Immunogenic Glycoprotein Research Articles

Immunosilencing a Highly Immunogenic Protein Trimerization Domain

Many therapeutic proteins and protein subunit vaccines contain heterologous trimerization domains, such as the widely used GCN4-based isoleucine zipper (IZ) and the T4 bacteriophage fibritin foldon (Fd) trimerization domains. We found that these domains induced potent anti-IZ or anti-Fd antibody responses in animals when fused to an HIV-1 envelope glycoprotein (Env) immunogen. To dampen IZ-induced responses, we constructed an IZ domain containing four N-linked glycans (IZN4) to shield the underlying protein surface. When fused to two different vaccine antigens, HIV-1 Env and influenza hemagglutinin (HA), IZN4 strongly reduced the antibody responses against the IZ, but did not affect the antibody titers against Env or HA. Silencing of immunogenic multimerization domains with glycans might be relevant for therapeutic proteins and protein vaccines.

Coupling of HIV-1 gp120-derived Core Protein to Paramagnetic Beads and Adsorption Assays

Analysis of the functional activity in polyclonal serum following immunization of a complex protein or glycoprotein immunogen is a very important but tedious process. Fine mapping of epitope specific antibodies is difficult when they are elicited at relatively low levels. In our recent study focused at developing an HIV-1 vaccine, we immunized rabbits with hyperglycosylated stable core immunogens, which were designed using high resolution structural information to elicit antibodies against the primary receptor-binding, CD4-binding site on HIV-1 gp120. Using a solid phase adsorption assay, we could map the serum antibodies to the conserved CD4-binding site, a known broadly neutralizing determinant on exterior envelope glycoprotein, gp120.

Minimizing fucosylation in insect cell‐derived glycoproteins reduces binding to IgE antibodies from the sera of patients with allergy

AbstractThe baculovirus/insect cell system has proven to be a very powerful tool for the expression of several therapeutics. Nevertheless, these products sometimes suffer from reduced biological activity and unwanted side effects. Several studies have demonstrated that glycosylation can greatly influence the structure, function, half‐life, antigenicity and immunogenicity of various glycoproteins. Yet, the glycosylation pattern of insect cell‐derived products is not favorable for many applications. Especially, the presence of core α1,3‐linked fucose bears the risk of causing immediate hypersensitivity reactions in patients with allergy. In this study, we evaluated the impact of fucose residues on the allergenic potential of an insect cell‐expressed vaccine candidate. In order to block the GDP‐L‐fucose de novo synthesis pathway, we integrated the Pseudomonas aeruginosa GDP‐6‐deoxy‐D‐lyxo‐4‐hexulose reductase (RMD) gene into a baculovirus backbone. This virus was then used for the expression of soluble influenza A virus hemagglutinin (HA). Expression studies showed that the co‐expression of RMD did not influence the overall level of recombinant protein secretion. We confirmed the result of our strategy by analyzing PNGase A‐released N‐glycans using MALDI‐TOF‐MS. In order to evaluate the biological impact of defucosylation of influenza HA we tested the binding activity of IgE derived from the sera of patients with allergy to the purified antigen. The non‐fucosylated HA showed a 10‐fold decrease in IgE binding levels as compared to wildtype variants.same article under 10.1002/biot.201400061.

Autoantibodies induced by chimeric cytokine-HIV envelope glycoprotein immunogens.

