Role of Immune system in health and diseases

1. Role of immune system
in health & Diseases
Presented by:
Ms. Smita Shukla
Assistant Professor

2. Classification of Microbes
What are Microbes?
 A microbe is any living thing that spends its
life at a size visible sometimes only with a
microscope.
 It is too tiny to be seen with the naked eye.
Microbes are the oldest form of life on Earth.

3. Prokaryotes (Bacteria)
Eubacter "True" bacteria
 Human pathogens
 Clinical or environmental
 One kingdom
Archaea
 Environmental organisms
 Second kingdom

4. Here is an outline of the major groups of
microorganisms:
Viruses
Bacteria
Algae
Fungi
Protozoa

5. Bacteria
Bacteria consist of only one cell, but they're a very
complex group of living things.
There are thousands of species of bacteria, but all of them
are basically one of three different shapes.
Some are rod- or stick-shaped; others are shaped like little
balls.
Others still are helical or spiral in shape.

6. Classification of bacteria
There are several approaches to bacterial classification

7. A. Morphological classsification.
Based on morphology bacteria are divided into
various groups
1. Filamentous or higher bacteria- Actinomycetes
2. True or lower bacteria
I. Gram positive bacilli
Aerobes- corynebacterium, bacillus
Anaerobes-Clostridium, lactobacillus
II. Gram positive cocci
III. Gram negative cocci
IV. Gram negative bacilli or rods

8. Gram-positive rods
Gram-negative rods
Gram-positive cocci
Gram-negative cocci

9. B.Nutritional classification
I. Based on Energy requirements
Phototrophs: Derive energy from sunlight
Chemotrophs: Use Chemicals
II. Based on ability to synthesize essential metabolites
Autotrophs: Synthesize organic compounds from
carbon dioxide and nitrogen
Heterotrophs: Depend on preformed organic
compounds eg. pathogens
III. Based on oxygen requirements
Aerobes
Anaerobes

10. Gram-positive
cocci
Anaerobic
Gram-positive rods
Anaerobic
Gram-negative rods
Anaerobic
Gram-positive cocci
Anaerobic
Gram-negative cocci

11. C. Based on temperature
Psychrophiles: Below 20°C
Mesophiles: 25-40°C
Thermophiles: 55-80°C

12. D. Classification based on staining reaction:
Based on Grams stain:
Gram positive bacteria
Gram negative bacteria

13. Bacterial
Pathogenicity

14. Microbial Mechanisms of Pathogenicity:
How Microorganisms Cause Disease

15. How do Bacterial Pathogens penetrate
Host Defenses?
1. Adherence - almost all pathogens have a
means to attach to host tissue
Binding Sites
Adhesins
Ligands

16. Some cells use fimbriae to adhere.
Fimbriae can play
a role in tissue
tropism.

17. Adhesins and ligands are usually on
Fimbriae
• Neisseria gonorrhoeae
• ETEC (Entertoxigenic
E. coli)
• Bordetello pertussis

18. Bacteria typically employ proteins known
as Adhesins to attach to host tissues, which
usually are located on ends of fimbriae.
Alternatively, adhesins can consist of
glycocalyx.

19. 2. Capsules
• Prevent phagocytosis
• Attachment
• Streptococcus
pneumoniae
• Klebsiella
pneumoniae
• Haemophilus
influenzae
• Bacillus anthracis
K. pneumoniae

20. Avoidance of Phagocytosis
Capsules are Involved in
avoidance of phagocyte-
mediated recognition and
attachment.

21. Cell Wall Components
M protein: Found on cell surface and fimbriae of
Streptococcus pyogenes. Mediates attachment
and helps resist phagocytosis. M-protein is heat
and acid resistant.
Waxes [ Mycolic Acid]: In cell wall of
Mycobacterium tuberculosis helps resist
digestion after phagocytosis and can multiply
inside WBC.

22. 3. Enzymes
• Many pathogens secrete enzymes
that contribute to their
pathogenicity

23. A. Leukocidins
• Attack certain types of WBC’s
• 1. Kills WBC’s which prevents phagocytosis
• 2. Releases & ruptures lysosomes
–lysosomes - contain powerful hydrolytic
enzymes which then cause more tissue damage

24. B. Hemolysins - cause the lysis of RBC’s
Streptococci

25. C. Coagulase - cause blood to coagulate
• Blood clots protect bacteria from
phagocytosis from WBC’s and other host
defenses
• Staphylococcus aureus - are often coagulase
positive
Fibrinogen ----------------- Fibrin ( Clot)

26. D. Kinases - enzymes that dissolve blood
clots
• 1. Streptokinase - Streptococci
• 2. Staphylokinase - Staphylococci
• Helps to spread bacteria - Bacteremia

27. E. Hyaluronidase
• Breaks down Hyaluronic acid (found in connective
tissues)
• “Spreading Factor”
• mixed with a drug to help spread the drug
through a body tissue
• Streptococci, Staphylococci, Clostridia and
pneumococci.

