Biomedical subjects

K Hamajima

Publications and source records attributed to K Hamajima.

At least 37 records · Page 2Linked to original sources

PubMed1998

Comparison of intranasal and intramuscular immunization against human immunodeficiency virus type 1 with a DNA-monophosphoryl lipid A adjuvant vaccine.

We compared immune responses to intranasal and intramuscular DNA vaccinations against human immunodeficiency virus type 1 with monophosphoryl lipid A (MPL) used as an adjuvant. Both routes of vaccination resulted in similar levels of cell-mediated immunity, but the intestinal secretory immunoglobulin A response was higher following intranasal immunization than after intramuscular immunization. MPL demonstrated its adjuvanticity in vaccination by both routes.

AIDS Vaccines↗

PubMed1998

Induction of systemic and mucosal immune responses to human immunodeficiency virus type 1 by a DNA vaccine formulated with QS-21 saponin adjuvant via intramuscular and intranasal routes.

Induction of mucosal and cell-mediated immunity is critical for development of an effective vaccine against human immunodeficiency virus (HIV). We compared intramuscular and intranasal immunizations with a DNA vaccine encoding env of HIV-1 and evaluated the QS-21 saponin adjuvant for augmentation of the systemic and mucosal immune responses to HIV-1 in a murine model. Vaccination via the two routes elicited comparable systemic immune responses, and QS-21 consistently enhanced antigen-specific serum immunoglobulin G2a (IgG2a) production, delayed-type hypersensitivity reaction, and cytolytic activity of splenocytes. Intestinal secretory IgA production and cytolytic activity of the mesenteric lymph node cells are preferentially elicited by intranasal immunization, and QS-21 augmented these activities as well. This adjuvant augmented production of interleukin-2 (IL-2) and gamma interferon (IFN-gamma) associated with decrease in IL-4 synthesis by antigen-restimulated splenocytes. The serum immunoglobulin subtype profile showed a dominant IgG2a response and less strong IgG1 and IgE production in a QS-21 dose-dependent manner. As expected, enhancements of humoral and cell-mediated immune responses by QS-21 were abrogated by treatment with anti-IL-2 and anti-IFN-gamma monoclonal antibodies. These results suggest that the intranasal route of DNA immunization is more efficient than the intramuscular route in inducing mucosal immunity mediated by sIgA and mesenteric lymphocytes. Furthermore, QS-21 is able to act as a mucosal adjuvant in DNA vaccination and demonstrates its immunomodulatory property via stimulation of the Th1 subset. This study emphasizes the importance of the route of immunization and the use of an adjuvant for effective DNA vaccination against HIV-1.

Adjuvants, Immunologic↗

PubMed1997

Cationic liposomes are a strong adjuvant for a DNA vaccine of human immunodeficiency virus type 1.

Liposomes have been widely used to enhance the immune response. In the present investigation, we studied their in vivo immunomodulation of an HIV-1-specific DNA vaccine candidate (pCMV160/REV) constructed with the cytomegalovirus (CMV) promoter-conjugated HIV-1 env and rev DNA plasmids. By immunizing with pCMV160/REV and cationic liposomes through various routes (intramuscular, intraperitoneal, subcutaneous, intradermal, and intranasal), we induced higher levels of both antibody production and delayed-type hypersensitivity (DTH) than by using DNA vaccine alone. The HIV-1-specific cytotoxic T lymphocyte (CTL) activity was observed to be stronger on immunization with the DNA vaccine and cationic liposome combination. The intramuscular, intraperitoneal, and intranasal inoculation routes were more effective in inducing strong DTH and antibody responses than the subcutaneous and intradermal routes. Taken together, these results suggest that cationic liposomes can be highly effective when used with DNA vaccines and administered by various routes.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Enhancement of cell-mediated immunity against HIV-1 induced by coinnoculation of plasmid-encoded HIV-1 antigen with plasmid expressing IL-12.

Previous investigations have demonstrated that CTL may play an important role in suppressing the disease progression of HIV infection. In this study, we inoculated mice with IL-12 expression plasmid together with plasmid-encoding HIV-1 envelope to enhance CTL activity by activating a Th1-type response. The results of delayed-type hypersensitivity using the footpad swelling response and of CTL activity clearly showed that HIV-1-specific cell-mediated immunity was enhanced by inoculation of the IL-12 expression plasmid. Quantitation of cytokine in the sera of IL-12-inoculated mice revealed that IFN-gamma significantly increased. The enhanced cell-mediated immunity responses were abrogated by combined administration of the IL-12 expression plasmid and neutralizing anti-IFN-gamma Ab. Together, these results suggest that enhanced virus-specific cell-mediated immunity occurred via an endogenously produced IFN-gamma by inoculation of IL-12 expression plasmid.

