Heterologous prime-boost regimen adenovector 35-circumsporozoite protein vaccine/recombinant Bacillus Calmette-Guérin expressing the Plasmodium falciparum circumsporozoite induces enhanced long-term memory immunity in BALB/c mice.

BACKGROUND: Sustained antibody levels are a hallmark of immunity against many pathogens, and induction of long-term durable antibody titers is an essential feature of effective vaccines. Heterologous prime-boost approaches with vectors are optimal strategies to improve a broad and prolonged immunogenicity of malaria vaccines. RESULTS: In this study, we demonstrate that the heterologous prime-boost regimen Ad35-CS/BCG-CS induces stronger immune responses by enhancing type 1 cellular producing-cells with high levels of CSp-specific IFN-γ and cytophilic IgG2a antibodies as compared to a homologous BCG-CS and a heterologous BCG-CS/CSp prime-boost regimen. Moreover, the heterologous prime-boost regimen elicits the highest level of LLPC-mediated immune responses. CONCLUSION: The increased IFN-γ-producing cell responses induced by the combination of Ad35-CS/BCG-CS and sustained type 1 antibody profile together with high levels of LLPCs may be essential for the development of long-term protective immunity against liver-stage parasites.

Cytolytic T lymphocyte recognition of the murine cytomegalovirus nonstructural immediate-early protein pp89 expressed by recombinant vaccinia virus.

The murine immediate-early (IE) protein pp89 is a nonstructural virus-encoded phosphoprotein residing in the nucleus of infected cells, where it acts as transcriptional activator. Frequency analysis has shown that in BALB/c mice the majority of virus-specific CTL recognize IE antigens. The present study was performed to assess whether pp89 causes membrane antigen expression detected by IE-specific CTL. Site-directed mutagenesis has been used to delete the introns from gene ieI, encoding pp89, for subsequent integration of the continuous coding sequence into the vaccinia virus genome. After infection with the vaccinia recombinant, the authentic pp89 was expressed in cells that became susceptible to lysis by an IE-specific CTL clone. Priming of mice with the vaccinia recombinant sensitized polyclonal CTL that recognized MCMV-infected cells and transfected cells expressing pp89. Thus, a herpesviral IE polypeptide with essential function in viral transcriptional regulation can also serve as a dominant antigen for the specific CTL response of the host.

Development and evaluation of a recombinant DNA vaccine candidate expressing porcine circovirus 2 structural protein

Porcine circovirus 2 (PCV2) is generally associated with the porcine circovirosis syndrome, which is considered an important disease of swine and has potentially serious economic impact on the swine industry worldwide. This article describes the construction of a recombinant plasmid expressing the PCV2 structural protein and the evaluation of cellular and humoral immune responses produced by this recombinant vaccine in BALB/c mice. The vaccine candidate was obtained and analyzed in vivo, in an effort to determine the ability to induce a specific immune response in mice. DNA was extracted from a Brazilian PCV2 isolate and the gene coding for Cap protein was amplified by PCR and inserted into an expression plasmid. Groups of BALB/c mice were inoculated intra-muscularly and intradermally in a 15-day interval, with 100 µg and 50 µg of the vaccine construct, respectively. Another group was inoculated intramuscularly with 100 µg of empty plasmid, corresponding to the control group. Seroconversion and cellular response in BALB/c mice were compared and used for vaccine evaluation. Seroconversion was analyzed by ELISA. After a series of 3 immunizations the spleen cells of the immunized animals were used to perform lymphocyte proliferation assays. Seroconversion to PCV2 was detected by ELISA in the animals inoculated with the vaccine construct when compared with control groups. Lymphocyte proliferation assays showed a stronger cell proliferation in the inoculated animals compared with the control group. Thus, the vaccine candidate construct demonstrated to be able to induce both humoral and cellular responses in inoculated mice.

Cloning, expression and purification of recombinant streptokinase: partial characterization of the protein expressed in Escherichia coli

We cloned the streptokinase (STK) gene of Streptococcus equisimilis in an expression vector of Escherichia coli to overexpress the profibrinolytic protein under the control of a tac promoter. Almost all the recombinant STK was exported to the periplasmic space and recovered after gentle lysozyme digestion of induced cells. The periplasmic fraction was chromatographed on DEAE Sepharose followed by chromatography on phenyl-agarose. Active proteins eluted between 4.5 and 0% ammonium sulfate, when a linear gradient was applied. Three major STK derivatives of 47.5 kDa, 45 kDa and 32 kDa were detected by Western blot analysis with a polyclonal antibody. The 32-kDa protein formed a complex with human plasminogen but did not exhibit Glu-plasminogen activator activity, as revealed by a zymographic assay, whereas the 45-kDa protein showed a Km = 0.70 µM and kcat = 0.82 s-1, when assayed with a chromogen-coupled substrate. These results suggest that these proteins are putative fragments of STK, possibly derived from partial degradation during the export pathway or the purification steps. The 47.5-kDa band corresponded to the native STK, as revealed by peptide sequencing

