Hugh S. Mason
Mason Lab Research:
My research involves genetic engineering of plants for recombinant protein production and improved quality traits, with a major focus on vaccines. My lab also works on the regulation of plant gene expression and multimeric protein assembly, with the aim of optimizing accumulation of foreign proteins in plants, and the testing of plant-derived vaccines by oral delivery in model test animals. The research comprises 3 main categories:
Plant-based vaccine production and testing. We use plants (potato, tomato, tobacco, alfalfa, and corn) as hosts for stable transformation and expression of vaccine antigens in edible tissues. Expression of foreign genes in plants may present challenging problems including transcription and mRNA processing, translation, assembly, and subcellular targeting. Since vaccine genes originate in diverse sources whose systems may be suboptimal for plant expression, we analyze coding sequences to identify potentially detrimental motifs that could mediate mRNA truncation or degradation, including polyadenylation signals, intron splice sites, and RNA instability motifs. We then use this information to design plant-optimized genes using plant-preferred codons. My lab has developed a number of useful expression cassettes using constitutive, chemically inducible, or tissue-specific promoters, viral translational enhancers, and efficient 3 elements, which we use routinely for antigen expression. After regeneration of the transgenic plant lines, we verify antigen expression and structure using specific immunoassays and biochemical characterization, then we use the edible material for animal trials to assess immunogenicity. Currently funded work in my laboratory includes development of plant-based vaccines for hepatitis B (NIH), human papillomavirus (NIH), Norwalk-like viruses (Japan Health Sciences Foundation), enteropathogenic E. coli (NIH), and plague (Department of Defense).
Novel plant gene expression systems. We are investigating the use of plant geminivirus elements to enhance the expression of foreign proteins in a tightly regulated manner. High expression of foreign proteins often causes toxic effects in plant cells and may interfere with plant growth and development. Thus regulated expression is necessary in order to obtain the most efficient protein production. Incorporation of expression cassettes within viral replicons that can be replicated in trans by a viral factor (Rep) expressed from an inducible promoter yields high copy number of the cassette and maximizes the transcription. This work is currently supported by two grants from NSF for 1) use of geminivirus elements to enhance transient protein expression in plant cell and root cultures, and 2) stable expression of recombinant proteins in plant cell cultures using regulated geminivirus-mediated gene amplification.
Multimeric protein assembly in plant cells. Using model vaccine antigens, we are investigating the synthesis, processing, and assembly of multimeric protein complexes in plants.
- Hepatitis B surface antigen (HBsAg) is directed to the plant cell ER membrane where it inserts and folds into antigenic configuration with intra- and inter-molecular disulfide bonds, and subsequent budding of membrane elements to form 20 nm particles. We are examining subcellular targeting strategies and involvement of ER molecular chaperones in this assembly process in plant cells (NIH grant).
- E. coli heat labile enterotoxin (LT) and the related cholera toxin (CT) are composed of a single A subunit and 5 B subunits that assemble to form a ganglioside-binding holotoxin complex. Mutant LT forms with attenuated toxicity are potent mucosal vaccine adjuvants, thus we are studying co-expression of LT-A and LT-B in plants.
- Norwalk virus capsid protein (NVCP) forms dimers and pentamers that assemble into a virus-like particle (VLP) with defined icosahedral symmetry. In plant cells only 50% of the NVCP subunits are extracted as VLP, thus we are investigating strategies to enhance this assembly process in plant cells, including involvement of other viral proteins and cytoplasmic molecular chaperones.
- Fusion proteins for vaccine epitopes are a means to deliver short peptides in a particulate form that will enhance uptake and immune system stimulation. We have created fusion proteins with HBsAg, LT-B, LT-A, and NVCP and are evaluating their potential for plant-based vaccine production and delivery. Efficient assembly of VLP or mucosally targeted LT fusions is essential for optimal vaccine activity.
