What is a host? Incorporating the microbiota into the damage-response framework

Arturo Casadevall, Liise-anne Pirofski

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Since proof of the germ theory of disease in the late 19th century, a major focus of the fields of microbiology and infectious diseases has been to seek differences between pathogenic and nonpathogenic microbes and the role that the host plays in microbial pathogenesis. Remarkably, despite the increasing recognition that host immunity plays a role in microbial pathogenesis, there has been little discussion about what constitutes a host. Historically, hosts have been viewed in the context of their fitness or immunological status and characterized by adjectives such as immune, immunocompetent, immunosuppressed, immunocompromised, or immunologically impaired. However, in recent years it has become apparent that the microbiota has profound effects on host homeostasis and susceptibility to microbial diseases in addition to its effects on host immunity. This raises the question of how to incorporate the microbiota into defining a host. This definitional problem is further complicated because neither host nor microbial properties are adequate to predict the outcome of host-microbe interaction because this outcome exhibits emergent properties. In this essay, we revisit the damage-response framework (DRF) of microbial pathogenesis and demonstrate how it can incorporate the rapidly accumulating information being generated by the microbiome revolution. We use the tenets of the DRF to put forth the following definition of a host: a host is an entity that houses an associated microbiome/microbiota and interacts with microbes such that the outcome results in damage, benefit, or indifference, thus resulting in the states of symbiosis, colonization, commensalism, latency, and disease.

Original languageEnglish (US)
Pages (from-to)2-7
Number of pages6
JournalInfection and Immunity
Volume83
Issue number1
DOIs
StatePublished - 2015

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Microbiota
Symbiosis
Germ Theory of Disease
Immunity
Microbiology
Communicable Diseases
Homeostasis

ASJC Scopus subject areas

  • Immunology
  • Microbiology
  • Parasitology
  • Infectious Diseases

Cite this

What is a host? Incorporating the microbiota into the damage-response framework. / Casadevall, Arturo; Pirofski, Liise-anne.

In: Infection and Immunity, Vol. 83, No. 1, 2015, p. 2-7.

Research output: Contribution to journalArticle

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