1. Vascular Adherence (cell rolling)
2. Diapedesis - process of neutrophils moving through EC into ECM
3. Activation - increased granules
4. Phagocytosis and Killing

Characteristic of neutrophils

Contain

Cationic proteins

Defensins (play a role in killing)

myeloperoxidase

Specific for Mature Neutrophils

Contain

lysozyme

NADPH

Lactoferrin (reduce ability to use Fe)

B-12 binding protein (reduce ability to use B-12)

Receptor Mediated

1. Attachment
2. Pseudopod Extension
3. Phagosome Formation
4. Granule Fusion
5. Phagolysosome Formation

Fragments of complement proteins released during activation.

Results in increased vascular permeability and attracts leukocytes.

CD8

T cells that kill other cells

Lysis of bacteria or cells by insertion of membrane attack complex derived from compliment activation

Immunity in which the participation of lymphocytes and macrophages is predominant.

Generally applied to Type IV Hypersensitivity

A protein produced as a result of interaction with antigen.

The protein has the ability to combine with the antigen that stimulated its production.

A phagocytic mononuclear cell found in tissues and at site of inflamation.

Also an accessory role is an antigen-presenting cell (APC)

Characterized by a multilobed nucleus

Phagocytic for bacteria and other particles

A substance capable of enhancing phagocytosis.

Antibodies and complement are the two main opsonins.

Monomuclear cell containing a densely packed nucleus and a small rim of cytoplasm.

Includes T cells and B cells.

Low MW proteins elaborated by infected cells.

Protect noninfected cells from viral infection.

Cytokines that also have immunomodulating functions.

Subdivision based on structural differences

IgG

IgA

IgM

IgE

IgD

Development of resistance to a foreign substance

Can be antibody-mediated, cell-mediated, or both

1. To produce, maintain, and distribute lymphocytes
2. To act as a filter
3. To return excess water from the interstitial space back to the general circulation

1. Start as pockets rather than tubes
2. Larger diameter
3. Have thinner walls
4. Flat and irregular in section

Special lymphatic capillaries in small intestine

Transport lipids from digestive tract

from the right lymphatic duct empties into the right subclavian vein

from the thoracic duct empties into the left subclavian vein

Presence of CD 56 and CD 16

Absence of CD 3

CD 8

binds to MHC class I molecules

CD 4

binds to MHC class II molecules

Distributed on all nucleated somatic cells

Present peptide antigens to CD 8 T cells

Distributed on antigen-presenting cells and activated T cells

Present peptide antigens to CD 4 T cells

Classical Pathway

Lectin Pathway

Alternative Pathway

IgM and IgG attach to pathogen

C1 binds to Ab

C3 is cleaved by C3 Convertase into C3a and C3b

Mannose-binding lectin binds to sugar residues found in microbial surface polysaccharides

Then the pathway follows the classical pathway from the cleaving of C3

Recruitment of Inflammatory Cells

Opsonization

Membrane Attack Complex

1. Neutrophil activation
2. neutrophil adhesion
3. promotes diapedesis and chemotaxis
4. monocyte activation to produce IL-1 and IL-6
5. Mast Cell degranulation

C3 is cleaved by C3 convertase into C3a and C3b

C3a is an anaphylatoxin

C3b leads to the MAC or Opsonization

Predisposition to Systemic Lupus Erethymetosis

Opsonization of immune complexes help keep them soluble, deficiency results in increased precipitation in tissues and inflammation.

Susceptibility to bacterial infections.

Lack of opsonization and inability to utilize MAC

Susceptibility to Gram Negative infections

Inability to attack outer membrane

Clinical manifestation is increased temperature and respiratory rate and decreased BP

Two chains (a and b) that have a transmembrane portion and a distal CDR.

This attaches to the MHC markers on a cell surface.

1. The native protein is denatured
2. Peptides are cut and placed in MHC "cradle"
3. MHC is exocytosed to the plasma membrane

• Progenetor cells give rise to many lymphocytes of different specificity
• An antigen comes in contact with a lymphocyte of correct specificity
• Clonal expansion due to being activated by presentation with antigen

Complementary Determinant Region

The domain on an immunoglobulin or T cell receptor that is variable and includes the active site.

