Comparative genomics analysis of triatomines reveals common first line and inducible immunity-related genes and the absence of Imd canonical components among hemimetabolous arthropods

Background

Insects operate complex humoral and cellular immune strategies to fend against invading microorganisms. The majority of these have been characterized in Drosophila and other dipterans. Information on hemipterans, including Triatominae vectors of Chagas disease remains incomplete and fractionated.

Results

We identified putative immune-related homologs of three Triatominae vectors of Chagas disease, Triatoma pallidipennis, T. dimidiata and T. infestans (TTTs), using comparative transcriptomics based on established immune response gene references, in conjunction with the predicted proteomes of Rhodnius prolixus, Cimex lecticularis and Acyrthosiphon pisum hemimetabolous. We present a compressive description of the humoral and cellular innate immune components of these TTTs and extend the immune information of other related hemipterans. Key homologs of the constitutive and induced immunity genes were identified in all the studied hemipterans.

Conclusions

Our results in the TTTs extend previous observations in other hemipterans lacking several components of the Imd signaling pathway. Comparison with other hexapods, using published data, revealed that the absence of various Imd canonical components is common in several hemimetabolous species.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2561-2) contains supplementary material, which is available to authorized users.

De Novo DNA Synthesis in Aedes aegypti Midgut Cells as a Complementary Strategy to Limit Dengue Viral Replication

Aedes aegypti is the main vector of Dengue Virus, carrying the virus during the whole mosquito life post-infection. Few mosquito fitness costs have been associated to the virus infection, thereby allowing for a swift dissemination. In order to diminish the mosquito population, public health agency use persistent chemicals with environmental impact for disease control. Most countries barely use biological controls, if at all. With the purpose of developing novel Dengue control strategies, a detailed understanding of the unexplored virus-vector interactions is urgently needed. Damage induced (through tissue injury or bacterial invasion) DNA duplication (endoreplication) has been described in insects during epithelial cells renewal. Here, we delved into the mosquito midgut tissue ability to synthesize DNA de novo; postulating that Dengue virus infection could trigger a protective endoreplication mechanism in some mosquito cells. We hypothesized that the Aedes aegypti orthologue of the Drosophila melanogaster hindsight gene (not previously annotated in Aedes aegypti transcriptome/genome) is part of the Delta-Notch pathway. The activation of this transcriptional cascade leads to genomic DNA endoreplication. The amplification of the genomic copies of specific genes ultimately limits the viral spreading during infection. Conversely, inhibiting DNA synthesis capacity, hence endoreplication, leads to a higher viral replication.

Biological and genetic aspects of crosses between phylogenetically close species of Mexican triatomines (Hemiptera: Reduviidae)

Reproductive isolation between Triatoma mexicana (Herrich-Scaeffer) and the six species of the Phyllosoma complex, belonging to the genus Meccus, was examined by analyzing the fertility of experimental hybrids. The percentage of couples with offspring was highest in the set of crosses between Meccus phyllosomus (Burmeister) and T. mexicana, and lowest in those between Meccus pallidipennis (Stål) and Meccus bassolsae (Alejandre-Aguilar, Nogueda-Torres, Cortés-Jiménez, Jurberg, Galvão, and Carcavallo) with respect to T. mexicana. Crosses between Meccus mazzottii (Usinger), Meccus picturatus (Usinger), and Meccus longipennis (Usinger) and T. mexicana had scarce offspring, whereas offspring from crosses between M. phyllosomus and T. mexicana were abundant. However, all F1 nymphs died in different instars before reaching sexual maturity. The biological evidence in this study suggests that different degrees of reproductive isolation exist between T mexicana and the different species of Meccus. Our data also support the current status of T. mexicana as a separate species.

Pathogen-insect interaction candidate molecules for transmission-blocking control strategies of vector borne diseases

OBJECTIVE

To analyze the current knowledge of pathogen-insect interactions amenable for the design of molecular-based control strategies of vector-borne diseases.

MATERIALS AND METHODS

We examined malaria, dengue, and Chagas disease pathogens and insect molecules that participate in interactions during their vectors infection.

RESULTS

Pathogen molecules that participate in the insect intestine invasion and induced vector immune molecules are presented, and their inclusion in transmission blocking vaccines (TBV) and in genetically modify insect (GMI) vectors or symbiotic bacteria are discussed.

CONCLUSIONS

Disruption of processes by blocking vector-pathogen interactions provides several candidates for molecular control strategies, but TBV and GMI efficacies are still limited and other secondary effects of GMI (improving transmission of other pathogens, affectation of other organisms) should be discarded.

Complete genome sequence of multidrug-resistant and NDM-producing Klebsiella variicola clinical isolates

Recently, global dissemination of NDM-producing Klebsiella variicola in hospital settings and natural environments has been described. This study described the whole-genome sequencing of multidrug-resistant phenotype and NDM-producing Klebsiella variicola clinical isolates.

Complete genome sequences of Klebsiella pneumoniae, Klebsiella quasipneumoniae, and Klebsiella variicola clinical isolates from an epidemiology study

An epidemiology study of Klebsiella spp. causing infections was carried out. In the study, K. pneumoniae was identified with a prevalence of 94.6%, K. quasipneumoniae with 3.8%, and K. variicola with 1.6%. Here, we report the draft genome sequence of four selected Klebsiella pneumoniae species complex (KpSC) clinical isolates obtained from different sources.