Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome (∼702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods.

The cell’s ability to sense and respond to specific stimuli is a complex system derived from precisely regulated protein-protein interactions. Some of these protein-protein interactions are mediated by the recognition of linear peptide motifs by protein modular domains. BRCT (BRCA1 C-terminal) domains and their linear motif counterparts, which contain phosphoserines, are one such pair-wise interaction system that seems to have evolved to serve as a surveillance system to monitor threats to the cell’s genetic integrity. Evidence indicates that BRCT domains found in tandem can cooperate to provide sequence specific binding of phosphorylated peptides as is the case for the breast and ovarian cancer susceptibility gene BRCA1 and the PAX transcription factor interacting protein PAXIP1. Particular interest has been paid to tandem BRCT domains as ‘readers’ of signaling events in the form of phosphorylated serine moieties induced by the activation of DNA damage response kinases ATM, ATR and DNA-PK. However, given the diversity of tandem BRCT containing proteins questions remain as to the origin and evolution of this domain. Here we discuss emerging views of the origin and evolving roles of tandem BRCT domain repeats in the DNA damage response.

The aim of this study was to assess the presence of piroplasms in dogs in the metropolitan region of the city of Piura, Peru. Two hundred and twelve canine blood samples were randomly collected. The deoxyribonucleic acid was extracted from each blood sample and was tested using the polymerase chain reaction, restriction fragment length polymorphism and sequence analyses. The study showed the occurrence of Babesia vogeli. For the first time, this approach revealed the presence of canine babesiosis caused by B. vogeli in Peru. This highlights the need to test for pathogens that might be responsible for causing canine babesiosis, through using proper molecular tools.

Chitinases are enzymes responsible for the hydrolysis of glycosidic linkages within chitin chains. In insects, chitinases are typically members of the multigenic glycoside hydrolase family 18 (GH18). They participate in the relocation of chitin during development and molt, and in digestion in detritivores and predatory insects, and they control the peritrophic membrane thickness. Chitin metabolism is a promising target for developing vector control strategies, and knowledge of the roles of chitinases may reveal new targets and illuminate unique aspects of their physiology and interaction with microorganisms. Rhodnius prolixus is an important vector of Chagas disease, which is caused by the parasite Trypanosoma cruzi. In this study, we performed annotation and structural characterization of nine chitinase and chitinase-like protein genes in the R. prolixus genome. The roles of their corresponding transcripts were studied in more depth; their physiological roles were studied through RNAi silencing. Phylogenetic analysis of coding sequences showed that these genes belong to different subfamilies of GH18 chitinases already described in other insects. The expression patterns of these genes in different tissues and developmental stages were initially characterized using RT-PCR. RNAi screening showed silencing of the gene family members with very different efficiencies. Based on the knockdown results and the general lack of information about subgroup VIII of GH18, the RpCht7 gene was chosen for phenotype analysis. RpCht7 knockdown doubled the mortality in starving fifth-instar nymphs compared to dsGFP-injected controls. However, it did not alter blood intake, diuresis, digestion, molting rate, molting defects, sexual ratio, percentage of hatching, or average hatching time. Nevertheless, female oviposition was reduced by 53% in RpCht7-silenced insects, and differences in oviposition occurred within 14–20 days after a saturating blood meal. These results suggest that RpCht7 may be involved in the reproductive physiology and vector fitness of R. prolixus.

This study aimed to study the prevalence of Anaplasmataceae organisms through the nested-PCR and phylogenetic analysis on domestic dogs in the Department of Piura, Peru. Two hundred and twelve canine blood samples were randomly collected on dogs from the central urban areas at the Piura Department in Peru. The extracted DNAs were tested, by nested-PCR based on 16SrRNA gene, to identify agents from Anaplasmataceae family. These results show that there was a prevalence of 18.5% (40/216) of positive dogs, 13.8% (30/216) for Ehrlichia canis, 7.4% (16/216) for Anaplasma platys and 0.1% (2/216) for Ehrlichia sp. confirmed by sequencing analysis. Co-positivity among Anaplasmataceae family species was present in 25% (10/40) of positive samples. There was a significant association among Anaplasmataceae family infection in dogs and the following variables: sex (p=0.034), presence of ticks (p=0.0001), and socio-economic status (p=0.001). There was no statistical association on the variables “living with other animals” and “age group” (p=0.1074). The partial sequences on the portion of the 16S rRNA gene, from positive samples for agents of Anaplasmataceae family demonstrated an identity of 97-100% with the isolated E. canis and A. platys obtained from the GenBank. This is the first study on infection by agents of Anaplasmataceae family in dogs in the Department of Piura, through molecular analysis.KEY WORDS: Anaplasmosis; Canis lupus; ehrlichiosis; molecular analysis; South America