Cytokines are often used as adjuvants to increase the immunogenicity of vaccines because they can improve the immune response and/or direct it into a desired direction. As an alternative to codelivering Ags and cytokines separately, they can be fused into a composite protein, with the advantage that both moieties act on the same immune cells. The HIV-1 envelope glycoprotein (Env) spike, located on the outside of virus particles and the only relevant protein for the induction of neutralizing Abs, is poorly immunogenic. The induction of anti-Env Abs can be improved by coupling Env proteins to costimulatory molecules such as a proliferation inducing ligand (APRIL). In this study, we evaluated the immunogenicity of chimeric molecules containing uncleaved Env gp140 fused to the species-matched cytokines IL-21 or GM-CSF in rabbits and mice. Each cytokine was either fused to the C terminus of Env or embedded within Env at the position of the variable loops 1 and 2. The cytokine components of the chimeric Env-GM-CSF and Env-IL-21 molecules were functional in vitro, but none of the Env-cytokine fusion proteins resulted in improved Ab responses in vivo. Both the Env-GM-CSF and the Env-IL-21 molecules induced strong anticytokine Ab responses in both test species. These autoimmune responses were independent of the location of the cytokine in the chimeric Env molecules in that they were induced by cytokines inserted within the variable loops 1 and 2 of Env or fused to its C terminus. The induction of undesired autoimmune responses should be considered when using cytokines as costimulatory molecules in fusion proteins.

Minimizing fucosylation in insect cell-derived glycoproteins reduces binding to IgE antibodies from the sera of patients with allergy.

The baculovirus/insect cell system has proven to be a very powerful tool for the expression of several therapeutics. Nevertheless, these products sometimes suffer from reduced biological activity and unwanted side effects. Several studies have demonstrated that glycosylation can greatly influence the structure, function, half-life, antigenicity and immunogenicity of various glycoproteins. Yet, the glycosylation pattern of insect cell-derived products is not favorable for many applications. Especially, the presence of core α1,3-linked fucose bears the risk of causing immediate hypersensitivity reactions in patients with allergy. In this study, we evaluated the impact of fucose residues on the allergenic potential of an insect cell-expressed vaccine candidate. In order to block the GDP-L-fucose de novo synthesis pathway, we integrated the Pseudomonas aeruginosa GDP-6-deoxy-D-lyxo-4-hexulose reductase (RMD) gene into a baculovirus backbone. This virus was then used for the expression of soluble influenza A virus hemagglutinin (HA). Expression studies showed that the co-expression of RMD did not influence the overall level of recombinant protein secretion. We confirmed the result of our strategy by analyzing PNGase A-released N-glycans using MALDI-TOF-MS. In order to evaluate the biological impact of defucosylation of influenza HA we tested the binding activity of IgE derived from the sera of patients with allergy to the purified antigen. The non-fucosylated HA showed a 10-fold decrease in IgE binding levels as compared to wildtype variants.

Induction of Specific Humoral and Cellular Immune Responses in a Mouse Model following Gene Fusion of HSP70C and Hantaan Virus Gn and S0.7 in an Adenoviral Vector

Heat shock proteins (HSPs) display adjuvant functions when given as fusion proteins to enhance vaccination efficiency. To evaluate enhanced potency of Hantaan virus (HTNV) glycoprotein (GP) and nucleocapsid protein (NP) immunogenicity by heat shock protein 70 (HSP70), a recombinant adenovirus rAd-GnS0.7-pCAG-HSP70C expression vector was developed by genetically linking the HSP70 C-terminal gene (HSP70 359–610 aa, HSP70C) to the Gn and 0.7 kb fragment of the NP (aa1–274-S0.7). C57BL/6 mice were immunized with these recombinant adenoviral vectors. A series of immunological assays determined the immunogenicity of the recombinant adenoviral vectors. The results showed that rAd-GnS0.7-pCAG-HSP70C induced a stronger humoral and cellular immune response than other recombinant adenoviruses (rAd-GnS0.7-pCAG and rAd-GnS0.7) and the HFRS vaccine control. Animal protection experiments showed that rAd-GnS0.7-pCAG-HSP70C was effective at protecting C57BL/6 mice from HTNV infection. The results of the immunological experiments showed that HSP70C lead to enhanced vaccine potency, and suggested significant potential in the development of genetically engineered vaccines against HTNV.

