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P Fast

Publications and source records attributed to P Fast.

15 recordsLinked to original sources

A Phase I safety and immunogenicity trial of UBI microparticulate monovalent HIV-1 MN oral peptide immunogen with parenteral boost in HIV-1 seronegative human subjects.

Thirty-three HIV-seronegative adults were recruited into a Phase I safety and immunogenicity HIV-1 vaccine trial. The immunogens were as follows: a synthetic, monovalent, octameric HIV-1 MN V3 peptide in aluminum hydroxide (alum) adjuvant administered by intramuscular delivery; and a similar product encapsulated in biodegradable micro-spheres composed of co-polymers of lactic and glycolic acids, administered by the oral route. These were administered in three sequential oral doses, followed by a parenteral boost. No serious adverse experiences were observed. Oral administration of this vaccine, alone or in combination with parenteral boosting, resulted in no significant humoral, cellular, or mucosal immune responses.

AIDS Vaccines↗

QS-21 promotes an adjuvant effect allowing for reduced antigen dose during HIV-1 envelope subunit immunization in humans.

Three separate studies were undertaken in HIV-1 uninfected persons to determine if the adjuvant QS-21 improves the magnitude or kinetics of immune responses induced by recombinant soluble gp120 HIV-1(MN) protein (rsgp120) immunization. The QS-21 was administered at two doses (50 and 100 microg), either alone or in combination with aluminum hydroxide (600 microg). At the highest doses of rsgp120 (100, 300, and 600 microg), QS-21 exerted no significant effect on either binding or neutralizing antibody titers. Antibody binding and neutralizing responses fell dramatically when rsgp120, formulated with alum alone, was given at low doses (3 and 30 microg). In contrast, antibody responses similar in titer to those in the high dose antigen groups were induced with the low dose rsgp120 formulated with QS-21. In addition, the lymphocyte proliferation and delayed type hypersensitivity skin testing were superior in the QS-21 recipients compared with the alum recipients at the low antigen doses. Moderate to severe pain was observed in majority of the volunteers receiving QS-21 formulations, and vasovagal episodes and hypertension were not infrequent. Thus, the use of QS-21 may provide a means to reduce the dose of a soluble protein immunogen.

AIDS Vaccines↗

A phase II study of two HIV type 1 envelope vaccines, comparing their immunogenicity in populations at risk for acquiring HIV type 1 infection. AIDS Vaccine Evaluation Group.

Several immunogens induce HIV-specific neutralization and in vitro lymphoproliferation in adults at low HIV-1 risk, but responses in persons at high HIV-1 risk are not known. We performed a multicenter, double-blinded, adjuvant-controlled trial with two gp120 vaccines in 296 HIV-1-uninfected volunteers, including 176 reporting higher HIV-1 risk activities. The immunogens were remarkably well tolerated. After three immunizations, 210 of 241 vaccinees (87%) developed neutralizing antibodies, which persisted in 59% after 2 years. The injection drug users receiving SF-2/gp120 had decreased antibody responses relative to the lower risk groups. Envelope-specific lymphoproliferation peaked after two immunizations, and 54% of vaccinees mounted a DTH reaction to gp120 after 4 years. In summary, these immunogens have low adverse reactogenicity and induce durable antibody and T cell responses to the prototype strains. Unexpected differences in antibody responses among diverse HIV-1 risk strata lend support to the conduct of expanded phase II trials in populations other than low-risk volunteers.

AIDS Vaccines↗

A canarypox vaccine expressing multiple human immunodeficiency virus type 1 genes given alone or with rgp120 elicits broad and durable CD8+ cytotoxic T lymphocyte responses in seronegative volunteers.

