Current status of veterinary vaccines

Additional Insertion of gC Gene Triggers Better Immune Efficacy of TK/gI/gE-Deleted Pseudorabies Virus in Mice

In recent years, pseudorabies virus (PRV) variants have resulted in an epidemic in swine herds and huge economic losses in China. Therefore, it is essential to develop an efficacious vaccine against the spread of PRV variants. Here, the triple-gene-deletion virus and the triple-gene-deletion plus gC virus were constructed by homologous recombination (HR). And then, their growth capacity, proliferation ability, and immune efficacy were evaluated. The results showed that the growth kinetics of the recombinant viruses were similar to those of the parental strain PRV-AH. Compared with the triple-gene-deletion virus group, the more dominant level of neutralizing antibody (NA) can be induced in the triple-gene-deletion plus gC virus group with the same 106.0 TCID50 dose after 4 and 6 weeks post-initial immunization (PII) (p < 0.0001). In addition, the antibody titers in mice immunized with the triple-gene-deletion plus gC virus were significantly higher than those immunized with triple-gene deletion virus with the same 105.0 TCID50 dose after 6 weeks PII (p < 0.001). More importantly, in the triple-gene-deletion plus gC virus group with 105.0 TCID50, the level of NA was close to that in the triple-gene deletion virus group with 106.0 TCID50 at 6 weeks PII. Meanwhile, the cytokines IL-4 and IFN-γ in sera were tested by enzyme-linked immunosorbent assay (ELISA) in each group. The highest level of IL-4 or IFN-γ was also elicited in the triple-gene deletion plus gC virus group at a dose of 106.0 TCID50. After challenge with PRV-AH, the survival rates of the triple-gene deletion plus gC virus immunized groups were higher than those of other groups. In immunized groups with 105.0 TCID50, the survival rate shows a significant difference between the triple-gene deletion plus gC virus group (75%, 6/8) and the triple-gene deletion virus group (12.5%, 1/8). In general, the immune efficacy of the PRV TK/gI/gE-deleted virus can be increased with additional gC insertion in mice, which has potential for developing an attenuated vaccine candidate for PRV control.

Mass spectrometry study on SARS-CoV-2 recombinant vaccine with comprehensive separation techniques to characterize complex heterogeneity

SARS-CoV-2, the causative agent of COVID-19, has imposed a major public health threat, which needs effective therapeutics and vaccination strategies. Several potential candidate vaccines being rapidly developed are in clinical evaluation and recombinant vaccine has gained much attention thanks to its potential for greater response predictability, improved efficacy, rapid development and reduced side effects. Recombinant vaccines are designed and manufactured using bacterial, yeast cells or mammalian cells. A small piece of DNA is taken from the virus or bacterium against which we want to protect and inserted into the manufacturing cells. Due to the extremely complex heterogeneity of SARS-CoV-2 recombinant vaccine, single technology platform cannot achieve thorough and accurate characterization of such difficult proteins so integrating comprehensive technologies is essential. This study illustrates an innovative workflow employing multiple separation techniques tandem high-resolution mass spectrometry for comprehensive and in-depth characterization of SARS-CoV-2 recombinant vaccine, including ultra-high performance liquid chromatography (UHPLC), ion exchange chromatography (IEX) and imaged capillary isoelectric focusing (icIEF). The integrated methodology focuses on the importance of cutting-edge icIEF-MS online coupling and icIEF fractionation applied to revealing the heterogeneity secret of SARS-CoV-2 recombinant vaccine.

Piloting delivery of PfSPZ vaccines for malaria through a cryogenic vaccine cold chain to travel and military medicine clinics

BACKGROUND

PfSPZ vaccines comprising Plasmodium falciparum (Pf) sporozoites (SPZ) have demonstrated > 90% protection against variant Pf malaria infections for at least 12 weeks; they are the only vaccines with the level of efficacy necessary to protect travellers. PfSPZ are eukaryotic cells stabilized by cryopreservation and distributed using a cryogenic (below -150 °C) cold chain. The Ebola vaccine and mRNA vaccines against SARS-CoV-2 pioneered uptake of vaccines requiring non-standard ultra-low temperature cold chains. The cryogenic cold chain using liquid nitrogen (LN2) vapour phase (LNVP) cryoshippers, is simpler, more efficient than -80, -20 or 2-8 °C cold chains, and does not use electricity. This study was conducted to evaluate implementation and integration of a cryogenically distributed vaccine at travel and military immunization clinics.

METHODS

We conducted sequential 28-day studies evaluating vaccine shipping, storage, maintenance and accession at two US military and two civilian travel health/immunization clinics. In each clinic, personnel were trained in equipment use, procurement and handling of LN2, temperature monitoring and inventory record keeping by in-person or video instruction.

RESULTS

Sites required 2-4 h/person for two persons to assimilate and develop the expertise to manage vaccine storage and LNVP operations. LN2 for recharging cryoshippers was delivered every 1-2 weeks. Vaccine ordering, receipt, storage and inventory control was conducted effectively. Simulated single dose vaccine cryovial retrieval and thawing were performed successfully in different travel clinic settings. Continuous temperature monitoring at each site was maintained with only one short excursion above -150 °C (-145 °C) through shipping, use and reverse logistics. Staff, during and at study conclusion, provided feedback that has been incorporated into our models for cold chain logistics.

CONCLUSIONS

These studies demonstrated that the training in delivery, storage, administration and integration of PfSPZ vaccines can be successfully managed in different immunization clinic settings for travellers and military personnel.

Antiviral effect of palmatine against infectious bronchitis virus through regulation of NF-κB/IRF7/JAK-STAT signalling pathway and apoptosis

1. Infectious bronchitis virus (IBV), a gamma-coronavirus, can infect chickens of all ages and leads to an acute contact respiratory infection. This study evaluated the anti-viral activity of palmatine, a natural non-flavonoid alkaloid, against IBV in chicken embryo kidney (CEK) cells.2. The half toxic concentration (CC50) of palmatine was 672.92 μM, the half inhibitory concentration (IC50) of palmatine against IBV was 7.76 μM and the selection index (SI) was 86.74.3. Mode of action assay showed that palmatine was able to directly inactivate IBV and inhibited the adsorption, penetration and intracellular replication of IBV.4. Palmatine significantly upregulated TRAF6, TAB1 and IKK-β compared with the IBV-infected group, leading to the increased expressions of pro-inflammatory cytokines IL-1β and TNF-α in the downstream NF-κB signalling pathway.5. Palmatine significantly up-regulated the levels of MDA5, MAVS, IRF7, IFN-α and IFN-β in the IRF7 pathway, inducing type I interferon production. It up-regulated the expression of 2'5'-oligoadenylate synthase (OAS) in the JAK-STAT pathway.6. IBV infection induced cell apoptosis and palmatine-treatment delayed the process of apoptosis by regulation of the expression of apoptosis-related genes (BAX, BCL-2, CASPASE-3 and CASPASE-8).7. Palmatine could exert anti-IBV activity through regulation of NF-κB/IRF7/JAK-STAT signalling pathways and apoptosis, providing a theoretical basis for the utilisation of palmatine to treat IBV infection.

