emerging diseases: from insect to man

diseases we haven't seen before suddenly appearing

a pathogen can gain host entry however non pathogens cant. pathogens are able to avoid host defences, non pathogens cant. pathogens are able to propagate inside the host cell and propagate to new host cells, non pathogens cant unless allowed by the host cell

through being vectors, supply and increase in gene flow and pathogens pre-adapting to the immune systems of invertebrates which are similar to that of mammals making it easier for pathogens to adapt and bypass mammalian immune systems. also through the injection and release of spores into the environment when insects are killed by spores

<p>the bacteria starts off as a host generalist which is versatile and can infect a range of different hosts. host restriction happens as a result of gene loss through deletion, restricting its ability to infect lots of different hosts (small host range). however, the gene gain that happens simultaneously makes the bacteria into a host specialist</p> Signup and view all the answers

<p>B cereus causes food poisoning and can infect animals and insects. in B. cereus, the plcR virulence regulator gene, which mediates many virulence factors in B.cereus is deleted. this results in the evolution into B. anthracis which causes the lethal anthrax infection. when the pclR gene is lost, PXO1, the anthrax toxin regulator, and PXO2 an antiphagocytic gene, are gained. these genes cause worse virulence than B. cereus, however because the pclR gene was deleted, B. anthracis can now only infect humans.</p> Signup and view all the answers

<p>if these two genes coexisted, the new strain would not be able to sporulate and would go extinct quickly, therefore the pclR gene is deleted.</p> Signup and view all the answers