Comparative genomics of Leishmania (Mundinia)

Visceral Leishmaniasis in Immunocompetent Hosts in Brescia: A Case Series and Analysis of Cytokine Cascade

Visceral leishmaniasis (VL) is a parasitic zoonosis caused by Leishmania spp. that usually manifests itself in immunocompromised subjects. It is a rare and neglected disease, and it is not endemic in the province of Brescia (Italy). Three cases of human VL occurred in Brescia from October to December 2021 in immunocompetent patients. We evaluated the patients looking for signs of underlying immunodeficiencies and conducted further epidemiological evaluations in the province of Brescia without success. An analysis of the sera levels of the main cytokines involved in the immune response to VL was performed. All patients presented a significant augmentation of CXCL-10, CCL-4, and IL-6. The patients tested during the acute phase showed an elevation of IL-1α, IL-5, IL-10, and IL-12, while in the recovery phase, higher levels of TNF-α and IL-7 were detected. Altogether, a predominant activation of the T-helper-2 pathway emerged during the acute phase of the parasite infection, while the cytokines associated with the T-helper-1 pathway were less represented. This imbalanced immune response to the parasite infection might play a crucial role in the development of VL in immunocompetent patients.

Genomes of Endotrypanum monterogeii from Panama and Zelonia costaricensis from Brazil: Expansion of Multigene Families in Leishmaniinae Parasites That Are Close Relatives of Leishmania spp

The Leishmaniinae subfamily of the Trypanosomatidae contains both genus Zelonia (monoxenous) and Endotrypanum (dixenous). They are amongst the nearest known relatives of Leishmania, which comprises many human pathogens widespread in the developing world. These closely related lineages are models for the genomic biology of monoxenous and dixenous parasites. Herein, we used comparative genomics to identify the orthologous groups (OGs) shared among 26 Leishmaniinae species to investigate gene family expansion/contraction and applied two phylogenomic approaches to confirm relationships within the subfamily. The Endotrypanum monterogeii and Zelonia costaricensis genomes were assembled, with sizes of 29.9 Mb and 38.0 Mb and 9.711 and 12.201 predicted protein-coding genes, respectively. The genome of E. monterogeii displayed a higher number of multicopy cell surface protein families, including glycoprotein 63 and glycoprotein 46, compared to Leishmania spp. The genome of Z. costaricensis presents expansions of BT1 and amino acid transporters and proteins containing leucine-rich repeat domains, as well as a loss of ABC-type transporters. In total, 415 and 85 lineage-specific OGs were identified in Z. costaricensis and E. monterogeii. The evolutionary relationships within the subfamily were confirmed using the supermatrix (3384 protein-coding genes) and supertree methods. Overall, this study showed new expansions of multigene families in monoxenous and dixenous parasites of the subfamily Leishmaniinae.

Complete assembly, annotation of virulence genes and CRISPR editing of the genome of Leishmania amazonensis PH8 strain

We report the sequencing and assembly of the PH8 strain of Leishmania amazonensis one of the etiological agents of leishmaniasis. After combining data from long Pacbio reads, short Illumina reads and synteny with the Leishmania mexicana genome, the sequence of 34 chromosomes with 8317 annotated genes was generated. Multigene families encoding three virulence factors, A2, amastins and the GP63 metalloproteases, were identified and compared to their annotation in other Leishmania species. As they have been recently recognized as virulence factors essential for disease establishment and progression of the infection, we also identified 14 genes encoding proteins involved in parasite iron and heme metabolism and compared to genes from other Trypanosomatids. To follow these studies with a genetic approach to address the role of virulence factors, we tested two CRISPR-Cas9 protocols to generate L. amazonensis knockout cell lines, using the Miltefosine transporter gene as a proof of concept.