Ab sees and binds to native conformation

T cell recognition requires processing and is going to be presented on an MHC molecule

Type 1 Helper T cell

INF-g released by innate system cells

activates macrophages or cause B cells to switch to IgG

Promotes bacterial clearance

Type 2 Helper T cells

IL-4 is released

Activate mast cells and eosinophils and cause B cells to switch production to IgE

Aids in response to parasites

pentamer

primary immune response

dimer

prevent attachment of pathogens to EC

monomer

primary and secondary immune response

monomer

binds to mast cells and basophils to cause them to release histamine

monomer

attached to surface of B cell

important in B cell activation

Somatic recombination

Point mutations

Class switching

Neutralization

Agglutination

Precipitation

Complement Fixation

[image]Variable region on the N-termini

Fc region is constant and may have transmembrane regions on C-termini if on B cell

Heavy Chains are 50 kD each

Light Chains are 25 kD each

Source: T Cells and NK Cells

Function: Activateion of macrophage and TH1 differentiation

Source:  Macrophages and T cells

Function:  Cell activation, fever, cachexia, antitumor

Source: T cells

Function:  Activates PMNs

Source:  Macrophages

Function:  Cell activation, fever

1-8 microns

coccus (cocci)

bacillus (bacilli)

spirochete

40+

1-2

N-acetyl glucosamide - N-acetyl muramic acid

Have b(1,4) linkages

L and D amino acids

Variability in these side chains are a typing mechanism for different species

Peptidoglycans

40+ layers

Transformation

Transduction

Conjugation

Meiosis

Zygote fusion

Gram Positive

Peptidoglycan layer is so thick that the MAC cannot penetrate the cell wall.

Waxes and Lipids

These hold onto the acid stains, which gives the cells their names.

Flagella

capsule

pili

cell wall

endospore

What are the major components of the prokaryotic cell that can become virulence factors?

Part of the outer membrane that mediates septic shock with a gram negative organism

Thick Peptidoglycan Layer (40⁺)

Teichoic Acids and Lipoteichoic Acids

Other Proteins and Carbohydrates

Important Components for Gram Positive Bacteria

Has an Outer Phospholipid Bilayer Membrane

Periplasmic Space

Single Layer of Peptidoglycan

Porins

Lipopolysaccharide (LPS)

Important Components for Gram Negative Bacteria

Where do b-lactamases reside in the gram negative bacteria?

b-lactamases are enzymes that break down b-lactams (penicillins).  Therefore, the organism is resistant to those microbials.

What is the importance of b-lactamases?

Bacteria in the Bloodstream (Bacteremia) breaks down.  A component of the lipopolysaccharide, Lipid A, helps is engulfed or attached to a macrophage.  The macrophage, which then releases IL-1 and TNF-a, which work synergistically to induce fever, vasodilation, and “leaky” capillaries for chemotaxis of immune cells into tissue. This allows a severe drop in blood pressure and volume.  

What Is Happening During Septic Shock?

Treatment centers around two key concepts:  dynamically addressing the primary pathogen responsible for the mediation into sepsis and reversing the hypersensitivity reaction within the individual.  Antibiotics such as tetracyclines have shown to be effective.  Surgical debriidement of infected tissue removes infected cells and bacterial mass.  However, this may lead to a susceptibility to an opportunistic pathogen.  Hemodynamic support, as in pushing fluids and vasopressor agents aid in the reversal of hypersensitivity reactions by the immune system.

What are accepted and developing methods for treating septic shock? 

Lysozyme hydrolyzes the backbone and is naturally found in tears, saliva, and nasal secretions

Naturally occurring enzyme that breaks down the peptidoglycan and where it is found

Main Chain is N-acetyl glucosamine and N-acetyl muramic acid (b1,4 linkage)

Cross-links are tetrapeptide with both L and D amino acids

Composition of the murein backbone (peptidoglycan)

It is found in all species, though is highly variable between species.  It is used for typing.

What is significant about the tetrapeptide sequence in the murein backbone?

At the b1,4 linkage between N-acetyl glucosamine and N-acetyl muramic acid

Where does lysozyme cleave the murein backbone?

Smooth bacteria include the O-antigen on the end of their LPS, while rough end at the core.         

What is the difference between smooth and rough bacteria?

Acid Fast Bacteria (Mycobacteria)

These bacteria have a cell wall that is composed of fatty acids and waxes that contribute to virulence.

K antigen

 Filament (major straight structure that is swung around)

Hook (where we have the bend)

Rings (insertions into the membranes)

Main components of the flagella

Pili

Hair-like proteins that are responsible for adhesion

Conjugation

Sex pili are used in which process

Fibular Layer

Protein coat on the surface of bacteria that can be a virulence factor

Lag Phase (first introduction to environment – active metabolism)

Log Phase (rapid cell growth – population doubling every generation)

Stationary Phase (balance between reproduction and death – endospores are formed)

Death Phase

Phases of Bacterial Growth

Bacteria that have 0-20°C  optimum growth.  No known psychrophilic human pathogens.

