Current Search: chloroplast transformation (x)
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- Title
- EVALUATION OF IMMUNOGENICITY OF TRANSGENIC CHLOROPLAST DERIVED PROTECTIVE ANTIGEN OF BACILLUS ANTHRACIS.
- Creator
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Koya, Vijay, Daniell, Henry, University of Central Florida
- Abstract / Description
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Anthrax, a fatal bacterial infection is caused by Bacillus anthracis, a gram-positive, spore forming, capsulated, rod shaped organism. Centers for Disease Control (CDC) lists anthrax as Category A biological agent due to its severity of impact on human health, high mortality rate, acuteness of the disease and potential for delivery as a biological weapon. The currently available human vaccine in the United States (AVA anthrax vaccine adsorbed) is prepared from Alum adsorbed formalin treated...
Show moreAnthrax, a fatal bacterial infection is caused by Bacillus anthracis, a gram-positive, spore forming, capsulated, rod shaped organism. Centers for Disease Control (CDC) lists anthrax as Category A biological agent due to its severity of impact on human health, high mortality rate, acuteness of the disease and potential for delivery as a biological weapon. The currently available human vaccine in the United States (AVA anthrax vaccine adsorbed) is prepared from Alum adsorbed formalin treated supernatant culture of toxigenic, non-encapsulated strain of Bacillus anthracis with the principle component being protective antigen (PA83). Evaluation of anthrax vaccine given to nearly 400,000 US military personnel by Vaccine Adverse Event Reporting System (VAERS) showed adverse effects such as flu-like symptoms, local pain, large degree of inflammation, edema, malaise, rash, arthralgia, and headache following vaccination. All the adverse reactions are attributed to the composition of vaccine components. These vaccine preparations contain trace contaminants of lethal and edema factors that contribute to the adverse side effects. Also, the current method of vaccine manufacture has limited production capacity.The production of PA83, in plants through chloroplast genetic engineering might eliminate the concerns of adverse side effects and the levels of expression would ensure the availability of vaccine for the human population in an environmentally friendly approach. The primary concern is whether the PA83 purified from transgenic chloroplasts is as immunogenic as the PA83 in the AVA. For this, PA83 has been expressed in transgenic chloroplasts of Nicotiana tabacum var. petit Havana, by inserting the pag (2205 bp) with the N-terminal 6X histidine tag, into the chloroplast genome by homologous recombination. Chloroplast integration of the pag was confirmed by PCR and Southern analysis. The PA83 protein was detected in transgenic chloroplasts by immunoblot analysis using anti-PA83 antibodies. Maximum expression levels of PA83 (14.17% TSP) were observed in mature leaves upon continuous illumination, due to the presence psbA 5'UTR, a light and developmentally regulated translation enhancer sequence. The PA83 has been purified by affinity chromatography using Ni resin columns. Chloroplast derived PA83 was functional in vitro and was able to lyse the mouse macrophages when combined with the lethal factor. The in vitro assays showed that the crude extracts contained up to 20ug/ml of functional PA83.The immunization studies of PA83 on Balb/c mice, revealed highly immunogenic IgG titers. Subcutaneous immunization with purified chloroplast derived PA83 with adjuvant yielded IgG titers up to 1:320,000, similar to that of the group immunized with PA83 derived from Bacillus anthracis. Immunization of groups with PA83 combined with alhydrogel adjuvant showed four - eight times higher immune response than the groups without adjuvant. The higher expression levels of PA83 in transgenic chloroplasts might ensure the availability of anthrax vaccine to the general public and the high immune response observed in the mouse model would enable the replacement of the current AVA with a cleaner and safer vaccine.
Show less - Date Issued
- 2004
- Identifier
- CFE0000298, ucf:46213
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000298
- Title
- PLANT-MADE ORAL VACCINES: EVALUATION OF CAPSULES.
- Creator
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New, James, Daniell, Henry, University of Central Florida
- Abstract / Description
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Antigen expression through the Chloroplast Transformation Technology (CTT) produces bioencapsulated subunit-vaccines, capable of eliciting immune responses when delivered orally. Considerable challenges to effective plant-based vaccines are the normalization of dosage and preservation of accumulated antigen, which is complicated by variable high water content and protease activity. This study critically examines the efficacy of lyophilization in dehydrating plant-tissues and preserving plant...
