Identification of Glycycometus malaysiensis (for the first time in Brazil), Blomia tropicalis and Dermatophagoides pteronyssinus through multiplex PCR

Blomia tropicalis and Dermatophagoides pteronyssinus play an important role in triggering allergy. Glycycometus malaysiensis causes IgE reaction in sensitive people, but is rarely reported in domestic dust, because it is morphologically similar to B. tropicalis making the identification of these species difficult. The identification of mites is mostly based on morphology, a time-consuming and ambiguous approach. Herein, we describe a multiplex polymerase chain reaction (mPCR) assay based on ribosomal DNA capable to identify mixed cultures of B. tropicalis, D. pteronyssinus and G. malaysiensis, and/or to identify these species from environmental dust. For this, the internal transcribed spacer 2 (ITS2) regions, flanked by partial sequences of the 5.8S and 28S genes, were PCR-amplified, cloned and sequenced. The sequences obtained were aligned with co-specific sequences available in the GenBank database for primer design and phylogenetic studies. Three pairs of primers were chosen to compose the mPCR assay, which was used to verify the frequency of different mites in house dust samples (n = 20) from homes of Salvador, Brazil. Blomia tropicalis was the most frequent, found in 95% of the samples, followed by G. malaysiensis (70%) and D. pteronyssinus (60%). Besides reporting for the first time the occurrence of G. malaysiensis in Brazil, our results confirm the good resolution of the ITS2 region for mite identification. Furthermore, the mPCR assay proved to be a fast and reliable tool for identifying these mites in mixed cultures and could be applied in future epidemiological studies, and for quality control of mite extract production for general use.

Intestinal polyparasitism and levels of mucosal anthelmintic SIgA in children from endemic areas in Northeastern Brazil

Interactions between parasites during co-infections are often complex and can impact immunization and treatment programmes, as well as disease outcomes and morbidity. However, little is known about these interactions and the mechanisms involved. In this study, a coproparasitological survey was carried out in school-age children living in endemic areas of parasitic infection in the state of Sergipe, Northeastern Brazil. Anti-helminth-specific and total secretory immunoglobulin-A (SIgA) levels were measured in stool and saliva samples and were compared in children presenting monoparasitism, polyparasitism (helminths and/or intestinal protozoa) and no infections. The survey showed that protozoa were more prevalent than helminths, and that there was a high frequency of polyparasitism in the studied population, mainly from combinations of protozoan species. Although less frequent, combinations between species of protozoa and helminths were also observed. The levels of salivary SIgA in these co-infected individuals were lower than the average observed in infections with helminths alone. Although the children participating in this survey were asymptomatic, and it was, therefore, not possible to evaluate the impact of salivary SIgA reduction on the diseases, and the study highlights the need for further investigations of co-infections by intestinal parasites and the effects on immune response induced by the interactions between different parasites.

In vivo cleavage of solubility tags as a tool to enhance the levels of soluble recombinant proteins in Escherichia coli

Recombinant proteins are generally fused with solubility enhancer tags to improve the folding and solubility of the target protein of interest. However, the fusion protein strategy usually requires expensive proteases to perform in vitro proteolysis and additional chromatographic steps to obtain tag-free recombinant proteins. Expression systems based on intracellular processing of solubility tags in Escherichia coli, through co-expression of a site-specific protease, simplify the recombinant protein purification process, and promote the screening of molecules that fail to remain soluble after tag removal. High yields of soluble target proteins have already been achieved using these protease co-expression systems. Herein, we review approaches for controlled intracellular processing systems tailored to produce soluble untagged proteins in E. coli. We discuss the different genetic systems available for intracellular processing of recombinant proteins regarding system design features, advantages, and limitations of the various strategies.

En route to personalized medicine: uncovering distinct IgE reactivity pattern to house dust mite components in Brazilian and Austrian allergic patients

AIM

Molecular sensitization profile analyses of allergic individuals to the house dust mites (HDM) Blomia tropicalis and Dermatophagoides pteronyssinus from Brazil and Austria, in the attempt to comprehend the individual contribution of the molecular components in the diagnosis of HDM allergy.