Cytomegalovirus Vaccine Strain Towne-Derived Dense Bodies Induce Broad Cellular Immune Responses and Neutralizing Antibodies That Prevent Infection of Fibroblasts and Epithelial Cells

Human cytomegalovirus (HCMV), a betaherpesvirus, can cause severe disease in immunosuppressed patients and following congenital infection. A vaccine that induces both humoral and cellular immunity may be required to prevent congenital infection. Dense bodies (DBs) are complex, noninfectious particles produced by HCMV-infected cells and may represent a vaccine option. As knowledge of the antigenicity and immunogenicity of DB is incomplete, we explored characterization methods and defined DB production methods, followed by systematic evaluation of neutralization and cell-mediated immune responses to the DB material in BALB/c mice. DBs purified from Towne-infected cultures treated with the viral terminase inhibitor 2-bromo-5,6-dichloro-1-beta-d-ribofuranosyl benzimidazole riboside (BDCRB) were characterized by nanoparticle tracking analysis (NTA), two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), immunoblotting, quantitative enzyme-linked immunosorbent assay, and other methods. The humoral and cellular immune responses to DBs were compared to the immunogenicity of glycoprotein B (gB) administered with the adjuvant AddaVax (gB/AddaVax). DBs induced neutralizing antibodies that prevented viral infection of cultured fibroblasts and epithelial cells and robust cell-mediated immune responses to multiple viral proteins, including pp65, gB, and UL48. In contrast, gB/AddaVax failed to induce neutralizing antibodies that prevented infection of epithelial cells, highlighting a critical difference in the humoral responses induced by these vaccine candidates. Our data advance the potential for the DB vaccine approach, demonstrate important immunogenicity properties, and strongly support the further evaluation of DBs as a CMV vaccine candidate.

A Single Dose of a DNA Vaccine Encoding Apa Coencapsulated with 6,6′-Trehalose Dimycolate in Microspheres Confers Long-Term Protection against Tuberculosis in Mycobacterium bovis BCG-Primed Mice

Mycobacterium bovis BCG prime DNA (Mycobacterium tuberculosis genes)-booster vaccinations have been shown to induce greater protection against tuberculosis (TB) than BCG alone. This heterologous prime-boost strategy is perhaps the most realistic vaccination for the future of TB infection control, especially in countries where TB is endemic. Moreover, a prime-boost regimen using biodegradable microspheres seems to be a promising immunization to stimulate a long-lasting immune response. The alanine proline antigen (Apa) is a highly immunogenic glycoprotein secreted by M. tuberculosis. This study investigated the immune protection of Apa DNA vaccine against intratracheal M. tuberculosis challenge in mice on the basis of a heterologous prime-boost regimen. BALB/c mice were subcutaneously primed with BCG and intramuscularly boosted with a single dose of plasmid carrying apa and 6,6'-trehalose dimycolate (TDM) adjuvant, coencapsulated in microspheres (BCG-APA), and were evaluated 30 and 70 days after challenge. This prime-boost strategy (BCG-APA) resulted in a significant reduction in the bacterial load in the lungs, thus leading to better preservation of the lung parenchyma, 70 days postinfection compared to BCG vaccinated mice. The profound effect of this heterologous prime-boost regimen in the experimental model supports its development as a feasible strategy for prevention of TB.

ES-62 prevents development of lupus-like pathology in the MRL/Lpr mouse (P5210)

Abstract The prevalence of autoimmunity in developing countries is lower than that in the developed world and this inverse relationship correlates with the level of chronic parasitic infections. Co-evolution of parasites with the human immune system has resulted in evasion strategies that prevent the host clearing the parasite yet limit pathology. One mechanism involves the release of immunomodulators like ES-62, secreted by the filarial nematode Acanthocheilonema viteae: ES-62 exhibits broad anti-inflammatory activity and therapeutic potential in autoimmune diseases such as rheumatoid arthritis. Here we show that ES-62 protects against nephritis, as indicated by proteinuria levels, in the murine MRL/Lpr model of systemic lupus erythematosus (SLE). It has been proposed that the pro-inflammatory cytokine IL-17 is a primary driver of disease, in mouse models as well as in SLE patients, but our data do not support targeting of IL-17 as the major protective mechanism underlying ES-62 efficacy. Indeed, and consistent with this, we have shown that neutralising antibodies specific for IL-17 do not block development of proteinuria. ES-62 is a large immunogenic glycoprotein and therefore not suitable for therapeutic use. Thus, since the active moiety of ES-62 is phosphorylcholine (PC), we have recently developed small molecular analogues based around PC that mimic the immunomodulatory effects of ES-62 in autoimmune disorders, including SLE.