Adoption of veterinary vaccines, determining factors, and barriers in Southwest Ethiopia: Implications for livestock health and disease management strategies

In Ethiopia, the use of veterinary vaccines to control animal diseases is an effective strategy. A study conducted in Southwest Ethiopia from October 2020 to October 2021 aimed to determine the adoption level of veterinary vaccines and factors affecting their use. The study used multistage random sampling to select districts and interviewed 476 farmers who had either adopted or not adopted the vaccines. The study found that certain diseases should be prioritized for vaccination to safeguard the health of cattle, sheep, goats, and poultry. These include anthrax (19.12 %), blackleg (17.65 %), foot and mouth disease (10.50 %), and lumpy skin disease (8.82 %) in cattle, and pasteurellosis (18.07 %), contagious caprine pleuropneumonia (15.97 %), peste des petits ruminants (14.15 %), and Orf (13.45 %) in sheep and goats. Newcastle disease (21.85 %), infectious bursal disease (19.33 %), and coccidiosis (17.02 %) were identified as high-priority diseases for flock health. Overall, 30.7 % of farmers were adopters of veterinary vaccines, while 69.3 % were non-adopters. The study identified several factors that influence the likelihood of adopting veterinary vaccines, including breed type (OR = 9.1, p < 0.0001), production size (OR = 9.7, p < 0.0001), production type (OR = 2.7, p < 0.0001), and farm location (OR = 9.8, p = 0.001). Common barriers to vaccination included a lack of disease knowledge, high vaccine costs, limited vaccine availability, and administration difficulties. Insights from the study can guide strategies for promoting veterinary vaccine adoption in Ethiopia. Stakeholders should pay attention to these findings since vaccine use is crucial for controlling animal diseases, enhancing animal health, and preventing economic losses. Further research is needed to investigate factors affecting enhanced veterinary vaccine adoption.

Applications and Potentials of a Silk Fibroin Nanoparticle Delivery System in Animal Husbandry

Silk fibroin (SF), a unique natural polymeric fibrous protein extracted from Bombyx mori cocoons, accounts for approximately 75% of the total mass of silk. It has great application prospects due to its outstanding biocompatibility, biodegradability, low immunogenicity, and mechanical stability. Additionally, it is non-toxic and environmentally friendly. Nanoparticle delivery systems constructed with SF can improve the bioavailability of the carriers, increase the loading rates, control the release behavior of the deliverables, and enhance their action efficiencies. Animal husbandry is an integral part of agriculture and plays a vital role in the development of the rural economy. However, the pillar industry experiences a lot of difficulties, like drug abuse while treating major animal diseases, and serious environmental pollution, restricting sustainable development. Interestingly, the limited use cases of silk fibroin nanoparticle (SF NP) delivery systems in animal husbandry, such as veterinary vaccines and feed additives, have shown great promise. This paper first reviews the SF NP delivery system with regard to its advantages, disadvantages, and applications. Moreover, we describe the application status and developmental prospects of SF NP delivery systems to provide theoretical references for further development in livestock production and promote the high-quality and healthy development of animal husbandry.

Canine distemper virus (CDV)-neutralizing activities of an anti-CDV canine-derived single-chain variable antibody fragment 4-15 (scFv 4-15) screened by phage display technology

Canine distemper virus (CDV) is a highly contagious pathogen that causes severe diarrhea, fever and vomiting in domestic dogs, posing a serious threat to the dog breeding industry. Currently, there are no effective therapeutic agents for emergency treatment despite the availability of vaccines against CDV infection. Single-chain fragment variable (scFv) antibody has been demonstrated to effectively inhibit virus infections, suggesting a potential candidate as a therapeutic agent for canine distemper. In this study, a phage-displayed scFv library was constructed from the peripheral blood lymphocytes of dog immunized intramuscularly with live-attenuated CDV vaccine, and was subjected to four rounds of pannings against CDV. Subsequent indirect enzyme-linked immunosorbent assay screening revealed high-affinity scFv antibodies specific to CDV, and indirect immunofluorescence assay screening revealed CDV-neutralizing activity of scFv antibodies. Our results showed that a scFv antibody 4-15 (scFv 4-15) with high-affinity binding to CDV and neutralizing activity against CDV was obtained, which displayed effective therapeutic potential in vivo for dogs challenged with a lethal dose of CDV. Conclusively, the scFv 4-15 with high-affinity binding and neutralizing activity to CDV that was obtained by phage display technology provides a promising candidate for the therapeutic agents against CDV infection.

Can the Revolution in mRNA-Based Vaccine Technologies Solve the Intractable Health Issues of Current Ruminant Production Systems?

To achieve the World Health Organization's global Sustainable Development Goals, increased production of high-quality protein for human consumption is required while minimizing, ideally reducing, environmental impacts. One way to achieve these goals is to address losses within current livestock production systems. Infectious diseases are key limiters of edible protein production, affecting both quantity and quality. In addition, some of these diseases are zoonotic threats and potential contributors to the emergence of antimicrobial resistance. Vaccination has proven to be highly successful in controlling and even eliminating several livestock diseases of economic importance. However, many livestock diseases, both existing and emerging, have proven to be recalcitrant targets for conventional vaccination technologies. The threat posed by the COVID-19 pandemic resulted in unprecedented global investment in vaccine technologies to accelerate the development of safe and efficacious vaccines. While several vaccination platforms emerged as front runners to meet this challenge, the clear winner is mRNA-based vaccination. The challenge now is for livestock industries and relevant stakeholders to harness these rapid advances in vaccination to address key diseases affecting livestock production. This review examines the key features of mRNA vaccines, as this technology has the potential to control infectious diseases of importance to livestock production that have proven otherwise difficult to control using conventional approaches. This review focuses on the challenging diseases of ruminants due to their importance in global protein production. Overall, the current literature suggests that, while mRNA vaccines have the potential to address challenges in veterinary medicine, further developments are likely to be required for this promise to be realized for ruminant and other livestock species.

Effect of dexamethasone on antibody response of horses to vaccination with a combined equine influenza virus and equine herpesvirus-1 vaccine

BACKGROUND

Dexamethasone is routinely administered to horses but its effect on the antibody response to a commercial EIV/EHV vaccine is unclear.

HYPOTHESIS

Horses receiving dexamethasone will have lower postvaccination antibody levels against EIV and EHV-1 than vaccinated controls.

ANIMALS

Fifty-five healthy adult research horses.

METHODS

Randomized cohort study. Control (no vaccine, group 1), vaccination only (EIV/EHV-1/EHV-4, Prestige 2, Merck Animal Health, group 2), vaccination and concurrent single intravenous dose of dexamethasone (approximately .05 mg/kg, group 3), vaccination and 3 intravenous doses of dexamethasone at 24 hours intervals (group 4). Serum SAA levels were measured on day 1 and day 3. Antibody levels against EIV (hemagglutination inhibition assay, Kentucky 2014 antigen) and EHV-1 (multiplex ELISA targeting total IgG and IgG 4/7) were measured on day 1 and day 30.

RESULTS

Significantly increased mean antibody titers after vaccination were only noted against EIV and only after the vaccination alone (n = 14, prevaccine mean [prvm] 166.9, SD 259.6, 95% CI 16.95-316.8; postvaccine mean [povm] 249.1, SD 257.2, 95% confidence interval [CI] 100.6-397.6, P = .02) and the single dose dexamethasone (n = 14, prvm 93.14, SD 72.2, CI 51.45-134.8; povm 185.1, SD 118, CI 116.7-253.6, P = .01), but not after multiple doses of dexamethasone (n = 14, prvm 194.3, SD 258.3, CI 45.16-343.4; povm 240.0, SD 235.7, CI 103.9-376.1, P > .05).

CONCLUSION

The effect of dexamethasone on the postvaccine antibody response varies depending on the dosing frequency and the antigen-specific antibody type.