METHODOLOGY

These analyses were made using a new in vitro multiplex allergen assay which allows simultaneous measurement of specific IgE against the whole allergen extract as well its components.

RESULTS AND CONCLUSION

The data showed that in Brazil the inclusion of the molecular components Blo t 5 and/or Blo t 21 major allergens and Blo t 2 can increase the sensitivity and specificity of the assay for the diagnosis of allergy to B. tropicalis, using matrix-based methodologies. Also we highlighted, for the first time, the importance of Blo t 2 analysis for a sensitive diagnosis, since some individuals were sensitized only to this molecular component. Regarding the sensitization profile of individuals sensitized to D. pteronyssinus, we point out the importance of analyzing the molecular components Der p23 and Der p 7, in addition to Der p 1 and Der p 2 for an accurate diagnosis based on matrices.

High-Quality Resolution of the Outbreak-Related Zika Virus Genome and Discovery of New Viruses Using Ion Torrent-Based Metatranscriptomics

Arboviruses, including the Zika virus, have recently emerged as one of the most important threats to human health. The use of metagenomics-based approaches has already proven valuable to aid surveillance of arboviral infections, and the ability to reconstruct complete viral genomes from metatranscriptomics data is key to the development of new control strategies for these diseases. Herein, we used RNA-based metatranscriptomics associated with Ion Torrent deep sequencing to allow for the high-quality reconstitution of an outbreak-related Zika virus (ZIKV) genome (10,739 nt), with extended 5'-UTR and 3'-UTR regions, using a newly-implemented bioinformatics approach. Besides allowing for the assembly of one of the largest complete ZIKV genomes to date, our strategy also yielded high-quality complete genomes of two arthropod-infecting viruses co-infecting C6/36 cell lines, namely: Alphamesonivirus 1 strain Salvador (20,194 nt) and Aedes albopictus totivirus-like (4618 nt); the latter likely represents a new viral species. Altogether, our results demonstrate that our bioinformatics approach associated with Ion Torrent sequencing allows for the high-quality reconstruction of known and unknown viral genomes, overcoming the main limitation of RNA deep sequencing for virus identification.

Immunomodulatory properties of Schistosoma mansoni proteins Sm200 and SmKI-1 in vitro and in a murine model of allergy to the mite Blomia tropicalis

The prevalence of allergic diseases in Brazil is one of the biggest in the world. Among these pathologies, we highlight asthma as one of the most importance. Asthma is characterized as a chronic inflammatory disease of airways, associated with hyperresponsiveness. Many environmental factors can trigger asthma symptoms, among them house dust mites can stimulate hypersensitivity type I reaction. The most common in house dust mite, in tropical countries, are Dermatophagoides pteronysinus and Blomia tropicalis. Several studies have shown that helminths, especially Schistosoma mansoni, lead to reduction of symptoms of atopy and allergic diseases. Therefore, the present study aims to evaluate the ability of recombinant S. mansoni proteins Sm200, and SmKI-1 to induce immunomodulation in vitro, using peripheral blood mononuclear cells (PBMCs) from atopic and non-atopic individuals, stimulated or not with B. tropicalis extract, and in vivo, in a murine model of allergy to the mite B. tropicalis. As results, we observed that the fragment called rSm200-3 and the protein rSmKI-1 stood out for their immunomodulatory potential, stimulating IL-10 production by human PBMCs in vitro. When these proteins were associated with B. tropicalis extract, it was observed the reduction of the production of the cytokine IL-5, with a statistically significant difference in non-atopic individual's cells. In vivo, both proteins presented similar results, with a reduction of IL-5 and IL-4 levels in lung homogenates and of serum IgE. SmKI-1 was also able to decrease the levels of EPO in lung homogenates and in BAL. These results showed that both proteins were able to downmodulate Th2 cells on human PBMCs, and in a murine model of allergy. However, SmKI-1 also reduced significantly the levels of EPO in BAL and lungs showing that this protein may be a good candidate to be used as a possible replacement or in conjunction with pharmacotherapy in individuals with unregulated immune response in asthma.

