ISCOM-Matrices Nanoformulation Using the Raw Aqueous Extract of Quillaja lancifolia (Q. brasiliensis)

Quillaja saponins have an intrinsic capacity to interact with membrane lipids that self-assembles in nanoparticles (immunostimulating complexes or ISCOM-matrices) with outstanding immunoadjuvant activity and low toxicity profile. However, the expensive and laborious purification processes applied to purify Quillaja saponins used to assemble ISCOM-matrices show an important drawback in the large-scale use of this vaccine adjuvant. Thus, in this study, we describe a protocol to appropriately formulate ISCOM-matrices using the raw aqueous extract (AE) of Quillaja lancifolia leaves. In the presence of lipids, AE was able to self-assemble in nanostructures that resembles immunostimulating complexes (ISCOM). These negatively charged nanoparticles of approximately 40 nm were characterized by transmission electron microscopy and dynamic light scattering. In addition, well-known saponins with remarkable immunoadjuvant activity, as QS-21, were detected into nanoparticles. Thus, the easier, robust, cheaper, and environmentally friendly method developed here may be an alternative to the classical methods for ISCOM-matrices production that use high-purified saponins.

Effects of tafenoquine against active, dormant and resistant Mycobacterium tuberculosis

Antimalarial drugs have been suggested as promising scaffolds with anti-tubercular activities. In this work, we demonstrated, for the first time, the effectiveness of tafenoquine against mycobacteria. Firstly, tafenoquine inhibited the growth of Mycobacterium smegmatis and Mycobacterium tuberculosis with lower MICs values as compared to other antimalarial drugs, such as mefloquine, chloroquine, and primaquine. Importantly, tafenoquine was active against three multi-drug resistant strains of M. tuberculosis with MIC values similar to pan-sensitive strains, suggesting that tafenoquine is capable of evading the major mechanisms of resistance found in drug-resistant clinical isolates of M. tuberculosis. Importantly, tafenoquine displayed a synergistic effect when combined with mefloquine. In addition, tafenoquine displayed an improved activity compared to the groups treated with both isoniazid and rifampicin in the six-week nutrient starved M. tuberculosis cultures. This finding suggests that further investigations of tafenoquine against dormant mycobacteria are worth pursuing. Moreover, different concentrations of tafenoquine ranging from 1.25 to 80 μM displayed different effects against M. tuberculosis, from moderate (reduction of a 1.8 log CFU/mL) to potent bactericidal (reduction of a 4.2 log CFU/mL) activities. Tafenoquine may represent a hit for further drug optimization and for future clinical development as a new anti-mycobacterial agent, especially in cases of resistant and/or dormant forms of tuberculosis.

Zika Virus Envelope Domain III Recombinant Protein Delivered With Saponin-Based Nanoadjuvant From Quillaja brasiliensis Enhances Anti-Zika Immune Responses, Including Neutralizing Antibodies and Splenocyte Proliferation

Nanoadjuvants that combine immunostimulatory properties and delivery systems reportedly bestow major improvements on the efficacy of recombinant, protein-based vaccines. Among these, self-assembled micellar formulations named ISCOMs (immune stimulating complexes) show a great ability to trigger powerful immunological responses against infectious pathogens. Here, a nanoadjuvant preparation, based on saponins from Quillaja brasiliensis, was evaluated together with an experimental Zika virus (ZIKV) vaccine (IQB80-zEDIII) and compared to an equivalent vaccine with alum as the standard adjuvant. The preparations were administered to mice in two doses (on days zero and 14) and immune responses were evaluated on day 28 post-priming. Serum levels of anti-Zika virus IgG, IgG1, IgG2b, IgG2c, IgG3 were significantly increased by the nanoadjuvant vaccine, compared to the mice that received the alum-adjuvanted vaccine or the unadjuvanted vaccine. In addition, a robust production of neutralizing antibodies and in vitro splenocyte proliferative responses were observed in mice immunized with IQB80-zEDIII nanoformulated vaccine. Therefore, the IQB80-zEDIII recombinant preparation seems to be a suitable candidate vaccine for ZIKV. Overall, this study identified saponin-based delivery systems as an adequate adjuvant for recombinant ZIKV vaccines and has important implications for recombinant protein-based vaccine formulations against other flaviviruses and possibly enveloped viruses.

