Microbiology Exam 3 Lecture

What controls the body’s nonspecific immune system?

The Innate Immune systme

What is the 1st line of defense?

Physical Barriers; outer layers of skin, secretions that flush away materials & kill microorganisms

What is the 2nd line of defense?

non-specific internal response, cells, chemical, and physiological responses

What are cells associated with the 2nd line of defense?

Macrophages, NK cells, Neutrophils

What are chemicals associated with the 2nd line of defense?

Interferons and Complement

What are physiologic responses associated with the 2nd line of defense?

Inflammation & fever

Type of Phagocytes

 Neutrophils & macrophages

What do Phagocytes do?

engulf pathogens & cell debris

What cells serve as Immunological surveillance?

Natural killer cells (NK)

What do NK cells do?

destroy abnormal cells via initiation of apoptosis

What are interferons?

chemical messengers that coordinate defenses against viral infections

What are complement?

Unleashes inflammatory chemicals that amplify all aspects of inflammatory response

What does inflammation do to the spread of infection?

it limits the spread of infection

What is innate immunity?

• Rapid response and Non-specific

• Made up of the first two lines of defenses

• Immunity you’re born with

What is adaptive immunity?

• Specific and built up over time

• 3rd line of defense

• Major players are cells and cellular response

• Involves the production of antibodies against specific microbes

• Immune memory

What is specific resistance?

 Recognizes and targets specific antigens

What is Humoral Immunity?

Acquired immunity that uses B-cells

How does Humoral Immunity affect cells?

• Binds temporarily to target cell

  • Temporarily inactivate

  • Mark for destruction by phagocytes or complement

What type of targets does Humoral Immunity target?

extracellular targets

What is cell-mediated immunity?

acquired immunity that uses T-cells, acts against target cells

How does cell-mediated immunity affect cells?

• Directly => kill infected cells

• Indirectly => releases chemicals that enhance inflammatory response; or activate other lymphocytes or macrophages

What type of target does cell-mediated immunity target?

cellular targets

how are B-lymphocytes activated and differentiated?

They are activated by helper T cells and then undergo clonal selection in which the B-cells will split into effector and memory cells

What are the 5 steps of lymphocyte development?

1. Origin

2. Maturation

3. Seeding secondary lymphoid organs and circulation

4. Antigen encounter and activation

5. Proliferation and Differentiation

Where do lymphocytes originate?

In red bone marrow

What happens during the maturation step for lymphocytes?

the cells mature in the bone marrow or the Thymus

What happens when the Lymphocytes begin seeding secondary lymphoid organs and circulation

They leave the bone marrow and “seed” the secondary lymphoid organs and circulate thru blood and lymph

What happens during the Antigen encounter and activation step?

A lymphocyte antigen receptors bind its antigen and then activates

What happens during the Proliferation and Differentiation step for B-lymphocytes?

• During clonal selection, where the naive lymphocytes have their first encounter with a antigen, if the correct signal is presented then the differentiation is complete

• The activated B-cells will split into 3 effector cells and 1 memory cell for every 4 cells produced

What are the two types of B-cells produced?

Effector and Memory

What types of cells are Effector B-cells?

Plasma Cells

What do plasma cells produce?

Antibodies

What is function of antibodies?

To bind to antigens to inactivate or destroy the pathogen

What do the constant regions of stem antibodies do?

dictates what Cells & chemicals antibodies can bind to can the antibody

What are the three parts of a Antibody?

• Variable Region

• Hinge Region

• Stem Region

What are the 5 types of Antibodies?

IgM, IgA, IgG, IgD, IgE

What are the characteristics of IgM?

• The first antibody released

• Pentamer

• Agglutinating agent

• Fixes and activates complement

What are the characteristics of IgA?

• Secretory (ex. mucus)

• Monomer/dimer

• Prevents entry of pathogens

What are the characteristics of IgD?

• Monomer

• Attached to the surface of B-cells

• B-cell receptor

What are the characteristics of IgG?

• Monomer

• 75-85% of antibodies in plasma

• Secondary and late primary responses

• Crosses placental barrier

What are the characteristics of IgE?

• Monomer

• Active in some allergies

• Active with parasites

• Causes mast cells and basophils to release histamine

What are the types of T-lymphocytes?

Helper, Cytotoxic, Regulatory and Memory

How do helper T affect B-cells?

Stimulate B cells to divide more rapidly and begin antibody formation

What are some important characteristics of Helper T cells?

• Play a central role in adaptive immune response

• Activate both humoral and cellular arms

• w/o it there is no immune response

• Activates CD8 cells

How do helper T cells affect the innate immune system?

• Amplification of Innate defences 

  • Amplify response 

  • Activate macrophages

  • Mobilize lymphocytes and macrophages and attract other types of WBCs

What do Cytotoxic T cells do?

Directly attack and kill other cells

What are targets of Cytotoxic T cells?

• Virus-infected cells

•  Cells with intracellular bacteria or parasites (Ex: Salmonella)

• Cancer Cells

• Foreign cells (transfusions/Transplants)

How do Cytotoxic T cells kill cells

They release perforins, which create pores in the cell, and granzymes which induce apoptosis of the cell

What is a primary immune response?

• Cell proliferation and differentiation upon the first antigen exposure

• Lag period: 3 to 6 days

• Peak levels of plasma antibody reached in 10 days

• Antibody levels then decline after

• Slower

What is a secondary immune response?

Re-exposed to the same antigen gives a faster, more prolonged, more effective response

What is the role of Lymphocytes?

Adaptive Immune system cells produced in bone marrow

What are some examples of immune deficiencies?

