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H L Robinson

Publications and source records attributed to H L Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Studies on antibody responses following neonatal immunization with influenza hemagglutinin DNA or protein.

Neonatal mice have immature immune systems with defects in several components of inflammatory, innate, and specific immune responses and develop a preferential T helper type 2 response following immunization with many vaccine antigens. These studies were undertaken to determine whether 1-day-old neonatal mice immunized with plasmid DNA expressing influenza A/PR/8/34 hemagglutinin (H1) by either intramuscular (im) or gene gun (gg) inoculation were capable of generating humoral responses comparable to those in mice immunized as adults. The newborn mice developed stable, long-lived, protective anti-H1-specific IgG responses similar in titer to those of adult DNA-immunized mice. However, unlike the adult im and gg DNA immunizations, which develop polarized IgG2a and IgG1 responses, respectively, mice immunized as neonates developed a variety of IgG1, IgG2a, and mixed IgG1/IgG2a responses regardless of the inoculation method. Boosting increased but did not change these antibody profiles. In contrast to the DNA immunizations, inoculations of newborn mice with an A/PR/8/34 viral protein subunit preparation failed to elicit an antibody response. Temporal studies revealed that both responsiveness to protein vaccination and development of polarized patterns of T help following DNA immunization appeared by 2 weeks of age.

Age Factors↗
PubMed1999

Neutralizing antibody-independent containment of immunodeficiency virus challenges by DNA priming and recombinant pox virus booster immunizations.

Eight different protocols were compared for their ability to raise protection against immunodeficiency virus challenges in rhesus macaques. The most promising containment of challenge infections was achieved by intradermal DNA priming followed by recombinant fowl pox virus booster immunizations. This containment did not require neutralizing antibody and was active for a series of challenges ending with a highly virulent virus with a primary isolate envelope heterologous to the immunizing strain.

Animals↗
PubMed1999

Effect of CpG methylation on isotype and magnitude of antibody responses to influenza hemagglutinin-expressing plasmid.

We previously showed that intramuscular saline DNA immunizations favor the development of an IgG2a-dominant Th1 immune response, whereas gene gun DNA immunizations stimulate the production of an IgG1-dominant Th2 immune response. Several studies have implicated immunostimulatory CpG sequences as the causative factor in the development of Th1 immune responses to saline DNA immunization. To determine whether the Th1 cytokine-inducing properties of CpG sequences in plasmid DNA (pDNA) were responsible for the induction of a Th1 immune response, in vitro methylated and untreated (nonmethylated) hemagglutinin-expressing pDNA were compared for immunogenicity. Methylation abrogated the immunostimulatory activity of pDNA for cultured splenocytes and significantly reduced antigen expression. However, methylation of pDNA was not associated with a change from the induction of IgG2a to IgG1. After immunization with the methylated plasmid, the magnitude of the immune response was reduced. However, the decline in the total antibody response matched the decline in antigen expression. The dose of DNA or the presence of lipopolysaccharide in pDNA likewise did not affect the preferential development of an IgG2a antibody response. Our findings reveal that high levels of CpG sequences are not required for raising IgG2a-predominant, Thl-biased immune responses to intramuscular injections of hemagglutinin-expressing DNA.

Animals↗
PubMed1999

Neutralizing antibody responses in Africa green monkeys naturally infected with simian immunodeficiency virus (SIVagm).

This study assessed the magnitude and cross-reactivity of the neutralizing antibody response generated by natural SIV infection in wild-caught African green monkeys. Neutralizing antibodies of variable potency, sometimes exceeding a titer of 1:1,000, were detected in 20 of 20 SIV-seropositive African green monkeys in Kenya. Detection of those neutralizing antibodies was dependent on the strain of virus and the cells used for assay, where the most sensitive detection was made with SIVagm1532 in Sup T1 cells. Potent neutralization of SIVagm1532 was seen with contemporaneous autologous serum. Potent neutralization was also detected with laboratory-passaged SIVmac251 and SIVsmB670, but not with SIVsmE660 and two additional strains of SIVagm. Serum samples from rhesus macaques (Macaca mulatta) experimentally infected with either SIVmac251 or SIVsmE660 were capable of low-level neutralization of SIVagm. These results indicate that natural infection with SIV can generate strain-specific neutralizing antibodies in African green monkeys. They also indicate that some neutralization determinants of SIVagm are partially shared with SIV strains that arose in sooty mangabys and were subsequently transmitted to rhesus macaques.

