovirus? |
Acute symptoms of rhinitis result from cell damage and soluble inflammatory mediators "bradykinins" They usually clear within 7 days, if they dont clear within 10 days it is often attributed to bacterial sinusitis |
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How do you treat colds? |
use ibuprofen, decongestants and antihistamines Use a nasal aspirator for infants Zinc gluconate lozenges and ginseng may reduce rhinitis symptoms and shorten duration of cold |
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What things in terms of treating colds remain unproven? |
Steam inhalation, bed rest, large vitamin C doses remain unproven |
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What is Coronaravirus? (named after ) |
it is enveloped ssRNA virus and is named after solar corona like appearance on the electron microscope |
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How is coronavirus transmitted? |
through aerosol 3 days incubation period Short lived immunity allows for reinfection Represents 1-30% of all colds many sub clinical (not serious) |
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What is SARS coronavirus? (first associated with... how many cases and deaths suspected host species was..) |
first associated with a severe lower respiratory tract infection in japan in 1992 causes over 7000+ cases and hundreds of deaths civet cat was the suspected host species |
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How is the diagnosis done for SARS coronavirus? |
it can be done through an ELISA test; HOWEVER not positive until day 20 of illness |
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What is MERS (middle eastern respiratory syndrome) (discovered in and where all cases have been associated with.. Who are reservoirs Human to human contact?) |
discovered in 2012 in saudi arabia All cases have been associated with travel to arabian peninsula Bats and Camals are reservoirs Potential human to human spread is possible but debated |
