Molecular basis of host specificity in human pathogenic bacteria

Abstract

Pathogenic bacteria display various levels of host specificity or tropism. While many bacteria can infect a wide range of hosts, certain bacteria have strict host selectivity for humans as obligate human pathogens. Understanding the genetic and molecular basis of host specificity in pathogenic bacteria is important for understanding pathogenic mechanisms, developing better animal models and designing new strategies and therapeutics for the control of microbial diseases. The molecular mechanisms of bacterial host specificity are much less understood than those of viral pathogens, in part due to the complexity of the molecular composition and cellular structure of bacterial cells. However, important progress has been made in identifying and characterizing molecular determinants of bacterial host specificity in the last two decades. It is now clear that the host specificity of bacterial pathogens is determined by multiple molecular interactions between the pathogens and their hosts. Furthermore, certain basic principles regarding the host specificity of bacterial pathogens have emerged from the existing literature. This review focuses on selected human pathogenic bacteria and our current understanding of their host specificity.

Evolution of host specialization in gut microbes: the bee gut as a model

“…36 Human-specific bacterial pathogens can evade host defenses by utilizing proteases to break down antibodies or by binding down-regulators of complement-mediated immunity. 34 Conversely, the host may develop specialized immune responses to encourage colonization of a beneficial microbiota, such as has been proposed for antimicrobial-peptide-mediated host specificity in Hydra. 37 Nutritionally, each host presents a unique selective environment In-vitro cultured strains were fed to sterile, newly-emerged adults, and total CFU counted from guts after 5 days.…”

“…34 In Vibrio fischeri, a bioluminescent symbiont of marine animals, specificity to the squid Euprymna scolopes critically depends on RscS, a sensor kinase that detects an as-yet unknown host factor and induces expression of exopolysaccharide that enables colonization. 35 V. fisheri strains that colonize fish, in contrast, lack RscS.…”

How Research on Microbiomes is Changing Biology: A Discussion on the Concept of the Organism

“…For instance, certain bacterial pathogens currently subject to intensive medical studies, such as Helicobacter pylori or Vibrio cholerae (see Pan et al 2014), have a detrimental impact on the human body; thus, in the case of such interactions, there is not much cooperation and a great deal of conflict. However, between pathogens and well-suited combinations such as aphids and Buchnera are numerous intermediate states of organismality, since the whole concept is not absolute but measured by degrees; the most obvious cases (cats, apes and so on) evolved from organisms that, perhaps millions of years ago, were characterised by a very low (or average) level of cohesion and interdependence among elements.…”

Human Placental and Decidual Organ Cultures to Study Infections at the Maternal-fetal Interface

“…Further, most microbial pathogens show host specificity, thus many animal models cannot fully recapitulate human infectious diseases. Certain organisms (Haemophilus influenzae, Salmonella typhi, Vibrio cholera, and numerous others) are strictly pathogenic in humans, while others, such as Listeria monocytogenes, show a more intermediate level of host specificity 1 . Host specificity has been documented in many aspects of pathogenesis, including colonization 2 , dissemination 3 , immune evasion 4 , and nutrient acquisition 5 .…”