BASIC IMMUNOLOGY.
BRIEF HISTORY OF IMMUNOLOGY AND VACCINOLOGY
Immunology began as a branch of microbiology. The study of infectious disease and the
body’s response to them has played a major role for the development of immunology.
Moreover, the concept of germ theory of disease has contributed to the field of immunology.
The notion of protective immunity can be traced back to the observation in the fifth century
BCE that individuals who had recovered from disease during the Plague of Athens were
protected from subsequent attacks. In the 10th century, people in ancient China often used
skin lesions of patients recovered from small pox to cure small pox in young children. Dried
crusts derived from small pox pustules were either inhaled through the nostrils or inserted
into small cuts in the skin; a technique known as variolation.
However, the birth of the science of immunology is most readily attributed to the
demonstration by Edward Jenner at the end of the 18th century that individuals
intentionally inoculated with material from cowpox-infected cattle were protected from
smallpox. Jenner baptized his process vaccination, after vaccinia, the name given to the
mild disease produced by cowpox. Small pox was the first disease that was eradicated
worldwide by vaccination.
In 1878, Pasteur accidentally injected chicken with an aged chicken cholera causing
bacterium culture. When these chicken were injected with a second dose of bacterium from a
fresh culture the birds survived the virulent form of the disease. This led to development of
an attenuated vaccine against chicken cholera in 1879. Pasteur went on to develop an
attenuated vaccine against rabies and swine erysipelas. Although Pasteur was remarkably
successful in developing effective vaccines, he had little knowledge of the concepts of
mechanisms involved.
In 1890, Emil von Behring and Shibasaburo Kitasato demonstrated protection induced by
vaccination was due to protective factors in blood by injecting healthy animals with serum
from animals infected with diphtheria. The vaccinated animals were found to be resistant to
the disease. Eventually these serum factors were recognized in 1930 as antibodies. However,
thirty years before antibodies were finally isolated and identified; Paul Ehrlich and others
had recognized that a specific antigen elicited the production of a specific antibody.
In 1884, Roux used serum from horses vaccinated against Corynebacterium diphtheria to
treat diphtheria in man. In 1883 even before the discovery that a serum component could
transfer immunity, Elie Metchnikoff demonstrated that cells also contribute to the immune
state of an animal. He observed that certain white blood cells, which he termed phagocytes,
ingested (phagocytosed) microorganisms and other foreign material. Noting that these
phagocytic cells were more active in animals that had been immunized, Metchnikoff
hypothesized that cells, rather than serum components, were the major effectors of immunity.
, The 20th century was an active time for research when most questions about the biology of
the immune system were raised and answers found. The current understanding of human and
animal immune system and its functions has remarkably improved. Recently the science of
immunology has grown rapidly due to advent of new molecular biology tools. The
development of effective vaccines represents one of the most promising approaches for
providing cost-effective interventions against infectious diseases in animal and against other
types of diseases such as cancer
Definition of Common terms:
Infection
Infection is the invasion of a host organism's body tissues by disease-causing agents
(pathogens). An infection may cause no symptoms and be subclinical, or it may cause
symptoms and be clinically apparent. An infection may remain localized, or it may spread
through the blood or lymphatic vessels to become systemic (body wide).
Resistance – It is the intrinsic /innate properties of an animal to survive exposure to
microorganism and their products. OR
Defence of a host against infecting agents (absolute and relative resistance)
- Absolute resistance – Complete insusceptibility of a host to a given specific infection
and mostly applies to species e.g. Equines are resistance to FMD.
- Relative resistance – it is the variation in individual reactions to a given infection.
Applies to individual in a given species e.g. Ndama cattle are resistant to trypanosomosis.
Virulence- The pathogenicity of a microbe
Avirulent- Lacking ability to cause disease/Reduced ability to cause disease
Pathogenesis- The process of progressive development of an infection from the start to the
end
Antigen – An antigen is any substance that causes the immune system to produce antibodies
against it. It may be a foreign substance from the environment such as chemicals, bacteria,
viruses, pollen or may also be formed within the body, as with bacterial toxins or tissue cells
Antibodies - Specialized proteins whose production is stimulated by the introduction of
antigens in the body. They mainly protect the body against related antigens in the future.
Microbe- A micro-organism (organism that can only be seen by a microscope)
Attenuation- The process of reducing the virulence of a pathogen
Bacterin- Killed bacteria normally used as a vaccine
Toxin – Substance produced by bacteria that is harmful to other organisms
Toxoid- Killed /inactivated toxin
Hapten – a substance which cannot induce immunological reaction in a host unless attached
to a carrier molecule.