Show moreAntigen expression through the Chloroplast Transformation Technology (CTT) produces bioencapsulated subunit-vaccines, capable of eliciting immune responses when delivered orally. Considerable challenges to effective plant-based vaccines are the normalization of dosage and preservation of accumulated antigen, which is complicated by variable high water content and protease activity. This study critically examines the efficacy of lyophilization in dehydrating plant-tissues and preserving plant-derived antigens with vaccine potential. Lyophilization was optimized through gravimetric analysis using lettuce expressing Protective Antigen (PA) of Bacillus anthracis (LS-HPAG) and the human autoantigen Proinsulin (Pins) fused to Cholera toxin subunit B (LS-CTB-Pins). Lyophilization for 48-hours was sufficient treatment to reduce lettuce to 4.57% of its original weight, which retained .058% water content in the bound state; these levels corresponded with oven-dried controls while antigen was stabilized for over a year of storage at room temperature. A simulated gastric fluid assay was applied to evaluate stability of plant derived antigens during digestion. It was observed that lettuce plant cells conferred protection through antigen bioencapsulation for up to an hour under enzymatic digestive conditions. LS-HPAG immunogenicity was then demonstrated through the induction of a PA-specific IgG response by through oral boosting of C57/BL6 test mice. Survival during toxin challenge demonstrated a protective immune response if 40% of animal immunized by plant-derived PA. Lastly, the inclusion of excipient and adjuvant additives will be considered and utilized for the development of prototype vaccine capsule formulations.
Show less - Date Issued
- 2011
- Identifier
- CFH0003861, ucf:44689
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003861
- Title
- EXPRESSION OF CHOLERA TOXIN B SUBUNIT-ROTAVIRUS NSP4 ENTEROTOXIN FUSION PROTEIN IN TRANSGENIC CHLOROPLASTS.
- Creator
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Kalluri, Anila, Daniell, Henry, University of Central Florida
- Abstract / Description
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Rotavirus, the major cause of life-threatening infantile gastroenteritis, is a member of the Reoviridae family and is considered to be the single most important cause of virus-based severe diarrheal illness in infants and young children particularly 6 months to 2 years of age in industrialized and developing countries. Infection in infants and young children is often accompanied by severe life threatening diarrhea, most commonly following primary infection. Diarrhea is the major cause of...
Show moreRotavirus, the major cause of life-threatening infantile gastroenteritis, is a member of the Reoviridae family and is considered to be the single most important cause of virus-based severe diarrheal illness in infants and young children particularly 6 months to 2 years of age in industrialized and developing countries. Infection in infants and young children is often accompanied by severe life threatening diarrhea, most commonly following primary infection. Diarrhea is the major cause of death among children around the world. Responsible for 4 to 6 million deaths per year according to the World Health Organization (WHO), diarrhea is especially dangerous for infants and young children. Globally, it is estimated that 1.4 billion episodes of diarrhea occur in children less than five years of age annually. In the United States alone, rotavirus causes more than 3 million cases of childhood diarrhea each year, leading to an estimated 55,000 to 100,000 hospitalizations and 20 to 100 deaths. And is a major cause of mortality for children in developing countries with approximately one million deaths annually. Rotaviruses belong to the family Reoviridae and are spherical 70-nm particles. The virus genome contains 11 segments of double-stranded RNA, each encoding a viral capsid or nonstructural protein. The identification of a rotavirus nonstructural protein gene (NSP4) encoding a peptide, which functions both as a viral enterotoxin and as a factor involved in the acquisition of host cell membrane during virus budding from cells, provides a new approach for mucosal immunization. Protein expression through chloroplast transformation system offers a number of advantages like high level of transgene expression, transgene containment via maternal inheritance, lack of gene silencing and position effect due to site specific gene integration and also the possibility of multi gene engineering in single transformation event. It is also an environmentally friendly approach due to effective gene containment and lack of transgene expression in pollen. To achieve an enhanced immune response to rotavirus infection, a fusion gene encoding the cholera toxin B subunit linked to rotavirus enterotoxin 90 aa protein (CTB-NSP490) was introduced into transgenic chloroplast and was transformed into chloroplast genome of Nicotiana tabacum by homologous recombination. The chloroplast integration of CTB-NSP4(90) fusion gene was confirmed in transgenic tobacco plants by PCR analysis. Southern blot analysis further confirmed site specific gene integration and homoplasmy. Immunoblot analysis of transformed chloroplast confirmed the expression of CTBNSP490 fusion protein both in monomeric and pentameric forms that retained the binding affinity to the enterocytes GM1 ganglioside receptor. Expression levels of CTB-NSP4 protein was quantified by GM1 ganglioside binding ELISA assay; mature leaves expressed CTB-NSP4 fusion protein to upto 2.45 % in total soluble protein, 100-400 fold higher than nuclear expression which was only 0.006%-0.026%. Antibody titration and virus challenge experiments will be performed in mice at Loma Linda University to evaluate the antigenic and protective properties of the chloroplast derived CTB-NSP4 fusion protein.
