True of false. Most respiratory tract infections are caused by viruses.
What are the 7 mechanisms used to protect the respiratory tract?
reduced temperature in the RT
mucins - "decoy" receptors
What are some properties of the influenza virus?
What are the 7 proteins encoded by the RNA segments of the influenza A virus?
ion channel (M2)
transcriptase complex (PB1, F2, PB2, PA, NP)
NS1 - blocks interferon-induced RNaseL pathway
NS2 - viral ribonucleoprotein transport
What are the steps in Influenza A virus replication?
transcription of RNPs > mRNA and cRNA
assembly and release
Which virulence factor of the Influenza A virus is the most important in regards to infection and immunity?
hemagglutinin (HA) - attachment and penetration
How is the Influenza A virus hemagglutinin activated?
proteolytic cleavage of HA0 to HA1 (binds sialic acid receptors) and HA2 (transmembrane domain and fusion peptide)
Describe the hemagglutinin fusion mechanism of the influenza A virus.
neutral pH - fusion peptide not exposed
acidic pH - conformational change in HA > fusion peptide exposed > inserts into membrane
What is the main function of Influenza A virus neuraminidase?
removes sialic acid from cell surface so virus can be released from the cell
What is the main target used by antivirals for Influenza A virus? Name the most common drug used for Influenza A virus?
targets neuraminidase; Tamiflu (oseltamivir)
What are the 2 types of antigenic variation used by the Influenza A virus?
antigenic drift - mutations
antigenic shift - genetic reassortment
What mechanism contributes to the high pathogenicity of the Avian Influenza H5N1 virus?
polybasic HA cleavage site - allows it to be activated by proteolytic enzymes found in many cell types
Which RNA virus has "helical symmetry", is enveloped, and is single stranded with a single segment?
What 2 glycoproteins do most paramyxoviruses have? (exceptions are measles virus and respiratory synctial virus (RSV))
HN - hemagglutinin and neuraminidase
F - fusion
A man brings his 7-year old son into your office with concerns about his son's swollen cheeks, fever, headache and ear pain. He tells you that his son has been like this for the past week and when the symptoms didn't go away he decided to bring him in. He goes on to tell you that his son has not been vaccinated due to fear of the potential side effects of vaccines. What is the diagnosis and what virus is most likely involved? How could this infection have been prevented?
Mumps; mumps virus; MMR vaccine
A woman brings her 2-year old daughter into your office with concerns about her daughter's 103 degree (F) fever and diarrhea. She tellls you that her daughter just doesn't seem to be feeling well, has been coughing a lot, and developed a rash about a week ago that began on her face and spread to her trunk and limbs. You exam the child and find Koplik's spots on her buccal mucosa. She also has inflammation of the conjunctiva. What is the diagnosis and what virus is most likely involved in this infection?
D. Measles, measles (rubeola) virus
A young child, who has not been vaccinated, is brought into your office with major lymph node swelling, a fever of 38 degrees (C), and a maculopapular rash. What is the the most likely diagnosis and what virus is involved in the infection? How could this infection have been prevented?
Rubella "German measles"; Togavirus; MMR vaccine
What are the most common birth defects associated with congenital rubella syndrome?
motor control defects
heart, brain, eye malformations
A 5-year old boy is brought into your office and presents with laryngitis, a "barking cough", stridor, hoarseness, fever, and N/V. What is the likely diagnosis and what virus is involved?
B. Croup; human parainfluenzavirus
Bronchiolitis is life threating in _____ and can be caused by many viruses, such as _____ (3 words), _____ (2 words), and _____. It may even progress to _____.
children; respiratory synctial virus; human metapneumovirus; HPIV-3; pneumonia
What are the 2 main paramyxovirus zoonoses that can be transmitted from animals to humans?
hendravirus (outbreak in horses)
nipah virus (outbreak in pigs)
What are the most common viral causes of pneumonia in young children? Older children? Adults?
young children: RSV, influenza A
older children: influenza A, parainfluenzavirus
adults: influenza A, adenovirus
What viruses are often associated with the common cold?
coxsackie virus, echovirus
A 22-year old woman comes into your office with complaints of a runny nose, watery eyes, sneezing and coughing. She has no fever and she says that she's had these symptoms for about a week. What is the most likely diagnosis?
Which RNA virus causes infection of the skin and mucosa?
RNA VIRUSES THAT CAUSE RESPIRATORY TRACT INFECTIONS - DR. HOLLAND)