Ion torrent-based nasopharyngeal swab metatranscriptomics in COVID-19

Herein, we describe the detection of a SARS-CoV-2 genome through metatranscriptome next-generation sequencing directly from the nasopharyngeal swab of a suspected case of local transmission of Covid-19, in Brazil. Depletion of human ribosomal RNA and use of an optimized in-house developed bioinformatics strategy contributed to successful detection of the virus.

Single-Input Regulatory Cascade for in vivo Removal of the Solubility Tag in Fusion Recombinant Proteins Produced by Escherichia coli

Solubility tags are commonly fused to target recombinant proteins to enhance their solubility and stability. In general, these protein tags must be removed to avoid misfolding of the partner protein and to allow for downstream applications. Nevertheless, in vitro tag removal increases process complexity and costs. Herein, we describe a synthetic biology-based strategy to permit in vivo removal of a solubility tag (EDA, KDPG aldolase), through co-expression of the fusion recombinant protein (EDA-EGFP) and the tag-cleaving protease (TEVp), in a controlled manner. Basically, the system uses three repressor proteins (LacI, cI434, and TetR) to regulate the expressions of EDA-EGFP and TEVp, in a regulatory cascade that culminates with the release of free soluble target protein (EGFP), following a single chemical induction by IPTG. The system worked consistently when all biological parts were cloned in a single plasmid, pSolubility(SOL)A (7.08 Kb, Amp^R), and transformed in Escherichia coli Rosetta (DE3) or BL21(DE3) strains. Total soluble recombinant protein yield (EDA-EGFP + free EGFP) was ca. 272.0 ± 60.1 μg/mL of culture, following IMAC purification; free EGFP composed great part (average = 46.5%; maximum = 67.3%) of the total purified protein fraction and was easily separated from remaining fusion EDA-EGFP (53 KDa) through filtration using a 50 KDa cut-off centrifugal filter.

Schistosoma mansoni SmKI-1 or Its C-Terminal Fragment Induces Partial Protection Against S. mansoni Infection in Mice

Current schistosomiasis control strategies are mainly based on chemotherapy, but the development of a vaccine against this parasitic disease would contribute to a long-lasting decrease in disease spectrum and transmission. When it comes to vaccine candidates, several genes encoding Schistosoma mansoni proteins expressed at the mammalian host-parasite interface have been tested. Among the most promising molecules are the proteins present on the tegument and digestive tract of the parasite. In this study, we evaluate the potential of SmKI-1, the first Kunitz-type protease inhibitor functionally characterized in S. mansoni, as a vaccine candidate. Bioinformatic analysis points to the C-terminal fragment as the main region of the molecule responsible for the development of a potential protective immune response induced by SmKI-1. Therefore, for the vaccine formulations, we produced the recombinant (r) SmKI-1 and two different fragments, its Kunitz (KI) domain and its C-terminal tail. First, we demonstrate that mice immunized with recombinant SmKI-1 (rSmKI-1) or its fragments, formulated with Freund's adjuvant, induced the production of IgG-specific antibodies. Further, all vaccine formulations tested here also induced a Th1-type of immune response, as suggested by the production of IFN-γ and TNF-α by protein-stimulated cultured splenocytes. However, the protective effect conferred by vaccination was only observed in groups which received rSmKI-1 or C-terminal domain vaccines. Mice administered with rSmKI-1 demonstrated reduction of 47% in worm burden, 36% in egg number in mouse livers, and 33% in area of liver granulomas. Additionally, mice injected with C-terminal domain showed reduction of 28% in worm burden, 38% in egg number in liver, and 25% in area of liver granulomas. In contrast, KI domain immunization was unable to reduce worm burden and ameliorate liver pathology after challenge infection. Taken together, our data demonstrated that SmKI-1 is a potential candidate for use in a vaccine to control schistosomiasis, and its C-terminal tail seems to be the main region of the molecule responsible for protection conferred by this antigen.