Human cytomegalovirus particles directly suppress CD4 T-lymphocyte activation and proliferation

CD4 T cells are important regulators of the immune system and are vital for mounting a strong immune response against viral infections. Human cytomegalovirus (HCMV) is known to be a strong modulator of the innate as well as adaptive immune responses. In this study, we found that HCMV directly inhibited proliferation of CD4 T cells and rendered them unresponsive to immunological stimuli. This effect was not observed when CD4 T cells were treated with herpes simplex virus-1/2 or measles virus. When stimulated with phytohemagglutinin, concanavalin A, or phorbol myristate acetate, HCMV-treated T cells were unable to proliferate, revealing an ability of HCMV to inhibit CD4 T cell response. Furthermore, HCMV also prevented proliferation of leukemic T-cell lines. HCMV-treated CD4 T cells expressed the activation markers CD45RO and CD69, were not apoptotic and produced decreased levels of the cytokines IL-4, IFN-γ and TNF-α, compared to untreated controls. The inhibitory effect of HCMV on CD4 T cell proliferation was not mediated by HCMV gH, gB or other immunogenic glycoproteins, since intravenous immunoglobulins or gB- or gH-specific neutralizing antibodies did not prevent the suppression of T-cell proliferation. Our observations show that HCMV inhibits CD4 T cell function with potential clinical consequences for both humoral and cell-mediated immune responses.

Preliminary study of the rabies virus glycoprotein eukaryotic expression plasmid and immunogenicity

Objective To construct the eukaryotic expression plasmid of the rabies virus glycoprotein gene DNA,and detect the immunogenicity.Methods Using RT-PCR amplified the glycoprotein gene of rabies virus CTN strain,sequenced and cloned into pcDNA5.0 (+) vector to construct the recombinant plasmid pcDNA5.0-G plasmid.Detect glycoprotein transient expression with transfecting the plasmid into 293T cells.Intramuscular immunization of BALB/c mice by the recombinant plasmid on day 0 and 7,then challenge by rabies virus CVS strain observed the mice survived.Results The results of the transient expression of glycoprotein abundantly expressed.The survival ratio of mice with CVS challenge after routine intramuscular injection of pcDNA5.0-G plasmid is 73.3％,and 6.7％ for the control group.Conclusion Rabies virus glycoprotein eukaryotic expression plasmid pcDNA5.0-G was successfully constructed,and has been good immunogenicity.It's to be the foundation for candidate DNA vaccine research and development. Key words: Rabies virus; Glycoprotein; Immunogenicity

New species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus shows an ortholog of the E. canis major immunogenic glycoprotein gp36 with a new sequence of tandem repeats

BackgroundEhrlichia species are the etiological agents of emerging and life-threatening tick-borne human zoonoses that inflict serious and fatal infections in companion animals and livestock. The aim of this paper was to phylogeneticaly characterise a new species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus from Minas Gerais, Brazil.MethodsThe agent was isolated from the hemolymph of Rhipicephalus (B.) microplus engorged females that had been collected from naturally infested cattle in a farm in the state of Minas Gerais, Brazil. This agent was then established and cultured in IDE8 tick cells. The molecular and phylogenetic analysis was based on 16S rRNA, groEL, dsb, gltA and gp36 genes. We used the maximum likelihood method to construct the phylogenetic trees.ResultsThe phylogenetic trees based on 16S rRNA, groEL, dsb and gltA showed that the Ehrlichia spp isolated in this study falls in a clade separated from any previously reported Ehrlichia spp. The molecular analysis of the ortholog of gp36, the major immunoreactive glycoproteins in E. canis and ortholog of the E. chaffeensis gp47, showed a unique tandem repeat of 9 amino acids (VPAASGDAQ) when compared with those reported for E. canis, E. chaffeensis and the related mucin-like protein in E. ruminantium.ConclusionsBased on the molecular and phylogenetic analysis of the 16S rRNA, groEL, dsb and gltA genes we concluded that this tick-derived microorganism isolated in Brazil is a new species, named E. mineirensis (UFMG-EV), with predicted novel antigenic properties in the gp36 ortholog glycoprotein. Further studies on this new Ehrlichia spp should address questions about its transmissibility by ticks and its pathogenicity for mammalian hosts.

