[show abstract][hide abstract] ABSTRACT: Application of tools of molecular biology and genomics is increasingly leading towards the development of recombinant protein-based biologics. As such, it is leading to an increased diversity of targets that have important health applications and require more flexible approaches for expression because of complex post-translational modifications. For example, Plasmodium parasites may have complex post-translationally modified proteins such as Pfs48/45 that do not carry N-linked glycans (Exp. Parasitol. 1998; 90, 165.) but contain potential N-linked glycosylation sites that can be aberrantly glycosylated during expression in mammalian and plant systems. Therefore, it is important to develop strategies for producing non-glycosylated forms of these targets to preserve biological activity and native conformation. In this study, we are describing in vivo deglycosylation of recombinant N-glycosylated proteins as a result of their transient co-expression with bacterial PNGase F (Peptide: N-glycosidase F). In addition, we show that the recognition of an in vivo deglycosylated plant-produced malaria vaccine candidate, Pfs48F1, by monoclonal antibodies I, III and V raised against various epitopes (I, III and V) of native Pfs48/45 of Plasmodium falciparum, was significantly stronger compared to that of the glycosylated form of plant-produced Pfs48F1. To our knowledge, neither in vivo enzymatic protein deglycosylation has been previously achieved in any eukaryotic system, including plants, nor has bacterial PNGase F been expressed in the plant system. Thus, here, we report for the first time the expression in plants of an active bacterial enzyme PNGase F and the production of recombinant proteins of interest in a non-glycosylated form.
[show abstract][hide abstract] ABSTRACT: Influenza virus is a globally important respiratory pathogen that causes a high degree of annual morbidity and mortality. Significant antigenic drift results in emergence of new, potentially pandemic, virus variants. The best prophylactic option for controlling emerging virus strains is to manufacture and administer pandemic vaccines in sufficient quantities and to do so in a timely manner without impacting the regular seasonal influenza vaccine capacity. Current, egg-based, influenza vaccine production is well established and provides an effective product, but has limited capacity and speed.
To satisfy the additional global demand for emerging influenza vaccines, high-performance cost-effective technologies need to be developed. Plants have a potential as an economic and efficient large-scale production platform for vaccine antigens.
In this study, a plant virus-based transient expression system was used to produce hemagglutinin (HA) proteins from the three vaccine strains used during the 2008-2009 influenza season, A/Brisbane/59/07 (H1N1), A/Brisbane/10/07 (H3N2), and B/Florida/4/06, as well as from the recently emerged novel H1N1 influenza A virus, A/California/04/09.
The recombinant plant-based HA proteins were engineered and produced in Nicotiana benthamiana plants within 2 months of obtaining the genetic sequences specific to each virus strain. These antigens expressed at the rate of 400-1300 mg/kg of fresh leaf tissue, with >70% solubility. Immunization of mice with these HA antigens induced serum anti-HA IgG and hemagglutination inhibition antibody responses at the levels considered protective against these virus infections.
These results demonstrate the feasibility of our transient plant expression system for the rapid production of influenza vaccine antigens.
Influenza and Other Respiratory Viruses 10/2011; 6(3):204-10. · 1.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: Plasmodium falciparum is transmitted to a new host after completing its sexual cycle within a mosquito. Developing vaccines against the parasite sexual stages is a critical component in the fight against malaria. We are targeting multiple proteins of P. falciparum which are found only on the surfaces of the sexual forms of the parasite and where antibodies against these proteins have been shown to block the progression of the parasite's life cycle in the mosquito and thus block transmission to the next human host. We have successfully produced a region of the Pfs230 antigen in our plant-based transient-expression system and evaluated this vaccine candidate in an animal model. This plant-produced protein, 230CMB, is expressed at approximately 800 mg/kg in fresh whole leaf tissue and is 100% soluble. Administration of 230CMB with >90% purity induces strong immune responses in rabbits with high titers of transmission-blocking antibodies, resulting in a greater than 99% reduction in oocyst counts in the presence of complement, as determined by a standard membrane feeding assay. Our data provide a clear perspective on the clinical development of a Pfs230-based transmission-blocking malaria vaccine.
