•Branches of Microbiology•Bacteriology

•Virology

•Mycology

•Parasitology

•Immunology

•Recombinant DNA technology

• Vaccines & Vaccination• Vaccines =are products produced from

microorganisms

• ### when introduced into a host

• ### stimulate immune system

• ### defense against particular microbial disease

Immunology

•Is a science dealing with immunity

Immunity = the body’s defense against particular pathogenic microorganism

• Or • =the ability to wardoff disease through

body defenses

•Susceptibility = lack of immunity

Immunology•Immune system = is a set of mechanisms that

protect an individual from infection , by recognizing, killing, & eliminating foreign pathogens or particle

•Antigen(Ag) = any substance that causes antibody formation (=immunogen)

•Antibody(Ab) = a protein produced by the body in response to an Ag & capable of combining specifically with that Ag

•

Immunology

•There are two types of immunity

•Innate immunity (non specific) = an individual genetically predetermined resistance to certain disease

•Adaptive immunity (specific) =immunity obtained during the life to produce specific response

Innate immunity

•Defenses that are present at birth

•The are always present & available to provide rapid responses to protect us against diseases

•First line

•Second line

Innate immunity

•Two components•

•First line of defense•

skin & mucous membrane

normal microbiota

Innate immunity

•

Second line of defense

phagocytosis

inflammation

fever

Antimicrobial substances

Innate immunityfirst line of defenses

Skin & mucous membranes

Physical factors :: barriers to entry or processes that remove microbes from the body surface

Chemical factors ::

substances made by the

body that inhibit microbial growth or

destroy them

The

Bod

y’s

Sur

face

s(f

rom

a m

icro

be’s

per

sepc

tive)

First line of defensesskin & mucous membrane /Physical

factors The skin is the most difficult surface to penetrate.

some microbes can penetrate mucous membranes but--------

Saliva ----- washes microbes

Respiratory tract– ciliary action remove microbes ---coughing & sneezing

First line of defensesskin & mucous membrane / Chemical

factors

•Oil glands of skin ---- inhibit the growth of microbes

•Perspiration --- washes microbes

•Lysozyme (tears, nasal secretions, & perspiration)

•High acidity of gastric juice – inhibit microbial growth in stomach

First line of defenses Normal microbiota

•Change the environment & prevent the growth of pathogens

• ##competing for essential nutrients

• ##production of inhibitory substances that suppress the growth of potential pathogen

Firs

t-Li

ne D

efen

se

Second line of defenses

•If a microbe penetrates the first line of defense

phagocytosis

inflammation

fever

Antimicrobial substances

Second line of defenses

•Phagocytes = a cell capable of engulfing & digesting particles that are harmful to the body

•Phagocytosis = the ingestion of microorganisms by a cell

phagocytosis

Second line of defenses Phagocytosis

•Phagocytes ==== WBC (=granulocytes, lymphocytes, monocytes)

• ## granulocytes (= neutrophils, basophils, eosinophils)

Leukocytes = White Blood Cells

Phagocytic Leukocytes

The mechanism of phagocytosis

Second line of defenses Phagocytosis

•The mechanism of phagocytosis•1 –the phagocytes are attracted to

microorganism•2—then adheres to microorganism

• • ##the adherence may be facilitated by

Opsonization (= coating the microorganism with serum proteins == opsonins==

Second line of defenses Phagocytosis

•3 –pseudopods of the phagocytes engulf the microorganism & enclose it in a phagocytic vesicle

•4 –the microorganisms are killed by lysosomal enzyme & oxidizing agent inside the phagocytes

Second line of defensesinflammation

• ****a host response to tissue damage characterized by redness, pain, heat, & swelling, & some time loss of function

Inflammation

Inflammation

Infla

mm

atio

nInflammation gives rise to localized reddening, swelling,

increased temperatures, and pain.

The function of inflammation is to localize tissue damage, localize responses, and then to restore tissue function.