Show less - Date Issued
- 2005
- Identifier
- CFE0000655, ucf:46540
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000655
- Title
- DETERMINANTS OF CHLOROPLAST GENE EXPRESSION AND APPLICATIONS OF CHLOROPLAST TRANSFORMATION IN LACTUCA SATIVA AND NICOTIANA TABACUM.
- Creator
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Ruhlman, Tracey, Daniell, Henry, University of Central Florida
- Abstract / Description
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Genetic modification of plastids in the model plant tobacco (Nicotiana tabacum) has demonstrated that numerous foreign gene products can accumulate to high levels in this setting. Plastid biotechnology is maturing to encompass the improvement of food and feed species and the production of biopharmaceutical proteins for oral delivery necessitating development of stable transplastomic edible plants. In the interest of establishing an edible platform we have investigated the use of native and...
Show moreGenetic modification of plastids in the model plant tobacco (Nicotiana tabacum) has demonstrated that numerous foreign gene products can accumulate to high levels in this setting. Plastid biotechnology is maturing to encompass the improvement of food and feed species and the production of biopharmaceutical proteins for oral delivery necessitating development of stable transplastomic edible plants. In the interest of establishing an edible platform we have investigated the use of native and foreign regulatory elements in relation to foreign gene expression in plastids. Multiple sequence alignments of intergenic regions for 20 species of angiosperm showed that despite 95% identity in the coding region, identity in the psbA upstream region is 59% across all taxa examined, other gene coding regions displayed sequence identity of 80-97%, whereas the non-coding regions were 45-79% suggesting that our physical data can be extrapolated beyond the model presented. We found that by exchanging psbA untranslated regions (UTRs) between N. tabacum and lettuce (Lactuca sativa), the expression of the CTB-proinsulin (CTB-Pins) monocistronic transcript declined by 84% and foreign protein accumulation was reduced by as much as 97% in mature leaves. Polyribosome association assays suggest that ribosome-free transgenic transcripts are stabilized where the native UTR is employed. RNA EMSA revealed that binding proteins interacted with psbA 5' UTRs in a species specific manner and the half life of the L. sativa 5'UTR-CTB-Pins mRNA was reduced by 3.7 fold in N. tabacum stromal extracts. Our data indicate that the use of species-specific regulatory elements could lead to establishment of reproducible plastid transformation in desirable target species such as L. sativa. Using transplastomic L. sativa for oral delivery of bioencapsulated CTB-Pins we delayed the onset of diabetes in NOD mice when retinyl acetate supplement was provided compared to untouched mice. In this 30 week study we monitored blood glucose levels and evaluated the in vitro suppressive capacity of regulatory T cells isolated from diabetic mice. Whether delay or prevention was achieved appeared to be a function of antigen dose as high dose resulted in a nine week delay of onset while low dose reduced the incidence of diabetes by 36%. In addition we have evaluated metabolic engineering in the N. tabacum model where we generated cis-genic lines expressing nucleus-encoded methionine pathway enzymes in plastids. Transplastomic expression of Cystathionine gamma-Synthase led to a three-fold increase in enzyme activity and a doubling of methionine content in leaves without a deleterious phenotype. In exploring molecular mechanisms supporting gene expression in plastids and applying transplastomic technology to real human problems this work seeks address the potential of plastid biotechnology for improvement of commodity crops and production of biopharmaceuticals.
Show less - Date Issued
- 2009
- Identifier
- CFE0002687, ucf:48236
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002687