Osteogenesis induced in goat bone marrow progenitor cells by recombinant adenovirus coexpressing bone morphogenetic protein 2 and basic fibroblast growth factor

Bone morphogenetic protein 2 (BMP2) and basic fibroblast growth factor (bFGF) have been shown to exhibit a synergistic effect to promote bone repair and healing. In this study, we constructed a novel adenovirus with high coexpression of BMP2 and bFGF and evaluated its effect on osteogenic differentiation of goat bone marrow progenitor cells (BMPCs). Recombinant adenovirus Ad-BMP2-bFGF was constructed by using the T2A sequence. BMPCs were isolated from goats by density gradient centrifugation and adherent cell culture, and were then infected with Ad-BMP2-bFGF or Ad-BMP2. Expression of BMP2 and bFGF was detected by ELISA, and alkaline phosphatase (ALP) activity was detected by an ALP assay kit. In addition, von Kossa staining and immunocytochemical staining of collagen II were performed on BMPCs 21 days after infection. There was a high coexpression of BMP2 and bFGF in BMPCs infected with Ad-BMP2-bFGF. Twenty-one days after infection, ALP activity was significantly higher in BMPCs infected with Ad-BMP2-bFGF than in those infected with Ad-BMP2. Larger and more mineralized calcium nodules, as well as stronger collagen II staining, were observed in BMPCs infected with Ad-BMP2-bFGF than in those infected with Ad-BMP2. In summary, we developed a novel adenovirus vector Ad-BMP2-bFGF for simultaneous high coexpression of BMP2 and bFGF, which could induce BMPCs to differentiate efficiently into osteoblasts.

The study of ligand binding specificities of the lipid binding proteins : recombinant human a-tocopherol transport protein (a-ttp), supernatant protein factor (spf) and S. cerevisiae Sec 14p for vitamin e (rrr-a-tocopherol) and other hydrophobic ligands.

One of the various functions of proteins in biological systems is the transport of small molecules, for this purpose proteins have naturally evolved special mechanisms to allow both ligand binding and its subsequent release to a target site; a process fundamental to many biological processes. Transport of Vitamin E (a-tocopherol), a lipid soluble antioxidant, to membranes helps in the protection of polyunsaturated fatty acids against peroxidative damage. In this research, the ligand binding characteristics of several members of the CRALTRIO family of lipid binding proteins was examined; the recombinant human a-Tocopherol Transfer Protein (a-TIP), Supernatant Protein Factor (SPF)ffocopherol Associated Protein (TAP), Cellular Retinaldehyde Binding Protein (CRALBP) and the phosphatidylinositol transfer protein from S. cerevisiae Sec 14p. Recombinant Sec 14p was expressed and purified from E. coli for comparison of tocopherol binding to the two other recombinant proteins postulated to traffic a-tocopherol. Competitive binding assays using [3H]-a-tocopherol and Lipidex-l000 resin allowed determination of the dissociation constants ~) of the CRAL-TRIO proteins for a-tocopherol and - 20 hydrophobic ligands for evaluation of the possible biological relevance of the binding interactions observed. The KIs (nM) for RRR-a-tocopherol are: a-TIP: 25.0, Sec 14p: 373, CRALBP: 528 and SPFffAP: 615. This indicates that all proteins recognize tocopherol but not with the same affinity. Sec 14p bound its native ligand PI with a KI of381 whereas SPFffAP bound PI (216) and y-tocopherol (268) similarly in contrast to the preferential binding ofRRR-a-tocopherol by a-TIP. Efforts to adequately represent biologically active SPFff AP involved investigation of tocopherol binding for several different recombinant proteins derived from different constructs and in the presence of different potential modulators (Ca+2, Mg+2, GTP and GDP); none of these conditions enhanced or inhibited a-tocopherol binding to SPF. This work suggests that only aTTP serves as the physiological mediator of a-tocopherol, yet structural homology between proteins allows common recognition of similar ligand features. In addition, several photo-affmity analogs of a-tocopherol were evaluated for their potential utility in further elucidation of a-TTP function or identification of novel tocopherol binding proteins.

Potential use of a recombinant replication-defective adenovirus vector carrying the C-terminal portion of the P97 adhesin protein as a vaccine against Mycoplasma hyopneumoniae in swine.