A plate of viruses: Viral metagenomics of supermarket chicken, pork and beef from Brazil

A viral metagenomics study was conducted in beef, pork, and chicken sold in supermarkets from Southern Brazil. From chicken, six distinct gyroviruses (GyV) were detected, including GyV3 and GyV6, which for the first time were detected in samples from avian species, plus a novel smacovirus species and two highly divergent circular Rep-encoding ssDNA (CRESS-DNA) viruses. From pork, genomes of numerous anelloviruses, porcine parvovirus 5 (PPV5) and 6 (PPV6), two new genomoviruses and two new CRESS-DNA viruses were found. Finally, two new CRESS-DNA genomes were recovered from beef. Although none of these viruses have history of transmission to humans, the findings reported here reveal that such agents are inevitably consumed in diets that include these types of meat.

First reported genome of an mcr-9-mediated colistin-resistant Salmonella Typhimurium isolate from Brazilian livestock

OBJECTIVES

To investigate the genetic context of colistin resistance in anmcr-9-harbouring Salmonella Typhimurium ST19 strain from swine in Brazil.

METHODS

Minimum inhibitory concentrations (MIC) to colistin were determined by broth microdilution. Whole-genome sequencing was performed on an Illumina MiSeq system, followed by de novo genome assembly using SPAdes 1.13.1. The draft genome sequence was annotated in Prokka using KBase online server. Downstream analyses for resistome and plasmid detection were performed using online tools available at the Center for Genomic Epidemiology. The strain was typed in silico using MLST 2.0. Phylogenetic analysis involving 24 other genomes ofSalmonella Typhimurium ST19 and mcr-9-harbouring Salmonella Typhimurium isolated from humans, livestock and foodstuff in different regions was also performed.

RESULTS

Assembly of the draft genome resulted in 5245 protein-coding sequences, 14 rRNAs, 83 tRNAs and a GC content of 51.81%. The strain was identified asSalmonella Typhimurium ST19 harbouring a 265.5-kb pN1566-2 plasmid carrying genes encoding resistance to colistin (mcr-9.1), aminoglycosides (aadA1), tetracycline [tet(C)] and sulfonamides (sul1). Our findings indicate that the Salmonella Typhimurium ST19 strain in this study showed low genetic variability compared with Salmonella Typhimurium ST19 isolated from swine and poultry in Brazil, and was less related to those reported in other countries.

CONCLUSIONS

This is the first reported genome of a phenotypically colistin-resistantSalmonella Typhimurium harbouring the mcr-9 variant in Brazilian livestock. This genome will aid global investigations on epidemiological and evolutionary aspects of plasmid-mediated colistin resistance and the role of colistin-resistant Salmonella Typhimurium ST19 lineage as a zoonotic pathogen.

Viral metagenomics in Brazilian Pekin ducks identifies two gyrovirus, including a new species, and the potentially pathogenic duck circovirus

Viral metagenomics coupled to high-throughput sequencing has provided a powerful tool for large-scale detection of known and unknown viruses associated to distinct hosts and environments. Using this approach, known and novel viruses have been characterized from sylvatic and commercial avian hosts, increasing our understanding of the viral diversity in these species. In the present work we applied an exploratory viral metagenomics on organs (spleen, liver and bursa of Fabricious) of Pekin ducks from Southern Brazil. The virome contained sequences related to a known duck pathogen (duck circovirus) and a number of other circular ssDNA viruses. Additionally, we detected avian gyrovirus 9 (to date detected only in human feces) and one new avian gyrovirus species, to which is proposed the name avian gyrovirus 13 (GyV13). This study is expected to contribute to the knowledge of the viral diversity in Pekin ducks.