Induction of CD8+ cytotoxic T cells is considered one of the important correlates for the protective efficacy of candidate human immunodeficiency virus type 1 (HIV-1) vaccines. To induce CD8+ cytotoxic T lymphocytes (CTLs) along with neutralizing antibody and CD4+ T cell help, a live canarypox virus construct expressing gp120, transmembrane gp41, the gag and protease genes, and sequences containing CTL epitopes in nef and pol was given simultaneously with, or followed by, rgp120 SF2. CD8+ CTLs were detected in 61% of volunteers at some time during the trial. Three to 6 months after the last immunization, the gene-specific responses were gag, 26/81; env, 17/77; nef, 12/77; and pol, 3/16. Simultaneous immunization with the canarypox vector and the subunit, beginning with the initial immunization, resulted in earlier antibody responses. In summary, a strategy of immunization with a canarypox vector expressing multiple genes of HIV-1 given with gp120 results in durable CD8+ CTL responses to a broad range of epitopes.

AIDS Vaccines↗

Preventing discrimination against volunteers in prophylactic HIV vaccine trials: lessons from a phase II trial.

CONTEXT: Preventive HIV vaccines can temporarily cause uninfected individuals to have positive results on HIV testing. As preparations are underway to mount larger efficacy trials, the social risks of trial participation should be studied. OBJECTIVE: To describe frequency of HIV testing and discrimination among participants in a preventive phase II HIV vaccine trial. PARTICIPANTS: 266 vaccine trial volunteers were eligible; 247 participated in a confidential survey. RESULTS: 63 volunteers (26% of respondents) reported 185 HIV tests during the prior 12 to 24 months; most tests were for other research studies, health care, insurance, incarceration, or employment. Only 5 volunteers reported having positive HIV test results. Volunteers reported 99 adverse social incidents or problems, 53 of which were related to the trial. The most common type of event occurred when volunteers disclosed their trial participation and were mistakenly presumed to be infected with HIV. Few reported difficulty obtaining insurance, job loss, and inadvertent disclosure of their participation in the trial. CONCLUSION: In this vaccine trial, few serious social harms were reported. Those who conduct HIV tests for insurance, employment, health care, or other reasons should be made aware that HIV vaccines can cause false-positive HIV test results. Those planning future trials must continue to provide needed support to volunteers. Social harms should be monitored with the same vigilance accorded to physical harms.

AIDS Serodiagnosis↗

Immune responses to human immunodeficiency virus (HIV) type 1 induced by canarypox expressing HIV-1MN gp120, HIV-1SF2 recombinant gp120, or both vaccines in seronegative adults. NIAID AIDS Vaccine Evaluation Group.

A safety and immunogenicity trial was conducted in vaccinia-immune and vaccinia-naive human immunodeficiency virus (HIV)-uninfected adults who were randomized to receive 10(6) or 10(7) TCID50 of canarypox (ALVAC) vector expressing HIV-1MN gp160 or 10(5.5) TCID50 of ALVAC-rabies virus glycoprotein control at 0 and 1 or 2 months and ALVAC-gp160 or 50 microg of HIV-1SF2 recombinant (r) gp120 in microfluidized emulsion at 9 and 12 months; others received rgp120 at 0, 1, 6, and 12 months. All vaccines were well-tolerated. Neither vaccinia-immune status before vaccination nor ALVAC dose affected HIV immune responses. HIV-1MN and HIV-1SF2 neutralizing antibodies were detected more often (100%) in ALVAC-gp160/rgp120 recipients than in recipients of ALVAC-gp160 (<65%) or rgp120 (89%) alone. ALVAC-gp160/rgp120 also elicited more frequent HIV V3-specific and fusion-inhibition antibodies, antibody-dependent cellular cytotoxicity, lymphoproliferation, and cytotoxic CD8+ T cell activity than did either vaccine alone. Trials with ALVAC expressing additional HIV components and rgp120 are underway.

AIDS Vaccines↗

Intermediate-size trials for the evaluation of HIV vaccine candidates: a workshop summary.

