Active immunity examples
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Examples of Active Immunity
Active immunity is a crucial aspect of the immune system, providing long-term protection against infectious diseases. This article explores various examples of active immunity, highlighting the mechanisms and applications of different vaccines and immunization strategies.
Oral Live Vaccines and Mucosal Immunity
One example of active immunity is the response elicited by oral live vaccines. These vaccines stimulate antibody-secreting cells (ASC) in the peripheral blood, which originate in the mucosa and reflect the mucosal immune response. A booster dose of a live bacterial vaccine given during active mucosal immunity results in a low ASC response, likely due to the inhibition of the vaccine's multiplication in the gut. This scenario exemplifies protective immunity when an orally immunized person encounters the pathogen in nature .
Types of Vaccines and Their Role in Active Immunity
Active immunity can be generated through various types of vaccines, including live attenuated, killed/inactivated, subunit, and toxoid vaccines. Each type of vaccine stimulates the adaptive immune response differently. Live attenuated vaccines, for instance, contain weakened forms of the pathogen that can still replicate and induce a strong immune response without causing disease. Killed or inactivated vaccines contain pathogens that have been killed, while subunit vaccines include only parts of the pathogen, such as proteins. Toxoid vaccines contain inactivated toxins produced by the pathogen .
Bacterial Vaccines and Prophylactic Use
Bacterial vaccines are another example of preparations that stimulate active immunity. These vaccines can be made from living or dead organisms, or extracts and derivatives of the organisms. They are used as general prophylactics to protect against future exposure to infections. For instance, scarlet fever prophylactic preparations contain antigens that stimulate the recipient to form antibodies, providing long-term immunity .
Vaccinia and Smallpox Immunization
The immunity developed towards vaccinia after successful vaccination is a classical example of artificially induced active immunity. This type of immunity can last for many years and is used to protect against smallpox. The calf is commonly employed for producing the vaccine-virus used in human smallpox vaccinations. Despite some challenges in utilizing the immune principles from vaccinated animals, the existence of immunity substances in the blood of vaccinated animals has been demonstrated .
Toxin-Antitoxin Mixtures
Active immunity can also be produced by injecting toxin-antitoxin mixtures. These mixtures, when balanced correctly, can induce long-lasting immunity without causing harmful effects. For example, guinea pigs injected with these mixtures developed active immunity lasting several years. This method shows promise for developing practical and controlled immunization strategies for humans .
Conclusion
Active immunity is a vital component of the immune system, providing long-term protection against various infectious diseases. Examples include the use of oral live vaccines, different types of commercially available vaccines, bacterial vaccines, and toxin-antitoxin mixtures. These strategies highlight the diverse mechanisms through which active immunity can be achieved, offering valuable insights for developing effective immunization programs.
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