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What is this lecture about?

Respiratory infections. 


  • Why are viruses very particular when it comes to infection certain cells?
  • How specific can they be?
  • What does it mean to be a generalist virus?
  • Are all organisms susceptible to some viruses?  

  • Viruses are particular in infection because of the affinity of viral surface proteins to their complementary proteins on the host cell
  • They can be so specific that they only infect one type of cells on one certain host
  • A generalist virus is one that infects different hosts
  • yes all types of organisms are susceptible to some virus 


  • What does the upper respiratory system consist of? 
  • What about the lower respiratory system?

  • Upper Resp. system consists of
    • Pharyngeal sinuses 
    • Nasal cavity 
    • Pharynx( Throat)
    • Epiglottis 
  • Lower Resp. System consists of 
    • Larynx
    • trachea
    • Bronchus

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What is significant about respiratory infections?

  1. major cause of outpatient visits in the US 
  2. Most are just nuisance but can be serious or fatal
    1. Hantavirus pulmonary syndrome is more than 50% fatal. 


How do viruses contribute to disease symptoms? What is the viral pathogenesis?

The enter the cell, invade, increase in number and kill the cell. 

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What is the immunopathology of viral infections?

  • They recruit inflammatory type cells such as macrophages and neutrophils
  • They release a range of molecules that end up damaging the cells 
    • Cytotoxic cytokines (INFs, TNF) 
    • Catatonic proteins 
    • Lipid mediators 
    • Metalloproteinases (MMPS)
      • Components of oxygen burs (Superoxides) 


What are the causes of the common cold?

  • Rhinoviruse: Naked, + ss RNA
  • Adenovirue: Naked, dsDNA 
  • Coronavirus: enveloped, + ss RNA 


What are the symptoms and pathogenesis of the common cold? 

  • Symptoms:
    • Scratchy throat
    • Nasal discharge
    • malaise
    • a cough 1-2 day incubation period
  • Pathogenesis: 
    • Infects the respiratory epithelium leading to stopping the function of ciliary.
    • increases mucus secretion
      • INF and ABs stop the infection 


What are the manifestations of respiratory infections? Table from slides. 

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  • What is the epidemiology of the common cold that is caused by Rhinovirus?
  • How is it transmitted? 

  • Remember Rhinovirus is: naked, + ss RNA
  • Its transmitted by aerosols, fomites or hand to hand contact
    • Commonly transmitted via person to person contact via inhalation of infected mucous and transfer to nose or eys
    • Children initiate outbreak due to poor hygiene 
  • A person could have 3-6 episodes per year and if you have cystic fibrosis or asthma its worse. 
  • The number of infections tend to decrease with age


  • How can you diagnose the common cold? 
  • What is the treatment of common cold?
  • how would you prevent it?

  • Diagnosis:
    • The symptoms of cold are usually diagnosis
  • Treatment
    • Pleconaril would reduce the severity and duration of a cold if it's taking early
    • other medications can relieve symptoms 
    • zn is suggested but might carry minor side effects 
  • Prevention:
    • Hand washing is the most important preventative measure 


  • What is Viral shedding in the case of Rhinovirus?

  • Respiratory secretions: sneezing, coughing or speaking 
  • Nasal secretion can contaminate hands and tissues.
    • Large droplets only got 1-3 feet but small tiny droplets can cloud in the air and all it takes is one virus to get you sick not many. 


What is adenoviridae? 

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  • What is the epidemiology of adenoviridae?  
  • how does it cause a respiratory infection?
  • How can you teat it?

  • One of many causes of the common cold
    • Also spread via respiratory droplets
    • Can survive on fomites and chlorinated water
  • It can cause respiratory infection by
    • being taken into cell lining of resp. tract via endocytosis 
    • causes sneezing, sore through, headache and malaise
  • Can result in intestinal tract infection
    • causes mild diarrhea 
  • Infection of the conjunctiva can result in pinkeye 
  • Treatment:
    • Gamma interferon
    • Attenuated vaccine available for military personnel


What is the Coxsackie A virus and what does it produce? 