There has been considerable debate over what evidence from preclinical and clinical studies is required to advance an HIV vaccine candidate to phase III efficacy testing. Given this situation, conduct of intermediate-size trials is proposed as a method for assessing the plausibility that a vaccine candidate would prevent chronic HIV infection. Designed to observe 45 incident infections in the control group, these preliminary efficacy trials could rule out candidates with low or no efficacy while advancing those candidates with some evidence of protection to definitive trials. In addition, these trials could provide clues about correlates of immunity. A threefold or greater difference in the postvaccination geometric mean titer of neutralizing antibody can be readily detected between infected and uninfected vaccinees. Differences in CD8+ cytotoxic T lymphocytes, however, are more difficult to detect. Intermediate-size trials could also discern a 0.5 log10 or greater difference in plasma HIV-1 RNA levels between infected vaccinees and infected controls. Such differences in viral load might suggest disease amelioration or reduction in infectiousness. Given the large variability in CD4 count and its relatively modest average decline in the year after infection, a slower decline in CD4 count among infected vaccinees would not be detectable. With limited resources, intermediate-size trials could contribute significantly to HIV vaccine development.

AIDS Vaccines↗

Safety profile of phase I and II preventive HIV type 1 envelope vaccination: experience of the NIAID AIDS Vaccine Evaluation Group.

The NIAID-sponsored AIDS Vaccine Evaluation Group was established in 1988 to perform phase I/II clinical trials with candidate preventive HIV-1 vaccines. This report includes safety data from 1398 HIV-negative, healthy volunteers who were enrolled into 25 phase I and 1 phase H multicentered, randomized, double-blind studies evaluating seven recombinant HIV-1 envelope vaccines, two V3 loop synthetic peptide vaccines, and two live poxvirus-vectored recombinant envelope vaccines. All studies but three were placebo controlled; the placebo was either the adjuvant alone or, in studies of recombinant poxvirus vaccines, it was the vector with no gene insert or a non-HIV gene insert. All candidate vaccines were generally well tolerated. The only adverse effects that were clearly related to vaccination were occasional acute local and systemic reactions that were associated with the adjuvants. Three adjuvants in particular were associated with moderate to severe local reactions: alum plus deoxycholate (ImmunoAg), MTP-PE (Biocine Corp.), and QS21 (Genentech, Inc.). MTP-PE was also associated with self-limited severe systemic reactions. There were no serious adverse laboratory toxicities and no evidence of significant immunosuppressive events after receipt of the candidate vaccines. A few volunteers experienced symptoms that might relate to an underlying immunopathologic mechanism (rash, hemolytic anemia, arthralgia), but their presentations were mild and their incidence was low. Eleven volunteers were diagnosed with malignancies during or after their participation, which was within the 95% confidence interval of the number of cases predicted by the National Cancer Institute SEER (Program for cancer surveillance, epidemiology, and end result reporting) database. In conclusion, the envelope-based recombinant or synthetic candidate HIV-1 vaccines appear to be safe and this work has prepared the way for the testing of increasingly complex candidate HIV-1 vaccines.

AIDS Vaccines↗

Neutralization of HIV-1.

A Workshop on Neutralization of HIV-1: Technology and reagents for analysis of prophylactic vaccines clinical trials, sponsored by the Food and Drug Administration (FDA) and the Division of AIDS, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), was held on April 19-20, 1993, in Bethesda, Maryland. This workshop brought together researchers who are involved in the development, testing, and evaluation of HIV-1 prophylactic vaccines. The major objectives were (1) to discuss critically the different neutralization and binding assays that are currently used in the evaluation of immune sera; (2) to identify assays that will measure the "most relevant" antibodies, which are likely to predict neutralization of primary isolates; and (3) to identify well-characterized reference reagents, which could be used to standardize neutralization assays used in laboratories around the world.

AIDS Serodiagnosis↗

The mechanism of sunlight-mediated inactivation of Bacillus thuringiensis crystals.