Advancements in Vaccine Adjuvants: The Journey from Alum to Nano Formulations

Vaccination is a groundbreaking approach in preventing and controlling infectious diseases. However, the effectiveness of vaccines can be greatly enhanced by the inclusion of adjuvants, which are substances that potentiate and modulate the immune response. This review is based on extensive searches in reputable databases such as Web of Science, PubMed, EMBASE, Scopus, and Google Scholar. The goal of this review is to provide a thorough analysis of the advances in the field of adjuvant research, to trace the evolution, and to understand the effects of the various adjuvants. Historically, alum was the pioneer in the field of adjuvants because it was the first to be approved for use in humans. It served as the foundation for subsequent research and innovation in the field. As science progressed, research shifted to identifying and exploiting the potential of newer adjuvants. One important area of interest is nano formulations. These advanced adjuvants have special properties that can be tailored to enhance the immune response to vaccines. The transition from traditional alum-based adjuvants to nano formulations is indicative of the dynamism and potential of vaccine research. Innovations in adjuvant research, particularly the development of nano formulations, are a promising step toward improving vaccine efficacy and safety. These advances have the potential to redefine the boundaries of vaccination and potentially expand the range of diseases that can be addressed with this approach. There is an optimistic view of the future in which improved vaccine formulations will contribute significantly to improving global health outcomes.

Alternatives to antibiotics in veterinary medicine: considerations for the management of Johne's disease

Antibiotic resistance has become a major health concern globally, with current predictions expecting deaths related to resistant infections to surpass those of cancer by 2050. Major efforts are being undertaken to develop derivative and novel alternatives to current antibiotic therapies in human medicine. What appears to be lacking however, are similar efforts into researching the application of those alternatives, such as (bacterio)phage therapy, in veterinary contexts. Agriculture is still undoubtedly the most prominent consumer of antibiotics, with up to 70% of annual antibiotic usage attributed to this sector, despite policies to reduce their use in food animals. This not only increases the risk of resistant infections spreading from farm to community but also the risk that animals may acquire species-specific infections that subvert treatment. While these diseases may not directly affect human welfare, they greatly affect the profit margin of industries reliant on livestock due to the cost of treatments and (more frequently) the losses associated with animal death. This means actively combatting animal infection not only benefits animal welfare but also global economies. In particular, targeting recurring or chronic conditions associated with certain livestock has the potential to greatly reduce financial losses. This can be achieved by developing novel diagnostics to quickly identify ill animals alongside the design of novel therapies. To explore this concept further, this review employs Johne's disease, a chronic gastroenteritis condition that affects ruminants, as a case study to exemplify the benefits of rapid diagnostics and effective treatment of chronic disease, with particular regard to the diagnostic and therapeutic potential of phage.

Effect of oral vitamin A supplementation on host immune response to infectious bronchitis virus infection in specific pathogen-free chicken

Vitamin A is a fat-soluble vitamin that is a crucial mediator of the immune system. In this study, we evaluated the effect of oral vitamin A supplementation on host immune responses to infectious bronchitis virus (IBV) infection in chickens. Forty 1-day-old specific pathogen-free (SPF) chickens were fed a basal diet and randomly divided into 2 groups (n = 20 birds per group). Chickens in the experimental group were treated orally with vitamin A (dissolved in 0.1 mL soybean oil, at a dose of 8,000 IU per kg diet) daily. Birds in the control group were orally administered 0.1 mL soybean oil without vitamin A until 21 d of age. On d 21 after birth, all chickens were infected with 0.1 mL of 10^6.5 50% median embryo infectious dose of a pathogenic IBV strain (CK/CH/LDL/091022) by intraocular and intranasal routes. The results demonstrated that oral vitamin A supplementation did not affect the clinical course of disease and growth performance of SPF chickens. However, vitamin A supplementation increased the IBV-specific IgG serum levels and decreased the viral load in some tissues of IBV-infected chickens. In addition, the results demonstrated that vitamin A supplementation decreased the expression levels of most immune-related molecules in some tissues of IBV-infected chickens. Vitamin A supplementation decreased the mRNA expression levels of some avian β-defensins (AvBD2, 3, 6, 7, 11, and 13) and increased the expression levels of AvBD9 and AvBD12 in some tissues of IBV-infected chickens. Similarly, vitamin A supplementation decreased the mRNA expression levels of some cytokines (interferon-γ, interleukin-1β [IL-1β], and IL-6) and increased the mRNA expression levels of IL-2 in some tissues of IBV-infected chickens. Furthermore, vitamin A supplementation decreased the mRNA expression levels of myeloid differentiation primary response protein 88, nuclear factor-κB p65, toll-like receptor 3, toll-like receptor 7, and CD4. In summary, the present study suggests that vitamin A supplementation enhances the immune function of SPF chickens against IBV infection by inhibiting viral replication, increasing the IBV-specific antibody titer, and suppressing the excessive inflammatory responses to IBV infection.

Immunogenicity of Different Types of Adjuvants and Nano-Adjuvants in Veterinary Vaccines: A Comprehensive Review

Vaccination is the best way to prevent and reduce the damage caused by infectious diseases in animals and humans. So, several vaccines are used for prophylactic purposes before the pathogen infects, while therapeutic vaccines strengthen the immune system after infection with the pathogen. Adjuvants are molecules, compounds, or macromolecules that enhance non-specific immunity and, in collaboration with antigen(s), can improve the body's immune responses and change the type of immune response. The potential and toxicity of adjuvants must be balanced to provide the safest stimulation with the fewest side effects. In order to overcome the limitations of adjuvants and the effective and controlled delivery of antigens, attention has been drawn to nano-carriers that can be a promising platform for better presenting and stimulating the immune system. Some studies show that nanoparticles have a more remarkable ability to act as adjuvants than microparticles. Because nano-adjuvants inactively target antigen-presenting cells (APCs) and change their chemical surface, nanoparticles also perform better in targeted antigen delivery because they cross biological barriers more easily. We collected and reviewed various types of nano-adjuvants with their specific roles in immunogenicity as a prominent strategy used in veterinary vaccines in this paper.

Rational Design of Live-Attenuated Vaccines against Genome-Reduced Pathogens

To develop safe and highly effective live vaccines, rational vaccine design is necessary. Here, we sought a simple approach to rationally develop a safe attenuated vaccine against the genome-reduced pathogen Erysipelothrix rhusiopathiae. We examined the mRNA expression of all conserved amino acid biosynthetic genes remaining in the genome after the reductive evolution of E. rhusiopathiae. Reverse transcription-quantitative PCR (qRT-PCR) analysis revealed that half of the 14 genes examined were upregulated during the infection of murine J774A.1 macrophages. Gene deletion was possible only for three proline biosynthesis genes, proB, proA, and proC, the last of which was upregulated 29-fold during infection. Five mutants bearing an in-frame deletion of one (ΔproB, ΔproA, or ΔproC mutant), two (ΔproBA mutant), or three (ΔproBAC mutant) genes exhibited attenuated growth during J774A.1 infection, and the attenuation and vaccine efficacy of these mutants were confirmed in mice and pigs. Thus, for the rational design of live vaccines against genome-reduced bacteria, the selective targeting of genes that escaped chromosomal deletions during evolution may be a simple approach for identifying genes which are specifically upregulated during infection. IMPORTANCE Identification of bacterial genes that are specifically upregulated during infection can lead to the rational construction of live vaccines. For this purpose, genome-based approaches, including DNA microarray analysis and IVET (in vivo expression technology), have been used so far; however, these methods can become laborious and time-consuming. In this study, we used a simple in silico approach and showed that in genome-reduced bacteria, the genes which evolutionarily remained conserved for metabolic adaptations during infection may be the best targets for the deletion and construction of live vaccines.

