Microbiology

B.E Pruitt & Jane J. Stein

AN INTRODUCTION

TORTORA • FUNKE • CASE

Chapter 18

Practical Applications of Immunology

Vaccine History• Variolation: Inoculation of smallpox into skin (18th century)

• Vaccination: Inoculation of cowpox into skin

• Herd immunity results when most of a population is immune to a disease.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Jenner• On 14th May 1796, Edward Jenner used cowpox-infected material obtained from the hand of Sarah Nemes, a milkmaid from his home village of Berkley in Gloucestershire to successfully vaccinate 8 year old James Phipps. On 1st July 1796, Jenner challenged the boy by deliberately inoculating him with material from a real case of smallpox.He did not become infected!

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

How Vaccines work• Trigger your own immune response– Artificially acquired active

immunity

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture. Virus, Bacterial or Toxins

•Attenuated - no longer virulent

•Inactivated or Killed - formalin, phenol or heat destroyed

Types of Vaccines• Attenuated whole agent vaccines:

– Live, attenuated (weakened) microbes - virus or bacteria

– Long term immunity

– May back mutate to virulent strain (rare)

• Inactivated (killed) vaccines:– Killed by formalin, phenol or heat

– Toxoids

– Not as long lasting

– Safe

• Subunit vaccine:– Uses fragments from virus or bacteria

• Produced by recombinant methods Recombinvac

– Safe

– Clean

• Conjugated vaccines:– Bind to larger particle or protein to enhance antigenicity

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

• DTaP - Trivalent (three in one)– Diphtheria: Purified diphtheria toxoid– Pertussis: Acellular fragments of B. pertussis– Tetanus: Purified tetanus toxoid

• Meningococcal meningitis: Purified polysaccharide from N. meningitidis

• Haemophilus influenzae type b meningitis: Polysaccharides conjugated with protein

• Pneumococcal conjugate vaccine: S. pneumoniae antigens conjugated with protein

Principal Vaccines Used in the United States to Prevent Bacterial Diseases in

Humans

Vaccine Schedule

• Smallpox: Live vaccinia virus• Poliomyelitis: Inactivated virus• Rabies: Inactivated virus• Hepatitis A: Inactivated virus• Influenza: Inactivated or attenuated virus• Measles: Attenuated virus• Mumps: Attenuated virus• Rubella: Attenuated virus• Chickenpox: Attenuated virus• Hepatitis B: Antigenic fragments (recombinant vaccine)

Principal Vaccines Used in the United States to Prevent Viral Diseases in

Humans

Other Diagnostic applications: Serological Tests

Diagnostic Immunological tests:• Direct tests detect antigens (from patient sample)• Indirect tests detect antibodies (in patient's serum)

Diagnostic Immunology: Precipitation Reactions

Precipitation Reactions:• Involve soluble

antigens with antibodies

• Precipitin Ring test

Figure 18.3

Agglutination Reactions• Involve particulate

antigens and antibodies

• Antigens may be:• On a cell (direct

agglutination) • Attached to latex

spheres (indirect or passive agglutination)

Figure 18.4

Hemagglutination

• Hemagglutination involves agglutination of RBCs.

Figure 18.7

Neutralization Reactions• Antibodies help eliminate the harmful effect of a virus or exotoxin

• Viral hemagglutination inhibition tests for the presence of antibodies in a patients serum by the antibodies' ability to prevent viruses from agglutinating RBCs.

Figure 18.8b

Antibody Titer

• Is the concentration of antibodies against a particular antigen

Figure 18.5

Complement Fixation

Figure 18.9.1

Complement Fixation

Figure 18.9.2

Fluorescent Antibody Techniques (Direct)

Figure 18.10a

Fluorescent Antibody Techniques (Indirect)

Figure 18.10b

Enzyme-Linked Immunosorbent Assay(Direct ELISA)

Figure 18.12a

Enzyme-Linked Immunosorbent Assay (Indirect ELISA)

Figure 18.12b

Serological Tests

Figure 18.13

Serological Tests: Summary• Precipitation: Soluble antigens • Agglutination: Particulate antigens• Hemagglutination: Agglutination of RBCs• Neutralization (inhibition): Inactivates toxin or virus• Fluorescent-antibody technique: Antibodies linked to

fluorescent dye• Complement fixation: RBCs are indicator• ELISA: Enzyme linked to antibody amplifies results for

easier visibility and more sensitivity.