Psychrophiles 

Bacteria that have 20-40°C preferred range, optimum 35-37°C = 98°F body temp (most human pathogens).  This causes special concerns with refrigerated foods

Mesophiles 

Bacteria that have 40-90°C growth range

can tolerate ~2=15% salt

facultative halophiles 

need up to 30% salt to grow

extreme halophiles 

differentiates based on hemolysis reactions

Blood agar

differentiates based on casease production

Milk agar

differentiates based on type of lactose fermentation (mixed acid/neutral)

MRVP broth

Differentiates based on lactose fermentation

MacConkey’s agar

Normal Flora of Skin

Staphylococcus epidermidis & S. aureus

Propionibacterium, Corynebacterium

Pityosporum & Candida (fungi)

Normal Flora of Upper Respiratory Tract

Staphylococcus epidermidis & S. aureus

Streptococcus pneumoniae, Hemophilus, Neisseria, diptheroids

Normal Flora of Mouth

Streptococcus, Lactobacillus,

Corynebacterium Actinomycetes, Treponema,

Bacteroides, Fusobacterium, Candida

Normal Flora of Large Intestine

Gram negative enterics (E. coli, Enterobacter, Citrobacter, Proteus, Klebsiella, Shigella), Enterococcus, Lactobacillus, Bacteroides, Fusobacterium, Clostridium, Candida

Normal Flora of Urethra

S.epidermidis, Micrococcus, Enterococcus,

Lactobacillus, Pseudomonas, Klebsiella, Proteus, diptheroids

Normal Flora of Vagina

Lactobacillus, Streptococcus, Staphylococcus,

Bacteroides, Clostridium, Candida, Trichomonas vaginalis (protozoan)

Normal Flora of Male external genitalia

Mycobacterium smegmatis, other skin flora

Damage to DNA

Protein Denaturation

Disruption of Cell Membrane of Wall

Removal of Sulfhydral Groups

Modes of Action for Antimicrobials

Plasmid

Specialized Genetic Elements Capable of Independent Replication

Transposons

Genetic Elements that Moves from One Gene Locus to Another

Transformation

Conjugation

Transduction

Mechanisms of Bacterial Genetic Transfer

N_t = N₀ 2ⁿ

where n is the number of generations

n = (log N_t – log N₀)/0.301

Equation for Unchecked Binary Fission

Time needed for a culture population to double

1.      Microbe found in diseased animals and absent from healthy animals

2.      Microbes isolated and grown in culture

3.      Cultures causes disease in healthy animals

4.      Microbe is re-isolated from diseased animals and re-cultured

Koch’s Postulates

Peak of Disease is known as 

1.      Incubation period (no signs or symptoms)

2.      Prodromal phase (vague symptoms)

3.      Invasive Phase (most severe signs and symptoms)

4.      Decline Phase (declining signs and symptoms)

5.      Convalescence Period

Phases of Bacterial Infection

Portals of Entry

Number of Invading Microbes

Adherence

Penetration or Evasion of Immune Defense

Cytopathic Effects

Portals of Exit

What are the Important Points of Transmission and Infectious Process

Pili

Lipoteichoic Acid, F and M Proteins

Virulence Factors that Deal with Adherence

Exotoxins are produced inside gram positive bacteria and are secreted or released into surrounding media.

Endotoxins are incorporated into the outer surface of the cell wall in gram negative bacteria.  They are liberated when the cell breaks apart.

What is the difference between Exotoxins and Endotoxins?

Fragment A (inhibits protein synthesis)

Fragment B (binds to surface of CD by CD2)

What are the two fragments of Diptheria Toxin

Protein A binds the Fc region of IgG

Why is Protein A expression on the surface of microbes considered an antiphagacytic agent?

Purification of Antibodies

What is Protein A also used for?

Genetic recombination presents a myriad of possible combinations for pili structure.

How do pili evade the immune system?