Animals↗
PubMed1999

DNA vaccines: basic mechanism and immune responses (Review).

DNA vaccines raise immune responses by expressing proteins in vaccinated hosts. Responses are raised by nanogram levels of protein expression. Popular methods of DNA delivery include intramuscular (i. m.) injections of DNA in saline and gene gun delivery of DNA-coated gold beads to the epidermis. Professional antigen-presenting cells derived from the bone marrow present DNA-expressed antigens to T-cells. Following gene gun immunizations directly transfected dendritic cells present antigens, whereas following i.m. immunizations both directly transfected dendritic cells and macrophages can present antigen. For both methods of DNA delivery, non-lymphoid cells can serve as factories of antigen for professional antigen presenting cells. Gene gun immunizations depend on antigen expression at the skin target whereas i.m. immunizations are largely independent of DNA expression in the muscle target. For both methods, antigen expression capable of initiating an immune response persists for about one month. intramuscular deliveries of DNA tend to raise type 1 T-cell help for intracellular and plasma membrane antigens but type 2 T-cell help for secreted antigens. Gene gun immunizations tend to raise type 2 T-cell help for both cell-associated and secreted antigens. In mice, DNA-raised immune responses can be equivalent to those raised by viral infections for both the height and longevity of antibody and cytotoxic T-cell responses.

Animals↗
PubMed1999

Route and method of delivery of DNA vaccine influence immune responses in mice and non-human primates.

BACKGROUND: In spite of the large number of studies that have evaluated DNA-based immunization, few have directly compared the immune responses generated by different routes of immunization, particularly in non-human primates. Here we examine the ability of a hepatitis B surface antigen (HBsAg)-encoding plasmid to induce immune responses in mice and non-human primates (rhesus monkeys: Macaca mulatta) after delivery by a number of routes. MATERIALS AND METHODS: Eight different injected [intraperitoneal (IP), intradermal (ID), intravenous (IV), intramuscular (IM), intraperineal (IPER), subcutaneous (SC), sublingual (SL), vaginal wall (VW)] and six noninjected [intranasal inhalation (INH), intranasal instillation (INS), intrarectal (IR), intravaginal (IVAG), ocular (Oc), oral feeding (oral)] routes and the gene gun (GG) were used to deliver HBsAg-expressing plasmid DNA to BALB/c mice. Sera were assessed for HBsAg-specific antibodies (anti-HBs, IgG, IgG1, IgG2a) and cytotoxic T lymphocyte (CTL) activity measured. Three of the most commonly used routes (IM, ID, GG) were compared in rhesus monkeys, also using HBsAg-expressing vectors. Monkeys were immunized with short (0-, 4- and 8-week) or long (0-, 12- and 24-week) intervals between boosts, and in the case of GG, also with different doses, and their sera were assessed for anti-HBs. RESULTS: In one study, anti-HBs were detected in plasma of mice treated by five of eight of the injected and none of the six noninjected routes. The highest levels of anti-HBs were induced by IM and IV injections, although significant titers were also obtained with SL and ID. Each of these routes also induced CTL, as did IPER and VW and one noninjected route (INH) that failed to induce antibodies. In a second study, GG (1.6 microg) was compared to ID and IM (100 microg) delivery. Significant titers were obtained by all routes after only one boost, with the highest levels detected by IM. Delivery to the skin by GG induced exclusively IgG1 antibodies (Th2-like) at 4 weeks and only very low IgG2a levels at later times; ID-immunized mice had predominantly IgG1 at 4 weeks and this changed to mixed IgG1/IgG2a over time. Responses with IM injection (in the leg or tongue) were predominantly IgG2a (Th1-like) at all times. IV injection gave mixed IgG1/IgG2a responses. In monkeys, in the first experiment, 1 mg DNA IM or ID at 0, 4, and 8 weeks gave equivalent anti-HB titers and 0.4 microg at the same times by GG induced lower titers. In the second experiment, 1 mg DNA IM or ID, or 3.2 microg by GG, at 0, 12, and 24 weeks, gave anti-HB values in the hierarchy of GG > IM > ID. Furthermore, high titers were retained after a single immunization in mice but fell off over time in the monkeys, even after boost. CONCLUSIONS: Route of administration of plasmid DNA vaccines influences the strength and nature of immune responses in mice and non-human primates. However, the results in mice were not always predictive of those in monkeys and this is likely true for humans as well. Optimal dose and immunization schedule will most likely vary between species. It is not clear whether results in non-human primates will be predictive of results in humans, thus additional studies are required. http://link.springer-ny.com/link/service/journals/00020/bibs /5n5p287. html

