RESUMO
The ability of Baculoviruses to hyper-express very late genes as polyhedrin, the major component of occlusion bodies (OBs) or polyhedra, has allowed the evolution of a system of great utility for biotechnology. The main function of polyhedra in nature is to protect Baculovirus in the environment. The possibility of incorporating foreign proteins into the crystal by fusing them to polyhedrin (POLH) opened novel potential biotechnological uses. In this review, we summarize different applications of Baculovirus chimeric OBs. Basically, the improvement of protein expression and purification with POLH as a fusion partner; the use of recombinant polyhedra as immunogens and antigens, and the incorporation of proteins into polyhedra to improve Baculoviruses as bioinsecticides. The results obtained in each area and the future trends in these topics are also discussed.
Assuntos
Baculoviridae/genética , Proteínas de Matriz de Corpos de Inclusão/genética , Proteínas Recombinantes de Fusão/genética , Animais , Biotecnologia , InseticidasRESUMO
Baculoviruses are large DNA virus of insects principally employed in recombinant protein expression. Its ability to form occlusion bodies (OBs), which are composed mainly of polyhedrin protein (POLH), makes them biotechnologically attractive, as these crystals (polyhedra) can incorporate foreign peptides and can be easily isolated. On the other hand, peptide microarrays allow rapid and inexpensive high-throughput serological screening of new candidates to be incorporated to OBs. To integrate these 2 biotechnological approaches, we worked on Babesia bovis, one of the causative agents of bovine babesiosis. Current molecular diagnosis of infection with B. bovis includes enzyme-linked immunosorbent assay (ELISA) techniques, which use merozoite lysate obtained from infected bovine erythrocytes. However, it is important to produce recombinant antigens that replace the use of crude antigens. Here, we describe a new biotechnological platform for the design of indirect ELISAs based on 5 antigenic peptides of 15 amino acid residues of B. bovis (ApBb), selected from a peptide microarray and expressed as a fusion to POLH. An Sf9POLHE44G packaging cell line infected with recombinant baculoviruses carrying POLH-ApBb fusions yielded higher levels of chimeric polyhedra, highlighting the advantage of a trans-contribution of a mutant copy of polyhedrin. Finally, the use of dissolved recombinant polyhedra as antigens was successful in an ELISA assay, as B. bovis-positive sera recognized the fusion POLH-ApBb. Thus, the use of this platform resulted in a promising alternative for molecular diagnosis of relevant infectious diseases.
Assuntos
Antígenos de Protozoários/imunologia , Babesia bovis/química , Babesiose/diagnóstico , Baculoviridae , Ensaio de Imunoadsorção Enzimática/métodos , Peptídeos/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Biotecnologia , Bovinos , Doenças dos Bovinos/diagnóstico , Ensaio de Imunoadsorção Enzimática/veterinária , Proteínas de Protozoários/imunologia , Proteínas Recombinantes/imunologiaRESUMO
Cyclodextrin glycosyltransferases (CGTases) are bacterial enzymes that catalyze starch conversion into cyclodextrins, which have several biotechnological applications including solubilization of hydrophobic compounds, masking of unpleasant odors and flavors in pharmaceutical preparations, and removal of cholesterol from food. Additionally, CGTases produce maltooligosaccharides, which are linear molecules with potential benefits for human health. Current research efforts are concentrated in the development of engineered enzymes with improved yield and/or particular product specificity. In this work, we analyzed the role of four residues of the CGTase from Paenibacillus barengoltzii as determinants of product specificity. Single mutations were introduced in the CGTase-encoding gene to obtain mutants A137V, A144V, L280A and M329I and the activity of recombinant proteins was evaluated. The residue at position 137 proved to be relevant for CGTase activity. Molecular dynamics studies demonstrated additionally that mutation A137V produces a perturbation in the catalytic site of the CGTase, which correlates with a 10-fold reduction in its catalytic efficiency. Moreover, this mutant showed increased production of maltooligosaccharides with a high degree of polymerization, mostly maltopentaose to maltoheptaose. Our results highlight the role of residue 137 as a determinant of product specificity in this CGTase and may be applied to the rational design of saccharide-producing enzymes.