Genomic analysis of Leishmania turanica strains from different regions of Central Asia

The evolution in Leishmania is governed by the opposite forces of clonality and sexual reproduction, with vicariance being an important factor. As such, Leishmania spp. populations may be monospecific or mixed. Leishmania turanica in Central Asia is a good model to compare these two types. In most areas, populations of L. turanica are mixed with L. gerbilli and L. major. Notably, co-infection with L. turanica in great gerbils helps L. major to withstand a break in the transmission cycle. Conversely, the populations of L. turanica in Mongolia are monospecific and geographically isolated. In this work, we compare genomes of several well-characterized strains of L. turanica originated from monospecific and mixed populations in Central Asia in order to shed light on genetic factors, which may drive evolution of these parasites in different settings. Our results illustrate that evolutionary differences between mixed and monospecific populations of L. turanica are not dramatic. On the level of large-scale genomic rearrangements, we confirmed that different genomic loci and different types of rearrangements may differentiate strains originated from mixed and monospecific populations, with genome translocations being the most prominent example. Our data suggests that L. turanica has a significantly higher level of chromosomal copy number variation between the strains compared to its sister species L. major with only one supernumerary chromosome. This suggests that L. turanica (in contrast to L. major) is in the active phase of evolutionary adaptation.

Comparative Genomic Analyses of New and Old World Viscerotropic Leishmanine Parasites: Further Insights into the Origins of Visceral Leishmaniasis Agents

Visceral leishmaniasis (VL), also known as kala-azar, is an anthropozoonotic disease affecting human populations on five continents. Aetiologic agents belong to the Leishmania (L.) donovani complex. Until the 1990s, three leishmanine parasites comprised this complex: L. (L.) donovani Laveran & Mesnil 1903, L. (L.) infantum Nicolle 1908, and L. (L.) chagasi Lainson & Shaw 1987 (=L. chagasi Cunha & Chagas 1937). The VL causal agent in the New World (NW) was previously identified as L. (L.) chagasi. After the development of molecular characterization, however, comparisons between L. (L.) chagasi and L. (L.) infantum showed high similarity, and L. (L.) chagasi was then regarded as synonymous with L. (L.) infantum. It was, therefore, suggested that L. (L.) chagasi was not native to the NW but had been introduced from the Old World by Iberian colonizers. However, in light of ecological evidence from the NW parasite’s enzootic cycle involving a wild phlebotomine vector (Lutzomyia longipalpis) and a wild mammal reservoir (the fox, Cerdocyon thous), we have recently analyzed by molecular clock comparisons of the DNA polymerase alpha subunit gene the whole-genome sequence of L. (L.) infantum chagasi of the most prevalent clinical form, atypical dermal leishmaniasis (ADL), from Honduras (Central America) with that of the same parasite from Brazil (South America), as well as those of L. (L.) donovani (India) and L. (L.) infantum (Europe), which revealed that the Honduran parasite is older ancestry (382,800 ya) than the parasite from Brazil (143,300 ya), L. (L.) donovani (33,776 ya), or L. (L.) infantum (13,000 ya). In the present work, we have now amplified the genomic comparisons among these leishmanine parasites, exploring mainly the variations in the genome for each chromosome, and the number of genomic SNPs for each chromosome. Although the results of this new analysis have confirmed a high genomic similarity (~99%) among these parasites [except L. (L.) donovani], the Honduran parasite revealed a single structural variation on chromosome 17, and the highest frequency of genomic SNPs (more than twice the number seen in the Brazilian one), which together to its extraordinary ancestry (382,800 ya) represent strong evidence that L. (L.) chagasi/L. (L.) infantum chagasi is, in fact, native to the NW, and therefore with valid taxonomic status. Furthermore, the Honduran parasite, the most ancestral viscerotropic leishmanine parasite, showed genomic and clinical taxonomic characteristics compatible with a new Leishmania species causing ADL in Central America.

