Molecular farming: Expanding the field of edible vaccines for sustainable fish aquaculture

Abstract

Vaccines represent one of the most promising strategies for mitigating economic losses imposed by infectious diseases to global aquaculture. While the majority of commercial vaccines employ injection as the main route of delivery, a substantial body of research explores other avenues for the stimulation of protective immunity. Oral vaccines, representing the most favourable and convenient solution for the aquaculture industry, have been at the forefront of scientific interest for the last couple of decades. The orchestrated effort resulted in identifying the main roadblocks on the path to an ideal edible vaccine and provided several ingenious solutions improving the activation of immunity, ensuring the stability of administered antigens and their uptake upon the passage through the stomach. In the presented review, we describe advances in the available knowledge of the processes prerequisite for developing protective mucosal vaccines and focus readers' attention on the untapped potential of plant‐based production systems in this effort. We propose that these approaches not only meet production demands but also fulfil all requirements of an oral vaccine, addressing all the obstacles, previously solved via separate strategies, in one platform. Thus, combined with the available knowledge of molecular adjuvants and produced for a fraction of the cost, plant‐based production, so‐called molecular farming, is an ideal candidate for vaccine development, paving the road to sustainable aquaculture.

The Plant Viruses and Molecular Farming: How Beneficial They Might Be for Human and Animal Health?

“…The possible cross-contamination of nearby growing food crops with recombinant genes stifled the efforts to produce vaccines in edible crops [ 18 ]. Efforts then turned to microalgae and certain plant species, which are generally recognized as safe (GRAS) by the FDA, resurrecting the hope that oral vaccines can be produced in photosynthetic organisms without processing [ 234 , 235 , 236 ]. Edible vaccines can stimulate mucosal immunity and might be the solution for reducing zoonotic diseases distributed by wild animals and an efficient method for vaccinating large groups of animals, especially aquatic animals [ 228 , 237 , 238 , 239 ].…”

Current status and development prospects of aquatic vaccines

“…and viruses ( 288 ). Compared to traditional vaccines, biocarrier vaccines are more effective at presenting antigens and antigen selectivity ( 205 , 289 ). Different vector vaccines can be prepared according to different antigen properties, or insert multiple exogenous antigens into the same vector vaccine to achieve the effect of one vaccine against several diseases.…”

“…Aquatic vaccines made from edible plants hold great promise for oral vaccines in aquaculture, as such transgenic plants can be directly crushed and added to feeds as additives to trigger a particular immune response. The best plants for edible vaccines include vegetables and fruits that have been shown to generate substantial amounts of exogenous proteins, such as lettuce, tomatoes, potatoes, rice, and cabbage ( 204 , 205 ). According to a study, feeding striped bream transgenic rice healing tissue with recombinantly expressed Iridovirus coat protein (MCP) dramatically increased the fish’s disease resistance ( 206 ).…”

Plant‐based feed additives in Cyprinus carpio aquaculture

“…A guide for methodology can be found in a previous study 161 . This could provide valuable insights onto long‐term utility of PFAs in fed carp aquaculture, as development of oral fish vaccines for training immunity is a cumbersome job, 164 or sometimes lack industrial motivation for low value carp aquaculture. One previous review discussed how plant models can be used to develop fish vaccine, 164 we opine certain components in PFAs could indirectly contribute too.…”

“…A guide for methodology can be found in a previous study. 161 This could provide valuable insights onto long-term utility of PFAs in fed carp aquaculture, as development of oral fish vaccines for training immunity is a cumbersome job, 164 or sometimes lack industrial motivation for low value T A B L E 5 List of potential circular-origin feed additives that can be tested in carp diets. carp aquaculture.…”