How does the body defend itself from yellow fever?

The body defends itself from yellow fever through several mechanisms:

Immune Response:

1. Adaptive Immune Response: After infection, the body's immune system produces antibodies specific to the yellow fever virus. These antibodies recognize and bind to the virus, preventing it from infecting cells.

2. Memory B and T Cells: Following the primary infection, memory B and T cells are generated. These cells "remember" the virus, enabling a faster and more robust immune response if re-infected in the future. This is the basis for long-term immunity against yellow fever.

Interferon Production:

- When infected with the yellow fever virus, cells produce interferons, which are proteins that inhibit viral replication. Interferons help limit the spread of the virus to uninfected cells.

Fever:

- Fever is a common symptom of yellow fever and serves as a defense mechanism. Elevated body temperatures can inhibit the replication and infectivity of the virus. It also promotes immune responses and circulation, facilitating the delivery of immune cells and antibodies to the affected tissues.

Complement System Activation:

- The complement system is a crucial part of the immune system. It helps destroy invading pathogens by tagging them for recognition and destruction by immune cells. In yellow fever infection, the complement system is activated, leading to the lysis of virus-infected cells.

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC):

- ADCC is a mechanism in which antibodies bound to infected cells recruit immune effector cells, such as natural killer (NK) cells, to recognize and kill virus-infected cells.

Vaccination:

- The most effective way to protect against yellow fever is through vaccination. The yellow fever vaccine is a live-attenuated vaccine, which induces robust immunity without causing severe disease. Vaccination stimulates the production of antibodies that provide long-lasting protection against the yellow fever virus.

These defense mechanisms work together to protect the body against yellow fever infection, leading to the resolution of symptoms and preventing severe complications.