Plant-based immunocontraceptive control of wildlife—“potentials, limitations, and possums”

Chemical Characterization, Free Radical Scavenging, and Cellular Antioxidant Properties of the Egadi Island Endemic Brassica macrocarpa Guss Leaf Extract

The genus Brassica is an important source of food in the Mediterranean diet with documented nutritional and medicinal properties. However, few studies have investigated the phytochemical composition and the biological activity of wild Sicilian taxa. Thus, we aimed to study the chemical profile and the antioxidant potential, in vitro and in LPS-stimulated RAW 264.7 cells, of a methanolic extract of leaves of wild Brassica macrocarpa Guss (B. macrocarpa) (Egadi Islands; Sicily-Italy). B. macrocarpa methanolic extract showed a large amount of glucosinolates and different phenolic compounds. It exhibited antioxidant activity in the DPPH assay and in LPS-stimulated RAW 264.7 cells, being able to reduce NO and ROS levels and NOS2 mRNA expression. Our study demonstrated that Sicilian B. macrocarpa methanolic extract, in LPS-stimulated macrophages, efficiently counteracts oxidative stress and displays radical scavenging activity. Future studies are required to identify the contribution of the single phytocomponents, to characterize the action mechanism, and to reveal possible applications in human health.

Immunogenicity and contraceptive efficacy of plant-produced putative mouse-specific contraceptive peptides

Rodent population control through contraception requires species-specific oral contraceptive vaccines. Therefore, in this study, we produced putative mouse-specific contraceptive peptides, mZP2 (from oocyte) and mIzumo1 (from sperm), in plants using Agrobacterium-mediated transient expression. Peptides were produced separately in Nicotiana benthamiana using constructs encoding antigens containing three copies of each peptide. We also determined the immunogenicity and contraceptive effects of the plant-produced antigens in female BALB/c mice. Mice immunized subcutaneously with a relatively low amount of antigen (5 µg/dose of each peptide in a mixture) showed systemic immune responses against mZP2-3 and mIzumo1-3 antigens. Moreover, the mean litter size of mice treated with the plant-produced antigens was reduced by 39% compared to that of the control mice. Notably, there was a significant negative correlation between the number of pups born and individual antibody levels against both antigens. Immunofluorescence assays demonstrated the binding of induced antibodies to the oocytes of BALB/c and wild-type mice in vivo and in vitro, respectively. Our study demonstrate the feasibility of producing small contraceptive peptides in plants that can be further used to develop oral contraceptive vaccines against mouse populations.

Anti-Inflammatory Potential of Brassicaceae-Derived Phytochemicals: In Vitro and In Vivo Evidence for a Putative Role in the Prevention and Treatment of IBD

Inflammatory bowel disease (IBD) is a group of intestinal disorders, of unknown etiology, characterized by chronic inflammation within the gut. They are gradually becoming critical because of the increasing incidence worldwide and improved diagnosis. Due to the important side effects observed during conventional therapy, natural bioactive components are now under intense investigation for the prevention and treatment of chronic illnesses. The Brassicaceae family comprises vegetables widely consumed all over the world. In recent decades, a growing body of literature has reported that extracts from the Brassicaceae family and their purified constituents have anti-inflammatory properties, which has generated interest from both the scientific community and clinicians. In this review, data from the literature are scrutinized and concisely presented demonstrating that Brassicaceae may have anti-IBD potential. The excellent biological activities of Brassicacea are widely attributable to their ability to regulate the levels of inflammatory and oxidant mediators, as well as their capacity for immunomodulatory regulation, maintenance of intestinal barrier integrity and intestinal flora balance. Possible future applications of bioactive-derived compounds from Brassicaceae for promoting intestinal health should be investigated.