Assuntos
Ciclodextrinas/biossíntese , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Mutagênese Sítio-Dirigida , Mutação , Oligossacarídeos/biossíntese , Paenibacillus/enzimologia , Sequência de Aminoácidos , Domínio Catalítico , Ciclização , Ciclodextrinas/metabolismo , Glucosiltransferases/química , Simulação de Dinâmica Molecular , Oligossacarídeos/metabolismo , Especificidade por SubstratoRESUMO
Transgenic domestic animals represent an alternative to bioreactors for large-scale production of biopharmaceuticals and could also provide more accurate biomedical models than rodents. However, their generation remains inefficient. Recently, DNA transposons allowed improved transgenesis efficiencies in mice and pigs. In this work, Tn5 and Sleeping Beauty (SB) transposon systems were evaluated for transgenesis by simple cytoplasmic injection in livestock zygotes. In the case of Tn5, the transposome complex of transposon nucleic acid and Tn5 protein was injected. In the case of SB, the supercoiled plasmids encoding a transposon and the SB transposase were co-injected. In vitro produced bovine zygotes were used to establish the cytoplasmic injection conditions. The in vitro cultured blastocysts were evaluated for reporter gene expression and genotyped. Subsequently, both transposon systems were injected in seasonally available ovine zygotes, employing transposons carrying the recombinant human factor IX driven by the beta-lactoglobulin promoter. The Tn5 approach did not result in transgenic lambs. In contrast, the Sleeping Beauty injection resulted in 2 lambs (29%) carrying the transgene. Both animals exhibited cellular mosaicism of the transgene. The extraembryonic tissues (placenta or umbilical cord) of three additional animals were also transgenic. These results show that transpositional transgenesis by cytoplasmic injection of SB transposon components can be applied for the production of transgenic lambs of pharmaceutical interest.
Assuntos
Bovinos/embriologia , Suínos/embriologia , Transposases/genética , Zigoto/metabolismo , Animais , Animais Geneticamente Modificados , Citoplasma , Reação em Cadeia da PolimeraseRESUMO
The recently developed engineered nucleases, such as zinc-finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated nuclease (Cas) 9, provide new opportunities for gene editing in a straightforward manner. However, few reports are available regarding CRISPR application and efficiency in cattle. Here, the CRISPR/Cas9 system was used with the aim of inducing knockout and knock-in alleles of the bovine PRNP gene, responsible for mad cow disease, both in bovine fetal fibroblasts and in IVF embryos. Five single-guide RNAs were designed to target 875 bp of PRNP exon 3, and all five were codelivered with Cas9. The feasibility of inducing homologous recombination (HR) was evaluated with a reporter vector carrying EGFP flanked by 1 kbp PRNP regions (pHRegfp). For somatic cells, plasmids coding for Cas9 and for each of the five single-guide RNAs (pCMVCas9 and pSPgRNAs) were transfected under two different conditions (1X and 2X). For IVF zygotes, cytoplasmic injection was conducted with either plasmids or mRNA. For plasmid injection groups, 1 pg pCMVCas9 + 0.1 pg of each pSPgRNA (DNA2X) was used per zygote. In the case of RNA, two amounts (RNA1X and RNA2X) were compared. To assess the occurrence of HR, a group additionally cotransfected or coinjected with pHRegfp plasmid was included. Somatic cell lysates were analyzed by polymerase chain reaction and surveyor assay. In the case of embryos, the in vitro development and the genotype of blastocysts were evaluated by polymerase chain reaction and sequencing. In somatic cells, 2X transfection resulted in indels and large deletions of the targeted PRNP region. Regarding embryo injection, higher blastocyst rates were obtained for RNA injected groups (46/103 [44.6%] and 55/116 [47.4%] for RNA1X and RNA2X) than for the DNA2X group (26/140 [18.6%], P < 0.05). In 46% (26/56) of the total sequenced blastocysts, specific gene editing was detected. The total number of genetic modifications (29) was higher than the total number of gene-edited embryos, as three blastocysts from the group RNA2X reported more than one type of modification. The modifications included indels (10/56; 17.9%) and large deletions (19/56; 33.9%). Moreover, it was possible to detect HR in 1/8 (12.5%) embryos treated with RNA2X. These results report that the CRISPR/Cas9 system can be applied for site-specific edition of the bovine genome, which could have a great impact on the development of large animals resistant to important zoonotic diseases.
Assuntos
Sistemas CRISPR-Cas , Bovinos/embriologia , Fertilização in vitro/veterinária , Engenharia Genética/veterinária , Proteínas Priônicas/metabolismo , Animais , Bovinos/genética , Feto/citologia , Fibroblastos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Mutação , Proteínas Priônicas/genéticaRESUMO
The Foot-and-mouth disease virus (FMDV) causes important economical losses in livestock farming. In order to develop a novel subunit vaccine against FMDV, we constructed recombinant baculoviruses that display the protein VP1 of FMDV on their surface, with either polar (fused to gp64) or nonpolar (fused to anchor membrane from VSV-G protein) distribution. Insect cells infected with the different recombinant baculoviruses expressed VP1 fusion protein to high levels. However, the recombinant VP1 protein was not carried by budded virions. Subcellular localization of VP1 revealed that the trafficking of the fusion protein to the cell plasma membrane was impaired. Our results suggest that VP1 contains cryptic domains that interfere with protein secretion and subsequent incorporation into budded baculoviruses.
