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FINAL NOTE. "Perhaps somewhat paradoxically, fixation of a costly adaptive immunity system is precluded not only when the innate immunity and suicide systems are highly effective but also when adaptive immunity itself performs at a high level. In such a case, hosts with and without adaptive immunity coexist in an environment where the pathogen is scarce (herd immunity effect)." https://lnkd.in/d9zsv9R View in LinkedIn

SINGLE ENTITY. "Important to note is that in many cases the interests of the bacterium and an already resident prophage become completely aligned upon obligately lytic phage infection (i.e. infection by phages that do not insert into the bacterial genome, but kill the bacterium instantly), such that they can be regarded as one genetic entity." https://lnkd.in/d53-z28 View in LinkedIn

RULES FOR DEVELOPMENT. "Evolution of suicide as a defense mechanism is only possible if (i) the host population is structured and (ii) the degree of immunity that the hosts can achieve by other means is limited. The widespread nature of suicide systems in prokaryotic genomes calls for a reconsideration of the relative importance of population structure for genome evolution." https://lnkd.in/d9zsv9R View in LinkedIn

LEADING THE RACE. "Studies on host-parasite local adaptation suggest that parasites are usually ahead of hosts in this coevolutionary arms race." https://lnkd.in/d9zsv9R View in LinkedIn

SOCIAL POPULATIONS. "The presence of programmed cell death systems in the great majority of prokaryotes strongly suggests that structured populations are the rule in microbial ecosystems. Indeed, some kind of social interaction, such as biofilm formation, is found on almost every bacterial group, and more advanced forms of sociality, such as quorum sensing, are often present in Proteobacteria and Firmicutes." https://lnkd.in/d9zsv9R View in LinkedIn

CONSTRAINTS. "In real biological communities, the efficacy of innate and adaptive immune systems is constrained by ecological factors such as population size, structure and diversity. The never-stopping arms race between hosts and pathogens sets a limit on the performance of defense strategies, which is determined by the ability of the host to keep the pace with pathogen escape mutations." https://lnkd.in/d9zsv9R View in LinkedIn

PRE-REQUISITES. "Population structure is required for the evolution of suicide. This pre-requisite had been previously proposed on the basis of experimental studies with a genetically engineered, suicidal strain of E. coli grown on agar plates and is theoretically extended here to a broader spectrum of population structures, suicide efficacies and co-occurring immune mechanisms." https://lnkd.in/d9zsv9R View in LinkedIn

LOW-COST SUICIDE. "Altogether, our findings demonstrate that low-cost suicide can evolve with ease, represents an effective host-defence strategy, and seems to be widespread among microbes. Moreover, low-cost suicide might also occur in higher organisms as exemplified by infected social insect workers leaving the colony to die in isolation." https://lnkd.in/d53-z28 View in LinkedIn

RANGE OF MEASURES. "Different defense mechanisms are geared to fight different threats. Immunity systems might be highly effective against certain threats but less proficient against others. Suicide can serve as a defense mechanism that acts on those threats against which the immunity systems are less effective." https://lnkd.in/d9zsv9R View in LinkedIn

LOW COST. "Recent experiments with suicide-prone E. coli have shown that at least when defense against highly virulent phages is involved, the cost of suicide could be quite low because the infected bacteria are moribund in any case and have virtually no chance to propagate. Conceivably, these experiments reflect the regime with failing immunity and subsequent low-cost suicide." https://lnkd.in/d9zsv9R View in LinkedIn