28. F. Collagenase
• Breaks down collagen (found in many connective
tissues)
• Clostridium perfringens - Gangrene
– uses this to spread through muscle tissue

29. H. Lecithinase
• Destroys lecithin ( phosphatidylcholine)
component of plasma membrane.
• Allowing pathogen to spread
• Clostridium perfringens

30. Summary of How Bacterial
Pathogens Penetrate Host Defenses
• 1. Adherence
• 2. Capsule
• 3. Enzymes
– A. leukocidins B. Hemolysins
– C. Coagulase D. Kinases
– E. Hyaluronidase F. Collagenase
– G. Necrotizing Factor H. Lecithinase

31. Generalized Stages of Infection
1. Entry of Pathogen
– Portal of Entry
2. Colonization
– Usually at the site of entry
3. Incubation Period
– Asymptomatic period
– Between the initial contact with the microbe
and the appearance of the first symptoms

32. 4. Prodromal Symptoms
– Initial Symptoms
5. Invasive period
– Increasing Severity of Symptoms
– Fever
– Inflammation and Swelling
– Tissue Damage
– Infection May Spread to Other Sites

33. 6. Decline of Infection
5. Convalescence

34. Course of Infectious Disease
Incubation period is the
interval between
exposure and illness
onset.
Convalescence is a
time of recuperation
and recovery from
illness.
Depending on various factors an
individual may still be infectious
during either incubation or
convalescence.

35. USEFUL
MICROORGANISM

36. ROLE OF MICROORGANISM

37. Roles microorganism in digestion

38. ONE OF THE MAIN COMPONENT OF
PLANT IS CELLULOSE

41. BACTERIA THAT HELP IN DIGESTION
1.Lactobacillus acidophilus
2.Bifidobacteria
3.Streptococus thermophilus
4.Lactobacilus bulgaricus

42. Where can we find these
bacteria except in intestines ?

43. MEDICINE
• Some type of microorganism produce
important drugs called ANTIBIOTICS..
• Functions of antibiotics….
• Weaken
• Destroy other microorganism
• Penicillium notatum is a GREEN MOULD
• Its produces antibiotic called PENICILLIN

44. AGRICULTURE
• Bacteria play important roles to promote the
plant growth..
• Bacteria
• Break down dead plants and dead animals by
releasing AMMONIA

45. AMMONIA
• Adds nitrogen into the soil
• The nitrogen fixing bacteria in the soil change
the ammonia into nitrates.
• This nitrates will be used by plants
Ammonia Nitrates
nitrogen fixing bacteria

46. INDUSTRY
• Bacteria are used in the production of
• Milk
• Yogurt
• Cheese
• Vinegar
• Soy sauce
• Chocolate
• Certain vitamin B
• Citric acids

47. VIRUSES

48. Living or Non-Living?
Infectious particles of nucleic acid and
proteins
Cannot “live” (reproduce) outside a host

49. 1st virus discovered-Tobacco Mosaic
Virus (TMV)

50. Are viruses alive?

51. Prokaryotes Vs. Eukaryotes Vs. Viruses
• No membrane
bound nucleus
• Has a cell wall
• Only a few
organelles or none
at all.
• Has a capsule
surrounding it
• Three main types.
• Nucleus with
membrane
• Only plants have
cell wall
• Contains many
organelles
• Has a lipid bi-layer
membrane
surrounding it.
• Specialized by
thousands of
different sizes and
shapes.
• No nucleus
• No membranes
• No organelles
• Cannot
reproduce on its
own
• Generally not
considered alive
by most
standards

52. VIRUS STRUCTURE

54. Adenovirus, a naked virus, with a polyhedral capsid and a fiber
at each corner

55. Influenza virus, surrounded by an envelope with
spikes

56. Virion Structure
Nucleic Acid
Spike
Projections
Protein
Capsid
Lipid Envelope
Virion
Associated
Polymerase

57. Polyhedral capsid attached to a
helical tail.

58. T4 Bacteriophage

59. Head
Tail fiber
DNA
Tail

60. Viral Infection

61. Viruses and Living Cells
• Viruses must infect a living cell in order
to grow and reproduce
• They also take advantage of the host’s
respiration, nutrition and all the other
functions that occur in living things
• Therefore, viruses are considered to be
parasites

62. Viral Reproduction
• Steps of Lytic Cycle
–Attachment
–Entry
–Replication
–Assembly
–Lysis/Release (lyses the cell)

63. In the lytic cycle, the
virus reproduces
itself using the host
cell's chemical
machinery.
The red spiral lines in
the drawing indicate
the virus's genetic
material.
The orange portion is
the outer shell that
protects it.