Mycoplasma hyopneumoniae causes severe economic losses to the swine industry worldwide and the prevention of its related disease, enzootic porcine pneumonia, remains a challenge. The P97 adhesin protein of M. hyopneumoniae should be a good candidate for the development of a subunit vaccine because antibodies produced against P97 could prevent the adhesion of the pathogen to the respiratory epithelial cells in vitro. In the present study, a P97 recombinant replication-defective adenovirus (rAdP97c) subunit vaccine efficiency was evaluated in pigs. The rAdP97c vaccine was found to induce both strong P97 specific humoral and cellular immune responses. The rAdP97c vaccinated pigs developed a lower amount of macroscopic lung lesions (18.5 ± 9.6%) compared to the unvaccinated and challenged animals (45.8 ± 11.5%). rAdP97c vaccine reduced significantly the severity of inflammatory response and the amount of M. hyopneumoniae in the respiratory tract. Furthermore, the average daily weight gain was slightly improved in the rAdP97c vaccinated pigs (0.672 ± 0.068 kg/day) compared to the unvaccinated and challenged animals (0.568 ± 0.104 kg/day). A bacterin-based commercial vaccine (Suvaxyn® MH-one) was more efficient to induce a protective immune response than rAdP97c even if it did not evoke a P97 specific immune response. These results suggest that immunodominant antigens other than P97 adhesin are also important in the induction of a protective immune response and should be taken into account in the future development of M. hyopneumoniae subunit vaccines.

Expression and purification of human respiratory syncytial virus recombinant fusion protein

The Human Respiratory Syncytial Virus (HRSV) fusion protein (F) was expressed in Escherichia call BL21A using the pET28a vector at 37 degrees C. The protein was purified from the soluble fraction using affinity resin. The structural quality of the recombinant fusion protein and the estimation of its secondary structure were obtained by circular dichroism. Structural models of the fusion protein presented 46% of the helices in agreement with the spectra by circular dichroism analysis. There are only few studies that succeeded in expressing the HRSV fusion protein in bacteria. This is a report on human fusion protein expression in E. call and structure analysis, representing a step forward in the development of fusion protein F inhibitors and the production of antibodies. (c) 2008 Elsevier Inc. All rights reserved.

Induction of neutralizing antibodies in mice immunized with an amino-terminal polypeptide of Streptococcus mutans P1 protein produced by a recombinant Bacillus subtilis strain

The oral pathogen Streptococcus mutans expresses a surface protein, P1, which interacts with the salivary pellicle on the tooth surface or with fluid-phase saliva, resulting in bacterial adhesion or aggregation, respectively. P1 is a target of protective immunity. Its N-terminal region has been associated with adhesion and aggregation functions and contains epitopes recognized by efficacious antibodies. In this study, we used Bacillus subtilis, a gram-positive expression host, to produce a recombinant N-terminal polypeptide of P1 (P1(39-512)) derived from the S. mutans strain UA159. Purified P1(39-512) reacted with an anti-full-length P1 antiserum as well as one raised against intact S. mutans cells, indicating preserved antigenicity. Immunization of mice with soluble and heat-denatured P1(39-512) induced antibodies that reacted specifically with native P1 on the surface of S. mutans cells. The anti-P1(39-512) antiserum was as effective at blocking saliva-mediated aggregation of S. mutans cells and better at blocking bacterial adhesion to saliva-coated plastic surfaces compared with the anti-full-length P1 antiserum. In addition, adsorption of the anti-P1 antiserum with P1(39-512) eliminated its ability to block the adhesion of S. mutans cells to abiotic surfaces. The present results indicate that P1(39-512), expressed and purified from a recombinant B. subtilis strain, maintains important immunological features of the native protein and represents an additional tool for the development of anticaries vaccines.

Expression and purification of human respiratory syncytial virus recombinant fusion protein

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

INFLUENCE OF DIETARY-PROTEIN INTAKE AND RECOMBINANT HUMAN SOMATOTROPIN ADMINISTRATION ON GROWTH AND BODY-COMPOSITION OF JUVENILE TAMBACU (A PIARACTUS-MESOPOTAMICUS X COLOSSOMA-MACROPOMUM CROSS)

This experiment was undertaken to study the interaction between level of dietary protein and recombinant human somatotropin (rhGH) administration on performance and body composition of juvenile tambacu (a crossbred Brazilian fish). A total of 72 juvenile tambacu, initially weighing and measuring (mean +/- s.e.m.) 23 +/- 2 g and 9 +/- 0.5 cm, respectively, were randomly divided into 18 groups of 4 fish each. Water temperature was 28 degrees C. Triplicate groups received one of two levels of dietary protein (15 and 30% as fed basis) and one of 3 doses of rhGH (0, 2 and 4 mu g/g) via intraperitoneal injection twice a week for 6 weeks, using a randomized complete block design. Somatotropin was noted to stimulate linear and body weight gain. The higher protein level supported increased growth in weight and length, but there was no interaction between protein level and rhGH dose for either parameter. Protein efficiency ratio and percentage protein deposited showed higher values on diets containing 15% protein. Somatotropin treatment did not significantly affect body composition, but there was a trend towards improved protein retention and reduced carcass lipid. In conclusion, the results of this experiment suggest that rhGH is able to stimulate linear gain in tambacu.