The action of localized leukocytes is enhanced via the attraction of neutrophils and monocytes normally found in circulation.

Microbial materials such as LPS, flagellin (making up bacterial flagella), and even bacterial DNA serve as indicators of infection which in turn activates the production of pro-inflammatory cytokines (= immune-system activating chemicals).

In addition to the cell-to-cell interactions underlying inflammation, the inflammatory response involves localized increases in blood flow, leakage of blood vessels, and attraction of leukocytes from the blood.

Second line of defensesfever

• ***is an abnormally high temperature produced in response to a bacterial or viral infection

• **fever is considered a defense against disease

Second line of defensesfever

•High body temp.• **intensifies the effect of antiviral interferon

• **increases production of transferrins that decrease the iron available to microbes

•Also high temp .• **speeds up the body's reaction it may help

body tissue repair them self's more quickly• **Ab. production have been shown to be

enhanced at elevated temp.

Second line of defensesantimicrobial substances

• ***the body produce certain antimicrobial substances that lyse microorganism

• ***the most important of these are the protein of the

• & Complement system

interferon

Interferon: An AntiviraldsRNA normally is not present

in cells.

Complement system

• ***it is a group of steps which composes a large number of components

• =serum proteins which activated each other in a sub sequential manner(

• to produce a specified action

•destroy invading microorganism

complement

Toll-Like ReceptorsIncluding

phagocyte-attracting cytokines.

Danger, I’m infected! signal.

Com

plem

ent 1 .Inactive

complement proteins are in constant circulation.

2 .Complement proteins are activated

by various mechanisms.

3 .These are the consequences...

Adaptive immunity

• Obtained during the life of the individual to produce specific response

•**particular pathogen & antigen

•**it takes time in days

•**cell-mediated & humoral components

•**exposure leads to immunological memory

•**lymphocytes, antigen-specific receptors & antibodies

Adaptive immunity

•Cell-mediated response (immunity)•Is based on T-cells (=type of lymphocytes)

•Humoral response (immunity)•Is based on antibodies

Adaptive immunity

•Antigen (Ag) = immunogen •Ags = are the foreign particles which

stimulate the immune system to secrete antibodies

•When Ag is introduced into the host, host cell induces the formation of specific antibody & T-lymphocytes that are reactive against the Ag (bacteria, viruses, pollen grains, dust…..)

Adaptive immunity

•Immunogenicity

•Is the ability to induce a humoral & cell mediated immune responses

Adaptive immunity

•Antibody (Ab)

•Abs = are proteins present on the surface of B-cells & secreted by plasma cells

• circulate in the blood where they search & kill the microbes

•Abs reside on the serum

Adaptive immunity

Adaptive immunity

• each Ab molecule consists of 4 peptides chains-----2 identical heavy chains

•----- 2 identical light chains

• binds with disulphide bond

•The first a.a of both chains are highly variable from which it binds with the Ag

Adaptive immunity

•Immunoglobulin classes

•5 classes based on the structure of their heavy chain constant region

•IgG•IgM•IgA•IgE•IgD

Adaptive immunity

• IgG == Is the most abundant class•

•== Has the ability to cross the placenta (= provides a major line of defense against infection for the newborn)

• •== complement activator

• •== bind on phagocyte & mediate

opsonization•

•== neutralization of bacterial toxins

•IgM == the first immunoglobulin class produced in a primary infection or primary response

• ==is the first immunoglobulin to be synthesizes by the neonate

•IgA == it is the predominant immunoglobulin class in external secretion (saliva, tears, breast milk & mucus of the bronchial, genitourinary & digestive tract)

•==it protect the external surfaces of the body from microbial attack (= prevent the adherence of microorganism to the surface of mucosal cells)

•IgE == bind to mast cells & basophiles

•

• degranulation

•Histamine

•Hay fever & asthma

immediate hypersensitivity

hypersensitivity

•IgD == involved with the differentiation of B-cells where it seems to be interacting with Ag