Selected publications, primary peer-reviewed:
Huang Z, Chen Q, Hjelm B, Arntzen C, Mason H (2009) A DNA replicon system for rapid high-level production of virus-like particles in plants. Biotechnol Bioeng, in press. Accepted Article Online: Feb 17 2009 2:09PM. DOI: 10.1002/bit.22299
Huang Z, LePore K, Elkin G, Thanavala Y, Mason HS (2008) High-yield rapid production of hepatitis B surface antigen in plant leaf by a viral expression system. Plant Biotechnol. J. 6 (2): 202–209.
Santi L, Batchelor L, Huang Z, Hjelm B, Kilbourne J, Arntzen CJ, Chen Q, Mason HS (2008) An efficient plant viral expression system generating orally immunogenic Norwalk virus-like particles. Vaccine 26:1846-1854.
Van Eck J, Conlin B, Garvin D, Mason H, Navarre D, Brown C (2007) Enhancing [beta]-carotene content in potato by RNAi-mediated silencing of the [beta]-carotene hydroxylase gene. American J. Potato Res., 84 (4):331-342.
Collens JI, Mason HS, Curtis WR (2007) Agrobacterium-mediated viral vector-amplified transient gene expression in Nicotiana glutinosa plant tissue culture. Biotechnol Prog. 23(3):570-6. Epub 2007 Apr 11.
Huang Z, Santi L, LePore K, Kilbourne J, Arntzen CJ, Mason HS (2006) Rapid, high-level production of hepatitis B core antigen in plant leaf and its immunogenicity in mice. Vaccine 24(14):2506-2513.
Santi L, Giritch A, Roy C, Marillonnet S, Klimyuk V, Gleba Y, Webb R, Arntzen C, Mason H (2006) Protection conferred by recombinant Yersinia pestis antigens produced by a rapid and highly scalable plant expression system. Proc. Natl. Acad. Sci. USA 103(4):861-866.
Alvarez ML, Pinyerd HL, Crisantes JD, Rigano MM, Pinkhasov J, Walmsley AM, Mason HS, Cardineau, GA (2006) Plant-made subunit vaccine against pneumonic and bubonic plague is orally immunogenic in mice. Vaccine 24(14): 2477-2490.
Saldaña S, Guadarrama FE, de Jesus Olivera Flores T, Arias N, López S, Arias C, Ruiz R, Mason H, Mor T, Richter L, Arntzen CJ, Gómez-Lim MA (2006) Production of rotavirus-like particles in tomato (Lycopersicon esculentum L.) fruit by expression of capsid proteins VP2 and VP6 and immunological studies. Viral Immunol. 19(1):42-53.
Zhang X, Buehner NA, Hutson AM, Estes MK, Mason HS (2006) Tomato is a highly effective vehicle for expression and oral immunization with Norwalk virus capsid protein. Plant Biotechnology Journal 4: 419-432.
Becerra-Arteaga A, Mason HS, Shuler ML (2006) Production, Secretion, and Stability of Human Secreted Alkaline Phosphatase in Tobacco NT1 Cell Suspension Cultures. Biotechnol. Prog., 22(6):1643-1649.
Thanavala Y, Mahoney M, Pal S, Scott A, Richter L, Natarajan N, Goodwin P, Arntzen CJ, Mason HS (2005) Immunogenicity in humans of an edible vaccine for hepatitis B. Proc. Natl. Acad. Sci. USA 102:3378-3382.
Huang Z, Elkin G, Maloney BJ, Beuhner N, Arntzen CJ, Thanavala Y, Mason HS (2005) Virus-like particle expression and assembly in plants: hepatitis B and Norwalk viruses. Vaccine 23:1851-1858.
Maloney BJ, Takeda N, Suzaki Y, Ami Y, Li TC, T Miyamura, Arntzen CJ, Mason HS (2005) Challenges in creating a vaccine to prevent hepatitis E. Vaccine 23:1870-1874.