A Vaccine Targeting Ovine Herpesvirus 2 Glycoprotein B Protects against Sheep-Associated Malignant Catarrhal Fever

Malignant catarrhal fever (MCF) is a complex and often fatal disease of ungulates. Effective vaccines are needed to avoid MCF outbreaks and mitigate losses. This study aimed to evaluate a sheep-associated MCF (SA-MCF) vaccine candidate targeting ovine herpesvirus 2 (OvHV-2) glycoprotein B (gB). Rabbits were used as a laboratory animal model to test the safety, immunogenicity, and protective efficacy of a chimeric virus consisting of a recombinant, non-pathogenic strain of alcelaphine herpesvirus-1 encoding OvHV-2 ORF8 to express gB (AlHV-1^∆ORF73/OvHV-2-ORF8). Viral-vectored immunizations were performed by using the AlHV-1^∆ORF73/OvHV-2-ORF8 chimera alone or as a DNA prime (OvHV-2-ORF8)-virus boost regimen. The viral vector was inoculated by intravenous or intramuscular routes and the DNA was delivered by intradermal shots using a gene gun. The vaccine candidates were deemed safe as no clinical signs were observed following any of the immunizations. Anti-OvHV-2 gB antibodies with neutralizing activity were induced by all immunogens. At three weeks post-final immunization, all animals were challenged intranasally with a lethal dose of OvHV-2. MCF protection rates ranging from 66.7% to 71.4% were observed in vaccinated rabbits, while all mock-vaccinated animals developed the disease. The significant protective efficacy obtained with the vaccine platforms tested in this study encourages further trials in relevant livestock species, such as cattle and bison.

Improved safety profile of inactivated Neethling strain of the Lumpy Skin Disease Vaccine

The Lumpy Skin Disease Virus (LSDV) Neethling vaccine strains have been used for decades for prophylactic immunization of domestic ruminants against the disease. Commercial products against Lumpy skin disease are supplied as live attenuated vaccines and often are associated with adverse reactions warranting studies towards development of safe and efficacious vaccine alternatives. The present study was designed to investigate the ability of Montanide™ Gel 01 PR adjuvanted inactivated Neethling vaccine strain of the lumpy skin disease to induce immune response in rabbits. Complete virus inactivation was achieved following treatment of live vaccine strain with binary ethyleneimine (BEI) at 2 mM final concentration. Inactivated virus antigen, formulated with Montanide™ Gel 01 was injected at 1,00E + 05 and 1,00E + 06 TCID₅₀ per dose in rabbits. The second injection with same vaccine dosages was administered 21 days after the primary vaccination. Rabbits that received a 1,00E + 05 TCID₅₀/dose of inactivated LSDV vaccine formulation induced maximum neutralizing antibody titres on day 13 post second vaccinations. Rabbits vaccinated and prime boosted with the 1,00E + 06 TCID₅₀/dose of inactivated LSDV vaccine formulation, induced neutralizing antibody titres on day 14 after first vaccination. The maximum antibody titres for the 1,00E + 06 TCID₅₀/dose of the inactivated LSDV vaccine formulation was obtained on day 35 post vaccination. The 1,00E + 06 TCID₅₀ dose of the inactivated LSDV vaccine Montanide™ Gel-01 PR formulation induced higher neutralizing antibodies. The Montanide^TM Gel-01 PR offers safer profile to oil adjuvants and can be developed further to protect target animals against LSDV in non-endemic areas.

Oral vaccination for sustainable disease prevention in aquaculture-an encapsulation approach

The prevalence of infectious diseases in the aquaculture industry and a limited number of safe and effective oral vaccines has imposed a challenge not only for fish immunity but also a threat to human health. The availability of fish oral vaccines has expanded recently, but little is known about how well they work and how they affect the immune system. The unsatisfactory efficacy of existing oral vaccinations is partly attributable to the antigen degradation in the adverse gastrointestinal environment of fishes, the highly tolerogenic gut environment, and inferior vaccine formulation. To overcome such challenges in designing: an easier, cost-efficient, and effective vaccination method, several encapsulation methods are being adopted to safeguard antigens from the intestinal atmosphere for their immunogenic functions. Oral vaccination is easily degraded by gastric acids and enzymes before reaching the immunological site; however, this issue can be solved by encapsulating antigens in poly-biodegradable nanoparticles, transgenic designed bacteria, plant systems, and live feeds. To enhance the immunological impact, each antigen delivery method operates at a different level. Utilizing nanotechnology, it has been possible to regulate vaccination parameters, target particular cells, and lower the antigen dosage with potent nanomaterials such as chitosan, poly D,L-lactic-co-glycolic acid (PLGA) as vaccine carriers. Live feeds such as Artemia salina can be utilized as bio-carrier, owing to their appropriate size and non-filter feed system, through a process called bio-encapsulation. It ensures the protection of antigens over the fish intestine and ensures complete uptake by immune cells in the hindgut for increased immune response. This review comprises recent advances in oral vaccination in aquaculture in terms of an encapsulation approach that can aid in future research.

Recombinant vaccines in 2022: a perspective from the cell factory

The last big outbreaks of Ebola fever in Africa, the thousands of avian influenza outbreaks across Europe, Asia, North America and Africa, the emergence of monkeypox virus in Europe and specially the COVID-19 pandemics have globally stressed the need for efficient, cost-effective vaccines against infectious diseases. Ideally, they should be based on transversal technologies of wide applicability. In this context, and pushed by the above-mentioned epidemiological needs, new and highly sophisticated DNA-or RNA-based vaccination strategies have been recently developed and applied at large-scale. Being very promising and effective, they still need to be assessed regarding the level of conferred long-term protection. Despite these fast-developing approaches, subunit vaccines, based on recombinant proteins obtained by conventional genetic engineering, still show a wide spectrum of interesting potentialities and an important margin for further development. In the 80’s, the first vaccination attempts with recombinant vaccines consisted in single structural proteins from viral pathogens, administered as soluble plain versions. In contrast, more complex formulations of recombinant antigens with particular geometries are progressively generated and explored in an attempt to mimic the multifaceted set of stimuli offered to the immune system by replicating pathogens. The diversity of recombinant antimicrobial vaccines and vaccine prototypes is revised here considering the cell factory types, through relevant examples of prototypes under development as well as already approved products.

Disease control tools to secure animal and public health in a densely populated world

Animal health is a prerequisite for global health, economic development, food security, food quality, and poverty reduction, while mitigating against climate change and biodiversity loss. We did a qualitative review of 53 infectious diseases in terrestrial animals with data from DISCONTOOLS, a specialist database and prioritisation model focusing on research gaps for improving infectious disease control in animals. Many diseases do not have any appropriate control tools, but the prioritisation model suggests that we should focus international efforts on Nipah virus infection, African swine fever, contagious bovine pleuropneumonia, peste des petits ruminants, sheeppox and goatpox, avian influenza, Rift Valley fever, foot and mouth disease, and bovine tuberculosis, for the greatest impact on the UN's Sustainable Development Goals. Easy to use and accurate diagnostics are available for many animal diseases. However, there is an urgent need for the development of stable and durable diagnostics that can differentiate infected animals from vaccinated animals, to exploit rapid technological advances, and to make diagnostics widely available and affordable. Veterinary vaccines are important for dealing with endemic, new, and emerging diseases. However, fundamental research is needed to improve the convenience of use and duration of immunity, and to establish performant marker vaccines. The largest gap in animal pharmaceuticals is the threat of pathogens developing resistance to available drugs, in particular for bacterial and parasitic (protozoal, helminth, and arthropod) pathogens. We propose and discuss five research priorities for animal health that will help to deliver a sustainable and healthy planet: vaccinology, antimicrobial resistance, climate mitigation and adaptation, digital health, and epidemic preparedness.