Campylobacter jejuni Outer Membrane Vesicles Play an Important Role in Bacterial Interactions with Human Intestinal Epithelial Cells

Campylobacter jejuni is the most prevalent cause of food-borne gastroenteritis in the developed world; however, the molecular basis of pathogenesis is unclear. Secretion of virulence factors is a key mechanism by which enteric bacterial pathogens interact with host cells to enhance survival and/or damage the host. However, C. jejuni lacks the virulence-associated secretion systems possessed by other enteric pathogens. Many bacterial pathogens utilize outer membrane vesicles (OMVs) for delivery of virulence factors into host cells. In the absence of prototypical virulence-associated secretion systems, OMVs could be an important alternative for the coordinated delivery of C. jejuni proteins into host cells. Proteomic analysis of C. jejuni 11168H OMVs identified 151 proteins, including periplasmic and outer membrane-associated proteins, but also many determinants known to be important in survival and pathogenesis, including the cytolethal distending toxin (CDT). C. jejuni OMVs contained 16 N-linked glycoproteins, indicating a delivery mechanism by which these periplasm-located yet immunogenic glycoproteins can interact with host cells. C. jejuni OMVs possess cytotoxic activity and induce a host immune response from T84 intestinal epithelial cells (IECs), which was not reduced by OMV pretreatment with proteinase K or polymyxin B prior to coincubation with IECs. Pretreatment of IECs with methyl-beta-cyclodextrin partially blocks OMV-induced host immune responses, indicating a role for lipid rafts in host cell plasma membranes during interactions with C. jejuni OMVs. OMVs isolated from a C. jejuni 11168H cdtA mutant induced interleukin-8 (IL-8) to the same extent as did wild-type OMVs, suggesting OMV induction of IL-8 is independent of CDT.

Optimizing expression of functional HIV envelopes in rVSV-ΔG vaccine vectors

Methods Using a combination of nucleotide sequence optimization and protein domain swapping, we have generated a panel of novel gene inserts for VSV vectors that encode chimeric HIV-1 and VSV glycoprotein immunogens (EnvG). A stable VERO cell line engineered to express human CD4 and CCR5 was used to rescue rVSV vectors in which the G gene was replaced with coding sequence for several different EnvG proteins.

Anticorps anti-médicament, auto-anticorps et traitements biologiques du psoriasis

The approval of substantial numbers of targeted biologic therapies (e.g., monoclonal antibodies, fusion proteins) for treatment of inflammatory diseases has positioned these drugs as important to fight chronic disorders such as psoriasis, rheumatoid arthritis and Crohn's disease. One of the concerns raised with the administration of biologic therapies is that because most of them are immunogenic glycoproteins they induce undesirable immune response leading to the generation of specific anti-drug antibodies (ADA). The development of "self" derived protein therapeutics (comprised of human germline sequence), such as recombinant "human" antibodies, helped to reduce the production of ADA but did not avoid all immunogenicity. Reduced efficacy and safety issues such as anaphylaxis or vasculitis accompany the development of ADA. In addition to immune reactions directed against the biologic therapies as a whole, some of them such as anti-TNFα are able to induce auto-immune response, notably antinuclear antibody (ANA). ANA development was associated with induced lupus and in psoriasis it was suggested that it may act as a marker of treatment failure to anti-TNFα. With a focus on psoriasis, this paper makes a current point on the consequences and challenges of the development of anti-drug antibodies and auto-immunity in patients who receive biologic therapies.