Zhang X, Mason HS (2005) Bean yellow dwarf virus replicons for high-level transgene expression in transgenic plants and cell cultures. Biotechnol. Bioeng. 93(2):271-279.Judge NA, Mason HS, O'Brien AD (2004) Plant cell-based intimin vaccine given orally to mice primed with intimin reduces time of Escherichia coli O157:H7 shedding in feces. Infect. Immun. 72:168-175.
Huang Z, Mason HS (2004) Conformational analysis of hepatitis B surface antigen fusions in an Agrobacterium-mediated transient expression system. Plant Biotechnol. J., 2:241-249.
Chikwamba RK, Scott MP, Mejia LB, Mason HS, Wang K (2003) Localization of a bacterial protein in starch granules of transgenic maize kernels. Proc. Natl. Acad. Sci. USA 100:11127-11132.
Smith ML, Richter L,. Arntzen CJ, Shuler ML, Mason HS (2003) Structural characterization of plant-derived hepatitis B surface antigen employed in oral immunization studies. Vaccine 21:4011-4021.
Warzecha H, Mason HS, Lane C, Tryggvesson A, Rybicki E, Williamson A, Clements JD, Rose RC (2003) Oral immunogenicity of human papillomavirus-like particles expressed in potato. J. Virol 77:8702-8711.
Sojikul P, Buehner N, Mason HS (2003) A plant signal peptide-hepatitis B surface antigen fusion protein with enhanced stability and immunogenicity expressed in plant cells. Proc. Natl. Acad. Sci. USA 100:2209-2214.
Mor TS, Moon Y-S, Palmer KE, Mason HS (2003) Geminivirus vectors for high level expression of foreign proteins in plant cells. Biotechnol. Bioeng. 81: 430-437.
Chikwamba R, McMurray J, Frame B, Scott P, Mason H, Wang K (2002). Expression of a bacterial antigen in maize: The role of regulatory sequences, inheritance and level of expression of the synthetic E. coli heat labile toxin B sub-unit (LT-B) in maize. Molecular Breeding 10: 253 - 263.
Chikwamba R, Cunnick J, Hathaway D, McMurray J, Mason HS, Wang K (2002). A functional antigen in a practical crop: Maize synthesized LT-B protects mice against Escherichia coli heat labile enterotoxin (LT) and cholera toxin (CT). Transgenic Research. 11:479-493.
Smith ML, Mason HS, Shuler ML (2002) Hepatitis B surface antigen (HBsAg) expression in plant cell culture; the kinetics of antigen accumulation in batch culture and its intracellular form. Biotechnol. Bioeng. 80, 812-822.
Kong Q, Richter L, Yang Y-F, Arntzen CJ, Mason HS, Thanavala Y (2001) Oral immunization with hepatitis B surface antigen expressed in transgenic plants. Proc. Natl. Acad. Sci. USA 98:11539-11544.
Mor TS, Sternfeld M, Soreq H, Arntzen CJ, Mason HS (2001) Expression of recombinant human acetylcholinesterase in transgenic tomato plants. Biotechnol. Bioeng. 75: 259-266.
Richter L, Thanavala Y, Arntzen CJ, Mason HS (2000) Production of hepatitis B surface antigen in transgenic plants for oral immunization. Nature Biotechnol. 18:1167-1171.
Tacket CO, Mason HS, Losonsky G, Estes MK, Levine MM, Arntzen CJ (2000) Human immune responses to a novel Norwalk virus vaccine delivered in transgenic potatoes. J. Infect. Dis. 182: 302-305.
Tacket CO, Mason HS, Losonsky G, Clements JD, Levine MM, Arntzen CJ (1998) Immunogenicity in humans of a recombinant bacterial antigen delivered in transgenic potato. Nature Medicine 4:607-609.