Impact of preweaning vaccination on host gene expression and antibody titers in healthy beef calves

The impact of preweaning vaccination for bovine respiratory viruses on cattle health and subsequent bovine respiratory disease morbidity has been widely studied yet questions remain regarding the impact of these vaccines on host response and gene expression. Six randomly selected calves were vaccinated twice preweaning (T1 and T3) with a modified live vaccine for respiratory pathogens and 6 randomly selected calves were left unvaccinated. Whole blood samples were taken at first vaccination (T1), seven days later (T2), at revaccination and castration (T3), and at weaning (T4), and utilized for RNA isolation and sequencing. Serum from T3 and T4 was analyzed for antibodies to BRSV, BVDV1a, and BHV1. Sequenced RNA for all 48 samples was bioinformatically processed with a HISAT2/StringTie pipeline, utilizing reference guided assembly with the ARS-UCD1.2 bovine genome. Differentially expressed genes were identified through analyzing the impact of time across all calves, influence of vaccination across treatment groups at each timepoint, and the interaction of time and vaccination. Calves, regardless of vaccine administration, demonstrated an increase in gene expression over time related to specialized proresolving mediator production, lipid metabolism, and stimulation of immunoregulatory T-cells. Vaccination was associated with gene expression related to natural killer cell activity and helper T-cell differentiation, enriching for an upregulation in Th17-related gene expression, and downregulated genes involved in complement system activity and coagulation mechanisms. Type-1 interferon production was unaffected by the influence of vaccination nor time. To our knowledge, this is the first study to evaluate mechanisms of vaccination and development in healthy calves through RNA sequencing analysis.

Haemonchosis in Sheep and Goats, Control Strategies and Development of Vaccines against Haemonchus contortus

Simple Summary

Haemonchus contortus is the most pathogenic blood-feeding parasitic nematode in sheep and goats, threatening animal welfare and causing tremendous economic losses to the small ruminant industry. This comprehensive review article sums up current control strategies, worm-derived antigens and recent advances in anti-Haemonchus vaccine development. New insights into antigen engineering and general considerations for clinical trials are discussed here.

Abstract

The evolutionary success of parasitic worms causes significant economic losses and animal health problems, including in the small ruminant industry. The hematophagous nematode Haemonchus contortus is a common endoparasite that infects wild and domestic ruminants worldwide, especially in tropical and subtropical regions. To date, the most commonly applied control strategy is the administration of anthelminthic drugs. The main disadvantages of these chemicals are their ecotoxic effects, the necessary withdrawal period (especially important in dairy animals) and the increasing development of resistance. Vaccines offer an attractive alternative control strategy against Haemonchus infections. In previous years, several potential vaccine antigens prepared from H. contortus using the latest technologies have been assessed in clinical trials using different methods and strategies. This review highlights the current state of knowledge on anti-H. contortus vaccines (covering native, recombinant and DNA-based vaccines), including an evaluation, as well a discussion of the challenges and achievements in developing protective, efficient, and long-lasting vaccines to control H. contortus infection and haemonchosis in small ruminants. This paper also addresses novel developments tackling the challenge of glycosylation of putative candidates in recombinant form.

Development of an attenuated vaccine against Koi Herpesvirus Disease (KHVD) suitable for oral administration and immersion

Since the end of the1990ies, Cyprinid herpesvirus 3 (also known as koi herpesvirus, KHV) has caused mass mortality events of koi and common carp all over the globe. This induced a high economic impact, since the KHV disease cannot be cured up to now, but only prevented by vaccination. Unfortunately, there is only one commercial vaccine available which is not approved in most countries. Therefore, there is an urgent need for new, safe and available vaccines. In this study, a live attenuated vaccine virus was generated by cell culture passages of virulent KHV, and shown to protect carp or koi after immersion or oral application against wild type challenge. An advantage of boost immunization was demonstrated, especially after oral application. Vaccination induced no or mild clinical signs and protecting antibodies have been measured. Additionally, the vaccine virus allowed differentiation of infected from vaccinated animals (DIVA) by PCR. The attenuation of the newly generated vaccine was tracked down to a partial deletion of open reading frame 150. This was confirmed by the generation of engineered ORF150 deletion mutants of wild-type KHV which exhibited a similar attenuation in vivo.

Enhancement of live vaccines by co-delivery of immune modulating proteins

Vaccines are very effective in providing protection against many infectious diseases. However, it has proven difficult to develop highly efficacious vaccines against some pathogens and so there is a continuing need to improve vaccine technologies. The first successful and widely used vaccines were based on attenuated pathogens (e.g., laboratory passaged Pasteurella multocida to vaccinate against fowl cholera) or closely related non-pathogenic organisms (e.g., cowpox to vaccinate against smallpox). Subsequently, live vaccines, either attenuated pathogens or non-pathogenic microorganisms modified to deliver heterologous antigens, have been successfully used to induce protective immune responses against many pathogens. Unlike conventional killed and subunit vaccines, live vaccines can deliver antigens to mucosal surfaces in a similar manner and context as the natural infection and hence can often produce a more appropriate and protective immune response. Despite these advantages, there is still a need to improve the immunogenicity of some live vaccines. The efficacy of injectable killed and subunit vaccines is usually enhanced using adjuvants such mineral salts, oils, and saponin, but such adjuvants cannot be used with live vaccines. Instead, live vaccines can be engineered to produce immunomodulatory molecules that can stimulate the immune system to induce more robust and long-lasting adaptive immune responses. This review focuses on research that has been undertaken to engineer live vaccines to produce immunomodulatory molecules that act as adjuvants to increase immunogenicity. Adjuvant strategies with varying mechanisms of action (inflammatory, antibody-mediated, cell-mediated) and delivery modes (oral, intramuscular, intranasal) have been investigated, with varying degrees of success. The goal of such research is to define adjuvant strategies that can be adapted to enhance live vaccine efficacy by triggering strong innate and adaptive immune responses and produce vaccines against a wider range of pathogens.

2022 AAHA Canine Vaccination Guidelines

These guidelines are an update and extension of previous AAHA peer-reviewed canine vaccination guidelines published in 2017. Vaccination is a cornerstone of canine preventive healthcare and one of the most cost-effective ways of maintaining a dog's health, longevity, and quality of life. Canine vaccination also serves a public health function by forming a barrier against several zoonotic diseases affecting dogs and humans. Canine vaccines are broadly categorized as containing core and noncore immunizing antigens, with administration recommendations based on assessment of individual patient risk factors. The guidelines include a comprehensive table listing canine core and noncore vaccines and a recommended vaccination and revaccination schedule for each vaccine. The guidelines explain the relevance of different vaccine formulations, including those containing modified-live virus, inactivated, and recombinant immunizing agents. Factors that potentially affect vaccine efficacy are addressed, including the patient's prevaccination immune status and vaccine duration of immunity. Because animal shelters are one of the most challenging environments for prevention and control of infectious diseases, the guidelines also provide recommendations for vaccination of dogs presented at or housed in animal shelters, including the appropriate response to an infectious disease outbreak in the shelter setting. The guidelines explain how practitioners can interpret a patient's serological status, including maternally derived antibody titers, as indicators of immune status and suitability for vaccination. Other topics covered include factors associated with postvaccination adverse events, vaccine storage and handling to preserve product efficacy, interpreting product labeling to ensure proper vaccine use, and using client education and healthcare team training to raise awareness of the importance of vaccinations.