Impact of Influenza Virus Adaptation Status on HA N-Glycosylation Patterns in Cell Culture-Based Vaccine Production

The highly abundant and strongly immunogenic influenza envelope glycoprotein hemagglutinin (HA) represents the main component of influenza vaccines. Human influenza vaccines are typically produced in embryonated chicken eggs. In addition, cell culture-derived vaccine production systems are currently being established. Since characteristics of glycoproteins such as the HA can be significantly influenced by N-glycosylation, the impact of host cells considered for vaccine manufacturing needs to be addressed. In this study MDCK cell-derived influenza A/PR/8/34 (H1N1) virus was adapted over four passages in AGE1.CR.pIX-cells. HA N-glycosylation patterns (normalized capillary electropherograms) were determined and analyzed using capillary gel electrophoresis with laser-induced fluorescence detection (each peak represents at least one distinct N-glycan structure). During the adaptation to AGE1.CR.pIX-cells, virus titers 24 hours postinfection improved. HA N-glycosylation patterns of MDCK and AGE1.CR.pIX-derived virus particles differed significantly after the first adaptation step. This clearly suggests that the structure of the viral antigens is strongly influenced by the host cell. Furthermore, AGE1.CR.pIX-derived antigens showed a tendency toward small glycans. Differences between glycan patterns of the four successive passages in AGE1.CR.pIX cell were minor; only low variability in relative peak height was noted in the HA N-glycosylation pattern.

The study of differences of antigenicity in rabbit intervertebral disc

Objective To reveal and compare the immunogenicity of glycoprotein from nucleus pulposus and collagen from anulus fibrosus in rabbit intervertebral disc. Methods According to the similarity principle of genome biology and the amount of nucleus pulposus in different intervertebral disc, Glycoprotein from nucleus pulposus was harvested from the intervertebral disc of 20 rabbits and placed into the psoas by anterolateral approach. Similar implantation of collagen from anulus fibrosus was performed in another 20 rabbits. The implantations of autologous muscle in rabbits serve as a control group.After one week,two weeks, four weeks, six weeks and eight weeks, the rabbits were killed, the tissue was harvested. HE staining was applied to detect the degree of vascularization and infiltration of lymphocytes. Immunohistochemistry were used for analysis of T-helper cells (CD4+) and cytotoxic T cells (CD8+) in the tissue. Results HE staining showed the infiltration of lymphocytes was found just one week after implantation and vascularization was seen at the 2nd week in the glycoprotein implanted group. However in collagen implant group,small amounts of lymphocytic and atypical vascularization were seen at the 4th week. Immunohistochemistry revealed that the proportion of activated T cells (CD4+ and CD8+) was significantly higher in the glycoproteinimplanted group at all time points, as compared with the collagen-implanted group and sham group. The proportion of activated T cells was higher in collagen-implated group than that of in sham group . Conclusion The glycoprotein in nucleus pulposus is easier to induce the differentiation and mature of T cell. The antigenicity of glycoprotein in nucleus pulposus was stronger than that of collagen in anulus fibrosus in rabbit intervertebral discs. Key words: Intervertebral disk; Autoimmunity; Antigens; Glycoproteins; Collagen

Characterization and expression of the pseudorabies virus (NYJ strain) glycoproteins in Bombyx mori cells and larvae