Genome-Wide Screening for Pathogenic Proteins and microRNAs Associated with Parasite-Host Interactions in Trypanosoma brucei

Tsetse flies are a type of blood-sucking insect living in diverse locations in sub-Saharan Africa. These insects can transmit the unicellular parasite Trypanosoma brucei (T. brucei) which causes African trypanosomiasis in mammals. There remain huge unmet needs for prevention, early detection, and effective treatments for this disease. Currently, few studies have investigated the molecular mechanisms of parasite-host interactions underlying African trypanosomiasis, mainly due to a lack of understanding of the T. brucei genome. In this study, we dissected the genomic and transcriptomic profiles of T. brucei by annotating the genome and analyzing the gene expression. We found about 5% of T. brucei proteins in the human proteome, while more than 80% of T. brucei protein in other trypanosomes. Sequence alignment analysis showed that 142 protein homologs were shared among T. brucei and mammalian genomes. We identified several novel proteins with pathogenic potential supported by their molecular functions in T. brucei, including 24 RNA-binding proteins and six variant surface glycoproteins. In addition, 26 novel microRNAs were characterized, among which five miRNAs were not found in the mammalian genomes. Topology analysis of the miRNA-gene network revealed three genes (RPS27A, UBA52 and GAPDH) involved in the regulation of critical pathways related to the development of African trypanosomiasis. In conclusion, our work opens a new door to understanding the parasite-host interaction mechanisms by resolving the genome and transcriptome of T. brucei.

Leishmania enriettii visceralises in the trachea, lungs, and spleen of Cavia porcellus

BACKGROUND

Leishmania (Mundinia) enriettii is a species commonly found in the guinea pig, Cavia porcellus. Although it is a dermotropic species, there is still an uncertainty regarding its ability to visceralise during Leishmania life cycle.

OBJECTIVE

Here, we investigated the ability of L. enriettii (strain L88) to visceralise in lungs, trachea, spleen, and liver of C. porcellus, its natural vertebrate host.

METHODS

Animals were infected sub-cutaneously in the nose and followed for 12 weeks using histological (hematoxilin-eosin) and molecular tools (polymerase chain reaction-restriction fragment length polymorphism - PCR-RFLP). To isolate parasite from C. porcellus, animals were experimentally infected for viscera removal and PCR typing targeting hsp70 gene.

FINDINGS

Histological analysis revealed intense and diffuse inflammation with the presence of amastigotes in the trachea, lung, and spleen up to 12 weeks post-infection (PI). Molecular analysis of paraffin-embedded tissues detected parasite DNA in the trachea and spleen between the 4th and 8th weeks PI. At the 12th PI, no parasite DNA was detected in any of the organs. To confirm that the spleen could serve as a temporary site for L. enriettii, we performed additional in vivo experiments. During 6th week PI, the parasite was isolated from the spleen confirming previous histopathological and PCR observations.

MAIN CONCLUSION

Leishmania enriettii (strain L88) was able to visceralise in the trachea, lung, and spleen of C. porcellus.

Genome Assembly and Genome Annotation of Leishmania martiniquensis Isolated from a Leishmaniasis Patient in Thailand

Leishmaniasis is a parasitic disease caused by Leishmania spp. with worldwide distribution. Autochthonous leishmaniasis has been reported to result from the infection by Leishmania martiniquensis in Thailand. This species was isolated in culture and subjected to high-throughput whole-genome sequencing. A total of 30.8 Mb in 36 chromosomes of the whole genome was assembled, annotated, and characterized. The L. martiniquensis under study was shown to segregate into the same clade and thus closely related to the previously identified L. martiniquensis (LU_Lmar_1.0), as determined by phylogenetic analysis of their genomic sequences along with those of representative kinetoplastid species. The total number of open reading frames genomewide predicts 8,209 protein-coding genes, of which 359 are putative virulence factors, including two previously known, e.g., cysteine proteinase C and superoxide dismutase B1. The results obtained from this study will be useful for further annotation and comparison with other Leishmania martiniquensis in the future.

Analyses of Leishmania-LRV Co-Phylogenetic Patterns and Evolutionary Variability of Viral Proteins

Leishmania spp. are important pathogens causing a vector-borne disease with a broad range of clinical manifestations from self-healing ulcers to the life-threatening visceral forms. Presence of Leishmania RNA virus (LRV) confers survival advantage to these parasites by suppressing anti-leishmanial immunity in the vertebrate host. The two viral species, LRV1 and LRV2 infect species of the subgenera Viannia and Leishmania, respectively. In this work we investigated co-phylogenetic patterns of leishmaniae and their viruses on a small scale (LRV2 in L. major) and demonstrated their predominant coevolution, occasionally broken by intraspecific host switches. Our analysis of the two viral genes, encoding the capsid and RNA-dependent RNA polymerase (RDRP), revealed them to be under the pressure of purifying selection, which was considerably stronger for the former gene across the whole tree. The selective pressure also differs between the LRV clades and correlates with the frequency of interspecific host switches. In addition, using experimental (capsid) and predicted (RDRP) models we demonstrated that the evolutionary variability across the structure is strikingly different in these two viral proteins.

