From Evolutionary Advantage to Disease Agents: Forensic Reevaluation of Host-Microbe Interactions and Pathogenicity

Abstract

As the “human microbiome era” continues, there is an increasing awareness of our resident microbiota and its indispensable role in our increased fitness as holobionts. However, the host-microbe relationship is not so clearly defined for some human symbionts. Here we discuss examples of “accidental pathogens”, meaning previously non-pathogenic and/or environmental microbes thought to have inadvertently experienced an evolutionary shift towards pathogenicity. For instance, symbionts such as Helicobacter pylori and JC Polyomavirus have been shown to accompany humans since prehistoric times and are still abundant in extant populations as part of the microbiome. And yet, the relationship between a subgroup of these microbes and their human hosts seems to have changed with time, and they have recently gained notoriety as gastrointestinal and neuropathogens, respectively. On the other hand, environmental microbes such as Legionella spp. have recently experienced a shift in host range and are now a major problem in industrialized countries as a result of artificial ecosystems. Other variables involved in this accidental phenomenon could be the apparent change or reduction in the diversity of human-associated microbiota because of modern medicine and lifestyles. All of this could result in an increased prevalence of “accidental pathogens” in the form of emerging pathogens.

Pre-Columbian zoonotic enteric parasites: An insight into Puerto Rican indigenous culture diets and life styles

“…The fact that there were mixed infections present in the coprolites may also indicate that these parasites may become frank pathogens only under certain circumstances and conditions that were not found in the pre-Columbian Antilles. This has been previously hypothesized with other present-day human pathogens detected in ancient cultures [64]. For instance, the Yanomami hunter-gatherer culture in the Amazonian jungle of Venezuela harbor the highest gastrointestinal microbial diversity detected to date in humans [65].…”

Forensic DNA Analysis

“…Lee et al examined the lungs of drowning victims and used 16S rRNA sequencing to suggest that the presence of aquatic microbiota in the closed organs may provide a marker for a diagnosis of drowning . Rivera-Pérez et al has examined “accidental pathogens”, which are previously nonpathogenic and/or environmental microbes that have inadvertently experienced an evolutionary shift toward pathogenicity . The published works of agricultural scientists have increased our knowledge concerning soil microbial communities which may indicate the potential location of a sample. ,, However, questions still arise involving the confounding effects of season, temperature change, rainfall, and other factors.…”

Biological Roles of Protein-Coding Tandem Repeats in the Yeast Candida Albicans

“…The latter could affect host recognition [ 72 ] similar to the mechanism used by Plasmodium falciparum to elude the host response [ 73 ]. Provided that the ability to cause disease on occasions, or survival of the host response triggered by causing disease, is selectively sufficiently advantageous [ 52 , 74 ], some TR-contingency genes could have evolved to have roles in candidiasis, that is, when C. albicans ’ interaction with the host changes from commensal to pathogenic.…”