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Section I. Mechanism of action of mRNA vaccines
The mRNA encapsulated in lipid carrier molecules is transferred to the cytoplasm by endocytosis and then released by endosomal escape. upon entry into the cytoplasm, the cellular translation mechanism is used to produce the target antigen. The ubiquitin-proteasome system then degrades the intracellular antigen into peptides which can be presented by major histocompatibility complex (MHC) class I molecules. Finally, MHC I-epitope complexes are recognised by CD8+ T cells to trigger specific immune responses. In addition, the associated antigen secreted into the extracellular compartment is taken up by antigen presenting cells (APCs), such as dendritic cells, macrophages and Langerhans cells. Following the proteolytic degradation and presentation of MHC class II molecules, the MHC II-epitope complex is recognised by CD4+ T cells to induce a CD4+-mediated immune response.
Section 2: Advantages and disadvantages of the main vaccine types, including mRNA vaccines
In general, the characteristics of an ideal vaccine for an animal infectious disease include.
(1) broad-spectrum protection against all isolates in all infected species to limit potential transmission
(2) the possibility of differentiation between infected and vaccinated animals
(3) The absence of recombination between vaccine and field strains.
(4) A robust and long-lasting immune response.
(5) Low manufacturing costs and simple administration. Therefore, new forms of vaccines are urgently needed. mRNA vaccine development offers new possibilities for the prevention and control of ASF.
Section 3. mRNA vaccine development for ASF is underway both nationally and internationally
On 18 April 2022 the American journal PORK reported that Genvax, a US company, had self-funded US$290,000 and received US$145,000 in funding from the US Food and Agriculture Research Foundation (FFAR) to develop a self-amplifying mRNA vaccine for African swine fever in collaboration with the US Department of Agriculture Plum Island Animal Disease Center (USDA-ARS-PIADC) (saRNA vaccine ( The saRNA vaccine is highly effective, safe and inexpensive, and can be rapidly deployed in the event of an outbreak; the short development cycle of saRNA also allows for rapid development of new vaccines against virus variants.
Section 4: Perspectives on mRNA vaccine development for ASF
Although only a few mRNA vaccines have been studied specifically in natural hosts for the prevention of animal infectious diseases, the success of human mRNA vaccines shows promise for mRNA vaccine development and application in veterinary medicine.
Prospects for T cell-directed mRNA vaccine development against ASFV
T cells play a central role in the cell-mediated immune response by recognising viral epitopes and directly destroying virus-infected cells. Thus, a T cell-directed vaccine consisting of immunodominant T cell epitopes of the pathogen is expected to provide an immune memory capable of preventing reinfection.