Filling the gaps in Leishmania naiffi and Leishmania guyanensis genome plasticity

Insufficient and irregular data reports on Leishmaniasis, issuing from the developing world, have left much to be desired in terms of understanding the molecular signatures producing distinct infectious phenotypes of the disease. Herein, we report on the complete genome sequencing of Leishmania naiffi and Leishmania guyanensis, sampled from patients in regions of Colombia and Venezuela. In this study, the isolates of cutaneous lesions from both species presented limited structural variation at the chromosomal level, low gene copy number variation, and high genetic heterogeneity. We compared these sequences to the reference genomes hitherto related from Brazil and French Guyana. Although of the same species, we note a consequential genomic disparity between the Venezuelan and French Guyanese isolates of L. guyanensis. Although less significant on the global schema of cutaneous and mucosal disease, such genomic studies of L. naiffi and L. guyanensis substantiate the gaps in understanding of the molecular architecture and multivariate clinical pictures of Leishmaniasis, on an international scale.

Chromosome-Scale Assembly of the Complete Genome Sequence of Leishmania (Mundinia) sp. Ghana, Isolate GH5, Strain LV757

Leishmania (Mundinia) sp. Ghana is a kinetoplastid parasite isolated in 2015 in Ghana. We report the complete genome sequence of L. (M.) sp. Ghana, sequenced using combined short-read and long-read technologies. This will facilitate greater understanding of this novel pathogen and its relationships within the subgenus Mundinia.

Chromosome-Scale Assembly of the Complete Genome Sequence of Leishmania (Mundinia) enriettii, Isolate CUR178, Strain LV763

Leishmania (Mundinia) enriettii is a parasitic kinetoplastid first isolated from a guinea pig in Brazil in 1946. We present the complete genome sequence of L. (M.) enriettii, isolate CUR178, strain LV763, sequenced using combined short-read and long-read technologies. This will facilitate a greater understanding of the genome diversity within L. (M.) enriettii.

Genomics of Trypanosomatidae: Where We Stand and What Needs to Be Done?

Trypanosomatids are easy to cultivate and they are (in many cases) amenable to genetic manipulation. Genome sequencing has become a standard tool routinely used in the study of these flagellates. In this review, we summarize the current state of the field and our vision of what needs to be done in order to achieve a more comprehensive picture of trypanosomatid evolution. This will also help to illuminate the lineage-specific proteins and pathways, which can be used as potential targets in treating diseases caused by these parasites.

A New Model Trypanosomatid, Novymonas esmeraldas: Genomic Perception of Its "Candidatus Pandoraea novymonadis" Endosymbiont

The closest relative of human pathogen Leishmania, the trypanosomatid Novymonas esmeraldas, harbors a bacterial endosymbiont “Candidatus Pandoraea novymonadis.” Based on genomic data, we performed a detailed characterization of the metabolic interactions of both partners. While in many respects the metabolism of N. esmeraldas resembles that of other Leishmaniinae, the endosymbiont provides the trypanosomatid with heme, essential amino acids, purines, some coenzymes, and vitamins. In return, N. esmeraldas shares with the bacterium several nonessential amino acids and phospholipids. Moreover, it complements its carbohydrate metabolism and urea cycle with enzymes missing from the “Ca. Pandoraea novymonadis” genome. The removal of the endosymbiont from N. esmeraldas results in a significant reduction of the overall translation rate, reduced expression of genes involved in lipid metabolism and mitochondrial respiratory activity, and downregulation of several aminoacyl-tRNA synthetases, enzymes involved in the synthesis of some amino acids, as well as proteins associated with autophagy. At the same time, the genes responsible for protection against reactive oxygen species and DNA repair become significantly upregulated in the aposymbiotic strain of this trypanosomatid. By knocking out a component of its flagellum, we turned N. esmeraldas into a new model trypanosomatid that is amenable to genetic manipulation using both conventional and CRISPR-Cas9-mediated approaches.

