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Dengue is the most prevalent arboviral infection, affecting millions of people every year. Attempts to control such infection are being made, and the development of a vaccine is a World Health Organization priority. Among the proteins being tested as vaccine candidates in preclinical settings is the non-structural protein 1 (NS1). In the present study, we tested the immune responses generated by targeting the NS1 protein to two different dendritic cell populations. Dendritic cells (DCs) are important antigen presenting cells, and targeting proteins to maturing DCs has proved to be an efficient means of immunization. Antigen targeting is accomplished by the use of a monoclonal antibody (mAb) directed against a DC cell surface receptor fused to the protein of interest. We used two mAbs (αDEC205 and αDCIR2) to target two distinct DC populations, expressing either DEC205 or DCIR2 endocytic receptors, respectively, in mice. The fusion mAbs were successfully produced, bound to their respective receptors, and were used to immunize BALB/c mice in the presence of polyriboinosinic: polyribocytidylic acid (poly (I:C)), as a DC maturation stimulus. We observed induction of strong anti-NS1 antibody responses and similar antigen binding affinity irrespectively of the DC population targeted. Nevertheless, the IgG1/IgG2a ratios were different between mouse groups immunized with αDEC-NS1 and αDCIR2-NS1 mAbs. When we tested the induction of cellular immune responses, the number of IFN-γ producing cells was higher in αDEC-NS1 immunized animals. In addition, mice immunized with the αDEC-NS1 mAb were significantly protected from a lethal intracranial challenge with the DENV2 NGC strain when compared to mice immunized with αDCIR2-NS1 mAb. Protection was partially mediated by CD4+ and CD8+ T cells as depletion of these populations reduced both survival and morbidity signs. We conclude that targeting the NS1 protein to the DEC205+ DC population with poly (I:C) opens perspectives for dengue vaccine development., Author Summary Dengue is one of the most prevalent viral infections. It affects millions of people every year and can be life-threatening if left untreated. The development of a dengue vaccine is a public health priority. In the present study, we decided to use a dengue virus derived protein, named non-structural protein 1 (NS1) in an immunization protocol that targets the antigen to dendritic cells (DCs). DCs are central for the induction of immunity against pathogens and there are a few DC populations already described. NS1 was engineered in fusion with two distinct monoclonal antibodies that are capable of binding two different receptors present on the surface of these cells. NS1 targeting to one DC population (known as DEC205+) was able to induce anti-NS1 immune responses and confer protection to mice challenged with serotype 2 dengue virus.

Landfarm soils are employed in industrial and petrochemical residue bioremediation. This process induces selective pressure directed towards microorganisms capable of degrading toxic compounds. Detailed description of taxa in these environments is difficult due to a lack of knowledge of culture conditions required for unknown microorganisms. A metagenomic approach permits identification of organisms without the need for culture. However, a DNA extraction step is first required, which can bias taxonomic representativeness and interfere with cloning steps by extracting interference substances. We developed a simplified DNA extraction procedure coupled with metagenomic DNA amplification in an effort to overcome these limitations. The amplified sequences were used to generate a metagenomic data set and the taxonomic and functional representativeness were evaluated in comparison with a data set built with DNA extracted by conventional methods. The simplified and optimized method of RAPD to access metagenomic information provides better representativeness of the taxonomical and metabolic aspects of the environmental samples.

Dengue virus (DENV) is the causative agent of dengue fever (DF), a mosquito-borne illness endemic to tropical and subtropical regions. There is currently no effective drug or vaccine formulation for the prevention of DF and its more severe forms, i.e., dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). There are two generally available experimental models for the study of DENV pathogenicity as well as the evaluation of potential vaccine candidates. The first model consists of non-human primates, which do not develop symptoms but rather a transient viremia. Second, mouse-adapted virus strains or immunocompromised mouse lineages are utilized, which display some of the pathological features of the infection observed in humans but may not be relevant to the results with regard to the wild-type original virus strains or mouse lineages. In this study, we describe a genetic and pathological study of a DENV2 clinical isolate, named JHA1, which is naturally capable of infecting and killing Balb/c mice and reproduces some of the symptoms observed in DENV-infected subjects. Sequence analyses demonstrated that the JHA1 isolate belongs to the American genotype group and carries genetic markers previously associated with neurovirulence in mouse-adapted virus strains. The JHA1 strain was lethal to immunocompetent mice following intracranial (i.c.) inoculation with a LD(50) of approximately 50 PFU. Mice infected with the JHA1 strain lost weight and exhibited general tissue damage and hematological disturbances, with similarity to those symptoms observed in infected humans. In addition, it was demonstrated that the JHA1 strain shares immunological determinants with the DENV2 NGC reference strain, as evaluated by cross-reactivity of anti-envelope glycoprotein (domain III) antibodies. The present results indicate that the JHA1 isolate may be a useful tool in the study of DENV pathogenicity and will help in the evaluation of anti-DENV vaccine formulations as well as potential therapeutic approaches.