  • Coxsackie A virus is 
    • Enterovirus
    • Naked + ss RNA virus 
  • Produce self-limiting lesions and fever 
    • Herpangina (Mouth and pharynx, resembling herpes lesions
    • Hand, foot, mouth disease
    • acute hemorrhagic conjunctivitis 
  • Causes some colds 


What is a coronavirus? how is it transmitted? what is its relation to the common cold? 

  1. Named coz of the corona like halos by their ENVELOPE 
    • + ss RNA virus 
  2. Transmitted via droplets from the upper respiratory tract 
  3. Second most common cause of the common cold


What are some coronavirus respiratory syndromes? 

  • SARS ( severe acute respiratory syndrome) and MERS ( middle east respiratory syndrome) 
  • The symptoms of both include high fever and respiratory distress 
  • No treatment or vaccine available 
  • QUARANTINE on infected individuals and use of face masks help reduce the risk of gettings SARS and MERS 


  • What is Rubella?
  • What is it known as? 
  • its one of the childhoold diseases that produces what? 
  • Where does infection begin and what are its characters?
  • is it more serious in children or adults?
  • what are the manifestation of rubella for adults?
  • Can it cause congenital diseases if it infects pregnant women?
  • How effective is the vaccine?

  • Rubella is an ENVELOPED, + ss RNA virus 
  • known as GERMAN measles 
  • 1/5 childhood diseases that causes skin rash
  • Infection begins in the respiratory system but spreads to rest of the body
  • Characterized by rash of flat pink spots 
  • Not serious in children
  • Adults would manifest into arthritis and encephilitis 
  • Can lead to congenital disease for infected pregnant women
  • Vaccination is effective

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What is the efficacy of vaccination against rubella? What has been occurring in recent years? 

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  • What is measles virus? 
  • is it more or less serious than rubella?
  • what is another name for measles?

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  • How does measles spread?
  • Where does it infect? 
  • What are kopliks spots?

  • Spread via respiratory droplets
  • requires a large dense population of people to spread
  • Can infect respiratory tract then the rest o the body
  • Koplik spots appear on mucous membranes of the mouth and they are signs of measles 
  • Lesions will appear on the body also to signify measles 

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  • What is a rare complication of measles?
  • How bad can it be?
  • What are the symptoms? 

  • Rare complication (7/ million) can result in pneumonia encephalitis and subacute sclerosing panencephalitis (SSPE) 
    • Slow progressive disease of CNS
    • Leads to personality change, memory loss, muscle spasm and blindness
    • Begins 1-10 years after infection and death occurs few years after symptoms appear
    • Cause is due to a defective virus without capsid moving from one brain cell to another via syncytia 
  • Vaccines have eliminated the endemic in US but its reemerging 


  • What is the diagnosis of measles?
  • What is the treatment?
  • How can you prevent it? 

  • Diagnosis:
    • Signs of measles; kopliks spots and body rash
  • Treatment
    • Anti-measles immunoglobin but has to be administered right after exposure 
  • How can you prevent it?
    • The vaccine in infancy and again in grade school
    • Measles frequent cause of death in other countries 


  • What are the characteristics of parainfluenza viruses (HPIV)? 
  • Whose most susceptible? 
  • How is transmitted? 
  • Which strains are associated with lower respiratory disease?
  • which strain associated with upper respiratory disease? 
  • What is COUP?
  • How long is recovery for most patients?
  • whats the available antiviral treatment?
  • what kind of care might it require? 

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  • What is mumps? 
  • how is transmitted? 
  • What is parotitis? 
  • What is a specific treatment?

  • Causes: Orchitis (Inflammation of the testes), meningitis, pancreatitis or deafness in one ear can occur 
  • Incubation is 12-21 days 
  • Infection can be asymptomatic 
  • Recovery is typically complete 
  • No specific treatment and Humans are the only natural host 
  • Vaccine almost eradicated mumps in the industrialized world. 