Inflammatory response of endothelial cells to hepatitis C virus recombinant envelope glycoprotein 2 protein exposure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Recombinant hepatitis C virus-envelope protein 2 interactions with low-density lipoprotein/CD81 receptors

Hepatitis C virus (HCV) envelope protein 2 (E2) is involved in viral binding to host cells. The aim of this work was to produce recombinant E2B and E2Y HCV proteins in Escherichia coli and Pichia pastoris, respectively, and to study their interactions with low-density lipoprotein receptor (LDLr) and CD81 in human umbilical vein endothelial cells (HUVEC) and the ECV304 bladder carcinoma cell line. To investigate the effects of human LDL and differences in protein structure (glycosylated or not) on binding efficiency, the recombinant proteins were either associated or not associated with lipoproteins before being assayed. The immunoreactivity of the recombinant proteins was analysed using pooled serum samples that were either positive or negative for hepatitis C. The cells were immunophenotyped by LDLr and CD81 using flow cytometry. Binding and binding inhibition assays were performed in the presence of LDL, foetal bovine serum (FCS) and specific antibodies. The results revealed that binding was reduced in the absence of FCS, but that the addition of human LDL rescued and increased binding capacity. In HUVEC cells, the use of antibodies to block LDLr led to a significant reduction in the binding of E2B and E2Y. CD81 antibodies did not affect E2B and E2Y binding. In ECV304 cells, blocking LDLr and CD81 produced similar effects, but they were not as marked as those that were observed in HUVEC cells. In conclusion, recombinant HCV E2 is dependent on LDL for its ability to bind to LDLr in HUVEC and ECV304 cells. These findings are relevant because E2 acts to anchor HCV to host cells; therefore, high blood levels of LDL could enhance viral infectivity in chronic hepatitis C patients.

A new heterologous fibrin sealant as scaffold to recombinant human bone morphogenetic protein-2 (rhBMP-2) and natural latex proteins for the repair of tibial bone defects

Tissue engineering has special interest in bone tissue aiming at future medical applications Studies have focused on recombinant human bone morphogenetic protein-2 (rhBMP-2) and natural latex proteins due to the osteogenic properties of rhBMP-2 and the angiogenic characteristic of fraction 1 protein (P-1) extracted from the rubber tree Hevea brasiliensis. Furthermore, heterologous fibrin sealant (FS) has been shown as a promising alternative in regenerative therapies. The aim of this study was to evaluate these substances for the repair of bone defects in rats. A bone defect measuring 3 mm in diameter was created in the proximal metaphysis of the left tibia of 60 rats and was implanted with rhBMP-2 or P-1 in combination with a new heterologous FS derived from snake venom. The animals were divided into six groups: control (unfilled bone defect), rhBMP-2 (defect filled with 5 mu g rhBMP-2), P-1 (defect filled with 5 mu g P-1), FS (defect filled with 8 mu g FS), FS/rhBMP-2 (defect filled with 8 mu g FS and 5 mu g rhBMP-2), FS/P-1 (defect filled with 8 mu g FS and 5 mu g P-1). The animals were sacrificed 2 and 6 weeks after surgery. The newly formed bone projected from the margins of the original bone and exhibited trabecular morphology and a disorganized arrangement of osteocyte lacunae. Immunohistochemical analysis showed intense expression of osteocalcin in all groups. Histometric analysis revealed a significant difference in all groups after 2 weeks (p < 0.05), except for the rhBMP-2 and FS/rhBMP-2 groups (p > 0.05). A statistically significant difference (p < 0.05) was observed in all groups after 6 weeks in relation to the volume of newly formed bone in the surgical area. In conclusion, the new heterologous fibrin sealant was found to be biocompatible and the combination with rhBMP-2 showed the highest osteogenic and osteoconductive capacity for bone healing. These findings suggest a promising application of this combination in the regeneration surgery.

Production of recombinant EMA-1 protein and its application for the diagnosis of Theileria equi using an enzyme immuno assay in horses from São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)