Metabolite of malaria induces vector blood-seeking, feeding, and susceptibility of host to infection

This is an interesting topic that some might question “where is the connection” between genes and the environment? Many examples are known, however, of co-evolution in which two (or more) organisms evolve together –– in adapting to their respective environments. To “fine-tune their genome” to the environment in which they live, one species might make use of another species by: [a] eating them (predator-prey), [b] living in or on them (parasitic), or [c] co-existing in a symbiotic (mutualistic) relationship with them.

The fascinating interrelationship [described in the attached report] is one further step into complexity. This involves the predator, the vector, and the host. It has been appreciated for years that malaria infection renders that infected human more attractive to Anopheles gambiae mosquitoes, when compared with the “uninfected” person, whereas the mechanism(s) (which also occurs in rodents and birds) have remained obscure. Authors herein found that an isoprenoid precursor produced by Plasmodium falciparum, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP), affects Anopheles gambiae blood-meal-seeking and -feeding behaviors –– as well as susceptibility to infection. HMBPP acts indirectly by triggering the host (human) red blood cells to increase the release of CO2, aldehydes, and mono-terpenes –– which, together, enhance vector (mosquito) attraction and stimulate vector feeding.

When offered in a blood meal, HMBPP modulates neural, anti-malarial, and oogenic gene transcription –– without affecting mosquito survival or fecundity. In a Plasmodium falciparum–infected blood meal, sporogony (the asexual process of spore formation in parasitic sporozoans) is increased. Therefore, feeding on an infected host (rather than “wasting time” feeding on an uninfected host) can be seen as an evolutionary advantage –– not to the mosquito vector per se, but rather to the parasite Plasmodium falciparum..!!

Science   10 Mar 2o17   355: 1076-1080

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