Immunoglobin G Sero-Dynamics Aided Host Specific Linear Epitope Identification and Differentiation of Infected from Vaccinated Hosts

Differentiation of infected from vaccinated hosts (DIVH) is a critical step in virus eradication programs. DIVH-compatible vaccines, however, take years to develop, and are therefore unavailable for fighting the sudden outbreaks that typically drive pandemics. Here, we establish a protocol for the swift and efficient development of DIVH assays, and show that this approach is compatible with any type of vaccines. Using porcine circovirus 2 (PCV2) as the experimental model, the first step is to use Immunoglobin G (IgG) sero-dynamics (IsD) curves to aid epitope discovery (IsDAED): PCV2 Cap peptides were categorized into three types: null interaction, nonspecific interaction (NSI), and specific interaction (SI). We subsequently compared IsDAED approach and traditional approach, and demonstrated identifying SI peptides and excluding NSI peptides supports efficient diagnostic kit development, specifically using a protein-peptide hybrid microarray (PPHM). IsDAED directed the design of a DIVH protocol for three types of PCV2 vaccines (while using a single PPHM). Finally, the DIVH protocol successfully differentiated infected pigs from vaccinated pigs at five farms. This IsDAED approach is almost certainly extendable to other viruses and host species. IMPORTANCE Sudden outbreaks of pandemics caused by virus, such as SARS-CoV-2, has been determined as a public health emergency of international concern. However, the development of a DIVH-compatible vaccine is time-consuming and full of uncertainty, which is unsuitable for an emergent situation like the ongoing COVID-19 pandemic. Along with the development and public health implementation of new vaccines to prevent human diseases, e.g., human papillomavirus vaccines for cervical cancer; enterovirus 71 vaccines for hand, foot, and mouth disease; and most recently SARS-CoV-2, there is an increasing demand for DIVH. Here, we use the IsDAED approach to confirm SI peptides and to exclude NSI peptides, finally to direct the design of a DIVH protocol. It is plausible that our IsDAED approach is applicable for other infectious disease.

Advances in Irradiated Livestock Vaccine Research and Production Addressing the Unmet Needs for Farmers and Veterinary Services in FAO/IAEA Member States

The Animal Production and Health section (APH) of the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture at the International Atomic Energy Agency has over the last 58 years provided technical and scientific support to more than 100 countries through co-ordinated research activities and technical co-operation projects in peaceful uses of nuclear technologies. A key component of this support has been the development of irradiated vaccines targeting diseases that are endemic to participating countries. APH laboratories has over the last decade developed new techniques and has put in place a framework that allows researchers from participating member states to develop relevant vaccines targeting local diseases while using irradiation as a tool for improving livestock resources.

Development of a Nanoparticle Multiepitope DNA Vaccine against Virulent Infectious Bronchitis Virus Challenge

To develop a safe and effective nanoparticle (NP) multiepitope DNA vaccine for controlling infectious bronchitis virus (IBV) infection, we inserted the multiepitope gene expression box SBNT into a eukaryotic expression vector pcDNA3.1(+) to construct a recombinant plasmid pcDNA/SBNT. The NP multiepitope DNA vaccine pcDNA/SBNT-NPs were prepared using chitosan to encapsulate the recombinant plasmid pcDNA/SBNT, with a high encapsulation efficiency of 94.90 ± 1.35%. These spherical pcDNA/SBNT-NPs were 140.9 ± 73.2 nm in diameter, with a mean ζ potential of +16.8 ± 4.3 mV. Our results showed that the chitosan NPs not only protected the plasmid DNA from DNase degradation but also mediated gene transfection in a slow-release manner. Immunization with pcDNA/SBNT-NPs induced a significant IBV-specific immune response and partially protected chickens against homologous IBV challenge. Therefore, the chitosan NPs could be a useful gene delivery system, and NP multiepitope DNA vaccines may be a potential alternative for use in the development of a novel, safe, and effective IBV vaccine.

γδ T cells in artiodactyls: Focus on swine

Vaccination is the most effective medical strategy for disease prevention but there is a need to improve livestock vaccine efficacy. Understanding the structure of the immune system of swine, which are considered a γδ T cell "high" species, and thus, particularly how to engage their γδ T cells for immune responses, may allow for development of vaccine optimization strategies. The propensity of γδ T cells to home to specific tissues, secrete pro-inflammatory and regulatory cytokines, exhibit memory or recall responses and even function as antigen-presenting cells for αβ T cells supports the concept that they have enormous potential for priming by next generation vaccine constructs to contribute to protective immunity. γδ T cells exhibit several innate-like antigen recognition properties including the ability to recognize antigen in the absence of presentation via major histocompatibility complex (MHC) molecules enabling γδ T cells to recognize an array of peptides but also non-peptide antigens in a T cell receptor-dependent manner. γδ T cell subpopulations in ruminants and swine can be distinguished based on differential expression of the hybrid co-receptor and pattern recognition receptors (PRR) known as workshop cluster 1 (WC1). Expression of various PRR and other innate-like immune receptors diversifies the antigen recognition potential of γδ T cells. Finally, γδ T cells in livestock are potent producers of critical master regulator cytokines such as interferon (IFN)-γ and interleukin (IL)-17, whose production orchestrates downstream cytokine and chemokine production by other cells, thereby shaping the immune response as a whole. Our knowledge of the biology, receptor expression and response to infectious diseases by swine γδ T cells is reviewed here.

Thermostable Vaccines in Veterinary Medicine: State of the Art and Opportunities to Be Seized

The COVID-19 pandemic has highlighted the weakness of the vaccine supply chain, and the lack of thermostable formulations is one of its major limitations. This study presents evidence from peer-reviewed literature on the development of thermostable vaccines for veterinary use. A systematic review and meta-analysis were performed to evaluate the immunogenicity and/or the efficacy/effectiveness of thermostable vaccines against infectious diseases. The selected studies (n = 78) assessed the vaccine’s heat stability under different temperature conditions and over different periods. Only one study assessed the exposure of the vaccine to freezing temperatures. Two field studies provided robust evidence on the immunogenicity of commercial vaccines stored at temperatures far in excess of the manufacturer’s recommended cold-chain conditions. The drying process was the most-used method to improve the vaccine’s thermostability, along with the use of different stabilizers. The pooled vaccine efficacy was estimated to be high (VE = 69%), highlighting the importance of vaccination in reducing the economic losses due to the disease impact. These findings provide evidence on the needs and benefits of developing a portfolio of heat- and freeze-stable veterinary vaccines to unleash the true potential of immunization as an essential component of improved animal health and welfare, reduce the burden of certain zoonotic events and thus contribute to economic resilience worldwide.