Detailed photostability studies were carried out using purified delta-endotoxin crystals from Bacillus thuringiensis subspecies HD-1 and HD-73. The mechanism and time course of sunlight inactivation was investigated by: (a) monitoring the tryptophan damage in the intact crystals by Raman spectroscopy, (b) amino acid analysis and (c) biological assays using insects. The results demonstrate that, for purified HD-1 or HD-73 crystals, the 300-380 nm range of the solar spectrum is largely responsible for bringing about crystal damage and consequent loss of toxicity. Purified Bacillus thuringiensis crystals that were exposed to fermentation liquor after cell lysis were more quickly degraded by sunlight than were crystals from cells that were lysed in water. This effect is attributed to adsorption of chromophores by crystals exposed to the fermenter liquor and the subsequent ability of these chromophores to act as photosensitizers. The importance of a photosensitization mechanism in crystal degradation was further emphasized by irradiating Bacillus thuringiensis crystals in vacuo. The latter crystals were found to be less damaged (20% tryptophan loss after 24 h irradiation by the solar spectrum) compared with crystals from the same sample irradiated in air (60% (60% tryptophan loss). Other methods of decreasing exposure of the crystals to oxygen, e.g. by using glycerol as a humectant, were also found to be successful in controlling photodamage. The results concerning photodegradation support a photosensitization mechanism involving the presence of exogenous (and possibly endogenous) chromophores which create singlet oxygen species upon irradiation by light.

Amino Acids↗

Mechanism of bcl-2 activation in human follicular lymphoma.

The t(14; 18) chromosomal translocation of human follicular lymphoma recombines the bcl-2 gene from chromosome 18 with the immunoglobulin heavy chain joining region. In the t(14; 18) translocation bearing cell line SU-DHL-6, this results not only in an inappropriately high rate of bcl-2 transcription for a mature B cell, but also in two potentially critical point mutations. To determine the relative importance of these mutations, we searched for their presence in DNA from the involved lymph nodes of 12 patients with t(14; 18) follicular lymphoma. bcl-2 genomic sequences were specifically amplified by the polymerase chain reaction technique and then directly sequenced. None of the 12 samples analysed revealed the codon 7 or codon 129 mutation detected in SU-DHL-6. We conclude that abnormal expression of bcl-2 rather than structural alterations at codon 7 or 129 play an important role in the disordered growth and differentiation of follicular B-cell lymphoma.

B-Lymphocytes↗

A human protein specific for the immunoglobulin octamer DNA motif contains a functional homeobox domain.

The homeobox domain is shared by Drosophila homeotic proteins, yeast mating type proteins, and some functionally uncharacterized mammalian proteins. A lymphoid-restricted human protein that binds to the immunoglobulin octamer regulatory motif was shown to contain an amino acid sequence that has 33% amino acid identity with the consensus sequence of the previously cloned homebox domains. This homeobox gene was localized to chromosome 19, thus mapping separately from other human homebox genes. A mutant protein containing amino acid substitutions within a putative helix-turn-helix motif in the homeobox domain did not bind DNA detectably. This human homeobox protein was shown to bind the same DNA sequence as the homeobox domains of the yeast mating type proteins and Drosophila homeotic protein, suggesting that homeobox proteins may have closely related DNA binding characteristics.

Amino Acid Sequence↗

Use of oligonucleotide probes to study the relatedness of delta-endotoxin genes among Bacillus thuringiensis subspecies and strains.

Fifteen Bacillus thuringiensis strains representing 13 serotypes were screened with five oligodeoxyribonucleotide probes specific for certain regions of two published sequences and one unpublished sequence of B. thuringiensis delta-endotoxin genes. Of the 15 cultures, 14 hybridized with at least one probe; the B. thuringiensis subsp. thompsoni strain alone did not hybridize. Two B. thuringiensis subsp. kurstaki strains of commercial interest, HD-1 and NRD-12, were found to be so closely related as to be indistinguishable with this technique; the same situation was found with strains from B. thuringiensis subspp. dendrolimus and sotto. Five strains were identified as probably containing only one endotoxin gene. A probe specific for the gene from the B. thuringiensis subsp. kurstaki HD-73 strain hybridized to only 3 of the 15 cultures tested. The hybridization data suggest that the DNA sequences coding for the C-terminal region of the endotoxin protein are as well conserved as those coding for the N-terminal toxic portion.

Bacillus thuringiensis↗