Adaptive immunity

•Active immunity=developed after Ag enter the body & the immune system responds with Abs ##### long lasting protection

• or•Passive immunity=developed when

Ab enter the body from an outside source #### short lived protection

Passive immunity

Adaptive immunity•Active immunity

•Naturally acquired active immunity (==follows a short time illness)

•(

• Or•Artificially acquired active immunity

(==vaccination)

Active immunity

illness

•vaccination

Active immunity

•###memory cells in the lymphoid tissues are responsible for producing Ab ,the cells remain active for many years & produce IgG immediately after Ag entry (=secondary immune response

Adaptive immunity

•Humoral immunity (response)

•Is based on antibodies

•Cell-mediated immunity(response)

•Is based on T-cells (=type of lymphocytes)

Humoral response•Abs bind to the Ag & facilitate their

elimination ##forming clusters ingested by

phagocytes

•##binding of Ab to m.o. can activate complement system lyses of m.o.

•##Ab bind to toxins or viruses prevent their binding to host cell (neutralization)

Cell-mediated response

Based on T-cells = type of lymphocytes

T-cells are of 2 types

T-helper

&

T-cytotoxic

Cell-mediated response

•When T-h interact with Ag molecule it becomes activated & begins to secrete cytokines activate B-cells Ab

• activate phagocytes kill

• activate T-c kill cells that display pathogen (virus)

•Autoimmunity•Results from a loss of self-tolerance

•The ability of a host to recognize & not make Abs against self

•Immune diseases === damage to ones own organs due to action of the immune system

•Rheumatoid arthritis =IgG, IgM & complement•deposited in joints severe pain

•Insulin dependent diabetes mellitus = destruction of insulin-secreting cells of the pancreas=cell-mediated autoimmune reaction

•Immunodeficiency === the absence of an adequate immune response

•Congenital = inherited

•Or

•Acquired = drugs , cancers , infectious disease

• AIDS

•

•

•vaccination

•immunization•the process of conferring immunity by

administering a vaccine

•Vaccines

• =are preparations of killed , inactivated or attenuated m.o or toxoids to induce artificially acquired active immunity

•Are the safest & most effective means of controlling infectious diseases

The effects of vaccination

•The response of the body to the first contact with an Ag is called the primary response , it is characterized by the appearance of IgM followed by IgG

•Subsequent contact with the same Ag results in a very high Ab titer & called the secondary or memory response , the Ab is primarily IgG

•Attenuated ( living but weakened microbes)•Long life immunity

•Humeral & cell mediated response•Reversion to virulence

•Inactivated (killed microbes)•Short life immunity

•Antibody only•Not reverse to virulance

•Subunit (antigenic fragments of microbes)

•Subunit

•Recombinant vaccines

•a cellular vaccines disrupted bacterial cell

Vaccination program

1m60d.90d.120d10m12m

18-24 m

6y.

BCG*

DTP****DTPolio.vIPVOPV

IPVOPV OPVOPVOPV

HiB***

HBV***Measles**

MMR**

Polio vaccines•IPV =inactivated polio vaccine (killed)

• ===injection

•OPV = attenuated polio vaccine

• ==orally

•intestine

•HiB = Haemophilus influenzae B• ==injection

•DTP = combination vaccines• diphtheria

• tetanus• pertusis

• ==injection•HiB + DTP === combination

•HBV = hepatitis virus type B = HBV surface antigen == biotechnology

•BCG = tuberculosis

• == Bacillus Calmett-Guerin

•MMR = measles virus + mumps virus + rubella virus

•Other vaccines•Pox virus

•Cholera

•Chicken pox

•Influenza virus

•Endemic area

•Travelling to endemic area

• ===vaccines should not given to pregnant women

• ===illness

• ===immunocompromized individuals

•Booster === to increase the power of effectiveness

Booster dose=== active immunizing agent usually smaller than the initial dose given to maintain immunity

•

Final Exam

•Good Luck