Evaluation of Cholera Toxin Adjuvanticity Effect on the Production of Specific Antibodies Induced by Avian Infectious Bronchitis Vaccine in Chickens

Cholera toxin (CT) is one of the most well-known immunostimulants. Mammalian studies have shown that CT can generate immune responses against antigen. However, it has not exhibited a definite effect on poultry yet. In this study, focusing on a cost-effective method, the effect of different concentrations of CT obtained from Vibrio cholerae biotype El Tor and serotype Inaba was investigated on the immunogenicity of infectious bronchitis vaccine. After culturing and concentrating CT, different concentrations of CT (0.1, 1, 2, and 5 micrograms) were combined with avian infectious bronchitis vaccine strain H120 produced by Razi Vaccine and Serum Research Institute (RVSRI) and, at 7 days of age, inoculated via the eye drop administration in 42 specific-pathogen-free chickens (seven groups of six chicks that included four experimental groups, two negative control groups (PBS and toxin), and one positive control group). Blood samples were taken weekly from the wing veins of the chickens, and the immunoglobulin G (IgG) titer was checked by enzyme-linked immunosorbent assay. The results showed that 2 µg of CT in comparison with other concentrations caused a significant increase in the antibody titer against avian infectious bronchitis in the blood serums of the chickens. One-way ANOVA test showed that all the results of this study were significant at P<0.05 level. Our data show that CT has the potential to further stimulate the immune system of chickens and may increase the immunogenicity of the infectious bronchitis vaccine. However, more research is needed to examine all aspects of the use of this toxin in animal vaccines.

Fundamentals of Fish Vaccination

Fish health management has become a critical component of disease control and is invaluable for improved harvests and sustainable aquaculture. Vaccination is generally accepted as the most effective prophylactic measure for fish disease prevention, on environmental, social, and economic grounds. Although the historical approach for developing fish vaccines was based on the principle of Louis Pasteur's "isolate, inactivate and inject," but their weak immunogenicity and low efficacies in many cases, have shifted the focus of fish vaccine development from traditional to next-generation technologies. However, before any fish vaccine can be successfully commercialized, several hurdles need to be overcome regarding the production cost, immunogenicity, effectiveness, mode of administration, environmental safety, and associated regulatory concerns. In this context, the chapter summarises the basic aspects of fish vaccination such as type of vaccine, modalities of vaccine delivery, the immunological basis of fish immunization as well as different challenges associated with the development process and future opportunities.

Avian Paramyxoviruses as Vectors for Vaccine Development

Avian paramyxoviruses (APMVs) have gained a great attention to be developed as vaccine vectors against human and veterinary pathogens. Avirulent APMVs are highly safe to be used as vaccine vectors for avian and non-avian species. APMV vectored vaccines induce robust cellular and humoral immune responses in a broad range of hosts. APMV vectors can be a good platform by facilitating rapid generation of vaccines against emerging pathogens. In this chapter, we discuss application of reverse genetics of APMVs for vaccine development, design of APMV vectored vaccines, cloning of protective antigen(s) into a vector, recovery of vectored vaccines and characterization of generated vaccine viruses.

Review: Livestock disease resilience: from individual to herd level

Infectious diseases are a major threat to the sustainable production of high-producing animals. Control efforts, such as vaccination or breeding approaches often target improvements to individual resilience to infections, i.e., they strengthen an animal's ability to cope with infection, rather than preventing infection per se. There is increasing evidence for the contribution of non-clinical carriers (animals that become infected and are infectious but do not develop clinical signs) to the overall health and production of livestock populations for a wide range of infectious diseases. Therefore, we strongly advocate a shift of focus from increasing the disease resilience of individual animals to herd disease resilience as the appropriate target for sustainable disease control in livestock. Herd disease resilience not only captures the direct effects of vaccination or host genetics on the health and production performance of individuals but also the indirect effects on the environmental pathogen load that herd members are exposed to. For diseases primarily caused by infectious pathogens shed by herd members, these indirect effects on herd resilience are mediated both by individual susceptibility to infection and by characteristics (magnitude of infectiousness, duration of infectious period) that influence pathogen shedding from infected individuals. We review what is currently known about how vaccination and selective breeding affect herd disease resilience and its underlying components, and outline the changes required for improvement. To this purpose, we also seek to clarify and harmonise the terminology used in the different animal science disciplines to facilitate future collaborative approaches to infectious disease control in livestock.

Non-specific effects of veterinary vaccines: a systematic review

The benefits of vaccines have been centred on their specific effects on subsequent infections by target pathogens. Recent studies, however, have opened up new insights into additional effects of vaccines known as non-specific effects (NSEs) or heterologous effects of vaccines. While several articles have reviewed epidemiological and immunological evidence for NSEs of vaccines in humans, similar works on veterinary vaccines are scarce. The objective of this paper was to review the findings of published studies on NSEs of vaccines developed or repurposed for use in animals. In total 8412 titles were retrieved from PubMed and CABI databases on the 30^th of April 2021. After the final stage of screening, 45 eligible articles were included in the review. Data from these articles were summarised and presented here. In general, most of the vaccines studied in the reviewed articles have beneficial NSEs against multiple pathogens and disease conditions. There were, however, fewe studies reporting detrimental NSEs from both non-live and live vaccines which is in contrast to the currently existing evidence of beneficial NSEs of live vaccines and detrimental NSEs of non-live vaccines. This review may be used as a complement for future review of RCT studies of NSEs of vaccines in animals and provide a useful addition to the evolving understanding of the NSEs of vaccines.

Immune Protective Efficacy of China's Traditional Inactivated and Attenuated Vaccines against the Prevalent Strains of Pasteurella multocida in Mice

Capsular type A and D strains of Pasteurella multocida are the main epidemic serogroups in pigs in China. In this study, we preliminarily evaluated the immune protective efficacy of the two traditional vaccines, an inactivated C44-1 aluminum-hydroxide-gel-adjuvanted (Alh–C44-1) vaccine and a live EO630 vaccine, against currently circulating strains of P. multocida in a mouse model. Mice immunized twice with conventional vaccines generated higher antibody titers, and significantly higher levels of IgG were observed in the mice inoculated with the inactivated Alh–C44-1 vaccine on day 35 (p < 0.05) than those with the live EO630 vaccine. The mice immune protection test showed that the vaccination groups had a 57% or 71% protection effect against the serogroup B strain, but had no protective effect against epidemic strains. In conclusion, our study found that the widely used traditional P. multocida vaccines in China provide good protection against homologous strains, but could not provide cross-protection against heterologous strains in a mouse model.

Multivalent poultry vaccine development using Protein Glycan Coupling Technology

BACKGROUND

Poultry is the world's most popular animal-based food and global production has tripled in the past 20 years alone. Low-cost vaccines that can be combined to protect poultry against multiple infections are a current global imperative. Glycoconjugate vaccines, which consist of an immunogenic protein covalently coupled to glycan antigens of the targeted pathogen, have a proven track record in human vaccinology, but have yet to be used for livestock due to prohibitively high manufacturing costs. To overcome this, we use Protein Glycan Coupling Technology (PGCT), which enables the production of glycoconjugates in bacterial cells at considerably reduced costs, to generate a candidate glycan-based live vaccine intended to simultaneously protect against Campylobacter jejuni, avian pathogenic Escherichia coli (APEC) and Clostridium perfringens. Campylobacter is the most common cause of food poisoning, whereas colibacillosis and necrotic enteritis are widespread and devastating infectious diseases in poultry.

RESULTS

We demonstrate the functional transfer of C. jejuni protein glycosylation (pgl) locus into the genome of APEC χ7122 serotype O78:H9. The integration caused mild attenuation of the χ7122 strain following oral inoculation of chickens without impairing its ability to colonise the respiratory tract. We exploit the χ7122 pgl integrant as bacterial vectors delivering a glycoprotein decorated with the C. jejuni heptasaccharide glycan antigen. To this end we engineered χ7122 pgl to express glycosylated NetB toxoid from C. perfringens and tested its ability to reduce caecal colonisation of chickens by C. jejuni and protect against intra-air sac challenge with the homologous APEC strain.

