Effects of selected fertilizers on the life history of Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B.

We tested the effects among a purportedly sustainable water-soluble fertilizer, a conventional water-soluble fertilizer, an alternation of these, a controlled-release fertilizer, and a clear water control on the life-history traits of sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae; =Bemisia argentifolii Bellows & Perring) biotype B reared on poinsettia (Euphorbia pulcherrima Willdenow ex Klotzch). Free amino acids in petioles were measured to estimate plant nutrient assimilation and phloem nutritional quality for B. tabaci biotype B. The sustainable fertilizer produced plants with the highest concentration of amino acids. In contrast, fecundity of whiteflies was lowest in plants treated with the sustainable fertilizer and the water control. The relationship between total amino acids in phloem and survival was significantly quadratic, with the highest survival at intermediate levels. Fecundity, however, was negatively correlated with total amino acid content of the maternal host plant. Variation in total amino acid concentration in petioles of plants treated within fertilizer treatments makes it difficult to predict whether a particular fertilizer will produce plants with enough amino acids to deleteriously affect both survivorship and fecundity and yet yield a plant of good quality. Despite this limitation, we can conclude that the use of this sustainable fertilizer will not cause increases in whitefly populations relative to plants fertilized with water-soluble and slow-release fertilizers that deliver the same level of nitrogen to the plant.

A phase I trial of an HLA-A1 restricted MAGE-3 epitope peptide with incomplete Freund's adjuvant in patients with resected high-risk melanoma.

Cytolytic and helper T cells recognize small peptide fragments of protein antigens that are intracellularly processed and delivered to the cell surface in conjunction with HLA molecules. In mice, peptide vaccines can protect against lethal virus infections and tumor challenges. To test whether epitope peptides derived from a human tumor antigen can induce immune responses in patients, a vaccine was prepared consisting of an HLA-A1-restricted epitope of the antigen MAGE-3 mixed with a pan-class II epitope peptide PADRE and emulsified with incomplete Freund's adjuvant. Eighteen patients with resected stages III and IV melanoma at high risk for relapse were vaccinated subcutaneously with increasing doses of the MAGE-3 vaccine ranging from 100 to 2,000 micrograms per injection four times, each 4 weeks apart. The purpose of the phase I trial was to assess the toxicity, tolerability, and immune responses to the vaccine. The vaccine was not toxic, with only one case of grade III lethargy, and most patients complaining of grade I or II local pain, swelling, and tenderness at the injection sites. Peripheral blood mononuclear cells (PBMC) were collected from most patients prior to and after vaccination and used for assessment of global levels of immunity prevaccination, and to measure immune responses to the MAGE-3 and PADRE peptides prior to and after vaccination. Significant defects in global immunity shown by anergy to DTH skin testing in 7 of 16 patients and decreased proliferation to PHA (phytohemagglutinin) and CASTA, a Candida albicans protein extract, were observed. Seven of nine patients showed an increased response to PADRE after restimulation in vitro. Five of 14 patients at doses from 100 to 2,000 micrograms demonstrated an immune response to MAGE-3 by cytolysis of MAGE-3-specific target cells. Release of gamma interferon by T cells from 8 patients at the 100, 1,000, or 2,000 micrograms dose was measured after vaccination, and only two of eight patients showed an increase indicating augmented antigen-specific immunity. These data suggest that immune responses can be detected against PADRE and MAGE-3 in vaccinated melanoma patients, albeit with a low frequency of effector cells.

Phase I trial of a MART-1 peptide vaccine with incomplete Freund's adjuvant for resected high-risk melanoma.

Twenty-five patients with high-risk resected stages IIB, III, and IV melanoma were immunized with a vaccine consisting of the minimal epitope, immunodominant 9-amino acid peptide derived from the MART-1 tumor antigen (AAGIGILTV) complexed with incomplete Freund's adjuvant. The last three patients received the MART-1(27-35) peptide with incomplete Freund's adjuvant mixed with CRL 1005, a block copolymer adjuvant. Patients were immunized with increasing doses of the MART-1(27-35) peptide in a Phase I trial to evaluate the toxicity, tolerability, and immune responses to the vaccine. Immunizations were administered every 3 weeks for a total of four injections, preceded by leukapheresis to obtain peripheral blood mononuclear cells for immune analyses, followed by a post-vaccine leukapheresis 3 weeks after the fourth vaccination. Skin testing with peptide and standard delayed-type hypersensitivity skin test reagents was also performed before and after vaccinations. Local pain and granuloma formation were observed in the majority of patients, as were fevers or lethargy of grade 1 or 2. No vaccine-related grade III/IV toxicity was observed. The vaccine was felt to be well tolerated. Twelve of 25 patients were anergic to skin testing at the initiation of the trial, and 13 of 25 developed a positive skin test response to the MART-1(27-35) peptide. Immune responses were measured by release of IFN-gamma in an ELISA assay by effector cells after multiple restimulations of peripheral blood mononuclear cells in the presence of MART-1(27-35) peptide-pulsed antigen-presenting cells. An ELISPOT assay was also developed to measure more quantitatively the change in numbers of peptide-specific effector cells after vaccination. Ten of 22 patients demonstrated an immune response to peptide-pulsed targets or tumor cells by ELISA assay after vaccination, as did 12 of 20 patients by ELISPOT. Nine of 25 patients have relapsed with a median of 16 months of follow-up, and 3 patients in this high-risk group have died. Immune response by ELISA correlated with prolonged relapse-free survival. These data suggest a significant proportion of patients with resected melanoma mount an antigen-specific immune response against a peptide vaccine and support further development of peptide vaccines for melanoma.

Dendritic cell secretion of IL-15 is induced by recombinant huCD40LT and augments the stimulation of antigen-specific cytolytic T cells.

Dendritic cells (DC) are professional antigen-presenting cells which stimulate strong proliferative and cytolytic T cell responses. Stimulation of CD40 on dendritic cells by its ligands and anti-CD40 antibodies induces maturation and enhances DC stimulatory ability. In order to understand the mechanism by which ligand:CD40 interactions augment DC function, we assessed the role of T cell stimulatory cytokines IL-12 and IL-15 in the function of DC stimulated with soluble trimeric CD40L, a recombinant fusion protein incorporating three covalently linked extracellular CD40L domains (huCD40LT). Peripheral blood derived DC treated with huCD40LT and/or IFN-gamma were used to stimulate T cell responses in vitro to specific antigens. DC treated with huCD40LT or IFN-gamma/huCD40LT stimulated enhanced T cell proliferation to CASTA, a soluble protein from C. albicans, induced T cells with augmented antigen-specific lysis, and increased the yield of antigen-specific IFN-gamma-producing T cells. IL-15 production by DC was enhanced in cultures treated with huCD40LT and correlated with expansion of antigen-specific cytolytic T cells. Addition of a neutralizing anti-IL-15 monoclonal antibody inhibited the expansion of viral and tumor antigen-specific T cells stimulated by IFN-gamma and huCD40LT-treated DC. In contrast, this enhanced stimulatory ability of DC did not appear to depend on synthesis of IL-12 since huCD40LT treatment stimulated the generation of antigen-specific cytokine producing and cytolytic T cells without increased IL-12 production. Addition of anti-IL-12 monoclonal antibody did not inhibit expansion of these cells. These data suggest that production of IL-15 but not IL-12 is an important factor in the enhanced immunostimulatory ability of huCD40LT-treated DC.