Question

Describe the adaptive immune response of the body to (and include attack mechanisms)

a. invading bacteria.

b. invading viruses.

Answer 1

Body's response to bacteria

3 ways

Complement medicated lysis

The first step of classical complement pathway require the binding of antibodies to the surface of the target bacteria. C1-C1 protein complex is formed.C1 initiates a cascade of cleavage and reforming of complement complexes that ends in the binding of several complement protein to the surface of the bacteria in the form of MAC or generate opsonin that label a bacteria for destruction.It produces pore which allow the entry of membrane damaging molecules

Via phagocytosis

After the bacteria are ingested by phagocytosis they are killed by various processes that occur inside the cell and broken into small fragments by enzymes

Circulating helper t cells recognise these bacterial fragments and begin to produce proteins called cytokines

Via cell mediated immunity

Some bacteria engulfed during phagocytosis avoid the killing mechanism of the phagocyte to survive inside cell.Eg mycobacterium tuberculosis.

macrophages are a common targets for intracellular bacteria that live inside cell compartments.These bacteria cannot be detected by complement or antibody are eliminated by cell mediated response

Infected macrophages present bacterial peptides on their cell surface using MHC II(major histocompatibility complex).This mechanism is called antigenic presentation

Immune response to virus

A virus invades a host cells so that it replicate the itself to maximum this is done by the enzyme reverse transcriptase

Major cells involved are cytotoxic t cells.They kill the cells that are indected with the virus.they have special receptors that help them to detect virus infected cells.Cytotoxic cells releases cytotoxix factors to kill the infected cell

NK cell (natural killer) also help in killing viruses

Via interferons

Infected cells produce interferons.Interferons prevent replication of viruses by directly preventing their ability to replicate within a infected cell.

Via antibodies

Antibodies neutralize the virus meaning that is no longer capable of infecting the host cell

They brinh anout agglutination of the virus

Another mechsnism is phagocytosis.