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 immunity first 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 Body’s Surfaces (from a microbe’s persepctive)

First line of defenses skin & 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 defenses skin & 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

First-Line Defense

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

Inflammation

 Inflammation 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 defenses fever *** is an abnormally high temperature produced in response to a bacterial or viral infection ** fever is considered a defense against disease

Second line of defenses fever 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 defenses antimicrobial 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 Antiviral dsRNA 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 Receptors Including phagocyte- attracting cytokines. Danger, I’m infected! signal.

Complement 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

each Ab molecule consists of 4 peptides chains identical heavy chains 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 Naturally acquired passive immunity (==immunoglobulin transferred from mother to baby to protect the fetus Or Artificially acquired passive immunity (==direct artificial injection of Ab into the host) Hepatitis Ig, serum containing antitoxin (tetanus)

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

6y m 12 m 10m120d90d.60d.1m *BCG DT****DTP OPV OPV IPV IPV Polio.v ***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