Recent advances and safety issues of transgenic plant-derived vaccines

Transgenic plant-derived vaccines comprise a new type of bioreactor that combines plant genetic engineering technology with an organism's immunological response. This combination can be considered as a bioreactor that is produced by introducing foreign genes into plants that elicit special immunogenicity when introduced into animals or human beings. In comparison with traditional vaccines, plant vaccines have some significant advantages, such as low cost, greater safety, and greater effectiveness. In a number of recent studies, antigen-specific proteins have been successfully expressed in various plant tissues and have even been tested in animals and human beings. Therefore, edible vaccines of transgenic plants have a bright future. This review begins with a discussion of the immune mechanism and expression systems for transgenic plant vaccines. Then, current advances in different transgenic plant vaccines will be analyzed, including vaccines against pathogenic viruses, bacteria, and eukaryotic parasites. In view of the low expression levels for antigens in plants, high-level expression strategies of foreign protein in transgenic plants are recommended. Finally, the existing safety problems in transgenic plant vaccines were put forward will be discussed along with a number of appropriate solutions that will hopefully lead to future clinical application of edible plant vaccines.

Role of transgenic plants in agriculture and biopharming

At present, environmental degradation and the consistently growing population are two main problems on the planet earth. Fulfilling the needs of this growing population is quite difficult from the limited arable land available on the globe. Although there are legal, social and political barriers to the utilization of biotechnology, advances in this field have substantially improved agriculture and human life to a great extent. One of the vital tools of biotechnology is genetic engineering (GE) which is used to modify plants, animals and microorganisms according to desired needs. In fact, genetic engineering facilitates the transfer of desired characteristics into other plants which is not possible through conventional plant breeding. A variety of crops have been engineered for enhanced resistance to a multitude of stresses such as herbicides, insecticides, viruses and a combination of biotic and abiotic stresses in different crops including rice, mustard, maize, potato, tomato, etc. Apart from the use of GE in agriculture, it is being extensively employed to modify the plants for enhanced production of vaccines, hormones, etc. Vaccines against certain diseases are certainly available in the market, but most of them are very costly. Developing countries cannot afford the disease control through such cost-intensive vaccines. Alternatively, efforts are being made to produce edible vaccines which are cheap and have many advantages over the commercialized vaccines. Transgenic plants generated for this purpose are capable of expressing recombinant proteins including viral and bacterial antigens and antibodies. Common food plants like banana, tomato, rice, carrot, etc. have been used to produce vaccines against certain diseases like hepatitis B, cholera, HIV, etc. Thus, the up- and down-regulation of desired genes which are used for the modification of plants have a marked role in the improvement of genetic crops. In this review, we have comprehensively discussed the role of genetic engineering in generating transgenic lines/cultivars of different crops with improved nutrient quality, biofuel production, enhanced production of vaccines and antibodies, increased resistance against insects, herbicides, diseases and abiotic stresses as well as the safety measures for their commercialization.

Overview of expression of hepatitis B surface antigen in transgenic plants

Hepatitis B virus (HBV), a pathogen for chronic liver infection, afflicts more than 350 million people world-wide. The effective way to control the virus is to take HBV vaccine. Hepatitis B surface antigen (HBsAg) is an effective protective antigen suitable for vaccine development. At present, "edible" vaccine based on transgenic plants is one of the most promising directions in novel types of vaccines. HBsAg production from transgenic plants has been carried out, and the transgenic plant expression systems have developed from model plants (such as tobacco, potato and tomato) to other various plant platforms. Crude or purified extracts of transformed plants have been found to conduct immunological responses and clinical trials for hepatitis B, which gave the researches of plant-based HBsAg production a big boost. The aim of this review was to summarize the recent data about plant-based HBsAg development including molecular biology of HBsAg gene, selection of expression vector, the expression of HBsAg gene in plants, as well as corresponding immunological responses in animal models or human.

Plant production of veterinary vaccines and therapeutics

Plant-derived biologicals for use in animal health are becoming an increasingly important target for research into alternative, improved methods for disease control. Although there are no commercial products on the market yet, the development and testing of oral, plant-based vaccines is now beyond the proof-of-principle stage. Vaccines, such as those developed for porcine transmissible gastroenteritis virus, have the potential to stimulate both mucosal and systemic, as well as, lactogenic immunity as has already been seen in target animal trials. Plants are a promising production system, but they must compete with existing vaccines and protein production platforms. In addition, regulatory hurdles will need to be overcome, and industry and public acceptance of the technology are important in establishing successful products.