The somatic proteins of Toxocara canis larvae and excretory-secretory products revealed by proteomics

Toxocariasis is a widespread helminth infection of dogs and cats, caused by Toxocara canis and Toxocara cati larvae, respectively. Toxocara spp. can cause zoonotic infections in humans by invading tissues and organs causing pathology. Toxocara spp. larvae release excretory-secretory molecules (TES) into the body of their host that are fundamental to the host-parasite interaction and could be used as targets for novel diagnostics and vaccines. In the present study, we identified 646 T. canis proteins from TES and larval extract using 1D-SDS PAGE followed by mass spectrometry. A wide range of proteins was identified that may play a role both in the induction of the host immune response and host pathology, and in parasite metabolism and survival. Among these proteins there are potential candidates for novel diagnostics and vaccines for dogs and cats toxocariases.

Efficient differentiation of Corynebacterium striatum, Corynebacterium amycolatum and Corynebacterium xerosis clinical isolates by multiplex PCR using novel species-specific primers

A multiplex-PCR (mPCR) assay was designed with species-specific primers which generate amplicons of 226bp, 434bp and 106bp for differentiating the species C. striatum, C. amycolatum, and C. xerosis, respectively. mPCR results were 100% in agreement with identifications achieved by 16S rRNA and rpoB gene sequencing and by VITEK-MS.

De novo assembly and characterization of the Trichuris trichiura adult worm transcriptome using Ion Torrent sequencing

Infection with helminthic parasites, including the soil-transmitted helminth Trichuris trichiura (human whipworm), has been shown to modulate host immune responses and, consequently, to have an impact on the development and manifestation of chronic human inflammatory diseases. De novo derivation of helminth proteomes from sequencing of transcriptomes will provide valuable data to aid identification of parasite proteins that could be evaluated as potential immunotherapeutic molecules in near future. Herein, we characterized the transcriptome of the adult stage of the human whipworm T. trichiura, using next-generation sequencing technology and a de novo assembly strategy. Nearly 17.6 million high-quality clean reads were assembled into 6414 contiguous sequences, with an N50 of 1606bp. In total, 5673 protein-encoding sequences were confidentially identified in the T. trichiura adult worm transcriptome; of these, 1013 sequences represent potential newly discovered proteins for the species, most of which presenting orthologs already annotated in the related species T. suis. A number of transcripts representing probable novel non-coding transcripts for the species T. trichiura were also identified. Among the most abundant transcripts, we found sequences that code for proteins involved in lipid transport, such as vitellogenins, and several chitin-binding proteins. Through a cross-species expression analysis of gene orthologs shared by T. trichiura and the closely related parasites T. suis and T. muris it was possible to find twenty-six protein-encoding genes that are consistently highly expressed in the adult stages of the three helminth species. Additionally, twenty transcripts could be identified that code for proteins previously detected by mass spectrometry analysis of protein fractions of the whipworm somatic extract that present immunomodulatory activities. Five of these transcripts were amongst the most highly expressed protein-encoding sequences in the T. trichiura adult worm. Besides, orthologs of proteins demonstrated to have potent immunomodulatory properties in related parasitic helminths were also predicted from the T. trichiura de novo assembled transcriptome.

A multivalent chimeric vaccine composed of Schistosoma mansoni SmTSP-2 and Sm29 was able to induce protection against infection in mice

Schistosoma mansoni is a blood fluke parasite responsible for schistosomiasis. The best long-term strategy to control schistosomiasis is through immunization combined with drug treatment. In this study, we cloned, expressed and purified SmTSP-2 fused to the N- and C-terminal halves of Sm29 and tested these chimeras as vaccine candidates using an adjuvant approved to be used in humans. The results demonstrated that vaccination with SmTSP-2 fused to N- or C-terminus of Sm29-induced reduction in worm burden and liver pathology when compared to control animals. Additionally, we detected high levels of mouse-specific IgG, IgG1 and IgG2a against both chimeras and significant amounts of IFN-γ and TNF-α and no IL-4. Finally, studies with sera from patients resistant to infection and living in schistosomiasis endemic areas revealed high levels of specific IgG to both chimeras when compared to healthy individuals. In conclusion, SmTSP-2/Sm29 chimeras tested here induced partial protection against infection and might be a potential vaccine candidate.