AIDS Vaccines↗

PubMed1997

Immunomodulatory effects of a plasmid expressing B7-2 on human immunodeficiency virus-1-specific cell-mediated immunity induced by a plasmid encoding the viral antigen.

B7 co-stimulation is essential for activating resting T cells following antigen recognition by the T cell receptor. To determine whether B7 has adjuvant activities on human immunodeficiency virus type-1 (HIV-1)-specific immunity induced by inoculation of a plasmid encoding HIV-1 env and rev (DNA vaccine), B7-1 and B7-2 expression plasmids were co-inoculated with the DNA vaccine. The delayed-type hypersensitivity response and cytotoxic T lymphocyte (CTL) activity were significantly enhanced when B7-2 expression plasmid was co-inoculated with the DNA vaccine, but were unaffected when the B7-1 expression plasmid was used with the vaccine instead. The immunological response enhanced by B7-2 decreased below the level of mice immunized with the DNA vaccine in combination with CTLA4Ig, an inhibitor of the B7/CD28 co-stimulatory signal, suggesting that this signal is critical for the enhanced response induced by co-inoculation of the DNA vaccine and B7-2 expression plasmid. This enhancement appeared to occur via an interferon-gamma (IFN-gamma)-dependent mechanism, as combined administration of the B7-2 plasmid and neutralizing anti-IFN-gamma antibody abrogated the virus-specific cell-mediated immunity. These results suggest that this gene-based co-inoculation strategy using HIV-1 viral antigen and B7-2 co-stimulatory molecule could be a powerful means of combating HIV-1 infection.

AIDS Vaccines↗

PubMed1997

Human immunodeficiency virus type-1-specific immune responses induced by DNA vaccination are greatly enhanced by mannan-coated diC14-amidine.

Use of mannan-coated N-t-butyl-N'-tetradecyl-3-tetradecylamino-propionamidine (diC14-amidine) as an adjuvant for a DNA vaccine encoding glycoprotein 160 of human immunodeficiency virus type-1 (HIV-1) enhanced the antigen-specific immune responses. The role of interferon-gamma (IFN-gamma) and interleukin-12 in the mechanism of adjuvant action was also evaluated. Coating of diC14-amidine with mannan significantly augmented the HIV-specific delayed-type hypersensitivity reaction induced by the immunogenic DNA. HIV-1-specific cytotoxic T lymphocyte activity was also markedly enhanced by the mannan-diC14-amidine cocktail. An immunomodulatory effect of this cocktail was inhibited by treatment with anti-IFN-gamma monoclonal antibody in vivo, which suggests that IFN-gamma plays an important role in inducing cell-mediated immunity by the DNA vaccine containing this adjuvant. The results of both antigen-specific immunoglobulin isotype analysis and cytokine measurement showed that the immunogenic DNA incorporated into mannan-coated diC14-amidine elicits Th1-biased immune responses.

AIDS Vaccines↗

PubMed1997

Strong augment effect of IL-12 expression plasmid on the induction of HIV-specific cytotoxic T lymphocyte activity by a peptide vaccine candidate.

We previously reported that repeated inoculation of VC1, a macromolecular multicomponent peptide vaccine emulsified with Freund's adjuvant (VC1-F), induced high cytotoxic T lymphocyte (CTL) levels and a substantial level of multivalent antibodies which neutralized various human immunodeficiency virus type 1 (HIV-1) isolates. In the present study, we report that inoculation of VC1-F plus interleukin (IL)-12 expression plasmid can induce a higher antigen-specific CTL response compared to that with VC1-F alone. VC1-F plus IL-12 expression plasmid or VC1-F alone were inoculated to BALB/c mice twice at interval of 2 weeks. Two weeks after the second inoculation, spleen effector cells from these mice were examined. Stronger CTL responses against target cells were observed from the inoculation of VC1-F plus IL-12 plasmid than from that with VC-1F alone, but there was no difference in antibody induction. The inoculation of VC1 plus IL-12 plasmid also produced higher CTL activity than the inoculation of VC1 alone. These augmented CTL activities were not observed using target cells pulsed with non-HIV-specific peptides and different class I haplotype cells. These data demonstrate that co-inoculation of cell-mediated immune potent antigen and IL-12 plasmids can enhance the antigen-specific CTL response. This may be a potential approach for the induction of cellular immunization against HIV-1 and other diseases.

