Alfalfa Plants (Medicago sativa L.) Expressing the 85B (MAP1609c) Antigen of Mycobacterium avium subsp. paratuberculosis Elicit Long-Lasting Immunity in Mice.

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Paratuberculosis, a contagious, untreatable, and chronic granulomatous enteritis that results in diarrhea, emaciation, and death in farmed ruminants (i.e., cattle, sheep, and goats). In this study, the Ag85B antigen from MAP was expressed in transgenic alfalfa as an attractive vaccine candidate. Agrobacterium-mediated transformation allowed the rescue of 56 putative transformed plants and transgenesis was confirmed in 19 lines by detection of the Ag85B gene (MAP1609c) by PCR. Line number 20 showed the highest Ag85B expression [840 ng Ag85B per gram of dry weight leaf tissue, 0.062% Total Soluble Protein (TSP)]. Antigenicity of the plant-made Ag85B was evidenced by its reactivity with a panel of sera from naturally MAP-infected animals, whereas immunogenicity was assessed in mice immunized by either oral or subcutaneous routes. The plant-made Ag85B antigen elicited humoral responses by the oral route when co-administered with cholera toxin as adjuvant; significant levels of anti-85B antibodies were induced in serum (IgG) and feces (IgA). Long-lasting immunity was evidenced at day 180 days post-first oral immunization. The obtained alfalfa lines expressing Ag85B constitute the first model of a plant-based vaccine targeting MAP. The initial immunogenicity assessment conducted in this study opens the path for a detailed characterization of the properties of this vaccine candidate.

Micropropagation and field performance of Yucca valida.

Yucca valida is an important potential source of steroidal saponins closely related to Yucca schidigera, the species that is commercially exploited from the wild as a source of steroidal extracts. Neither of the species has been domesticated mainly because of their slow growth and long life span before harvesting. Here, we report a micropropagation method to generate isogenic or clonal lines for plantation purposes. Seventeen clonal lines were propagated and evaluated over a period of 26 months in an experimental plantation and compared with the performance of plants from seeds. The large variability found between the plants derived from seeds is manifested in the differences observed between the different clonal lines; however, these present a much smaller internal coefficient of variation than the one observed in the population of plants derived from seeds. Some clonal lines perform in a superior manner indicating that a process of selection and cloning can generate lines of fast growing individuals for plantations that can satisfy the demand for these materials without putting a natural resource at risk.