Administration, Cutaneous↗
PubMed1998

Immunogenicity of DNA vaccines expressing human immunodeficiency virus type 1 envelope glycoprotein with and without deletions in the V1/2 and V3 regions.

DNA vaccines that express the human immunodeficiency virus type 1 HXB-2 envelope glycoprotein (Env) with or without deletions of the major variable regions V1/V2 and V3 were tested for the ability to raise enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody in New Zealand White (NZW) rabbits. Three forms of the Envs were examined: gp120, the surface (SU) receptor-binding domain; gp140, the entire extracellular domain of Env; and gp160, the complete form of Env. For the forms of Env containing the variable regions, the gp120-expressing DNA plasmid was more immunogenic than the gp140- or gp160-expressing DNA plasmids. Removing the V1/2 and V3 variable regions increased the immunogenicity of the gp140- and gp160-expressing DNAs. Deletion of the variable regions also resulted in antibody responses against determinants that were not presented by the forms of Env containing the variable regions. Despite the improved immunogenicity, removing the V1/V2 and V3 domains did not improve the ability of Env to raise neutralizing antibodies. These results suggest that increasing the exposure of internal structures of Env that include the CD4-binding site does not necessarily result in the generation of better neutralizing antibody.

AIDS Vaccines↗
PubMed1998

Studies of the neutralizing activity and avidity of anti-human immunodeficiency virus type 1 Env antibody elicited by DNA priming and protein boosting.

DNA vaccination is an effective means of eliciting strong antibody responses to a number of viral antigens. However, DNA immunization alone has not generated persistent, high-titer antibody and neutralizing antibody responses to human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env). We have previously reported that DNA-primed anti-Env antibody responses can be augmented by boosting with Env-expressing recombinant vaccinia viruses. We report here that recombinant Env protein provides a more effective boost of DNA-initiated antibody responses. In rabbits primed with Env-expressing plasmids, protein boosting increased titer, persistence, neutralizing activity, and avidity of anti-Env responses. While titers increased rapidly after boosting, avidity and neutralizing activity matured more slowly over a 6-month period following protein boosting. DNA priming and protein immunization with HIV-1 HXB-2 Env elicited neutralizing antibody for T cell line-adapted, but not primary isolate, viruses. The most effective neutralizing antibody responses were observed after priming with plasmids which expressed noninfectious virus-like particles. In contrast to immunizations with HIV-1 Env, DNA immunizations with the influenza virus hemagglutinin glycoprotein did not require a protein boost to achieve high-titer antibody with good avidity and persistence.

AIDS Vaccines↗
PubMed1997

The dominant role of bone marrow-derived cells in CTL induction following plasmid DNA immunization at different sites.

Although plasmid DNA immunization provides an effective means of inducing CTL responses to an expressed Ag, the mechanism by which CTL precursors are activated remains to be established. Insights could be gained by identifying the cells responsible for Ag presentation when DNA is introduced into different tissue sites. By immunizing parent into F1 bone marrow chimeric mice with an influenza nucleoprotein-expressing plasmid, we have demonstrated that the key cells in this presentation process for both gene gun-mediated epidermal injection and needle intramuscular injection of plasmid DNA are bone marrow derived. Furthermore, as assessed by intramuscular injection, coexpression of nucleoprotein with the costimulatory molecule B7-2, or the cytokines granulocyte-macrophage CSF and IL-12, did not convert nonhemopoietic cells into APCs. Thus, for two distinctly different modes of DNA immunization, in one case with or without coexpressed immunostimulatory factors, the APCs were consistently found to be of hemopoietic origin.