AIDS Vaccines↗

PubMed1997

Arginine-481 mutation abolishes ligand-binding of the AMPA-selective glutamate receptor channel alpha1-subunit.

Arginine-481 is located in the putative agonist-binding region preceding the putative transmembrane segment M1 of the alpha1-subunit of the AMPA-selective glutamate receptor (GluR) channel. This amino acid is completely conserved among GluR proteins. A site-directed mutagenesis study using a baculovirus expression system showed that substitution of glutamate, glutamine and lysine for arginine-481 of the recombinant alpha1-subunit protein abolishes binding to [3H]AMPA completely. The present study provides the first direct experimental evidence that the conserved charged arginine-481 residue is essential, directly or indirectly, for the acquisition of ligand-binding activity by the receptor protein.

Animals↗

PubMed1997

DNA vaccination followed by macromolecular multicomponent peptide vaccination against HIV-1 induces strong antigen-specific immunity.

The induction of a strong and long-lasting immunity characterized by both a humoral and cell-mediated immune (CMI) response is one of the most important considerations in developing an effective HIV vaccine. In previous studies, we have independently developed both DNA vaccine and macromolecular multicomponent peptide vaccine (VC1) candidates. In the present study, we attempted to optimize the vaccination protocol using mice, guinea pigs, rabbits and Macaca fuscata monkeys. Repeated vaccination with VC1 induced a substantial level of multivalent antibodies which neutralized various HIV-1 strains, as determined using a p24 inhibition assay. On the other hand, repeated immunization with DNA vaccine induced and sustained high levels of cytotoxic T lymphocytes (CTLs). In addition, when DNA vaccination was followed by multicomponent peptide vaccination, levels of both humoral immunity and CMI increased, and this effect continued for at least 10 months. These data clearly demonstrate that for inducing HIV-1 specific immunity, immunization with DNA vaccine followed by VC1 boosting produces better results than immunizing with either vaccine alone.

AIDS Vaccines↗

PubMed1997

HIV-1-specific cell-mediated immunity is enhanced by co-inoculation of TCA3 expression plasmid with DNA vaccine.

We developed a candidate DNA vaccine designated pCMV160IIIB with pcREV (pCMV160IIIB/REV) that encodes gp160 of human immunodeficiency virus (HIV)-1IIIB and Rev driven by the cytomegalovirus (CMV) promotor. This vaccine induced both HIV-1-specific antibodies and cytotoxic T lymphocyte (CTL) activity. In the present study, we inoculated the TCA3 expression plasmid into mouse skeletal muscle with pCMV160IIIB/REV to determine whether this cytokine expression plasmid was able to modify the immune response. Results of a delayed-type hypersensitivity (DTH) assay using footpad swelling as well as those of a CTL assay clearly demonstrated that cell-mediated immunity (CMI) elicited by co-inoculation of pCMV160IIIB/REV with the TCA3 expression plasmid was markedly enhanced compared with that obtained using pCMV160IIIB/REV alone. When TCA3 expression plasmid was inoculated with anti-TCA3 antibody, enhancement of the DTH response was suppressed below the level of that obtained with pCMV160IIIB/REV alone. The titre of HIV-1-specific IgG2a was slightly high when pCMV160IIIB/REV was co-inoculated with this plasmid, suggesting that T-helper 1 (Th1) response was predominant in TCA3-inoculated mice. Infiltration of mononuclear cells was seen in the muscles at sites where TCA3 expression plasmid had been inoculated. Our present data suggest that TCA3 expression plasmid has potent adjuvant activity that results in an augmented CMI response.

AIDS Vaccines↗

PubMed1997

HIV-1-specific cell-mediated immune responses induced by DNA vaccination were enhanced by mannan-coated liposomes and inhibited by anti-interferon-gamma antibody.

The adjuvant effect of mannan-coated liposomes on human immunodeficiency virus type-1 (HIV-1) DNA vaccine and the mechanism of this enhancement were studied. Coating of cationic liposomes with mannan significantly enhanced the ability of this vaccine to induce an HIV-specific delayed-type hypersensitivity (DTH) response. HIV-specific cytotoxic T-cell (CTL) activity elicited by DNA vaccination was also significantly enhanced with the mannan-liposome cocktail. This mannan-liposome-mediated activity was greatly inhibited by in vivo injection of anti-interferon (IFN)-gamma antibody, which suggests that IFN-gamma plays an important role in this HIV-specific immune response. The results of both isotype-specific antibody and cytokine analysis revealed that mannan-liposome-mediated DNA vaccination enhances Th1-mediated immunity.