Penicillians

cephalasporins

bacitracin

vancomycin

Antimicrobials that Inhibit Cell Wall Synthesis

Quinolones

rifampin

Antimicrobials that Inhibit Nucleic Acid Replication and Transcription

Chloramphenicol

erythromycin

tetracyclines

streptomycin

Antimicrobials that Inhibit Translation

Sulfanilamides

trimethoprim

Polymyxin B

Antimicrobials that Cause Injury to Plasma Membrane

Viral Size

Capsid

Protein Shell That Coats And Encloses Nucleic Acid (RNA Or DNA)

Capsomere

Make Up Capsid.  Morphologic Units (Polypeptides) 

Classified as + or -.  Lipid containing membrane surrounding some viral particles. 

Becomes very important when we look at the release of some viral particles.

As the virus exits the cell, it may carry host membrane components.

Describe the Envelope of a Viral Particle

Nucleocapsid

Protein/Nucleic Acid Complex 

naked ssDNA viron with icosahedral symmetry that causes 5^th disease

Parvoviridae

enveloped dsDNA viron with icosahedral symmetry that causes HPV and genital warts

Papillomaviridae

dsDNA viron with complex symmetry and coats that causes Herpes Type 1 and 2

Herpesviridae

enveloped RNA viron that causes SARS

Coronaviridae

enveloped RNA viron that causes HIV

Retoviridae

enveloped RNA viron with helical symmetry that causes flu

Orthomyxoviridae

enveloped RNA viron with helical symmetry that causes rabies

Rhabdoviridae

Attachment

Penetration

Uncoating

Expression of viral genome

Synthesis of viral components

Assembly

Release

Basic Steps for Viral Replication Cycle

Causes Mononucleosis

Attaches via CD21 on B cells

Epstein-Barr Virus

Respiratory

Most exposure to the environment

The most common port of entry for viral infections is

Cilia, lymphocytes, macrophages, IgA

Localized Immune Response to Respiratory Viral Infections

Sub-Saharan Africa

22.5 million cases

Especially in Zimbabwe and Botswana

Binding and Entry

Reverse Transcription

Replication

Budding

Maturation

When the CD4 cell count falls below 200 cells/ml

and/or

A typical AIDS-defining illness is observed

Erythema infectisum.

Mild constitutional symptoms may accompany the rash, which has a typical “slapped cheek” appearance.  Join involvement is a prominent feature in adult cases.  The symptoms mimic RA.

Clinical manifestation of parvovirus (Fifth Disease)

Treated symptomatically

Treatment for Fifth Disease

Oropharyngeal:  HSV-1 involves the buccal and gingival mucosa of the mouth.  Symptoms include fever, sore throat, vesicular and ulcerative lesions, gingivostomatitis, and malaise.

Keratoconjunctivitis: HSV-1 may occur in the eye, producing sever keratoconjunctivtis

Genital Herpes: HSV-2 causes genital herpes is characterized by vesiculoulcertive lesions of the penis of the male or the cervic, vulva, vagina, and perineum of the female

Clinical manifestations of Herpesviruses

Several antiviral drugs have proved effective against HSV infections, including acyclovir, valacyclovir, and vidarabine.  Acyclovir is currently the standard therapy. 

All are inhibitors of viral DNA synthesis.

Treatment of Herpes

Symptoms of classic influenza usually appear abruptly and include chills, headache, and dry cough, followed closely by high fever, generalized muscular aches, malaise, and anorexia.

Clinical manifestation of orthomyxovirus (influenza)

The NA inhibitors zanamivir and oseltamivir were approved in 1999 for treatment of both influenza A and B. 

To be maximally effective, the drugs must be administered very early in the disease.

Treatment of Influenza

The human coronavirses produce “colds” usually afebrile in adults.  The tymptoms are similar to those produced by rhinovirses, typified by nasal discharge and malaise. 

Symptoms usually last about 1 week.

Clinical manifestation of coronavirus (SARS)

There is no proven treatment and no vaccine.

Treatment for SARS

The clinical spectrum can be divided into three phases

a short prodromal phase – malaise, anorexia, headache, photophobia, nausea, sore throat and/or fever

acute neurologic phase – signs of nervous system dysfunction

coma phase

Clinical manifestation of rabies

Prevention by Vaccine

Treatment of Rabies

Source: T Cells and NK Cells

Function: Activateion of macrophage and TH1 differentiation

Source:  Macrophages and T cells

Function:  Cell activation, fever, cachexia, antitumor

Source: T cells

Function:  Activates PMNs

Source:  Macrophages

Function:  Cell activation, fever

Spores germinate in the tissue at the site of entry, and growth of the vegetative organisms results in formation of gelatinous edema and congestion.  Bacilli spread via lymphatics to bloodstream shortly before and after death.

Characteristics of spores of Bacillus anthracis