Animals↗
PubMed1997

Differential dependence on target site tissue for gene gun and intramuscular DNA immunizations.

Surgical ablations revealed different dependencies on the injection site tissue for i.m. needle and epidermal gene gun DNA immunizations. Excision of an injected muscle bundle within 10 min of DNA inoculation did not affect the magnitude or longevity of Ag-specific Ab responses. By contrast, biopsy of the skin target site up to 24 h after gene gun bombardment completely abrogated the Ab response in the majority of mice. The form of a DNA-expressed Ag (membrane bound, secreted, or intracellular) did not affect the temporal requirements for the skin and muscle target sites. Skin cells, but not muscle cells, were also required for DNA-induced CTL. We conclude that transfected cells in gene gun-bombarded skin, but not needle-injected muscle, play a central role in DNA-initiated Ab and CTL responses.

Animals↗
PubMed1997

Screening of HIV-1 Env glycoproteins for the ability to raise neutralizing antibody using DNA immunization and recombinant vaccinia virus boosting.

HIV-1 envelopes from two series of primary isolates (from Swedish patients 5 and 6), from JR-FL and BaL (prototypic monocyte/macrophage tropic viruses) and from HXB-2 (a prototypic T-cell-line-adapted virus), have been screened for their ability to elicit neutralizing antibody to HIV-1. Rabbits were primed by gene gun inoculation with plasmids expressing secreted monomeric (gp120) and oligomeric (gp140) forms of each Env. After four to six DNA immunizations administered over a 1-year period, rabbits were boosted with 10(8) plaque-forming units of a mixture of seven recombinant vaccinia viruses which express chimeric gp140 Envs (primary clade B sequences in a IIIb-related BH10 backbone). Neutralizing antibodies were assayed against two T-cell-line-adapted viruses (MN and IIIb), two non-syncytium-inducing (NSI) and two syncytium-inducing (SI) primary isolates, and two HIV-1-NL4-3-recombinants with patients 5 or 6 Envs (NL4-3/5A, NL4-3/6C). The DNA priming and recombinant vaccinia virus boosting raised low titers of neutralizing antibody in 10 of 19 rabbits. The highest titers of neutralizing activity (approximately 1:150 for MN) were raised in rabbits DNA primed with Envs from Swedish patients 5. These sera cross neutralized IIIb and MN but did not neutralize the primary isolates or the NL4-3 recombinant with the homologous 5A Env. Sera from rabbits primed with the HXB-2 Env DNA were, for the most part, type-specific for neutralization of IIIb. In one of three assays, sera from rabbits primed with plasmids expressing the JR-FL and BaL had possible low titer neutralizing activity for two NSI, but not two SI, primary isolates. Our results highlight the low immunogenic potential of the HIV-1 Env and demonstrate that different Envs have different potentials to raise low titer neutralizing antibody.

AIDS Vaccines↗
PubMed1997

HIV-1 Env glycoproteins from two series of primary isolates: replication phenotype and immunogenicity.

Seven envelope regions from two series of patient isolates have been molecularly cloned and analyzed for replication phenotypes and immunogenicity. Growth potential was analyzed for env sequences substituted into an HIV-1-NL4-3 backbone (NL4-3/env recombinants). Immunogenicity studies were conducted on secreted monomeric (gp120) and oligomeric (gp140) forms of the Envs using Env-expressing plasmid DNAs for immunizations. The env regions of the patient isolates conferred a spectrum of replication kinetics and cytotropisms on the NL4-3/env recombinants. Both patient series included non-syncytium-inducing viruses with no ability to grow on T-cell lines, and highly syncytium inducing viruses which grew well on T-cell lines. These differences in growth potential did not correlate with the ability of the DNA-expressed Envs to raise antibody in rabbits. Rather, the relative immunogenicity of the Envs was patient and form specific. The Envs from patient 5 raised higher titers of antibody than the Envs from patient 6. For each primary Env, the gp120 form of the Env raised higher titers of antibody than the gp140 form. Thus, structural features of Env that affect replication do not necessarily affect the ability to raise antibody.