64. Viruses Enter Living Cells
Viruses enter plant cells through tiny rips in the
cell wall.
Viruses enter animal cells by endocytosis.

65. Viriods
• Much smaller than viruses
• Just consist of small sRNA molecule
• No protein coat
• Infect plants

67. Protozoa

68. Protozoa:
• The word protozoa is come from Greek
protozoon word meaning “First Animal”.
• Protozoa are unicellular (may be Multicellular)
Eukaryotic microorganism.

69. Characteristics
• Mostly Unicellular organism with fully
functional cell
• Live freely, may be parasitic or symbiotic
• Protozoa are chemo-hetrotrops
• They are motile have locomotive organelles.
E.g. Flagella and Cilia for movement

70. Nutrition
• Mostly protozoa feed on dead plants and animal
debris while some (trophozoites) feed on bacteria
and Algae.
• Parasitic Protozoa feeds on the fluids and tissues
of their host(e.g. Plasma and blood cells)
• Some Protozoa live in symbiotic relationship
with other plants and animals

71. Reproduction in Protozoa
• Protozoa can reproduce their off spring by both
Sexual and Asexual methods
• Asexual methods of reproduction are:
– Budding
– Binary Fission
– Schizogony or Multiple Fission
• Sexual Methods
– Conjugation
– Gametogony

72. Disease Caused Protozoa
Disease Causative Agent
Malaria Plasmodium
(P. Falciparum, P. Oval,P. Vivax,
P.malariae)
Giardiasis (diarrhea) Giardia intestinalis
Amoebic Dysentery Entamoeba histolytica
Toxoplasmosis
(immune deficiency )
Toxoplasma gondii
Cryptosporidiosis Cryptosporidia
Sleeping sickness Trypanosoma
Leishmmaniasis (kala-azar) Leishmania

73. Antiprotozoal Drugs
• Examples of antiprotozoal drugs include:
Chloroquine Mefloquine and Pyrimethamine.
These are used in malaria treatment.
• Metronidazole was developed as an
antiprotozoal drug. It induces strand breaks in
the DNA of sensitive organisms and also
disrupts membrane integrity.

74. FUNGI

75. Characteristics of Fungi
• Body form
–unicellular
–filamentous (tube-like strands called hypha
(singular) or hyphae (plural)
mycelium = aggregate of hyphae
sclerotium = hardened mass of mycelium
that generally serves as an overwintering
stage.

76. • Heterotrophy - 'other food'
–Saprophytes or saprobes - feed on dead
tissues or organic waste (decomposers)
–Symbionts - mutually beneficial
relationship between a fungus and
another organism
–Parasites - feeding on living tissue of a
host.
• Parasites that cause disease are called
pathogens.

77. Fungi as Saprobes and Decomposers

78. Mycorrhizae
• “Fungus roots”
• Mutualism between:
– Fungus (nutrient & water uptake for plant)
– Plant (carbohydrate for fungus)
• Extremely important ecological role of fungi!

79. Lichens
• “Mutualism”
between
–Fungus – structure
–Algae or
cyanobacterium –
provides food

80. Fungi are Spore-ific!!!
• Spores - asexual (product of mitosis) or sexual
(product of meiosis) in origin.
• Purpose of Spores
– Allows the fungus to move to new food source.
– Resistant stage - allows fungus to survive periods
of adversity.
– Means of introducing new genetic combinations
into a population

81. HUMAN-FUNGUS INTERACTIONS
• Beneficial Effects of Fungi
– Decomposition - nutrient and carbon
recycling.
– Biosynthetic factories. Can be used to produce
drugs, antibiotics, alcohol, acids, food (e.g.,
fermented products, mushrooms).
– Model organisms for biochemical and genetic
studies.

82. Harmful Effects of Fungi
–Destruction of food, lumber, paper, and
cloth.
–Animal and human diseases, including
allergies.
–Toxins produced by poisonous mushrooms
and within food (e.g., grain, cheese, etc.).
–Plant diseases.