(Nanowerk Highlights) Preventing animal epidemics is very important because they can have a direct impact on food and nutrition security, the economy, and can cause outbreaks of zoonotic diseases that threaten human health. The spread of infectious diseases in animals creates a significant economic loss for the aquaculture industry. For example, an outbreak of highly pathogenic avian flu from 2014 to 2015 affected an estimated 50 million poultry, causing nearly US$3.3 billion in losses to the United States economy.
The epidemic could also significantly reduce the availability of animal products such as meat, milk and eggs, which are the main sources of protein and other essential nutrients for humans. For example, an outbreak of African Swine Fever in China in 2018 led to the culling of millions of pigs, causing a significant shortage of pork, a staple food in China.
In addition, some animal infections are zoonotic and can be transmitted to humans, accounting for more than 60% of human infectious diseases and pose a major threat to global health. This disease can cause a serious public health crisis. For example, the 2009 H1N1 influenza pandemic originating in pigs resulted in hundreds of thousands of human deaths worldwide. More recently, the COVID-19 pandemic, which is believed to have originated in wildlife, has caused millions of deaths globally, highlighting the potential for animal diseases to jump to humans and cause widespread disease.
In addition, animal epidemics can have a devastating impact on wildlife populations and biodiversity. Diseases can spread quickly among wild animals, causing mass deaths that can affect the balance of ecosystems. For example, white nose syndrome in bats, caused by a fungus, has caused the deaths of millions of bats in North America, raising concerns about the potential impact on the populations of insects bats help control.
Limitations of Traditional and Adjuvant Vaccines
Traditional vaccines and adjuvants, although important in disease prevention, have limitations. Attenuated vaccines often have poor immunogenicity and require repeated vaccinations, whereas live attenuated vaccines pose a risk of return of the pathogen. Subunit vaccines, which were developed to improve vaccine safety and tolerability, are less immunogenic than whole pathogens.
Nucleic acid vaccines, a new generation of vaccines, have been studied extensively for their safety, large-scale reproducibility, and ability to induce humoral and cellular immune responses. However, inefficient delivery and low transfection efficiency of naked nucleic acids pose challenges to the development of these vaccines.
In the face of increasing epidemics and the urgent need for effective prevention strategies, a recent scientific review paper on Advanced Functional Materials (“Nanotechnology Advancement Toward Vaccine Development Against Animal Infectious Diseases”) offers a new perspective. The authors investigate the potential of nanotechnology in the development of vaccines for animal infectious diseases, emphasizing its role in overcoming the limitations of traditional vaccines and adjuvants.
The Role of Nanotechnology in Vaccine Development
Nanotechnology has emerged as a revolutionary tool in vaccine development, offering unique physicochemical characteristics that provide new prospects for animal vaccine development. Various nanoparticles (NPs) have been developed to circumvent the limitations of traditional vaccines and adjuvants, offering more benefits and broad application potential in animal vaccine development.
On in vitro formulation level, nanoparticles improve antigenic immunogenicity and stability. They provide a scaffold for the repeated display of antigen, allowing multiple antigen copies to be distributed on the surface in a highly ordered manner. This facilitates the maintenance of antigen conformation and provides superior immunogenicity. The insertion of cobalt porphyrin-phospholipid (CoPoP) into the lipid bilayer, for example, allows polyhistidine-tagged recombinant antigens to be anchored to the liposome surface, thereby increasing the immunogenicity of the vaccine.
Nanoparticles also play an important role in increasing the stability of vaccines. They protect antigens from enzymatic degradation, help them pass through various biological barriers, and enhance in vitro vaccine stability. This breaks the dependence on the cold chain, extends the storage period, and reduces the antigen dosage, greatly reducing the cost of preparation, storage and transportation.
In addition to increasing immunogenicity and stability, nanoparticles can also be used as adjuvants. They can be loaded with immunostimulating adjuvants, such as toll-like receptor (TLR) agonists and cytokines, to increase adjuvant delivery efficiency and activity. Compared with traditional adjuvants, nanoparticle-based adjuvants provide more benefits and have broad application potential in the development of animal vaccines.
On life level of immunity, nanoparticles facilitate key stages in the immune process from the start of vaccination of different routes to the induction of the eventual immune response. They facilitate antigen delivery, cellular uptake, antigen presentation, and lymphocyte activation, contributing to a more robust and effective immune response.
However, the authors also highlight the need for further research on the distribution and metabolic behavior of nanoparticles after vaccination via different routes. The impact of nanomaterial degradation on vaccine stability also needs to be studied further. Despite these challenges, rational vaccine formulation design based on nanotechnology offers the possibility of maintaining antigen conformation, providing long-term protection and resisting viral mutations.
Biosafety Risks Associated with Use of Nanoparticles in Animals
The authors emphasize that while nanoparticles offer significant advantages in vaccine development, it is critical to consider and evaluate their potential safety risks.
The toxicity of nanoparticles is mainly determined by their size, composition, method of synthesis, and dosage. For example, gold nanoparticles exert size-dependent toxic effects on cells, including oxidative stress, accumulation of autophagosomes, and lysosomal disruption. In addition, bare gold nanoparticles show high levels of aggregation and accumulation in the liver and spleen, where they cannot be metabolized and can cause irreversible toxic effects. To improve the distribution of gold nanoparticles, smaller sized GSH modified gold nanoclusters have been developed.
The authors also highlighted the potential developmental toxicity of highly soluble and functionalized single-walled carbon nanotubes (SWCNT) to newly hatched larvae, emphasizing the need to consider and evaluate the safety of chronic exposure to carbon nanotubes in aquatic environments.
Biodegradation concerns associated with nanoparticles have led to the use of degradable nanoparticles in animal vaccines. Biodegradable polymer nanoparticles, for example, have attracted widespread attention. However, the authors note that the potential safety risks posed by nanoparticles during veterinary vaccine development need to be considered. Efforts are underway to develop biocompatible nanoparticles by exploring biodegradable nanomaterials and improving synthesis processes without the use of toxic solvents.
In conclusion, while there are challenges to be overcome, the potential of nanotechnology in the development of animal infectious disease vaccines is enormous. With continued research and development, nanotechnology can revolutionize the field of veterinary vaccine development, offering more effective strategies in fighting animal infectious diseases, ultimately contributing to the harmonious coexistence of humans and animals.
– Michael is the author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: A Small Future And
Nanoengineering: Skills and Tools for Making Technology Invisible
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