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An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, helminths, and fungi which could cause serious problems to the health of the host organism if not cleared from the body.
The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory, where each pathogen is "remembered" by a signature antigen. [55] The adaptive immune response is antigen-specific and requires the recognition of specific "non-self" antigens during a process called antigen ...
For infections to occur, the virus has to hijack host factors and evade the host immune response for efficient replication. Viral replication frequently requires complex interactions between the virus and host factors that may result in deleterious effects in the host, which confers the virus its pathogenicity.
The following outline is provided as an overview of and topical guide to concepts related to infectious diseases in humans.. Infection – transmission, entry/invasion after evading/overcoming defense, establishment, and replication of disease-causing microscopic organisms (pathogens) inside a host organism, and the reaction of host tissues to them and to the toxins they produce.
In biology, it refers to damage caused to an organism by its own immune response, as a result of an infection. It could be due to mismatch between pathogen and host species, and often occurs when an animal pathogen infects a human (e.g. avian flu leads to a cytokine storm which contributes to the increased mortality rate).
Infections can be caused by a wide range of pathogens, most prominently bacteria and viruses. [2] Hosts can fight infections using their immune systems. Mammalian hosts react to infections with an innate response, often involving inflammation, followed by an adaptive response. Treatment for infections depends on the type of pathogen involved.
Within the host, pathogens can do a variety of things to cause disease and trigger the immune response. Microbes and fungi cause symptoms due to their high rate of reproduction and tissue invasion. This causes an immune response, resulting in common symptoms as phagocytes break down the bacteria within the host.
immunoevasion, evasion of the host's immune response [1] [2] [3] immunosuppression, inhibition of the host's immune response (this includes leukocidin-mediated cell death) [1] entry into and exit out of cells (if the pathogen is an intracellular one) [4] obtain nutrition from the host [1] Specific pathogens possess a wide array of virulence ...