• Hodgkin’s Disease

• Acquired Immune deficiency syndrome (AIDS)

What are some examples of Autoimmune diseases?

Rheumatoid Arthritis and Guillain barre syndrome

What are some benefits of a fever?

• Inhibits repro of bacteria and virus

• Promotes interferon activity

• Increases activity of adaptive immunity

• Accelerates tissue repair

• Increase CAMs on endothelium of capillaries in lymph nodes

What are some risks of a fever?

• Significant if above 100 degrees F

• Dangerous above 103 F in children

• Changes in metabolic pathways and denaturation of proteins

• Possible seizures, brain damage @ 106F or greater, death @ 109F or above

Process of the innate immune system responding to a wound

1. Wound happens

2. Release of inflammatory and chemotactic factors

3. Vascular changes

   • Vasodilation, increase in capillary permeability, display of CAMs

4. Recruitment of immune cells

   • Margination, Diapedesis, Chemotaxis

5. Delivery of plasma proteins

Margination

WBCs slow down and align on the vessel wall

Diapedesis

blood cells leave vessels and enter the CT

Chemotaxis

blood cells follow chemical gradient

What is Active Humoral Immunity?

when B cells encounter antigens and produce specific antibodies against them

What is naturally acquired Active Humoral Immunity?

 Infection, contact with pathogen

What is artificially acquired Active Humoral Immunity?

 Vaccines; dead or attenuated pathogens

What is Passive Humoral Immunity?

readymade antibodies introduced to the body, immune memory doesn’t occur

What is naturally acquired passive Humoral Immunity?

antibodies delivered to fetus vis placenta or to infant thru milk

What is artificially acquired passive Humoral Immunity?

injection of serum, such as gamma globulin or convalescent plasma

What family is influenza from?

Orthomyxoviridae

What type of genome is Influenza?

segmented, single stranded RNA

How many segements does influenza have?

8

What does the N stand for?

Neuraminidase

What does the Neuraminidase do?

• Responsible for new virus release

• Antibodies restrict the spread of and protect

How many subtypes of Neuraminidase are there?

11 subtypes

What does the H stand for?

Hemagglutinin

what does the Hemagglutinin do?

• Attachment to cell receptors

• Agglutinate RBCs

• Neutralizing antibodies

• Major Determinants of pathogenicity

How many subtypes of Hemagglutinin are there?

18 subtypes

Pathogenesis of Influenza

• Entry via Aeresol

• HA attaches to columnar epithelial cells of the respiratory tract

• Viral replication

• Exit Cell via NA

• Spread to more cells

• Exit host via cough, droplets

What are the antigenic types of Influenza?

A, B, and C

What are the characteristics of Influenza A?

• Infect multiple species => Humans, birds (wild & poultry), other animals (pigs, horses, dogs, marine mammals)

• Most Common

• The most common transmission is intraspecies

• Novel virus

• Has surface glycoproteins

What are the characteristics of Influenza B?

• Not categorized into subtypes

• Included in yearly vaccines

• Doesn’t undergo antigenic shift

What are the characteristics of Influenza C?

• Mild Symptoms

• Not included in flu vaccine

What does the A represent in A/Fujian/411/2002 (H3N2)?

Type of Influenza

What does Fujian represent in A/Fujian/411/2002 (H3N2)?

Town/area where first isolated

What does 411 represent in A/Fujian/411/2002 (H3N2)?

the number of isolates/strains

What does 2002 represent in A/Fujian/411/2002 (H3N2)?

The year of Isolation

What does (H3N2) represent in A/Fujian/411/2002 (H3N2)?

the Major type of HA and NA

What is antigenic Shift?

Genetic Reassortment between human and animal virus, very fast usually ends up in pandemics

What is antigenic Drift?

Point mutations in the HA gene with lead to minor changes to the main surface proteins, Causes seasonal epidemics

What is a pandemic?

Spread over multiple countries or continents, it causes large-scale social disruption, economic loss, and hardship

What type of protein is needed for a influenza pandemic to start?

A Novel HA protein

What is a Epidemic?

Large number of people within a community, population, or region are affected, causing localized disruption, economic loss, and hardship

What is a seasonal sickness?

happens constantly every season, most people have immunity

What groups of people are most likely to encounter complications affiliated with Influenza?

the young, elderly, and persons with chronic cardio-pulmonary disease 

What are some disease known to occur because of complications affiliated with Influenza?

• Bacterial Pneumonia

• Influenza Pneumonia

• Cytokine Storm

• Viral Superinfection

What are some diagnostic tests used for Influenza?

• Immunofluorescence

•  Cell culture (viral tissue and rapid cell)

•  Rapid Molecular Assay

• Antigen Detections

•  RT-PCR

What are some immune responses affiliated with Influenza?

• release of cytokines

• antibody-secreting plasma cells

• activated macrophages

• B-cell production

What are the types of Influenza Vaccines?

• Trivalent

  • Two A and one B

• Quadrivalent

  • Two A and two B

What are the two ways in which the Influenza vaccine can be administered?

Intramuscularly and Intranasal

What group is recommended to be given the Intranasal version of the influenza vaccine?

people 65 and over

Why yearly influenza vaccinations?

It is recommended because immunity declines the year after vaccination and because the strains of the influenza virus change from year to year

What are some allergen concerns affiliated with the influenza vaccines?

Egg allergies because the vaccine is made in embryonated chicken eggs

What are some possible side effects affiliated with the Influenza vaccine?

• pain and redness around the injection site

• flu-like symptoms

• in rare cases Guillain barre