Immunology of infectious Disease Flashcards
What are the features of Extracellular Bacterial infections?
Multiply outside the host cell Tissue Destruction Induce inflammation! Toxins that kill host cells Immunity by killing EC bacteria and neurrialize toxin
How does the innate immunity deal with EC bacteria?
Phagocytosis= first line of defense
Neutrophils in Blood
Macrophages in tissue
Pahgocytes recognize bacterial structures(polysaccharides, peptides,
Fc Receptors and C3b receptors to bind IgG and C3b
Phagocytes remove bacteria in the lymph nodes and the spleen
What are examples ofExtracellular Bacteria?
Staph, strep, Neisseria, E coli, Clostridium
What is the first immune cell to arrive at the site of infection?
Neutrophils.
What are the most important opsonins?
C3b and IgG
WHat is the Fe binding molecule that keeps it from bacteria?
Lactoferrin
What activates the Alternative pathway of compliment activation?
Peptidoglycan and LPS
Leads to lysis or opsinization
What complement deficiencies lead to Neisseria Infections?
C5-C9 dificiencies
What is the effect of Complement on G- and G+ bacteria?
Lyses G- Bacteria
Opsonizes G+ bacteria
How does Adaptive immunity attack extracellular bacteria?
IgG opsonizes and enhances Phagocytosis
Toxin specific Ab neutralizes toxins
IgM and IgG activate classical complement => Lyse Bacteria
What Immunoglobulin can cross the placenta?
IgG
What type of infections is baby vulnerable to at 6 mo old?
S. Pneumo
N meningiditis
H. influenzae B
What Bacteria produce M protein? What does it do?
S. Pyogenes and S. Pneumo
Many forms mean that one type of Ab may not work against next infection
What is the Ig at Mucosal sites?
IgA
Fixes Comlement
What happens to a Pt that is Deficient in IgA?
IgM Ab can compensate
Can be more suceptible to URT infections (mucosa)
How do EC bacteria evade immunity?
Polysaccharide capsule Variation of surface antigen IgA Protease(Neisseria and Hemophilus) Interfere with complement activation(S. Pyogenes, S pneumo) S. Typhi => Type 3 secretion system
What are the bad effects of the Immune response?
Septic Shock: HypoTn and DIC
Superantigens
What are the disease Causing Ab?
Rheumatic Fever
Post Strep glomerulonephritis
What Bacteria are included in Spirochetes?
Treponema Pallidum
Borrelia Burgdorpheri
Leptospira
What are features of Spirochete Infections
Cant penetrate unbroken skin
Arthropod vectors
Local Multiplication
Periods of latency
How does the immune system fight Spirochete infections?
Neutrophils, Phago
ADAPTIVE better
T pallidum => strong cell mediated and humoral immunity
Th1
Ab => opsonzation + protective immunity after latent syphilis
Classical compliment for Borrelia
How does T pallidum evade immunity
lacks virulence factors
Hard to kill
How does B Burgdorpheri evade immunity
Coats with amorphous host material => prevents phagocytosis and complement andevades adaptive imm.
What are the bad effects of immunity to Spirochetes?
2^ syphilis###