Gene Annotation and Transcriptome Delineation on a De Novo Genome Assembly for the Reference Leishmania major Friedlin Strain

Leishmania major is the main causative agent of cutaneous leishmaniasis in humans. The Friedlin strain of this species (LmjF) was chosen when a multi-laboratory consortium undertook the objective of deciphering the first genome sequence for a parasite of the genus Leishmania. The objective was successfully attained in 2005, and this represented a milestone for Leishmania molecular biology studies around the world. Although the LmjF genome sequence was done following a shotgun strategy and using classical Sanger sequencing, the results were excellent, and this genome assembly served as the reference for subsequent genome assemblies in other Leishmania species. Here, we present a new assembly for the genome of this strain (named LMJFC for clarity), generated by the combination of two high throughput sequencing platforms, Illumina short-read sequencing and PacBio Single Molecular Real-Time (SMRT) sequencing, which provides long-read sequences. Apart from resolving uncertain nucleotide positions, several genomic regions were reorganized and a more precise composition of tandemly repeated gene loci was attained. Additionally, the genome annotation was improved by adding 542 genes and more accurate coding-sequences defined for around two hundred genes, based on the transcriptome delimitation also carried out in this work. As a result, we are providing gene models (including untranslated regions and introns) for 11,238 genes. Genomic information ultimately determines the biology of every organism; therefore, our understanding of molecular mechanisms will depend on the availability of precise genome sequences and accurate gene annotations. In this regard, this work is providing an improved genome sequence and updated transcriptome annotations for the reference L. major Friedlin strain.

The Maze Pathway of Coevolution: A Critical Review over the Leishmania and Its Endosymbiotic History

The description of the genus Leishmania as the causative agent of leishmaniasis occurred in the modern age. However, evolutionary studies suggest that the origin of Leishmania can be traced back to the Mesozoic era. Subsequently, during its evolutionary process, it achieved worldwide dispersion predating the breakup of the Gondwana supercontinent. It is assumed that this parasite evolved from monoxenic Trypanosomatidae. Phylogenetic studies locate dixenous Leishmania in a well-supported clade, in the recently named subfamily Leishmaniinae, which also includes monoxenous trypanosomatids. Virus-like particles have been reported in many species of this family. To date, several Leishmania species have been reported to be infected by Leishmania RNA virus (LRV) and Leishbunyavirus (LBV). Since the first descriptions of LRVs decades ago, differences in their genomic structures have been highlighted, leading to the designation of LRV1 in L. (Viannia) species and LRV2 in L. (Leishmania) species. There are strong indications that viruses that infect Leishmania spp. have the ability to enhance parasitic survival in humans as well as in experimental infections, through highly complex and specialized mechanisms. Phylogenetic analyses of these viruses have shown that their genomic differences correlate with the parasite species infected, suggesting a coevolutionary process. Herein, we will explore what has been described in the literature regarding the relationship between Leishmania and endosymbiotic Leishmania viruses and what is known about this association that could contribute to discussions about the worldwide dispersion of Leishmania.

Genome Analysis of Endotrypanum and Porcisia spp., Closest Phylogenetic Relatives of Leishmania, Highlights the Role of Amastins in Shaping Pathogenicity

While numerous genomes of Leishmania spp. have been sequenced and analyzed, an understanding of the evolutionary history of these organisms remains limited due to the unavailability of the sequence data for their closest known relatives, Endotrypanum and Porcisia spp., infecting sloths and porcupines. We have sequenced and analyzed genomes of three members of this clade in order to fill this gap. Their comparative analyses revealed only minute differences from Leishmaniamajor genome in terms of metabolic capacities. We also documented that the number of genes under positive selection on the Endotrypanum/Porcisia branch is rather small, with the flagellum-related group of genes being over-represented. Most significantly, the analysis of gene family evolution revealed a substantially reduced repertoire of surface proteins, such as amastins and biopterin transporters BT1 in the Endotrypanum/Porcisia species when compared to amastigote-dwelling Leishmania. This reduction was especially pronounced for δ-amastins, a subfamily of cell surface proteins crucial in the propagation of Leishmania amastigotes inside vertebrate macrophages and, apparently, dispensable for Endotrypanum/Porcisia, which do not infect such cells.

