Question

Explain how the immune system both responds to and controls toxoplasma gondii infection in the brain.

Answer 1

• Toxoplasma gonadii is a protozoan parasite which mainly affect warm blooded organisms
• there are 3 infectious stages - tachyzoites, bradyzoites in tissue cyst and sporozoites in oocyst
• wild cat is the only definitive host and in it the prasite acquires sexual maturity and human is an intermediate host
• human get infection from tachyoites from cat faces or by the consumption of uncooked meat
• toxoplasma has the ability to cross BBB
• It works by suppressing the immune cells action in the host.
• They affects the neural system and especially brain , and alters their functions leading to various disorders.
• But it won't kill the host, on which they relay on.
• Mechanism:-
• By using a protein present in them they are get entered into the macrophages in the host body thus altering its expression and function.
• thus it form anti-inflammatory M2 macrophages by transforming pro- inflammatory macrophages(M1)
• Thus T cell response and function is downregulated.
• And it also downregulates STAT-1.
• Hence we can conclude that it reduces our immune response by reducing M1 and ATAT-1, and by increasing M2 , STAT-3 and STAT-6 functions.
• how our immune system work to suppress and remove this infection
• on invasion of the pathogen, our immune sensors directs the production of cytokines and chemokines
• our APCs will also get activted thus activating the expression of CD8+ receptors and T helper cell
• these all together produces interferon gamma, that can increase the immune response of cells that can infect with toxoplasma gonadii
• interferon inducible GTPase inducible nitric oxide synthase and indole amine 2,3 dioxygenase also will inturn will get activated by interferon gamma and suppress and kills these parasite