Sm10.3, a member of the micro-exon gene 4 (MEG-4) family, induces erythrocyte agglutination in vitro and partially protects vaccinated mice against Schistosoma mansoni infection

Background

The parasitic flatworm Schistosoma mansoni is a blood fluke that causes schistosomiasis. Current schistosomiasis control strategies are mainly based on chemotherapy, but many researchers believe that the best long-term strategy to control disease is a combination of drug treatment and immunization with an anti-schistosome vaccine. Numerous antigens that are expressed at the interface between the parasite and the mammalian host have been assessed. Among the most promising molecules are the proteins present in the tegument and digestive tract of the parasite.

Methodology/Principal Findings

In this study, we evaluated the potential of Sm10.3, a member of the micro-exon gene 4 (MEG-4) family, for use as part of a recombinant vaccine. We confirmed by real-time PCR that Sm10.3 was expressed at all stages of the parasite life cycle. The localization of Sm10.3 on the surface and lumen of the esophageal and intestinal tract in adult worms and lung-stage schistosomula was confirmed by confocal microscopy. We also show preliminary evidence that rSm10.3 induces erythrocyte agglutination in vitro. Immunization of mice with rSm10.3 induced a mixed Th1/Th2-type response, as IFN-γ, TNF-α, and low levels of IL-5 were detected in the supernatant of cultured splenocytes. The protective effect conferred by vaccination with rSm10.3 was demonstrated by 25.5–32% reduction in the worm burden, 32.9–43.6% reduction in the number of eggs per gram of hepatic tissue, a 23.8% reduction in the number of granulomas, an 11.8% reduction in the area of the granulomas and a 39.8% reduction in granuloma fibrosis.

Conclusions/Significance

Our data suggest that Sm10.3 is a potential candidate for use in developing a multi-antigen vaccine to control schistosomiasis and provide the first evidence for a possible role for Sm10.3 in the blood feeding process.

Schistosomiasis mainly occurs in developing countries and is the most important human helminth infection in terms of global mortality. This parasitic disease affects more than 200 million people worldwide and causes more than 250,000 deaths per year. Current schistosomiasis control strategies are mainly based on chemotherapy, but many researchers believe that the best long-term strategy for controlling schistosomiasis is a combination of drug treatment and immunization with an anti-schistosome vaccine. Consequently, significant effort has been dedicated to developing and characterizing an anti-schistosome vaccine. Over the last five years, considerable data have been generated regarding the genomics, transcriptomics and proteomics of Schistosoma mansoni. In the present study, we characterize the Sm10.3 protein and evaluate its potential to protect against S. mansoni infection in a murine model. We demonstrate that Sm10.3 is primarily expressed during the stages of the parasite life cycle that involve infection and disease development in the human host. Sm10.3 is located on the surface of the digestive epithelia of adult female worms, an important host/parasite interface. Moreover, the vaccination of mice with rSm10.3 confers partial protection against S. mansoni. Taken together, our data suggest that Sm10.3 may be a useful component of a multi-antigen vaccine against schistosomiasis.

IPSE/alpha-1 of Schistosoma mansoni egg induces enlargement of granuloma but does not alter Th2 balance after infection

Schistosomiasis is a parasitic disease with more than 200 million people infected worldwide. The formation of granulomas around eggs trapped in the liver is the main cause of disease morbidity. Therefore, the aim of this investigation was to characterize the immunopathological response induced by the recombinant (r) IPSE/alpha-1 egg protein in mice. Herein, we have shown that splenocytes from mice immunized with rIPSE/alpha-1 produced IFN-gamma, TNF-alpha, IL-4, IL-5 and IL-13 characterizing a mixed Th1/Th2 type of immune response. Pathological analysis of the liver revealed that there was no alteration in the number of eggs and granulomas; however, we observed an increase in granuloma area in immunized mice. Furthermore, eosinophil peroxidase assay showed that there was no alteration in the eosinophil infiltration in the liver; however, n-acetyl-beta-glucosaminidase measurement revealed an increase in macrophage activity. Despite the alteration in the profile of liver inflammatory cells in rIPSE immunized mice, the production of chemokines such as CCL2, CCL3, CCL5 and CCL11 was unaltered compared with the control group. In conclusion, IPSE/alpha-1 immunization induces a mixed Th1/Th2 type of immune response and enlargement of hepatic granuloma caused by an increased macrophage activity, but does not alter Th2 cytokines following infection.