Catalase impairs Leishmania mexicana development and virulence

Catalase is one of the most abundant enzymes on Earth. It decomposes hydrogen peroxide, thus protecting cells from dangerous reactive oxygen species. The catalase-encoding gene is conspicuously absent from the genome of most representatives of the family Trypanosomatidae. Here, we expressed this protein from the Leishmania mexicana Β-TUBULIN locus using a novel bicistronic expression system, which relies on the 2A peptide of Teschovirus A. We demonstrated that catalase-expressing parasites are severely compromised in their ability to develop in insects, to be transmitted and to infect mice, and to cause clinical manifestation in their mammalian host. Taken together, our data support the hypothesis that the presence of catalase is not compatible with the dixenous life cycle of Leishmania, resulting in loss of this gene from the genome during the evolution of these parasites.

Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses

Euglenozoa is a species-rich group of protists, which have extremely diverse lifestyles and a range of features that distinguish them from other eukaryotes. They are composed of free-living and parasitic kinetoplastids, mostly free-living diplonemids, heterotrophic and photosynthetic euglenids, as well as deep-sea symbiontids. Although they form a well-supported monophyletic group, these morphologically rather distinct groups are almost never treated together in a comparative manner, as attempted here. We present an updated taxonomy, complemented by photos of representative species, with notes on diversity, distribution and biology of euglenozoans. For kinetoplastids, we propose a significantly modified taxonomy that reflects the latest findings. Finally, we summarize what is known about viruses infecting euglenozoans, as well as their relationships with ecto- and endosymbiotic bacteria.

Diverse telomeres in trypanosomatids

Telomeres are the ends of linear eukaryotic chromosomes facilitating the resolution of the ‘end replication and protection’ problems, associated with linearity. At the nucleotide level, telomeres typically represent stretches of tandemly arranged telomeric repeats, which vary in length and sequence among different groups of organisms. Recently, a composition of the telomere-associated protein complex has been scrutinized in Trypanosoma brucei. In this work, we subjected proteins from that list to a more detailed bioinformatic analysis and delineated a core set of 20 conserved proteins putatively associated with telomeres in trypanosomatids. Out of these, two proteins (Ku70 and Ku80) are conspicuously missing in representatives of the genus Blastocrithidia, yet telomeres in these species do not appear to be affected. In this work, based on the analysis of a large set of trypanosomatids widely different in their phylogenetic position and life strategies, we demonstrated that telomeres of trypanosomatids are diverse in length, even within groups of closely related species. Our analysis showed that the expression of two proteins predicted to be associated with telomeres (those encoding telomerase and telomere-associated hypothetical protein orthologous to Tb927.6.4330) may directly affect and account for the differences in telomere length within the species of the Leishmania mexicana complex.

The Remarkable Metabolism of Vickermania ingenoplastis: Genomic Predictions

A recently redescribed two-flagellar trypanosomatid Vickermania ingenoplastis is insensitive to the classical inhibitors of respiration and thrives under anaerobic conditions. Using genomic and transcriptomic data, we analyzed its genes of the core metabolism and documented that subunits of the mitochondrial respiratory complexes III and IV are ablated, while those of complexes I, II, and V are all present, along with an alternative oxidase. This explains the previously reported conversion of glucose to acetate and succinate by aerobic fermentation. Glycolytic pyruvate is metabolized to acetate and ethanol by pyruvate dismutation, whereby a unique type of alcohol dehydrogenase (shared only with Phytomonas spp.) processes an excess of reducing equivalents formed under anaerobic conditions, leading to the formation of ethanol. Succinate (formed to maintain the glycosomal redox balance) is converted to propionate by a cyclic process involving three enzymes of the mitochondrial methyl-malonyl-CoA pathway, via a cyclic process, which results in the formation of additional ATP. The unusual structure of the V. ingenoplastis genome and its similarity with that of Phytomonas spp. imply their relatedness or convergent evolution. Nevertheless, a critical difference between these two trypanosomatids is that the former has significantly increased its genome size by gene duplications, while the latter streamlined its genome.