To characterize the NYJ strain of pseudorabies virus (PRV; Alphaherpesvirus of swine) isolated from the serum of an infected swine in Korea, the nucleotide sequence of three major glycoproteins (gB, gC, and gD) was analyzed. The expression of most potent immunogenic glycoprotein (gD) was also investigated using a Bombyx mori nucleopolyhedrovirus (BmNPV) expression system. The length of the glycoprotein genes corresponding to gB, gC, and gD of the NYJ strain were 2751 bp, 1443 bp, and 1203, respectively, and their identity ranged from 94.2% to 99.8% when compared with other strains. Phylogenetic analyses using these sequences showed that the NYJ strain forms a distinct branch with high bootstrap support. A novel transfer vector (pBmKSK4) was engineered with the polyhedrin promoter of BmNPV and a 6xHis tag to express glycoprotein gD in Bm5 cells and silkworm, B. mori, larvae. The immunogenicity of recombinant gD was demonstrated by its specific detection in both Bm5 cells and silkworm larvae by porcine anti-PRV antibody. The results of this study have implications both for the taxonomy of Korean PRV strains and vaccine development.

Induction of NADPH oxidase activity and reactive oxygen species production by a single Trypanosoma cruzi antigen

Trypanosoma cruzi is an intracellular protozoan parasite that predominantly invades mononuclear phagocytes and is able to establish a persistent infection. The production of reactive oxygen species (ROS) by phagocytes is an innate defence mechanism against microorganisms. It has been postulated that ROS such as superoxide anion (O 2), hydrogen peroxide and peroxynitrite, may play a crucial role in the control of pathogen growth. However, information on parasite molecules able to trigger ROS production is scarce. In this work, we investigated whether cruzipain, an immunogenic glycoprotein from T. cruzi, was able to trigger the oxidative burst by murine cells. By employing chemiluminiscense and flow-cytometric analysis, we demonstrated that cruzipain induced ROS production in splenocytes from non-immune and cruzipain immune C57BL/6 mice and in a Raw 264.7 macrophage cell line. We also identified an O 2 − molecule as one of the ROS produced after antigen stimulation. Cruzipain stimulation induced NOX2 (gp91 phox) and p47 phox expression, as well as the co-localisation of both NADPH oxidase enzyme subunits. In the current study, we provide evidence that cruzipain not only increased ROS production but also promoted IL-6 and IL-1β cytokine production. Taken together, we believe these results demonstrate for the first time that cruzipain, a single parasite molecule, in the absence of infection, favors oxidative burst in murine cells. This represents an important advance in the knowledge of parasite molecules that interact with the phagocyte defence mechanism.

Influence of Novel CD4 Binding-Defective HIV-1 Envelope Glycoprotein Immunogens on Neutralizing Antibody and T-Cell Responses in Nonhuman Primates

The high-affinity in vivo interaction between soluble HIV-1 envelope glycoprotein (Env) immunogens and primate CD4 results in conformational changes that alter the immunogenicity of the gp120 subunit. Because the conserved binding site on gp120 that directly interacts with CD4 is a major vaccine target, we sought to better understand the impact of in vivo Env-CD4 interactions during vaccination. Rhesus macaques were immunized with soluble wild-type (WT) Env trimers, and two trimer immunogens rendered CD4 binding defective through distinct mechanisms. In one variant, we introduced a mutation that directly disrupts CD4 binding (368D/R). In the second variant, we introduced three mutations (423I/M, 425N/K, and 431G/E) that disrupt CD4 binding indirectly by altering a gp120 subdomain known as the bridging sheet, which is required for locking Env into a stable interaction with CD4. Following immunization, Env-specific binding antibody titers and frequencies of Env-specific memory B cells were comparable between the groups. However, the quality of neutralizing antibody responses induced by the variants was distinctly different. Antibodies against the coreceptor binding site were elicited by WT trimers but not the CD4 binding-defective trimers, while antibodies against the CD4 binding site were elicited by the WT and the 423I/M, 425N/K, and 431G/E trimers but not the 368D/R trimers. Furthermore, the CD4 binding-defective trimer variants stimulated less potent neutralizing antibody activity against neutralization-sensitive viruses than WT trimers. Overall, our studies do not reveal any potential negative effects imparted by the in vivo interaction between WT Env and primate CD4 on the generation of functional T cells and antibodies in response to soluble Env vaccination.