Respiratory Tract Infections Holland Flashcards
80% of Respiratory Tract Infections are caused by?
Viruses
Protective mechanisms of respiratory tract?
Reduced temperature Mucous (mucins) Cilia Toll-like receptors interferons IgA
Why is influenza A unique among RNA viruses?
Replicates in the nucleus
What is the role of hemagglutinin influenza
KEY TO INFECTION AND IMMUNITY
attachment AND penetration
what happens to show the fusion peptide?
low pH induces conformational shift in HA, fusion peptide is exposed! inserts into target membrane. membranes are drawn close together, locally disrupted, FUSE.
What role does neuraminidase play?
Removes sialic acid from cell surface (so do not reinfect same cell) removes sialic acid from mucins (serve as decoy receptors for virions, inactivating them!)
What is the MOA of amaditine/rimiantidine?
target the m2 ion channel, blocking uncoating.
Which antibodies are the strongest neutralizers?
ANTI-HA stronger than anti NA
Antigenic drift for influenza
MINOR antigenic changes in HA and NA resulting from mutations. driven by selection for resistance…
reason why we need to change the vaccines annually!
Antigenic Shift for influenza
MAJOR antigenic change in HAorNA or both!
How? genetic reassortment after one cell infected by 2 different viruses
What process leads to a pandemic strain of flu?
ANTIGENIC SHIFT! little pre-existing immunity in the human population
What population was most affected by the 1918 flu?
Young adults! 25-34 range
Which virus from the orthomyxoviridiae family is most significant?
influenza (A, B, C)
What are the characteristics of the paramyxoviridae family of viruses?
Enveloped with HN and F proteins, -ssRNA, nucleocapsid with helical symmetry
What role does the F glygoprotein play in paramyxoviridae pathogenesis?
Fusion activity!activated by proteolytic cleavage. results in multinucleated cells
What is the most common cause of croup?
HPIV-1
What are the features of croup?
infection and inflamm of larynx,trachea, bronchi,narrowing the airway –>dyspnea
BARKING cough/stridor (sound on inhalation)
What is the most common cause of laryngitis in adults
Human parainfluenza virus
What is the primary cause of bronchiolitis in children?
Respiratory Synctial Virus- life threatening!!!!
what are the two most common causes of lower respiratory tract infections in children?
- RSV
2. human metapneumovirus
Viral causes of pneumonia?
HPIV, RSV, hMSPV, influenzavirus,adenovirus,coronavirus
What virus’ natural host is the fruit bat?
henipavirus.
human case fatality rate = 60%
what are the manifestations of MUMPS?
after long incubation period (2-3wks) painful swelling of parotid gland swelling of cheeks and jaws ear pain fever and headache less frequent- meningitis/orchitis/rash
What are the manifestations of Measles
Respiratory spread, fever, malaise, cough, coryza, headache, CONJUNCTIVITIS, KOPLIKS SPOTS(blue-white spots on red buccal mucosa), rash (starts on FACE spread to trunk and limbs)
What are the important characteristics of Rubella?
+RNA
lymph node swelling, maculopapular rash, fever, arthritis, congenitial syndrome
EBV symptomology?
primary infections are asymptomatic (maybe sore throat/fever)
secondary infection- infectious mononucleosis
What are heterophile antibodies?
Antibodies against unusual antigens, antigens to which a person has not been exposed. Caused by activation of B cells by EBV… result is secretion of antibodies even though cells were not exposed to antigen. basis for mono test
What role does EBV play on B cells?
virus causes the B cells (G0 phase) to become activated and enter the cell cycle, leading to heterophile antibodies
what is the most common childhood cancer in equatorial Africa?
Burkitt’s Lymphoma (associated with EBV)
Tumor cells are EBV+ B cells and express EBER (Epstein bar early rna) and viral protein, EBNA-1
myc overexpression
what is nasopharyngeal carcinoma?
epithelial cell cancer. tumors contain EBV DNA.
viral genes: EBER, EBNA-1, LMP1 +2
Where are tumors most prevalent in hairy oral leukoplakia
TRICK QUESTION!!! NOT TUMORS!! sites of active EBV replication.
white, wart-like lesions on sides of tongue. AIDS patients
What is the main differentiating characteristic between cytalomegavirus and EBV?
ONLY EBV has heterophile antibodies!
What are the modes of transmission for adenovirus?
Respiratory, fecal/oral, iatrogenic spread
In what population is Acute Respiratory Disease from adenovirus most common?
Military recruits! crowded living under stress. vaccine for them, types 4, 7
What are the features of pharyngoconjunctival fever?
Adenovirus infection, conjunctivitis + upper respiratory tract infection.
can initiate direct to eye. SWIMMING POOL transmission!
Does the adenovirus cause GI disease?
Although most types replicate in the GI tract, normally do not cause disease in adults. Types 40and 41 associated with infant gastroenteritis
What virus is responsible for “shipyard eye”?
adenovirus– epidemic keratoconjunctivitis
involves both cornea and conjunctiva, highly contagious.
The adenovirus enters the cell by endocytosis. What receptor (s) bind the virus?
CAR and integrins
What are the features of parvovirus?
VERY small, nonenveloped, linear, ssDNA
B19- fifth disease, transient aplastic crisis, hydrops fetalis.
What is erythema infectiosum? what causes it?
Fifth disease caused by B19 infection. Two phases:
- Nonspecific, flu-like, dispersion by viremia, immune complex form
- deposition of immune complexes, eryth rash and transient arthritis
How does B19 cause transient aplastic crisis?
Persons with hemolytic anemia have very few reticulocytes. B19 replicates in erythroid precursor cells in BONE MARROW– life threatening.