Ultraconserved element bait set for trypanosomatida target enrichment and phylogenetics

Lack of knowledge of taxonomic biodiversity and reliable genetic markers in Trypanosomatidae limit our understanding of their phylogenetic relationships. Ultraconserved elements (UCEs) have improved phylogenetic analyses and inferences in many vertebrate and invertebrate taxa. However, it is unknown whether protozoans have these markers, their abundance, and if these could be reliably used for phylogenetics. In this study I design a target enrichment bait set for UCE loci for this group. In silico testing showed good loci recovery rates across 63 taxa and produced consistent, highly supported phylogenetic trees. This bait set adds a new resource of useful genetic markers for Trypanosomatidae phylogenetics.

Host-parasite interactions in vector-borne protozoan infections

Protists embrace many species, some of which may be either occasional or permanent parasites of vertebrate animals. Between the parasite species, several of medical and veterinary importance are vector-transmitted. The ecology and epidemiology of vector-borne parasitoses, including babesiosis, leishmaniasis and malaria, are particularly complex, as they are influenced by many factors, such as vector reproductive efficiency and geographical spread, vectorial capacity, host immunity, travel and human behaviour and climatic factors. Transmission dynamics are determined by the interactions between pathogen, vector, host and environmental factors and, given their complexity, many different types of mathematical models have been developed to understand them. A good basic knowledge of vector-pathogen relationships and transmission dynamics is thus essential for disease surveillance and control interventions and may help in understanding the spread of epidemics and be useful for public health planning.

Application of next generation sequencing (NGS) for descriptive analysis of 30 genomes of Leishmania infantum isolates in Middle-North Brazil

Visceral leishmaniasis (VL) is a life-threatening disease caused by the protozoa Leishmania donovani and L. infantum. Likely, L. infantum was introduced in the New World by the Iberic colonizers. Due to recent introduction, the genetic diversity is low. Access to genomic information through the sequencing of Leishmania isolates allows the characterization of populations through the identification and analysis of variations. Population structure information may reveal important data on disease dynamics. Aiming to describe the genetic diversity of L. infantum from the Middle-North, Brazil, next generation sequencing of 30 Leishmania isolates obtained in the city of Teresina, from where the disease dispersed, was performed. The variations were categorized accordingly to the genome region and impact and provided the basis for chromosomal ploidy and population structure analysis. The results showed low diversity between the isolates and the Iberic reference genome JPCM5. Most variations were seen in non-coding regions, with modifying impact. The ploidy number analysis showed aneuploid profile. The population structure analysis revealed the presence of two L. infantum populations identified in Teresina. Further population genetics studies with a larger number of isolates should be performed in order to identify the genetic background associated with virulence and parasite ecology.

The First Non-LRV RNA Virus in Leishmania

In this work, we describe the first Leishmania-infecting leishbunyavirus-the first virus other than Leishmania RNA virus (LRV) found in trypanosomatid parasites. Its host is Leishmania martiniquensis, a human pathogen causing infections with a wide range of manifestations from asymptomatic to severe visceral disease. This virus (LmarLBV1) possesses many characteristic features of leishbunyaviruses, such as tripartite organization of its RNA genome, with ORFs encoding RNA-dependent RNA polymerase, surface glycoprotein, and nucleoprotein on L, M, and S segments, respectively. Our phylogenetic analyses suggest that LmarLBV1 originated from leishbunyaviruses of monoxenous trypanosomatids and, probably, is a result of genomic re-assortment. The LmarLBV1 facilitates parasites' infectivity in vitro in primary murine macrophages model. The discovery of a virus in L. martiniquensis poses the question of whether it influences pathogenicity of this parasite in vivo, similarly to the LRV in other Leishmania species.