Virulence Factors and Evasion of the Human Defense System of Fungus

Dimorphic fungi known as Candida albicans are the most studied and most common fungal pathogens in humans and avoid the human complement system. It fills the oral and urogenital tract, the surface of the gastrointestinal tract and causes a series of infectious diseases depending on the characteristics of the host's potential defects. As a former hospital employee, I have witnessed the direct information of this increasing amount that caused my curiosity and studied the reasons and ways this fungus can achieve this toxicity.

Ustilago maydis is a pathogenic plant fungus that produces ut in corn and corn. Plants have evolved an effective defense system against pathogenic microorganisms such as Liriomyza sativae. Rapid defense response after pathogen challenge is an oxidative burst in which plants produce reactive oxygen species at the site the plant is about to invade. U. maydis responds to oxidative bursts by an oxidative stress response regulated by the gene YAP1. This reaction protects U. maydis from host defense and is required for pathogen toxicity. Also, U. Maidis has a well-established recombinant DNA repair system that functions during mitosis and meiosis. This system can help pathogens survive DNA damage caused by oxidative defense reactions of host plants against infection.

Bacterial pathogenic factors such as glycocalyx and various adhesins enable colonization in the host, immune evasion and establishment of disease. Septicemia caused by Gram-negative bacteria is thought to be mainly caused by host reaction to the lipid A component of lipopolysaccharide (also known as endotoxin). Sepsis caused by gram positive bacteria may be caused by an immune response to cell wall lipoteichoic acid. Bacterial exotoxins as superantigens may also cause sepsis. In the absence of antigen presentation, superantigens bind to both the major histocompatibility complex and the T cell receptor. This forced receptor interaction induces the production of pro-inflammatory chemical signals (cytokines) in T cells

S. pyogenes produces various pathogenic factors and numerous diseases. Toxicity factors of group A streptococci include: (1) M protein, fibronectin binding protein (protein F) and lipoteichoic acid; (2) hyaluronic acid capsule as immunological camouflage and inhibition of phagocytosis. (3) exotoxin original (erythrocyte) toxin such as streptokinase, streptomycin (DNase B), invasin such as hyaluronidase, streptolysin, (4) exotherm causing scar red fever, systemic toxic shock syndrome etc