[show abstract][hide abstract] ABSTRACT: Malaria is a serious and sometimes fatal mosquito-borne disease caused by a protozoan parasite. Each year, it is estimated that over one million people are killed by malaria, yet the disease is preventable and treatable. Developing vaccines against the parasite is a critical component in the fight against malaria and these vaccines can target different stages of the pathogen's life cycle. We are targeting sexual stage proteins of P. falciparum which are found on the surface of the parasite reproductive cells present in the mosquito gut. Antibodies against these proteins block the progression of the parasite's life cycle in the mosquito, and thus block transmission to the next human host. Transmission blocking vaccines are essential to the malaria eradication program to ease the disease burden at the population level. We have successfully produced multiple versions of the Pfs25 antigen in a plant virus-based transient expression system and have evaluated these vaccine candidates in an animal model. The targets are expressed in plants at a high level, are soluble and most importantly, generate strong transmission blocking activity as determined by a standard membrane feeding assay. These data demonstrate the feasibility of expressing Plasmodium antigens in a plant-based system for the economic production of a transmission blocking vaccine against malaria.
Human vaccines 01/2011; 7 Suppl:191-8. · 3.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: H5N1 avian influenza continues to be a potential pandemic threat. Several vaccine candidates based on potentially pandemic influenza strains and antiviral drugs have been tested in preclinical and clinical studies. The data obtained so far have shown some promise, but have also revealed some shortcomings with both of these approaches. We have identified and characterized an H5N1 neuraminidasespecific monoclonal antibody which specifically inhibits N1 neuraminidase activity of highly pathogenic avian influenza (HPAI) strains from clades 1 and 2. We have also shown the protective efficacy of this antibody in animal challenge models using homologous virus. Specific and effective inhibition of N1 NA could make this mAb a useful therapeutic tool in the treatment of human infection, in particular with oseltamivirand zanamivir-resistant strains of HPAI.
Human vaccines 01/2011; 7 Suppl:199-204. · 3.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: In 2009, a novel H1N1 swine influenza virus was isolated from infected humans in Mexico and the United States, and rapidly spread around the world. Another virus, a highly pathogenic avian influenza virus of the H5N1 subtype, identified by the World Health Organization as a potential pandemic threat in 1997, continues to be a significant risk. While vaccination is the preferred strategy for the prevention and control of influenza infections, the traditional egg-based approach to producing influenza vaccines does not provide sufficient capacity and adequate speed to satisfy global needs to combat newly emerging strains, seasonal or potentially pandemic. Significant efforts are underway to develop and implement new cell substrates with improved efficiency for influenza vaccine development and manufacturing. In recent years, plants have been used to produce recombinant proteins including subunit vaccines and antibodies. The main advantages of using plant systems for the production of vaccine antigens against influenza are their independence from pathogenic viruses, and cost and time efficiency. Here, we describe the large-scale production of recombinant hemagglutinin proteins from A/California/04/09 (H1N1) and A/Indonesia/05/05 (H5N1) strains of influenza virus in Nicotiana benthamiana plants, and their immunogenicity (serum hemagglutination inhibition and virus neutralizing antibodies), and safety in animal models. These results support the testing of these candidate vaccines in human volunteers and also the utility of our plant expression system for large-scale recombinant influenza vaccine production.
Human vaccines 01/2011; 7 Suppl:41-50. · 3.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: Yersinia pestis continues to pose a threat as a potential biological weapon and is recognized by public health experts as a re-emerging infectious disease. Therefore there is great interest in developing a safe and effective vaccine. Vaccines against plague containing both the Fraction 1 (F1) and V antigens of Y. pestis have shown promise in protecting animal models against pneumonic plague, the deadliest form of the disease. Here we report on a plague vaccine consisting of the F1 and LcrV antigens fused to a single carrier molecule, the thermostable enzyme lichenase from Clostridium thermocellum, and expressed in and purified from Nicotiana benthamiana plants. When administered to Cynomolgus Macaques this purified plant-produced vaccine induced high titers of serum IgG, mainly of the IgG1 isotype, against both F1 and LcrV. These immunized animals were subsequently challenged and the LcrV-F1 plant-produced vaccine conferred complete protection against aerosolized Y. pestis.