BRIEF HISTORY OF IMMUNOLOGY AND VACCINOLOGY
Immunology began as a branch of microbiology. The study of infectious disease and the
body’s response to them has played a major role for the development of immunology.
Moreover, the concept of germ theory of disease has contributed to the field of immunology.
The notion of protective immunity can be traced back to the observation in the fifth century
BCE that individuals who had recovered from disease during the Plague of Athens were
protected from subsequent attacks. In the 10th century, people in ancient China often used
skin lesions of patients recovered from small pox to cure small pox in young children. Dried
crusts derived from small pox pustules were either inhaled through the nostrils or inserted
into small cuts in the skin; a technique known as variolation.
However, the birth of the science of immunology is most readily attributed to the
demonstration by Edward Jenner at the end of the 18th century that individuals
intentionally inoculated with material from cowpox-infected cattle were protected from
smallpox. Jenner baptized his process vaccination, after vaccinia, the name given to the
mild disease produced by cowpox. Small pox was the first disease that was eradicated
worldwide by vaccination.
In 1878, Pasteur accidentally injected chicken with an aged chicken cholera causing
bacterium culture. When these chicken were injected with a second dose of bacterium from a
fresh culture the birds survived the virulent form of the disease. This led to development of
an attenuated vaccine against chicken cholera in 1879. Pasteur went on to develop an
attenuated vaccine against rabies and swine erysipelas. Although Pasteur was remarkably
successful in developing effective vaccines, he had little knowledge of the concepts of
mechanisms involved.
In 1890, Emil von Behring and Shibasaburo Kitasato demonstrated protection induced by
vaccination was due to protective factors in blood by injecting healthy animals with serum
from animals infected with diphtheria. The vaccinated animals were found to be resistant to
the disease. Eventually these serum factors were recognized in 1930 as antibodies. However,
thirty years before antibodies were finally isolated and identified; Paul Ehrlich and others
had recognized that a specific antigen elicited the production of a specific antibody.
In 1884, Roux used serum from horses vaccinated against Corynebacterium diphtheria to
treat diphtheria in man. In 1883 even before the discovery that a serum component could
transfer immunity, Elie Metchnikoff demonstrated that cells also contribute to the immune
state of an animal. He observed that certain white blood cells, which he termed phagocytes,
ingested (phagocytosed) microorganisms and other foreign material. Noting that these
phagocytic cells were more active in animals that had been immunized, Metchnikoff
hypothesized that cells, rather than serum components, were the major effectors of immunity.
, The 20th century was an active time for research when most questions about the biology of
the immune system were raised and answers found. The current understanding of human and
animal immune system and its functions has remarkably improved. Recently the science of
immunology has grown rapidly due to advent of new molecular biology tools. The
development of effective vaccines represents one of the most promising approaches for
providing cost-effective interventions against infectious diseases in animal and against other
types of diseases such as cancer
Definition of Common terms:
Infection
Infection is the invasion of a host organism's body tissues by disease-causing agents
(pathogens). An infection may cause no symptoms and be subclinical, or it may cause
symptoms and be clinically apparent. An infection may remain localized, or it may spread
through the blood or lymphatic vessels to become systemic (body wide).
Resistance – It is the intrinsic /innate properties of an animal to survive exposure to
microorganism and their products. OR
Defence of a host against infecting agents (absolute and relative resistance)
- Absolute resistance – Complete insusceptibility of a host to a given specific infection
and mostly applies to species e.g. Equines are resistance to FMD.
- Relative resistance – it is the variation in individual reactions to a given infection.
Applies to individual in a given species e.g. Ndama cattle are resistant to trypanosomosis.
Virulence- The pathogenicity of a microbe
Avirulent- Lacking ability to cause disease/Reduced ability to cause disease
Pathogenesis- The process of progressive development of an infection from the start to the
end
Antigen – An antigen is any substance that causes the immune system to produce antibodies
against it. It may be a foreign substance from the environment such as chemicals, bacteria,
viruses, pollen or may also be formed within the body, as with bacterial toxins or tissue cells
Antibodies - Specialized proteins whose production is stimulated by the introduction of
antigens in the body. They mainly protect the body against related antigens in the future.
Microbe- A micro-organism (organism that can only be seen by a microscope)
Attenuation- The process of reducing the virulence of a pathogen
Bacterin- Killed bacteria normally used as a vaccine
Toxin – Substance produced by bacteria that is harmful to other organisms
Toxoid- Killed /inactivated toxin
Hapten – a substance which cannot induce immunological reaction in a host unless attached
to a carrier molecule.