Type 1 herpes virus (HSV-1) glycoprotein D (gD) enhances antigen-specific immune responses, particularly CD8(+) T cell responses, in mice immunized with DNA vaccines encoding hybrid proteins genetically fused with the target antigen at a site near the C-terminal end. These effects are attributed to the interaction of gD with the herpes virus entry mediator (HVEM) and the concomitant blockade of a coinhibitory mechanism mediated by the B- and T-lymphocyte attenuator (BTLA). However, questions concerning the requirement for endogenous synthesis of the antigen or the adjuvant/antigen fusion itself have not been addressed so far. In the present study, we investigated these points using purified recombinant gDs, genetically fused or not with type 16 papilloma virus (HPV-16) E7 oncoprotein. Soluble recombinant gDs, but not denatured forms, retained the ability to bind surface-exposed cellular receptors of HVEM-expressing U937 cells. In addition, in vivo administration of the recombinant proteins, particularly gD genetically fused with E7 (gDE7), promoted the activation of dendritic cells (DC) and antigen-specific cytotoxic CD8(+) T cells. More relevantly, mice immunized with the gDE7 protein developed complete preventive and partial therapeutic antitumor protection, as measured in mice following the implantation of TC-1 cells expressing HPV-16 oncoproteins. Collectively, these results demonstrate that the T cell adjuvant effects of the HSV-1 gD protein did not require endogenous synthesis and could be demonstrated in mice immunized with purified recombinant proteins.

The dengue virus NS1 protein has been shown to be a protective antigen under different experimental conditions but the recombinant protein produced in bacterial expression systems is usually not soluble and loses structural and immunological features of the native viral protein. In the present study, experimental conditions leading to purification and refolding of the recombinant dengue virus type 2 (DENV-2) NS1 protein expressed in Escherichia coli are described. The refolded recombinant protein was recovered as heat-stable soluble dimers with preserved structural features, as demonstrated by spectroscopic methods. In addition, antibodies against epitopes of the NS1 protein expressed in eukaryotic cells recognized the refolded protein expressed in E. coli but not the denatured form or the same protein submitted to a different refolding condition. Collectively, the results demonstrate that the recombinant NS1 protein preserved important conformation and antigenic determinants of the native virus protein and represents a valuable reagent either for the development of vaccines or for diagnostic methods.

The need for the prospecting for and identification of new biomolecules is a reality. Molecular techniques allow access to the metabolic potential of microorganisms via the isolation of DNA from environmental samples, i.e., without the application of micro- bial culture techniques. With its great biological diversity, the Atlantic Rainforest biome has a soil rich in organic matter, some components of which interfere negatively in the reactions necessary for the ex- ploitation of its biotechnological potential. Here, we describe a proto- col for the optimization of the treatment of soil samples before DNA extraction. The new methodology gives higher yield and quality of extracted DNA as compared with pre-existing techniques, facilitat- ing the amplification and digestion of environmental DNA, and thus allows optimal exploitation of the genetic potential of the Atlantic Rainforest biome.