AIDS Vaccines↗

PubMed1997

Monophosphoryl lipid A enhances both humoral and cell-mediated immune responses to DNA vaccination against human immunodeficiency virus type 1.

To enhance immunity induced by DNA vaccination against human immunodeficiency virus type 1 (HIV-1), we evaluated the efficacy of monophosphoryl lipid A (MPL), an adjuvant of bacterial origin. BALB/c mice were intramuscularly injected with immunogenic DNA, encoding the env and rev genes of the HIV-1(IIIB) strain, formulated with MPL dissolved in different vehicles (MPL in stable emulsion and MPL in aqueous formulation). The sera from mice immunized with the two preparations of MPL revealed 2(6) to 2(9) times higher HIV-1-specific immunoglobulin G (IgG) titers than the sera from mice immunized without MPL. In virus neutralization tests for HIV-1(IIIB), by p24 assay and antifusion assay of infected MOLT-4 cells, MPL tends to elicit antibody more protective than antibody elicited without adjuvant. MPL also elicited stronger delayed-type hypersensitivity and cytotoxic-T-lymphocyte activity against HIV-1(IIIB) compared to DNA alone. HIV-1-specific IgG subclass analysis showed that MPL tends to facilitate IgG2a production, suggesting enhancement of a predominant T-helper-type-1 response, and this enhancement may help to facilitate protective-antibody induction. Furthermore, a chloramphenicol acetyltransferase (CAT) assay was employed to determine whether MPL affected the gene expression process. Interestingly, both MPL preparations reduced CAT activity in the muscle injected with CAT expression vector but increased anti-CAT antibody production. These results indicate that MPL acts as an effective adjuvant for immunogenic DNA injection despite reduced expression of encoding protein in muscle. We conclude that MPL has a strong adjuvant effect on DNA vaccination against HIV-1.

AIDS Vaccines↗

PubMed1996

Induction of HIV-1 Nef-specific cytotoxic T lymphocytes by Nef-expressing DNA vaccine.

Recently, some individuals who have remained seronegative despite definite exposure to HIV-1 have been reported. Among these individuals, an unusually high frequency of HIV-1 Nef-specific cytotoxic T lymphocytes was observed. Direct injection of plasmid DNA encoding foreign antigen can elicit both cell-mediated immunity and antibody responses (DNA vaccine). We constructed an HIV-1 Nef-expressing plasmid, and we induced HIV-1 Nef-specific cytotoxic T lymphocytes. This is the first report of inducing HIV-1 Nef-specific cytotoxic T lymphocytes by DNA vaccine.

Amino Acid Sequence↗

PubMed1995

A macromolecular multicomponent peptide vaccine prepared using the glutaraldehyde conjugation method with strong immunogenicity for HIV-1.

The immunogenicity of a newly constructed macromolecular multicomponent peptide vaccine candidate against human immunodeficiency virus type 1 (HIV-1) was compared with that of previously reported vaccine candidates. This vaccine candidate is composed of a macromolecular multicomponent peptide complex consisting of three V3 region peptides, one Gag region peptide, and CD4-binding site peptide and was constructed using the multiple-antigen peptide and glutaraldehyde methods. Sera from rabbits immunized with this newly constructed vaccine showed strong antibody titers against each constituent peptide antigen. Furthermore, these antibodies exhibited strong neutralizing and antifusion activity toward HIV-1IIB, HIV-1MN, and fresh isolates from Japanese HIV-seropositive individuals. These results show that this new vaccine candidate has the capacity to induce strong, polyvalent immunogenicity and therefore may prove to be a powerful peptide vaccine against HIV-1 infection.

AIDS Vaccines↗

PubMed1995

Expression and characterization of the zeta 1 subunit of the N-methyl-D-aspartate (NMDA) receptor channel in a baculovirus system.

