Caracterización del genoma de Haemoproteus (Haemoproteus) columbae: como herramienta para el estudio evolutivo del orden Haemosporida

Abstract

Research on malaria has focused during a long time on the parasites that infect humans.However, it is also true that most information about the biology of this parasites comes from experimental models. For this reason, this thesis focuses on a Haemosporida parasite closely related to the Plasmodium genus, which is the Haemoproteus parasites.

Methods include standardizing an experimental animal model for the Haemoproteus transmission. The approach involved the natural host Rock Pigeon (Columba livia), the louse flies (Pseudolynchia canariensis) which are the vectors and the parasite Haemoproteus columbae. The first hole in the road to overcoming was to increase the number of parasites present inthe blood sample (parasitemia); in this way, it was possible to reduce the gap between the proportion of host DNA and parasite DNA. Besides, there was necessary to standardize the conditions to reared louse flies in the lab, and the methodologies that allow following the infection both in the vector and in the vertebrate host these results are shown in Chapter 6.

On the other hand, total genomic DNA was sequenced on Illumina HiSeqX 150-bp technology, resulting in a total of 628'859.636 pair-end reads. It allows obtaining the complete apicoplast and mitochondrial genomes, with enough coverage to be considered reference genomes. These results are shown in Chapters 7 and 8.

Regarding the Apigenome, phylogenetic, phylogenomic and evolutionary analyses were carried out, highlighting an evolutionary dynamic related to GC content bias within Haemosporida order, which had an impact on the Substitution Saturation of coding sequences aswell as in the Codon Usage. Finally, a draft nuclear genome was assembled, and 3976 genes were annotated. Likewise, evidence of LTR-transposon sequences was found, which play acritical role in the evolutionary dynamics of genomes (Chapter 8).

In conclusion, this thesis present to the scientific community an experimental animal modelthat undoubtedly will allow new approximations to characterize the life cycle of vector-borne parasites. The apicoplast genome of this parasite allowed us to study the evolutionary dynamics of this organelle inside and outside the Haemosporida order. Finally, we generate thefirst draft genome of parasite belonging to Haemoproteus genus, subgenus Haemoproteus,which it could be useful for genetic, immunological, evolutionary, and ecological studies,among others. Altogether, this thesis generates valuable information that open possibilities to explore new approaches to characterize in-depth the biology, evolution and phylogenetic relationships of apicomplexan parasites.