The study finding a group of microorganisms known as kinetoplastids including the parasites; that cause devastating diseases such as African sleeping sickness, Chagas disease, and leishmaniasis. For each species, this includes a stage in which parasites adhere to insect tissue via a hemidesmosome-like structure. They share an ability to adhere to the insides of their insect hosts, using a specialized protein structure.
But by using a non disease causing kinetoplastid species called Crithidia fasciculata; the study identifying the number of genes involving in adherence in its mosquito host. Although this structure has been described morphologically; it has never been molecularly characterizing. These mechanisms of adherence seem to be across kinetoplastid species, so the hope is that our insights about Crithidia will tell us something about adherence in the medically relevant species.
Parasites blocking disease
By using the biochemical model to understand features of parasitic disease, as it is easily grown in the lab. Megan Povelones, whose specialty is African trypanosomiasis, was familiar with it from her doctoral studies at Johns Hopkins University, and the subject came up in conversations with her spouse. Research has focused on ways to harness the power of the mosquito’s own immune defenses to stop them from transmitting disease.
An advantage of C. fasciculata is that adherent parasites can be generated both in vitro, allowing a direct comparison to cultured swimming forms, as well as in vivo within the mosquito. Using RNAseq, we identify genes associated with adherence in C. fasciculata. As almost all of these genes have orthologs in other kinetoplastid species, our findings may reveal shared mechanisms of adherence, allowing investigation of a crucial step in parasite development and disease transmission.
Crithidia infects mosquitoes
However, the fact that Crithidia infects mosquitoes but is not a human or animal pathogen; that little was knowing about its life cycle; and that there had been some electron microscope studies doing that show the parasite is actually adhering to the mosquito gut with a very specific type of structure; that people had described as a hemidesmosome. Together they set out to investigate what happens to enable the parasite to hold on to the inside of the mosquito; a trait believing to be critical for disease transmission.
That Crithidia parasites exist in both a swimming form, with a tail-like appendage called a flagellum, and an adhering form; that even sticks to the surface of the plastic dishes in which they were growing in the lab. The swimming form was favoring when the culture dishes were placing on a shaker; while the adherent form, which divided to form rosette structures; was more likely to develop when the dishes were keeping stationary.