Molecular and phylogenetic analyses of Salmonella Gallinarum trace the origin and diversification of recent outbreaks of fowl typhoid in poultry farms

Fowl typhoid (FT) and pullorum disease (PD) are two important poultry infections caused by Salmonella enterica subsp. enterica serotype Gallinarum (S. Gallinarum). S. Gallinarum strains are adapted to birds and classified into biovars Gallinarum (bvGA) and Pullorum (bvPU) as they are the causative agent of FT and PD, respectively. In Brazil, FT/PD outbreaks have been reported along the last 50 years, but there was a recent increase of FT field reports with the suspicion it could be due to virulence reversion of the attenuated live vaccine SG9R. In this study, we applied molecular biology assays and phylogenetic methods to detect and investigate S. Gallinarum isolates from commercial poultry flocks in order to understand the evolutionary history and origin of the recent FT outbreaks in Brazil. S. Gallinarum isolates were obtained from thirteen different poultry flocks with clinical signs of FT/PD from 2013 to 2015. These isolates were serotyped, tested with three specific PCR (for the detection of bvGA, bvPU and live vaccine strain SG9R) and submitted to sequencing of a variable genome region (ISR analysis). The complete genome of one bvGA strain (BR_RS12) was also compared to other S. Gallinarum complete genomes (including other two Brazilian ones: bvGA 287/91 and bvPU FCVA198). PCR detected all thirteen isolates as S. Gallinarum (eight bvGA and five bvPU), none positive for SG9R strain. ISR analysis revealed that all eight bvGA isolates showed exactly the same nucleotide sequences with 100% similarity to reference strains, while two patterns were observed for bvPU. Genome phylogeny demonstrated distinct clades for bvGA and bvPU, with the bvGA clade showing a clear subdivision including three genomes: SG9R vaccine, the respective SG9 parent strain and one SG9R revertant field isolate (MB4523). The evolutionary rate of the total S. Gallinarum genome was calculated at 6.15×10^-7 substitutions/site/year, with 2.8 observed substitutions per year per genome (1 SNP per 4292 bases). Phylodynamics analysis estimated that at least two introductions of S. Gallinarum bvGA happened in Brazil, the first in 1885 and the second in 1950. The Brazilian bvGA genomes 287/91 and BR_RS12 analyzed here were related to the early and the late introductions, respectively. In conclusion, these results indicate the occurrence of S. Gallinarum strains associated with FT outbreaks that have been circulating for more than 50 years in Brazil and are not originated from virulence reversion of the SG9R vaccine.

Genotypic and antimicrobial characterization of pathogenic bacteria at different stages of cattle slaughtering in southern Brazil

Meat can be contaminated in different stages of the slaughtering process and the identification of these stages is the starting point to implement adequate control measures. The objectives of this study were to assess the presence of pathogenic microorganisms in cattle carcasses, to identify the most important contamination points of the slaughtering process, and to evaluate the possible risk factors related to them in a cattle slaughterhouse. To this aim, 108 cattle carcasses were sampled at three stages of the slaughtering process: Point 1 (hides after bleeding); Point 2 (carcasses after hide removal); and Point 3 (carcasses immediately after division). Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Livingstone were isolated from the carcasses. Phenotypic and genotypic characterization indicated that there was cross-contamination among animals, since bacteria with identical genotypic and phenotypic profiles were isolated from different animals at the same sampling day. Furthermore, this is the first report about the isolation of E. coli O157:H7 in a bovine slaughterhouse from southern Brazil.

Immunoadjuvant activity, toxicity assays, and determination by UPLC/Q-TOF-MS of triterpenic saponins from Chenopodium quinoa seeds

The adjuvant activity of Chenopodium quinoa (quinoa) saponins on the humoral and cellular immune responses of mice subcutaneously immunized with ovalbumin (OVA) was evaluated. Two quinoa saponin fractions were obtained, FQ70 and FQ90, and 10 saponins were determined by UPLC/Q-TOF-MS. Mice were immunized subcutaneously with OVA alone or adjuvanted with Quil A (adjuvant control), FQ70, or FQ90. FQ70 and FQ90 significantly enhanced the amount of anti-OVA-specific antibodies in serum (IgG, IgG1, and IgG2b) in immunized mice. The adjuvant effect of FQ70 was significantly greater than that of FQ90. However, delayed type hypersensitivity responses were higher in mice immunized with OVA adjuvanted with FQ90 than mice treated with FQ70. Concanavalin A (Con A)-, lipopolysaccharide-, and OVA-stimulated splenocyte proliferation were measured, and FQ90 significantly enhanced the Con A-induced splenocyte proliferation. The results suggested that the two quinoa saponin fractions enhanced significantly the production of humoral and cellular immune responses to OVA in mice.