Using a baculovirus expression vector system, the zeta 1 subunit of the mouse N-methyl-D-aspartate (NMDA) receptor channel was expressed in Spodoptera frugiperda insect cells. The peptide corresponding to the C-terminus of the zeta 1 subunit was synthesized by using the multiple antigen peptide (MAP) system, and an antibody to the synthetic peptide was produced. Immunoblotting using the newly developed antibody revealed the major 122-kDa and the minor 104-kDa protein bands. The effect of tunicamycin on the immunoblots and [35S]methionine/[35S]cysteine metabolic radiolabeling suggested that the two bands corresponded to glycosylated and non-N-glycosylated forms, respectively. Membranes prepared from insect cells infected with the recombinant virus had the binding activity of antagonist ligand 5,7-[3-3H]dichlorokynurenate (DCKA) of a glycine recognition domain of the receptor. Both immunofluorescence labeling and the [3H]DCKA binding assays also showed a greater level of expression (Bmax = 51 pmol/mg protein) in the insect cells. The ligand binding characteristics of the receptors expressed in insect cells suggested that the single zeta 1 subunit protein has glycine antagonist binding properties comparable to those of the native NMDA receptor channels. The lack of DCKA-binding activity of the non-N-glycosylated NMDA receptor expressed in the presence of tunicamycin suggested that N-linked oligosaccharide is essentially required for expression of a functional receptor in insect cells. This is the first report describing the importance of N-glycosylation for the acquisition of ligand binding to NMDA receptor channel subunit protein.

Animals↗

PubMed1995

Neutralization of HIV-1 by secretory IgA induced by oral immunization with a new macromolecular multicomponent peptide vaccine candidate.

Control of pandemic infection of human immunodeficiency virus type 1 (HIV-1) requires some means of developing mucosal immunity against HIV-1 because sexual transmission of the virus occurs mainly through the mucosal tissues. However, there is no evidence as yet that the secretory immunoglobulin A (IgA) antibody induced by immunization with antigens in experimental animals can neutralize HIV-1. We demonstrate here that oral immunization with a new macromolecular peptide antigen and cholera toxin (CT) induces a high titre (1:2") of gut-associated and secretory IgA antibody to HIV-1. Using three different neutralizing assays, we clearly demonstrate that this secretory IgA antibody is able to neutralize HIV-1IIIB, HIV-1SF2 and HIV-1MN. Our new approach may prove to be important in the development of a mucosal vaccine that will provide protection of mucosal surfaces against HIV-1.

AIDS Vaccines↗

PubMed1995

Induction of potent humoral and cell-mediated immune responses following direct injection of DNA encoding the HIV type 1 env and rev gene products.

DNA vaccines have the potential of giving rise to a potent cell-mediated immune response by inducing intracellular synthesis and subsequent antigenic presentation of encoded antigens. We have tested a DNA vaccine specific for human immunodeficiency virus type 1 (HIV-1) by the injection of animals with expression plasmids encoding the HIV-1 envelope protein and the Rev regulatory protein. Injection of both plasmids into mice, rabbits, or macaques was found to induce high levels of specific antibodies capable of efficiently inhibiting both HIV-1 infection and envelope-mediated cell fusion. A readily detectable delayed-type hypersensitivity (DTH) response was demonstrable in injected mice and lymphocytes derived from these proliferated in response to an HIV-1 envelope V3 loop-specific peptide. Interestingly, the injected mice or macaques also developed a strong cytotoxic T lymphocyte (CTL) response against target cells pulsed with the V3 peptide. Taken together, these data demonstrate that injection of HIV-1 gene expression plasmids can induce potent humoral and cell-mediated immune responses and suggest that DNA vaccines may prove to be significantly beneficial as a means of immunizing against HIV-1.

Animals↗

PubMed1995

Antibody responses raised against a conformational V3 loop peptide of HIV-1.

The amino acid sequence of the principal neutralizing determinant (PND) of 224 cases of human immunodeficiency virus type 1 (HIV-1) was determined and the most frequently occurring sequence was used as a peptide antigen for studying virus-specific antibody responses. In our present study, a linear peptide of the most frequent PND was first synthesized and then oxidized to create a disulfide-bridged loop conformation. Then, in order to construct a macromolecular structure for the purpose of increasing antigenicity, the synthetic peptide was conjugated to a core peptide. We compared the immunogenicity of the disulfide-bridged loop PND peptide antigen (AG4) and the linear PND peptide antigen (AG5). After immunizing rabbits 5 and 6 times with both peptides, the results obtained using ELISA revealed that AG4 (conformational-loop type) was more capable of inducing a high titer of antigen-specific antibodies than was AG5 (linear type). Despite an amino acid sequence homology of 72%, a 1:8 dilution of serum raised against AG4 inhibited 81.9% of HIV-1IIIB-mediated cell fusion, suggesting that conformational V3 loop peptide is able to elicit an antibody response which is strongly HIV-1-specific.

Amino Acid Sequence↗