Evolution of pathogen tolerance and emerging infections: A missing experimental paradigm

Abstract

Researchers worldwide are repeatedly warning us against future zoonotic diseases resulting from humankind’s insurgence into natural ecosystems. The same zoonotic pathogens that cause severe infections in a human host frequently fail to produce any disease outcome in their natural hosts. What precise features of the immune system enable natural reservoirs to carry these pathogens so efficiently? To understand these effects, we highlight the importance of tracing the evolutionary basis of pathogen tolerance in reservoir hosts, while drawing implications from their diverse physiological and life-history traits, and ecological contexts of host-pathogen interactions. Long-term co-evolution might allow reservoir hosts to modulate immunity and evolve tolerance to zoonotic pathogens, increasing their circulation and infectious period. Such processes can also create a genetically diverse pathogen pool by allowing more mutations and genetic exchanges between circulating strains, thereby harboring rare alive-on-arrival variants with extended infectivity to new hosts (i.e., spillover). Finally, we end by underscoring the indispensability of a large multidisciplinary empirical framework to explore the proposed link between evolved tolerance, pathogen prevalence, and spillover in the wild.

Evolution of a cis -Acting SNP That Controls Type VI Secretion in Vibrio cholerae

“…There remains a pressing public health need to understand the emergence of pathogens from environmental reservoirs ( 54 ). Efforts such as microbial genome wide association studies ( 55 ) to identify genetic variants in genomes that are associated with phenotypes like virulence and antibiotic sensitivity will be bolstered by knowledge of the ecological and evolutionary processes that promote pathogen-host association.…”

Evolution of a cis-acting SNP that controls Type VI Secretion in Vibrio cholerae

“…There remains a pressing public health need to understand the emergence of pathogens from environmental reservoirs (53). Efforts such as Microbial Genome Wide Association Studies (54) to identify genetic variants in genomes that are associated with phenotypes like virulence and antibiotic sensitivity, will be bolstered by knowledge of the ecological and evolutionary processes that promote pathogen-host association.…”

Critical View on the Importance of Host Defense Strategies on Virus Distribution of Bee Viruses: What Can We Learn from SARS-CoV-2 Variants?

“…It is our opinion that with the current knowledge the time is right to integrate and look at the host’s defense strategies and their role in viral dynamics in a multi-host system. SARS-CoV-2 and the few studies on animals highlight the importance of these defense strategies in shaping viral epidemiology, such as virus tolerance, which can result in super-spreaders [ 6 , 37 ].…”

“…As further research on these bee host-virus interactions continues, our understanding of these mechanisms keeps growing [ 34 , 35 , 36 ]. This knowledge can be of great assistance in understanding the immunological background of what makes a host tolerant to a certain virus, as data from current research in non-bee hosts suggests there appears to be a lack or suppression of the immune response to the infection [ 37 ]. However, although the immune pathways of bees are relatively well characterized, knowledge on viral cell entry of bee viruses is a crucial factor that is currently missing to obtain a full picture of host viral dynamics.…”