In vitro development of Haemoproteus columbae (Haemosporida: Haemoproteidae), with perspectives for genomic studies of avian haemosporidian parasites

The evolutionary origin of wildlife and human malaria parasites (Plasmodium spp.) has been discussed for several decades. The lack of genomic data about species of wildlife haemosporidian parasites related to Plasmodium limits the number of taxa available for phylogenetic analysis. Genomic data about avian parasites of the genus Haemoproteus parasites, the sister genus to Plasmodium are still not available, mainly due to difficulties in obtaining pure DNA of parasites inhabiting nucleated avian host cells. Recent studies show that microgametes of Haemoproteus (Parahaemoproteus) spp. develop in vitro and can be isolated by simple centrifugation, allowing the isolation of pure parasite DNA for genomic studies. However, in vitro development of Haemoproteus (Haemoproteus) spp. has not been investigated, and it is unclear if microgametes of these parasites also can be obtained under in vitro conditions. Here, we provide the first data about the in vitro development of Haemoproteus (Haemoproteus) columbae, a widespread avian haemosporidian parasite, which is specific to pigeons and doves (Columbiformes) and is transmitted by hippoboscid flies (Diptera, Hippoboscidae). In vitro gametogenesis and ookinete development of H. columbae were studied using a strain isolated from a feral Rock Pigeon (Columba livia) in Bogota-Colombia. The morphological events leading to exflagellation, fertilization and ookinete formation, as well as the rate of development of these stages were followed in vitro at 40 degrees C, 19 degrees C and 15 degrees C for 48 h. Macrogametes, microgametes, zygotes and initial stages of ookinete development were observed in all temperatures, but mature ookinetes were seen only at 40 degrees C. The largest diversity of sporogonic stages of H. columbae were present at 40 degrees C however, exflagellation, fertilization of macrogametes and development of immature ookinetes were also observed at 15 degrees C and 19 degrees C. Morphological and morphometric features of these stages in vitro were described and illustrated. This study demonstrates a requirement of high temperature for the successful development of mature ookinetes of H. columbae, but not gametes. We show that 1) parasites of the in vitro at 15-19 degrees C, as is the case in H. (Parahaemoproteus) spp. to obtain pure DNA for genomic studies. (C) 2015 Elsevier Inc. All rights reserved.