The complement system plays a crucial role in the innate defense against common pathogens. Activation of complement leads to robust and efficient proteolytic cascades, which terminate in opsonization and lysis of the ...The complement system plays a crucial role in the innate defense against common pathogens. Activation of complement leads to robust and efficient proteolytic cascades, which terminate in opsonization and lysis of the pathogen as well as in the generation of the classical inflammatory response through the production of potent proinflammatory molecules. More recently, however, the role of complement in the immune response has been expanded due to observations that link complement activation to adaptive immune responses. It is now appreciated that complement is a functional bridge between innate and adaptive immune responses that allows an integrated host defense to pathogenic challenges. As such, a study of its functions allows insight into the molecular underpinnings of host-pathogen interactions as well as the organization and orchestration of the host immune response. This review attempts to summarize the roles that complement plays in both innate and adaptive immune responses and the consequences of these interactions on host defense.展开更多
A virus that can cause a global pandemic must be highly adaptive to human conditions.Such adaptation is not likely to have emerged suddenly but,instead,may have evolved step by step with each step favored by natural s...A virus that can cause a global pandemic must be highly adaptive to human conditions.Such adaptation is not likely to have emerged suddenly but,instead,may have evolved step by step with each step favored by natural selection.It is thus necessary to develop a theory about the origin in order to guide the search.Here,we propose such a model whereby evolution occurs in both the virus and the hosts(where the evolution is somatic;i.e.,in the immune system).The hosts comprise three groups–the wild animal hosts,the nearby human population,and farther-away human populations.The theory suggests that the conditions under which the pandemic has initially evolved are:(i)an abundance of wild animals in the place of origin(PL_(0));(ii)a nearby human population of low density;(iii)frequent and long-term animal-human contacts to permit step-by-step evolution;and(iv)a level of herd immunity in the animal and human hosts.In this model,the evolving virus may have regularly spread out of PL_(0) although such invasions often fail,leaving sporadic cases of early infections.The place of the first epidemic(PL_(1)),where humans are immunologically naïve to the virus,is likely a distance away from PL_(0).Finally,this current model is only a first attempt and more theoretical models can be expected to guide the search for the origin of SARS-CoV-2.展开更多
文摘The complement system plays a crucial role in the innate defense against common pathogens. Activation of complement leads to robust and efficient proteolytic cascades, which terminate in opsonization and lysis of the pathogen as well as in the generation of the classical inflammatory response through the production of potent proinflammatory molecules. More recently, however, the role of complement in the immune response has been expanded due to observations that link complement activation to adaptive immune responses. It is now appreciated that complement is a functional bridge between innate and adaptive immune responses that allows an integrated host defense to pathogenic challenges. As such, a study of its functions allows insight into the molecular underpinnings of host-pathogen interactions as well as the organization and orchestration of the host immune response. This review attempts to summarize the roles that complement plays in both innate and adaptive immune responses and the consequences of these interactions on host defense.
基金supported by the National Natural Science Foundation of China (31730046, 91731000, 31900417, and 81972691)Guangdong Basic and Applied Basic Research Foundation (2020B1515020030, 2019A1515010708)the National Key Research and Development Project of China (2020YFC0847000)
文摘A virus that can cause a global pandemic must be highly adaptive to human conditions.Such adaptation is not likely to have emerged suddenly but,instead,may have evolved step by step with each step favored by natural selection.It is thus necessary to develop a theory about the origin in order to guide the search.Here,we propose such a model whereby evolution occurs in both the virus and the hosts(where the evolution is somatic;i.e.,in the immune system).The hosts comprise three groups–the wild animal hosts,the nearby human population,and farther-away human populations.The theory suggests that the conditions under which the pandemic has initially evolved are:(i)an abundance of wild animals in the place of origin(PL_(0));(ii)a nearby human population of low density;(iii)frequent and long-term animal-human contacts to permit step-by-step evolution;and(iv)a level of herd immunity in the animal and human hosts.In this model,the evolving virus may have regularly spread out of PL_(0) although such invasions often fail,leaving sporadic cases of early infections.The place of the first epidemic(PL_(1)),where humans are immunologically naïve to the virus,is likely a distance away from PL_(0).Finally,this current model is only a first attempt and more theoretical models can be expected to guide the search for the origin of SARS-CoV-2.