[show abstract][hide abstract] ABSTRACT: Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype have been identified as a potential pandemic threat by the World Health Organization (WHO). Since 1997, these viruses have been spreading from Asia to Europe and Africa with increasing genetic and antigenic diversities. Vaccination is the preferred strategy for the prevention and control of influenza infections and the availability of a system for the rapid engineering and production of vaccines is required in the event of an influenza pandemic. In this study, we engineered and produced recombinant hemagglutinin (HA) from A/Bar-headed Goose/Qinghai/1A/05 (clade 2.2) and A/Anhui/1/2005 (clade 2.3) in Nicotiana benthamiana plants. Immunization of mice with these plant-derived HA antigens elicited serum hemagglutination inhibition (HI) and virus neutralization (VN) antibodies. These results suggest the utility of our plant-expression system for recombinant influenza vaccine production.
[show abstract][hide abstract] ABSTRACT: The global spread of highly pathogenic avian influenza virus (H5N1 subtype) has promoted efforts to develop human vaccines against potential pandemic outbreaks. However, current platforms for influenza vaccine production are cumbersome, limited in scalability and often require the handling of live infectious virus. We describe the production of hemagglutinin from the A/Indonesia/05/05 strain of H5N1 influenza virus by transient expression in plants, and demonstrate the immunogenicity and protective efficacy of the vaccine candidate in animal models. Immunization of mice and ferrets with plant-derived hemagglutinin elicited serum hemagglutinin-inhibiting antibodies and protected the ferrets against challenge infection with a homologous virus. This demonstrates that plant-derived H5 HA is immunogenic in mice and ferrets, and can induce protective immunity against infection with highly pathogenic avian influenza virus. Plants could therefore be suitable as a platform for the rapid, large-scale production of influenza vaccines in the face of a pandemic.
[show abstract][hide abstract] ABSTRACT: Cell substrates are a key component of successful vaccine development and throughout the last several decades there has been a dramatic increase in the types of cells available for vaccine production. Nevertheless, there is a continued demand for new and innovative approaches for vaccine development and manufacturing. Recent developments involving cells of insect and plant origin are attracting considerable scientific interest. Here we review vaccine antigen production in plant-based systems as was presented by Dr. Vidadi Yusibov of Fraunhofer USA Center for Molecular Biotechnology at the IABS International Scientific Workshop on NEW CELLS FOR NEW VACCINES II that was held in Wilmington, Delaware on September 17-19, 2007.
[show abstract][hide abstract] ABSTRACT: Influenza A viruses are of major concern for public health, causing worldwide epidemics associated with high morbidity and mortality. Vaccines are critical for protection against influenza, but given the recent emergence of new strains with pandemic potential, and some limitations of the current production systems, there is a need for new approaches for vaccine development.
To demonstrate the immunogenicity and protective efficacy of plant-produced influenza antigens. Method We engineered, using influenza A/Wyoming/3/03 (H3N2) as a model virus, the stem and globular domains of hemagglutinin (HA) produced in plants as fusions to a carrier protein and used purified antigens with and without adjuvant for ferret immunization.
These plant-produced antigens were highly immunogenic and conferred complete protection against infection in the ferret challenge model. The addition of plant-produced neuraminidase was shown to enhance the immune response in ferrets.
Plants can be used as a production vehicle for vaccine development against influenza. Domains of HA can generate protective immune responses in ferrets.
Influenza and Other Respiratory Viruses 02/2008; 2(1):33-40. · 1.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: Historically, most vaccines have been based on killed or live-attenuated infectious agents. Although very successful at immunizing populations against disease, both approaches raise safety concerns and often have limited production capacity. This has resulted in increased emphasis on the development of subunit vaccines. Several recombinant systems have been considered for subunit vaccine manufacture, including plants, which offer advantages both in cost and in scale of production. We have developed a plant expression system utilizing a 'launch vector', which combines the advantageous features of standard agrobacterial binary plasmids and plant viral vectors, to achieve high-level target antigen expression in plants. As an additional feature, to aid in target expression, stability and purification, we have engineered a thermostable carrier molecule to which antigens are fused. We have applied this launch vector/carrier system to engineer and express target antigens from various pathogens, including, influenza A/Vietnam/04 (H5N1) virus.
Influenza and Other Respiratory Viruses 02/2007; 1(1):19-25. · 1.47 Impact Factor