Research Advances on Transgenic Plant Vaccines

In recent years, with the development of genetics molecular biology and plant biotechnology, the vaccination (e.g. genetic engineering subunit vaccine, living vector vaccine, nucleic acid vaccine) programs are taking on a prosperous evolvement. In particular, the technology of the use of transgenic plants to produce human or animal therapeutic vaccines receives increasing attention. Expressing vaccine candidates in vegetables and fruits open up a new avenue for producing oral/edible vaccines. Transgenic plant vaccine disquisitions exhibit a tempting latent exploiting foreground. There are a lot of advantages for transgenic plant vaccines, such as low cost, easiness of storage, and convenient immune-inoculation. Some productions converged in edible tissues, so they can be consumed directly without isolation and purification. Up to now, many transgenic plant vaccine productions have been investigated and developed. In this review, recent advances on plant-derived recombinant protein expression systems, infectious targets, and delivery systems are presented. Some issues of high concern such as biosafety and public health are also discussed. Special attention is given to the prospects and limitations on transgenic plant vaccines.

Immunisation of the male tammar wallaby (Macropus eugenii) with spermatozoa elicits epididymal antigen-specific antibody secretion and compromised fertilisation rate

Immunocontraception has been proposed as an effective and humane means of controlling overabundant kangaroo populations in Australia. We have examined the feasibility of using a sperm-based vaccine for this purpose using a model macropod species, the tammar wallaby (Macropus eugenii). This study has demonstrated immunocontraception in a marsupial species following immunisation of males with homologous spermatozoa. Serum anti-sperm IgG titres were associated with a significant reduction in fertilisation rates following mating with superovulated female wallabies. Antigen-specific IgG penetrated the reproductive tract at the rete testis and bound spermatozoa in vivo. IgG was detected bound to the acrosome and midpiece regions of both epididymal and ejaculated spermatozoa. The absence of adverse testicular pathology and sperm movement effects suggests that contraception may have been achieved by antibody-mediated blocking of sperm surface antigens essential for fertilisation. This study demonstrates that a contraceptive vaccine targeting sperm antigens has potential for fertility control in male macropods.

Application of pharmaceutical drug delivery for biological control of the common brushtail possum in New Zealand: a review

The common brushtail possum (Trichosurus vulpecula) is the most significant vertebrate pest in New Zealand, being a major ecological threat to the indigenous biodiversity and an economic threat as a vector for bovine tuberculosis. Novel and effective strategies to reduce the population of T. vulpecula are needed urgently. Several biocontrol agents are currently being assessed and from research to date it is likely that the biocontrol agents will be peptide or protein molecules. It is not possible to administer such biocontrol agents alone because they would be degraded rapidly in the animal, especially if delivered orally. Technologies used in the pharmaceutical industry to design efficacious drug-delivery systems for humans and animals can be applied to the design of delivery systems for biocontrol agents used in wildlife management, although there are some unique challenges that must be overcome.

Genetic resistance to bovine tuberculosis in the Iberian wild boar

Bovine tuberculosis (bTB) is an important re-emerging zoonotic disease, causing major economic losses and constraining international trade of animals and their products. Despite eradication programmes, some countries continue to encounter outbreaks, mainly due to wildlife acting as primary hosts or reservoirs. While the genetic component of tuberculosis in humans and cattle is well documented, the role of genetic factors as modulators of bTB resistance remains unclear for natural populations. To address this issue, we investigated the relative contribution of host genetic variability to susceptibility to bTB infection and disease progression in wild boars from southern Spain. We found that genetic heterozygosity is an important predictor of bTB, not only modulating resistance to infection but also influencing containment of disease progression in infected individuals. Our results provide further evidence that host genetic variability plays a central role in natural populations. Testing each marker separately reveals evidence of both general and single-locus associative effects on bTB and several loci reveal high homology to regions of the genome with known immune function. Our results may prove to be crucial for understanding outbreaks of bTB in wildlife that could potentially affect domestic livestock and humans.