Mason HS, Haq TA, Clements JD, Arntzen CJ (1998) Edible vaccine protects mice against E. coli heat-labile enterotoxin (LT): potatoes expressing a synthetic LT-B gene. Vaccine 16:1336-1343.
Mason HS, Ball J, Shi JJ, Jiang X, Estes MK, Arntzen CJ (1996) Expression and immunogenicity of Norwalk virus capsid protein from transgenic tobacco and potato. Proc. Natl. Acad. Sci. USA 93: 5335-5340.
Thanavala Y, Yang Y-F, Lyons P, Mason HS, Arntzen C. (1995) Immunogenicity of transgenic plant-derived hepatitis B surface antigen. Proc. Natl. Acad. Sci. USA 92:3358-3361.
Haq TA, Mason HS, Clements JD, Arntzen CJ. (1995) Oral immunization with a recombinant bacterial antigen produced in transgenic plants. Science 268:714-716.
Mason H, DeWald D, Mullet J. (1993) Identification of a methyl jasmonate responsive domain in the soybean vspB promoter. Plant Cell 5:241-251.
Mason H, Lam D, Arntzen CJ. (1992) Expression of hepatitis B surface antigen in transgenic plants. Proc. Natl. Acad. Sci. USA 89:11745-11749.
Selected publications, invited reviews:
Arntzen C, Mason H, Khalsa G (2007) Designing and delivering plant-based vaccines for the developing world. PETRIA J. Plant Pathol. 17:55-70.
Santi L, Mason HS (2007) Vaccines Produced in Transgenic Plants. Encyclopedia of Biotechnology in Agriculture and Food. Santi L, Huang Z, Mason H (2006) Virus-like particles production in green plants. Methods 40(1):66-76.
Thanavala Y, Huang Z, Mason HS (2006) Plant-derived vaccines: a look back at the highlights and a view to the challenges on the road ahead. Expert Rev Vaccines 5(2):249-260.
Mayo KJ, Gonazales BJ, Mason HS (2006) Genetic transformation of tobacco NT1 cells with Agrobacterium tumefaciens. Nat Protoc. 1(3):1105-11. http://www.natureprotocols.com/2006/08/17/genetic_transformation_of_toba.php
Arntzen CJ, Mahoney RT, Mason HS, Kirk DD (2005) Oral Vaccines Derived from Transgenic Plants. In: Vaccines: Preventing disease and protecting health.
Khalsa G, Mason HS, Arntzen CJ (2004) Plant-Derived Vaccines: Progress and Constraints. In: Fischer R, Schillberg S, Eds. Molecular Farming, pp. 135-160. (Published Online: 6 Jun 2005)
Mor TS, Mason HS, Kirk D, Arntzen CJ, Cardineau GA (2004) Plants as a delivery vehicle for orally delivered subunit vaccines. In: New Generation Vaccines, Third Edition (Levine M, Ed.), pp. 305-311. Marcel Dekker, New York.
Mason HS, Warzecha H, Mor TS, Arntzen CJ (2002) Edible plant vaccines: applications for prophylactic and therapeutic molecular medicine. Trends Mol. Med.8:324-329.
Mason HS (2002) Plant-based vaccines: Expression and oral immunogenicity. In Vitro Cell. Devel. Biol. Plant 38:237-240.
Tacket CO, Mason HS (1999) A review of oral vaccination with transgenic vegetables. Microbes & Infection 1:1-7.
Mason HS, Arntzen CJ (1998) Edible vaccines -- the future for paediatric vaccines delivery? Vaccines: Children and Practice, 1:13-15.
Arntzen CJ, Mason HS (1997) Oral vaccine production in the edible tissues of transgenic plants. In: New Generation Vaccines, Second Edition (Eds. Levine MM, Woodrow GC, Kaper JB, Cobon GS) Marcel Dekker, New York, Pages 263-277.
Mason HS, Arntzen CJ (1995) Transgenic plants as vaccine production systems. Trends Biotechnol. 13:388-392.