Lec22 Vaccines for Bacterial Pathogens Flashcards
What is equation for vaccine efficacy?
VE % = ((ARU-ARV) / ARU) * 100
ARU = attack rate in unvaccinated ARV = attack rate in vaccinated
Why is pertussis efficacy so much lower?
- immunity is not long-lasting
What is rationale for multidose vaccine schedules and booster doses?
immunlogic memory –> when exposed to antigen first time have lag time, second time have bigger and quicker response
What are bacterial vaccines designed to cause?
creation of
- antibodies to neutralize bacterial toxins
- antibodies to promote opsinization/phagocytosis
- antibodies to promote complement-mediated lysis
What are viral vaccines designed to cause?
- antibodies to neutralize virus
- antibodies to promote complement binding
- CD8 T to kill virus-infected cells
What are bacterial virluence factors of clostiridum tenani?
- exotoxins including tetanospasmin = potent neurotoxin
What are bacterial virulence factors of bordetella pertussis?
filamentous hemagglutinin and promotes adhesion to epithelial cells and elaborate pertussin = major pertussis toxin
What is role of polysaccharide capsule?
- protects from phagocytosis
What are the 3 major polysacchardie encapsulated systemic bacterial pathogens of childhood?
- haemophilus influenzae type B
- strep pneumoniae
- neisseria meningitidis
peak = 6-18 months old
What disease associated wtih haemophilus influenzae type B
- in non-immune population most common cause of meningitis, septic arthritis, sepsis, pneumonia
What disease associated wtih strep pneumoniae?
- sepsis, meningitis, pneumonia
What disease associated wtih neisseria meningitidis?
- sepsis, meningitis
What is mech of immunity to polysacchardie antigens in children?
- largely T cell independent antigens so poor memory response
- anti-PS humoral response not reliable until 2 yrs old, thus pure polysacchardie vaccines ineffective
- maternal antibodies wane by 4-6 months
What are protein-PS conjugate vaccines?
- covalent linkage of PS to protein
- allow immune system to handle PS more like T -dependent antigens
- get goot anti-PS antibody response much earlier
What is mech of PS-protein vaccine function?
- PS-sepecific B cell takes up Pr-PS conjugate
- protein component degraded into peptides
- peptides from Pr component presented via MHC-II to T cell receptor on peptide-specific CD4 cell
- CD4 cell stimulates proliferation and differentiation of PS-specific B cells to plasma cells
- PS specific plasma cells secrete specific anti-PS antibodies