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  • What is an MMR vaccine?
    • what is the recommendation of the vaccine and what are the ages?

  • Measles, Mumps and Rubella = MMR 
  • Two doses, 12-15 months and 11-12 years old 


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  • What is the disease of respiratory syncytial virus? 
  • Why isnt there a vrius for it? 

Enveloped unsegmented ssRNA 

RSV causes a disease of the lower respiratory tract; leads to syncytia formation in the lung which in and causes the destruction of membranes 


  • Infection results in dyspnea because of plug small air passages bu Mucus, fibrin and dead cells
  • Leading causes of fatal respiratory disease in children
  • The immune response ends up damaging the lung, therefore, its hard to make a vaccine for it because the weakest form of the virus will cause an immune response that will damage the cells. 


  • What is the epidemiology of RSV infection
  • What is the diagnosis, treatment and prevention of RSV infection?

  • Epidemiology:
    • RSV is prevalent in the united states
    • Virus transmitted via fomites, hands and respiratory droplets
  • Diagnosis:
    • Signs of respiratory distress that resembles RSV
    • Verified by serological test 
  • Treatment
    • Supportive treatment AKA nothing really just prayers
  • Prevention is 
    • Handwashing, and health care workers to wear goggles, gloves, mask and gowns 


What does orthomyxoviridae cause? 

  • Enveloped, segmented negative ss RNA virus
  • Capsid containing segmented genome leads to Flu


  • What is influenza? 
  • Causes?
  • What does the genome consist of?
  • What is the envelope studded with? what are they important for? 

  • Influenza is caused by orthomyxovirus Type A and B 
  • Genome consists of 8 different ss RNA molecules, encoding 10 proteins. 
  • Enevlope is studded with two glycoproteins (NA) neuraminidase and HA hemagglutinin 


What is the course of action of Influenza virus after it infects a cell? 


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  • Which of influenza shows substantial variation in their H and N proteins? 
  • What do HA and NA determine? 
  • What is NA ?
  • What is HA?

  • Influenza A virus shows substantial variation in their H and N proteins but Influenza B and C dont. 
  • HA and NA determine the antigenic specificity if the virus 
  • NA is neuraminidase
    • Provides virus access to the cell surface by hydrolyzing mucus in the lung ( CELL RELEASE) 
  • HA is hemagluttinin 
    • Attaches to pulmonary epithelial cells and triger endocytosis ( CELL ENTRY) 


  • What is the biggest problem with influenza? 
  • What are the processes of mutations common in influenza? 
  • What was the recent pandemic of Influenza and what is the worst?

  • The problem is that flu virus is very variable
  • Mutations in HA and NA results in new strains 
    • Two processes for Mutations
      • Antigenic drift (usually causes small change)
      • Antigenic shift (usually big change) 
  • Occurs in mostly dense populations 
  • Most recent pandemics was the 2009 H1N1 virus and most famous one is the Spanish flu that killed 40 million worldwide. 


What is antigenic drift? 

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What is influenza Antigenic shift? 

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What are the signs of influenza? 

  • Fever, Malaise, headache mylagia (Muscle pain) 
  • Induced by cytokines released as part of immune response 


What is the pathogenisis of influenza? 

  • Enter via the respiratory route
    • Incubation is one day 
  • multiply in lung epithelial lining cells 
  • This causes the destruction of epithelial lining 
    • Most patients die due to secondary bacterial infections not the flu itself 


What is the diagnosis of influenza? Treatment? Prevention? 

  • Symptoms:
    • Signs and symptoms during a community-wide outbreak 
    • Lab tests can distinguish between different strains
  • Treatment 
    • Oseltamivir or zanamivir which inhibit type A and B neuraminidase 
  • Prevention 
    • Immunisation with a multivalent vaccine
    • Inactivated virus in chicken eggs
    • Typically 2 strains of Type A+1 strain of type B 
    • Protect against the strains included in the vaccine only