Understanding Viral Mutations and Immune Responses

VIRUS H5N1

1a) Genetic Changes and Protein Expression

Changes are mutations of genetic material. Proteins are bound to gene expression. Genetic mutations must occur, or changes in proteins result from the translation process.

b) Immunity to H5N1

No person has been documented as having been infected with H5N1 antigens and subsequently acquired immunological memory that protects them.

2. Vaccine Efficacy and Viral Mutation

A vaccine produces a primary immune response (antigen-antibody) and a vaccinated person acquires immunological memory to respond effectively to the infection. Therefore, injecting a non-replicating virus (which possesses the same antigen) is difficult. In the case of the H5N1 virus, if it mutates easily, the vaccine might no longer match the strain causing infection, rendering the vaccine ineffective.

SERUM ROUX

1. Passive Immunity

Vaccination can cure diphtheria because immunized animals produce antibodies against the bacteria. Passive immunity provides antibodies produced by an immunized individual.

2. Active Immunity

Active immunity can prevent illness from bacteria because the protein antigens are recognized as foreign by the immune system. T lymphocytes activate B lymphocytes, which then produce antibodies. Subsequently, if the person is infected, the memory B cells provide protection.

ANTIGEN CONCENTRATION (For Students)

1a) Antibody Specificity

Antibodies have a very specific area of recognition for different antigens. Each antibody joins only in the region of the antigen for which it was synthesized.

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4B. IMMUNE RESPONSE FRAMEWORK

1. Primary vs. Secondary Response

When a person is infected by a microorganism, it acts as an antigen and causes the production of antibodies. The immune system generates a primary response, which usually overcomes the infection but stimulates the production of Memory B cells. When the individual comes into contact with the same microorganism a second time, this triggers the secondary response. The B lymphocytes produce antibodies that neutralize the antigens and prevent reinfection. The secondary response is more intense and faster.

2. Types of Immunity

• Nonspecific (Innate): Absorbs bacteria regardless of the species.
• Specific (Adaptive): Leukocytes produce antibodies against specific antigens.

VARICELLA (CHICKENPOX) IMMUNITY

1. Post-Infection Immunity

When a person has had chickenpox, the T lymphocytes in the immune response are activated, leading to plasma B cells that secrete neutralizing antibodies against the virus. Simultaneously, memory B cells are formed. If the individual is later exposed to the varicella virus, these antibodies occur, and reinfection does not happen (secondary immune response).

2. Artificial Immunity

Artificial immunity is caused by the use of techniques that encourage the body's response:

• Vaccine: Artificial active immunity (preventive measure of disease).
• Immunoglobulin: Artificial passive immunity (curative measure).

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Blood Group Agglutination

Agglutination occurs where antigens (e.g., Antigen B) recognize and join with anti-B antibodies. These antibodies are produced by the B lymphocytes of a person who received B blood type because the immune system recognized Antigen B as foreign. The T lymphocytes initially recognized the antigen and stimulated the B lymphocytes in the response.