The dengue virus non-structural 1 (NS1) protein contributes to evasion of host immune defenses and represents a target for immune responses. Evidences generated in experimental models, as well as the immune responses elicited by infected individuals, showed that induction of anti-NS1 immunity correlates with protective immunity but may also result in the generation of cross-reactive antibodies that recognize platelets and proteins involved in the coagulation cascade. In the present work, we evaluated the immune responses, protection to type 2 dengue virus (DENV2) challenges and safety parameters in BALB/c mice vaccinated with a recombinant NS1 protein in combination with three different adjuvants: aluminum hydroxide (alum), Freund's adjuvant (FA) or a genetically detoxified derivative of the heat-labile toxin (LT(G33D)), originally produced by some enterotoxigenic Escherichia coli (ETEC) strains. Mice were subcutaneously (s.c.) immunized with different vaccine formulations and the induced NS1-specific responses, including serum antibodies and T cell responses, were measured. Mice were also subjected to lethal challenges with the DENV2 NGC strain. The results showed that maximal protective immunity (50%) was achieved in mice vaccinated with NS1 in combination with LT(G33D). Analyses of the NS1-specific immune responses showed that the anti-virus protection correlated mainly with the serum anti-NS1 antibody responses including higher avidity to the target antigen. Mice immunized with LT(G33D) elicited a prevailing IgG2a subclass response and generated antibodies with stronger affinity to the antigen than those generated in mice immunized with the other vaccine formulations. The vaccine formulations were also evaluated regarding induction of deleterious side effects and, in contrast to mice immunized with the FA-adjuvanted vaccine, no significant hepatic damage or enhanced C-reactive protein levels were detected in mice immunized with NS1 and LT(G33D.) Similarly, no detectable alterations in bleeding time and hematological parameters were detected in mice vaccinated with NS1 and LT(G33D). Altogether, these results indicate that the combination of a purified recombinant NS1 and a nontoxic LT derivative is a promising alternative for the generation of safe and effective protein-based anti-dengue vaccine.

O Semliki Forest Vírus recombinante (rSFV) vem sendo apontado como um dos vetores virais mais promissores, tanto para a expressão de proteínas de interesse biotecnológico, como para a utilização como vetor vacinal. Neste trabalho obtivemos um rSFV carregando o gene da proteína verde fluorescente GFP (rSFV-GFP), que foi utilizado para a padronização de métodos de obtenção do vetor viral e de sua titulação, duas etapas importantes para os trabalhos que utilizam rSFVs. Por meio da análise da expressão da GFP em células BHK-21 infectadas por lotes de vírus obtidos por um reagente de transfecção lipídico ou por eletroporação, estabelecemos as melhores condições de obtenção dos rSFV e de sua utilização para a infecção e produção de proteínas recombinantes de interesse. Além disso, padronizamos criteriosamente uma metodologia de RT-PCR quantitativa (qRT-PCR) absoluta, baseada em uma curva padrão, para realizar a titulação de partículas rSFV, independentemente do gene heterólogo clonado. A análise direta da quantidade de células infectadas, por citometria de fluxo e por microscopia de fluorescência, fez do rSFV-GFP a ferramenta adequada para nossos estudos de titulação viral por qRT-PCR. Foi demonstrada a associação entre o número de cópias do RNA viral utilizado para a infecção das células e a quantidade de células expressando GFP. Essa abordagem levou ao desenvolvimento de competências técnica e tecnológica (construção, avaliação e titulação) que facilitarão a obtenção de outros rSFV de interesse. Concluímos que a eletroporação é o melhor método de obtenção das partículas e que o título viral, determinado por qRT-PCR, pode ser utilizado para calcular o volume de um lote de rSFV necessário para obter a multiplicidade de infeção desejada. The recombinant Semliki Forest Virus (rSFV) has been considered as one of the most promising viral vectors, both for the expression of proteins of biotechnological interest or as a vector for immunizations. In this study, an rSFV carrying the gene of the green fluorescent protein (GFP) was obtained (rSFV-GFP) and used for the standardization of rSFV production and of a novel titration methodology. Through the analysis of the amounts of GFP expressed in BHK-21 cells infected with virus stocks obtained by transfection with a lipid reagent or electroporation, we established the best conditions for rSFV production based on the production of this recombinant protein. In addition, a standardized method of absolute quantitative RT-PCR (qRT-PCR), based in a standard curve and applicable to virtually all rSFV particles, regardless of the heterologous gene cloned, was validated. The direct analysis of the quantity of infected cells, by flow cytometry and fluorescence microscopy, confirmed that the rSFV-GFP was an appropriated tool to support ours studies of viral titration by qRT-PCR. It was demonstrated the association between the amount of copies of viral RNA used for culture infection and the amount of GFP expression. This approach led to the development of technical and technological competence (construction, evaluation and titration) in the laboratory, that shall help the establishment of other rSFV of interest. We concluded that electroporation is the best methodology to obtain rSFV particles and the viral titre, as determined by qRT-PCR, can be used to calculate the volume of an rSFV stock necessary to obtain the desired multiplicity of infection.