AIDS Vaccines↗
PubMed1997

Different T helper cell types and antibody isotypes generated by saline and gene gun DNA immunization.

Several routes and methods of DNA immunization have been shown to generate Ab, Th cells, and CTL responses. However, few studies have directly compared the immune responses generated by different routes and methods of DNA immunization. Utilizing an influenza hemagglutinin (H1)-expressing plasmid, we compared the immune response produced by saline injection of DNA into skin or muscle, and gene gun immunization of skin or muscle. We found that saline-DNA immunization raised a predominantly Th1 response with mostly IgG2a anti-H1 Ab, while gene gun DNA immunization produced a predominantly Th2 response with mostly IgG1 anti-H1 Abs. These distinct types of immune responses were generated by the method, not the route, of DNA immunization. The initial immunization established the Th cell-type of the immune response. The Th cell-type did not change with further DNA immunizations by the same or the alternate method, or after a viral challenge. The ability to generate different Th types was not due to differences in the doses of DNA used in saline and gene gun DNA immunization. These findings have important implications for vaccine design and studies of the mechanism of Th cell differentiation.

Animals↗
PubMed1997

DNA vaccines.

DNA vaccines use eukaryotic expression vectors to produce immunizing proteins in the vaccinated host. Popular methods of delivery are intramuscular and intradermal saline injections of DNA and gene gun bombardment of skin with DNA-coated gold beads. The method of DNA inoculation (gene gun versus intramuscular injection) and the form of the DNA-expressed antigen (cell-associated versus secreted) determine whether T-cell help will be primarily type 1 or type 2. Mechanistically, gene gun-delivered DNA initiates responses by transfected or antigen-bearing epidermal Langerhans cells that move in lymph from bombarded skin to the draining lymph nodes. Following i.m. injections, the functional DNA appears to move as free DNA through blood to the spleen where professional antigen presenting cells initiate responses. Preclinical trials with DNA vaccines have had outstanding success. DNA-based immunizations have provided protection against viral, bacterial and parasitic diseases, modulated the effects of autoimmune and allergic disease, and provided some hope for the control of cancer.

Antigen Presentation↗
PubMed1997

Early studies on DNA-based immunizations for measles virus.

DNA-mediated immunizations have been used to raise neutralizing antibodies for measles virus. Single inoculations of plasmids expressing measles hemagglutinin or fusion glycoproteins raised neutralizing antibody in BALB/c mice. Plasmids expressing the hemagglutinin glycoprotein (both normal and secreted) raised neutralizing responses that persisted for 1 year. For both forms of hemagglutinin, the effectiveness of the raised antibody (ratio of neutralizing activity to ELISA activity) was similar. High titers of neutralizing antibody were also raised by inoculation of rabbits with the hemagglutinin and fusion glycoprotein-expressing plasmids.

Animals↗
PubMed1997

Protective immunity induced by rotavirus DNA vaccines.

It is estimated that Group A rotavirus diarrhea causes as many as one million deaths per year in children worldwide, and effective vaccines will be essential for their control. Plasmid DNA vaccines encoding murine rotaviral proteins VP4, VP6, or VP7 were tested in adult BALB/c mice for their ability to induce immune responses and provide protection against rotavirus challenge. The vaccines were administered by inoculation into cells of the epidermis with an Accell gene gun. (Auragen, Inc., Middleton, WI, USA). Each vaccine elicited rotavirus-specific serum antibodies as measured by ELISA. Virus neutralizing antibodies were detected in mice receiving plasmid DNAs encoding for outer capsid proteins VP4 and VP7, but not for VP6, an inner capsid protein, and all of the vaccines generated virus-specific CTL responses. Each vaccine was effective in protecting mice against infection after homotypic rotavirus (100 ID50) challenge, showing reductions (P < 0.0002) in viral excretion measured over a 9 day period. Increased rotavirus-specific intestinal IgA antibodies were seen in vaccinated mice after rotavirus challenge, particularly in mice that received the VP6 DNA vaccine. This suggests that intracellular IgA-mediated neutralization may be involved in protective immunity induced by the VP6 DNA vaccine, and may represent a new mechanism for protection by DNA vaccines.

Animals↗