Surveillance of avian malaria and related haemoparasites in common terns (Sterna hirundo) on the Atlantic coast of South America

Haemosporidia (Apicomplexa, Haemosporida) are protozoa that infect vertebrate blood cells and are transmitted by vectors. Among vertebrates, birds possess the greatest diversity of haemosporidia, historically placed in 3 genera: Haemoproteus, Leucocytozoon and Plasmodium, the causative agent of avian malaria. In South America, existing data on haemosporidia are spatially and temporally dispersed, so increased surveillance is needed to improve the determination and diagnosis of these parasites. During the non-breeding season in 2020 and 2021, 60 common terns (Sterna hirundo) were captured and bled as part of ongoing research on the population health of migratory birds on the Argentinian Atlantic coast. Blood samples and blood smears were obtained. Fifty-eight samples were screened for Plasmodium, Haemoproteus and Leucocytozoon, as well as for Babesia parasites by nested polymerase chain reaction and by microscopic examination of smears. Two positive samples for Plasmodium were found. The cytochrome b lineages detected in the present study are found for the first time, and are close to Plasmodium lineages found in other bird orders. The low prevalence (3.6%) of haemoparasites found in this research was similar to those reported for previous studies on seabirds, including Charadriiformes. Our findings provide new information about the distribution and prevalence of haemosporidian parasites from charadriiforms in the southernmost part of South America, which remains understudied

Stimulation and quantification of Babesia divergens gametocytogenesis

Background Babesia divergens is the most common blood parasite in Europe causing babesiosis, a tick-borne malaria-like disease. Despite an increasing focus on B. divergens, especially regarding veterinary and human medicine, the sexual development of Babesia is poorly understood. Development of Babesia sexual stages in the host blood (gametocytes) plays a decisive role in parasite acquisition by the tick vector. However, the exact mechanism of gametocytogenesis is still unexplained. Methods Babesia divergens gametocytes are characterized by expression of bdccp1, bdccp2 and bdccp3 genes. Using previously described sequences of bdccp1, bdccp2 and bdccp3, we have established a quantitative real-time PCR (qRT-PCR) assay for detection and assessment of the efficiency of B. divergens gametocytes production in bovine blood. We analysed fluctuations in expression of bdccp genes during cultivation in vitro, as well as in cultures treated with different drugs and stimuli. Results We demonstrated that all B. divergens clonal lines tested, originally derived from naturally infected cows, exhibited sexual stages. Furthermore, sexual commitment was stimulated during continuous growth of the cultures, by addition of specific stress-inducing drugs or by alternating cultivation conditions. Expression of bdccp genes was greatly reduced or even lost after long-term cultivation, suggesting possible problems in the artificial infections of ticks in feeding assays in vitro. Conclusions Our research provides insight into sexual development of B. divergens and may facilitate the development of transmission models in vitro, enabling a more detailed understanding of Babesia-tick interactions

Production de la chimiokine aviaire CCL20 en système CELO et potentiel adjuvant en liaison avec un fragment de l'hémagglutinine du virus influenza aviaire

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Characterization and diversity of Babesia sp. YLG, a new member of the Peircei group infecting Mediterranean yellow-legged gulls (Larus michahellis)

International audienceAvian infecting piroplasms are largely under-studied compared to other hemoparasites, and this paucity of information has blurred our phylogenetic and biological comprehension of this important group as a whole. In the present study, we detected and characterized Babesia from yellow-legged gull (Larus michahellis) chicks from a colony in southern France. Based on morphological and molecular characterizations, a new Babesia species belonging to the Peircei group, a clade of avian-specific piroplasms, was identified. Due to the complexity of species delineations and the low number of parasites characterized in this clade to date, a species name was not yet attributed; we refer to it for now as Babesia sp. YLG (Yellow-Legged Gull). High prevalence (85% and 58% in 2019 and 2020, respectively) and high parasitemia (up to 20% of parasitized erythrocytes) were recorded in chicks, without any obvious clinical signs of infection. Although the 16 isolates had identical 18S rRNA gene sequences, 6 genetic variants were described based on partial cox1 sequencing, with evidence of chicks co-infected by two variants. Transmission of Babesia sp. YLG via the soft tick Ornithodoros maritimus is discussed

A soft tick vector of Babesia sp. YLG in Yellow-legged gull (Larus michahellis) nests

International audienceBabesia sp. YLG has recently been described in Yellow-legged gull (Larus michahellis) chicks and belongs to the Peircei clade in the new classification of Piroplasms. Here, we studied Babesia sp. YLG vectorial transmission by ticks in the simplified environment of a single seabird breeding colony where the Yellow-legged gull is the sole vertebrate host, Ornithodoros maritimus (syn. Alectorobius maritimus) the sole tick species, and Babesia sp. YLG is the only blood parasite species detected in chicks of the colony. We collected ticks over four years, maintained certain individuals through moulting or oviposition, and dissected fresh ticks to isolate different organs and test for the presence of the parasite using molecular assays. We report the first strong evidence of a Piroplasmidae transmitted by a soft tick. Indeed, Babesia sp. YLG DNA was detected in the salivary glands of nymphs, females and males, a necessary organ to infect for transmission to a new vertebrate host. Parasite DNA was also found in tick ovaries, which could indicate possible transovarial transmission. Our detection of Babesia sp. YLG DNA in several male testes and in endospermatophores, and notably in a parasite-free female (uninfected ovaries and salivary glands), raise the interesting possibility of sexual transmission from infected males to uninfected females. Future work in this system will now need to focus on the degree to which the parasite can be maintained locally by ticks and the epidemiological consequences of infection for both O. maritimus and its avian host

Identification de candidats vaccins contre la babésiose ovine dans le cadre du projet européen FP7 KBBE Pirovac : intérêt de RAP-1 (Rhoptry-Associated-Protein 1)

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Additional file 5: Figure S4. of Stimulation and quantification of Babesia divergens gametocytogenesis

Relative expression of bdccp genes in various bovine clonal lines of B. divergens. Gene expression was normalized using the gapdh reference gene. Expression in the clone 2210A G2 was set at 100 % and all other values were expressed relative to this. (PDF 49 kb

Additional file 6: Figure S5. of Stimulation and quantification of Babesia divergens gametocytogenesis

Continuous culture growth. Relative expression of bdccp genes (A) and parasitemia levels (B) during the continuous growth of B. divergens clone 2210A G2. Gene expression was normalized using the gapdh reference gene. The expression in the highest individual replicate 1 DPI was set at 100 % and all other values were expressed relative to this. (PDF 48 kb

Additional file 4: Figure S3. of Stimulation and quantification of Babesia divergens gametocytogenesis

Comparison of stability of reference genes. Reference genes were evaluated by comparisons of all reference genes using Ct values. The first sample in each gene analysis was set at 100 % and all other values were normalized to this. (PDF 66 kb