To survive, organisms must continually adapt to continually evolving invading organisms. Hosts and pathogens are the key players of a continous conflict in which natural selection aids pathogens to increase virulence to escape host surveillance, and hosts to acquire adequate defence strategies. In both cases, these achievements are limited by several factors such as the genetic fitness and the number of genes required, much larger than that available in the genome. Moreover, since the pathogen usually has a very shorter life than the host, it has to fix new mutations favoring virulence much faster than the host can evolve effective defense mechanisms. Another constrain concerns the host that must avoid adverse effects which may derive from the defence system itself. Once resistance and counter resistance are genetically assessed, both the host and the pathogen evolve in response to mutually exerted pressures. This is generally referred to as the "Red Queen Paradigm", that highlights the significance of biotic versus abiotic factors that lead to constant evolutionary changes. Evolution acts at different levels: biotic factors mainly shape species diversity over short time periods, whereas changes in the physical environment such as climate changes drive evolution at a large scale, during much longer time. Much of our current knowledge of infection biology is based on studies of the immune system in humans and mice. In contrast, much less attention has been paid to immune response in lower vertebrates. Since many features of immune defence mechanisms have been acquired throughout evolution, studying the evolution of successful pathogen virulence mechanisms highlights the potential weaknesses in host immune defenses. On the other hand, investigating the defence mechanisms which species other than tetrapods have evolved to counter infectious agents may allow to identify novel molecules and strategies useful to manage an infection in the host' s favor. So far, few attempts have been made at considering host and pathogen as interacting partners into a common evolutionary framework. A short overview on how the host-pathogen interaction has been shaped by evolution will be given.
Evolution of the immune response to pathogens
Maria Rosaria Coscia
2016
Abstract
To survive, organisms must continually adapt to continually evolving invading organisms. Hosts and pathogens are the key players of a continous conflict in which natural selection aids pathogens to increase virulence to escape host surveillance, and hosts to acquire adequate defence strategies. In both cases, these achievements are limited by several factors such as the genetic fitness and the number of genes required, much larger than that available in the genome. Moreover, since the pathogen usually has a very shorter life than the host, it has to fix new mutations favoring virulence much faster than the host can evolve effective defense mechanisms. Another constrain concerns the host that must avoid adverse effects which may derive from the defence system itself. Once resistance and counter resistance are genetically assessed, both the host and the pathogen evolve in response to mutually exerted pressures. This is generally referred to as the "Red Queen Paradigm", that highlights the significance of biotic versus abiotic factors that lead to constant evolutionary changes. Evolution acts at different levels: biotic factors mainly shape species diversity over short time periods, whereas changes in the physical environment such as climate changes drive evolution at a large scale, during much longer time. Much of our current knowledge of infection biology is based on studies of the immune system in humans and mice. In contrast, much less attention has been paid to immune response in lower vertebrates. Since many features of immune defence mechanisms have been acquired throughout evolution, studying the evolution of successful pathogen virulence mechanisms highlights the potential weaknesses in host immune defenses. On the other hand, investigating the defence mechanisms which species other than tetrapods have evolved to counter infectious agents may allow to identify novel molecules and strategies useful to manage an infection in the host' s favor. So far, few attempts have been made at considering host and pathogen as interacting partners into a common evolutionary framework. A short overview on how the host-pathogen interaction has been shaped by evolution will be given.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
