Parasitism, defense mechanism

The immune system in vertebrates provides a defense mechanism against foreign parasites such as viruses and bacteria. Three main properties are essential to its successful operation specific recognition of foreign molecules, the ability to destroy the foreign parasite, and a memory mechanism that allows a more rapid response to a second infection by the same microorganism. 

Parasites have often developed unique ways of protection from the defense mechanisms of the host. 

The methylation of DNA at CpG islands has also turned out to be an important regulator for cell development, the differentiated proteome and the regulation of cell survival [237,238]. Indeed the implications of this chemical modification have been linked to DNA accessibility, chromatin fluidity and cell transformation [239,240]. DNA methylation is required for genomic stability and believed to act as an inert epigenetic marker in germinal cells and preimplantation embryos [238]. Presumably, DNA methylation is required for the heritable transmission of chromatin structure, which prevents the expression of terminally silenced genes in differentiated tissues, and provides a host-defense mechanism against parasitic transposable elements [241]. 

Immunology/infectious diseases Diseases affecting the defense mechanisms of the body. Studies in this area include AIDS, auto-immune diseases, bacterial infections, chronic fatigue syndrome, common cold, genital herpes, genital warts, hepatitis, HIV infections, immunosuppressive, influenza, lyme disease, meningitis, parasite and protozoan infections, strep throat, vaccines, viral infections, and others. 

Oxidative damage caused by reactive oxygen species has been called oxidative stress . Biological systems contain powerful enzymatic and non-enzymatic antioxidant mechanisms, and oxidative stress denotes a shift in the pro-oxidant/antioxidant balance in favor of the former (1). Reactive oxygen species are important mediators of several forms of cell damage in parasites and this discussion will focus on the defense mechanisms of parasites against these species. 

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