Assuntos
Baculoviridae/química , Baculoviridae/genética , Proteínas do Capsídeo/análise , Proteínas do Capsídeo/genética , Técnicas de Visualização da Superfície Celular/métodos , Vetores Genéticos , Animais , Vírus da Febre Aftosa/genética , Transporte Proteico , Proteínas Recombinantes de Fusão/análise , Proteínas Recombinantes de Fusão/genética , Células Sf9 , SpodopteraRESUMO
Baculoviruses (Bvs) potentiate the immune response against soluble antigens. We investigated whether Bv could be used as immunoactivator in foot-and-mouth disease (FMD) vaccines using the BALB/c mouse model. Mice were vaccinated with a single dose of inactivated FMDV (iFMDV), iFMDV+Bv, Bv, or culture medium. Humoral and cellular immune responses were higher in animals immunized with iFMDV+Bv than in mice vaccinated with iFMDV alone. Animals receiving iFMDV+Bv had significantly lower viremia at 2, 4 and 7dpv, than those immunized with iFMDV alone. In order to prolong the immune response, iFMDV oil vaccine was co-inoculated with Bv. Animals receiving iFMDV oil vaccine+Bv were protected two days earlier than those receiving the iFMDV oil vaccine alone. Both formulations protected until 14dpv, the last day of the experiment. This is the first report in which Bv is used as an adjuvant in a FMDV vaccine.
Assuntos
Baculoviridae/imunologia , Vírus da Febre Aftosa/imunologia , Febre Aftosa/imunologia , Vacinas Virais/administração & dosagem , Animais , Anticorpos Antivirais/imunologia , Feminino , Febre Aftosa/prevenção & controle , Imunidade Celular/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia , Vacinas Virais/imunologiaRESUMO
Epinotia aporema granulovirus (EpapGV) has attracted interest as a potential biocontrol agent of the soybean pest Epinotia aporema in Argentina. Studies on virus/host interactions conducted so far have lacked an accurate method to assess the progress of virus load during the infection process. The present paper reports the development of a real-time PCR for EpapGV and its application to describe viral kinetics following ingestion of two different virus doses by last-instar E. aporema larvae. Real-time PCR was shown to be a reliable method to detect and quantify the presence of EpapGV in the analyzed samples. The increase in virus titer (log) exhibited a sigmoidal pattern, with an exponential growth phase between 24 and 48 h postinfection for both initial doses tested.
Assuntos
Baculoviridae/isolamento & purificação , Lepidópteros/virologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Animais , Baculoviridae/química , Baculoviridae/classificação , Baculoviridae/genética , Cinética , Proteínas Virais/química , Proteínas Virais/genéticaRESUMO
Insect genomics is a growing area of research. To exploit fully the genomic data that are being generated, high-throughput systems for the functional characterization of insect proteins and their interactomes are required. In this work, a Gateway-compatible vector set for expression of fluorescent fusion proteins in insect cells was developed. The vector set was designed to express a protein of interest fused to any of four different fluorescent proteins [green fluorescent protein (GFP), cyan fluorescent protein (CFP), yellow fluorescent protein (YFP) and mCherry] by either the C-terminal or the N-terminal ends. Additionally, a collection of organelle-specific fluorescent markers was assembled for colocalization with fluorescent recombinant proteins of interest. Moreover, the vector set was proven to be suitable for simultaneously detecting up to three proteins by multiple labelling. The use of the vector set was exemplified by defining the subcellular distribution of Mal de Río Cuarto virus (MRCV) outer coat protein P10 and by analysing the in vivo self-interaction of the MRCV viroplasm matrix protein P9-1 in Förster resonance energy transfer (FRET) experiments. In conclusion, we have developed a valuable tool for high-throughput studies of protein subcellular localization that will aid in the elucidation of the function of newly described insect and virus proteins.
Assuntos
Vetores Genéticos , Insetos/genética , Imagem Molecular , Animais , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Linhagem Celular , Transferência Ressonante de Energia de Fluorescência , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Insetos/metabolismo , RatosRESUMO
A strategy for the production of virus-like particles (VLPs) from simian rotavirus in larvae of the lepidopteran Spodoptera frugiperda is described. VP2 and VP6 coding sequences were co-expressed in larvae co-infected with recombinant baculovirus and these structural proteins self-assembled into VLPs that were secreted and accumulated in the haemolymph. Under electron microscopy, VLPs produced in larvae were indistinguishable from those produced in Sf9 insect cell cultures. The results showed that it is possible to obtain rotavirus VLPs in larvae reducing significantly the costs of production, making this approach an alternative for the manufacture of live rotavirus vaccines.