CONCLUSIONS

We generated a candidate glycan-based multivalent live vaccine with the potential to induce protection against key avian and zoonotic pathogens (C. jejuni, APEC, C. perfringens). The live vaccine failed to significantly reduce Campylobacter colonisation under the conditions tested but was protective against homologous APEC challenge. Nevertheless, we present a strategy towards the production of low-cost "live-attenuated multivalent vaccine factories" with the ability to express glycoconjugates in poultry.

Systematic Review of the Interaction between Nutrition and Immunity in Livestock: Effect of Dietary Supplementation with Synthetic Amino Acids

Infectious diseases represent one of the most critical threats to animal production worldwide. Due to the rise of pathogen resistance and consumer concern about chemical-free and environmentally friendly productions, the use of antimicrobials drugs is no longer desirable. The close relationship between nutrition and infection has led to numerous studies about livestock. The impact of feeding strategies, including synthetic amino acid supplementation, on host response to various infections has been investigated in different livestock animals. This systematic review provides a synthesis of the experimental studies on the interactions between synthetic amino acid supplementation and immune response to infectious diseases in livestock. Following PRISMA guidelines, quantitative research was conducted using two literature databases, PubMed and Web of Science. The eligibility criteria for the research articles were: (1) the host is a livestock animal; (2) the supplementation with at least one synthetic amino acid; (3) at least one mediator of immunity is measured; (4) at least one production trait is measured. Data were extracted from 58 selected studies. Articles on poultry were the most numerous; few contained experiments using ruminants and pigs. Most of the authors hypothesized that synthetic amino acid supplementation would particularly improve the animals' immune response against intracellular pathogens. An increase in T and natural killer lymphocytes and macrophages activation, intracellular redox state, lymphocytes proliferation and antibodies production were the most described immune mechanisms associated with synthetic amino acid supplementation. Most of the selected studies focused on three amino acids (methionine, threonine and arginine), all of which are associated with a significant improvement of the host immune response. The use of synthetic amino acid supplementation appears as an encouraging perspective for livestock infectious disease management, and research must concentrate on more analytical studies using these three amino acids.

Flow Cytometric Evaluation of CD4+ and CD8+ T-cell Immune Response in SPF Chickens Induced by Fowlpox Vaccine

Fowlpox (FP) is a viral disease that is widely distributed throughout the world. The disease has an economic impact on the poultry industry, and its prevalence has even been reported in vaccinated flocks. The present study used flow cytometry to evaluate the CD4⁺ and CD8⁺ T-cell immune response of chicks induced by FP vaccine. 120 specific pathogen-free (SPF) 21-day-old chicks were randomly divided into three groups of 40. One group was used as negative control with PBS inoculation, the other two groups were inoculated with the local fowlpox vaccine produced by Razi Institute and commercial FP vaccines, and they were kept for five weeks. Peripheral blood mononuclear cells (PBMC) were isolated using Ficoll-Hypaque density gradients and the percentages of CD3⁺, CD3⁺, CD4⁺, and CD3⁺CD8⁺ T lymphocytes were analyzed with flow cytometry. Seven days post-immunization, a maximum (90-100%) swelling formation ("take") on the vaccination site was observed. The ratios of CD4⁺ to CD8⁺ T-lymphocytes in both vaccinated groups were significantly higher (p < 0.05) than the control group inoculated with PBS. The percentages of CD3⁺, CD3⁺CD4⁺, and CD3⁺CD8⁺ T-lymphocytes were increased in chickens vaccinated with commercial and local FP vaccines. There were no significant differences between the groups receiving commercial and local fowl pox vaccines. The present study showed that protective immunity could be associated with increased cellular immune responses, which has been interpreted as enhancing T-cell proliferation and increasing CD4⁺ to CD8⁺ ratios through vaccination with the FP vaccine. This study further suggests that the induction of enhanced immune responses is due mainly to the Th1-type response.

Host Antiviral Responses against Avian Infectious Bronchitis Virus (IBV): Focus on Innate Immunity

Avian infectious bronchitis virus (IBV) is an important gammacoronavirus. The virus is highly contagious, can infect chickens of all ages, and causes considerable economic losses in the poultry industry worldwide. In the last few decades, numerous studies have been published regarding pathogenicity, vaccination, and host immunity-virus interaction. In particular, innate immunity serves as the first line of defense against invasive pathogens and plays an important role in the pathogenetic process of IBV infection. This review focuses on fundamental aspects of host innate immune responses after IBV infection, including identification of conserved viral structures and different components of host with antiviral activity, which could provide useful information for novel vaccine development, vaccination strategies, and intervention programs.

Exosome-Based Vaccines: Pros and Cons in the World of Animal Health

Due to the emergence of antibiotic resistance and new and more complex diseases that affect livestock animal health and food security, the control of epidemics has become a top priority worldwide. Vaccination represents the most important and cost-effective measure to control infectious diseases in animal health, but it represents only 23% of the total global animal health market, highlighting the need to develop new vaccines. A recent strategy in animal health vaccination is the use of extracellular vesicles (EVs), lipid bilayer nanovesicles produced by almost all living cells, including both prokaryotes and eukaryotes. EVs have been evaluated as a prominent source of viral antigens to elicit specific immune responses and to develop new vaccination platforms as viruses and EVs share biogenesis pathways. Preliminary trials with lymphocytic choriomeningitis virus infection (LCMV), porcine reproductive and respiratory syndrome virus (PRRSV), and Marek's disease virus (MDV) have demonstrated that EVs have a role in the activation of cellular and antibody immune responses. Moreover, in parasitic diseases such as Eimeria (chickens) and Plasmodium yoelii (mice) protection has been achieved. Research into EVs is therefore opening an opportunity for new strategies to overcome old problems affecting food security, animal health, and emerging diseases. Here, we review different conventional approaches for vaccine design and compare them with examples of EV-based vaccines that have already been tested in relation to animal health.

Reducing the Risk of Transmission of Critical Antimicrobial Resistance Determinants From Contaminated Pork Products to Humans in South-East Asia

Antimicrobial resistance (AMR) is a critical challenge worldwide as it impacts public health, especially via contamination in the food chain and in healthcare-associated infections. In relation to farming, the systems used, waste management on farms, and the production line process are all determinants reflecting the risk of AMR emergence and rate of contamination of foodstuffs. This review focuses on South East Asia (SEA), which contains diverse regions covering 11 countries, each having different levels of development, customs, laws, and regulations. Routinely, here as elsewhere antimicrobials are still used for three indications: therapy, prevention, and growth promotion, and these are the fundamental drivers of AMR development and persistence. The accuracy of detection of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) depends on the laboratory standards applicable in the various institutes and countries, and this affects the consistency of regional data. Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae are the standard proxy species used for indicating AMR-associated nosocomial infections and healthcare-associated infections. Pig feces and wastewater have been suspected as one of the hotspots for spread and circulation of ARB and ARG. As part of AMR surveillance in a One Health approach, clonal typing is used to identify bacterial clonal transmission from the production process to consumers and patients - although to date there have been few published definitive studies about this in SEA. Various alternatives to antibiotics are available to reduce antibiotic use on farms. Certain of these alternatives together with improved disease prevention methods are essential tools to reduce antimicrobial usage in swine farms and to support global policy. This review highlights evidence for potential transfer of resistant bacteria from food animals to humans, and awareness and understanding of AMR through a description of the occurrence of AMR in pig farm food chains under SEA management systems. The latter includes a description of standard pig farming practices, detection of AMR and clonal analysis of bacteria, and AMR in the food chain and associated environments. Finally, the possibility of using alternatives to antibiotics and improving policies for future strategies in combating AMR in a SEA context are outlined.

Evaluation of Protective Efficacy of Influenza Virus Like Particles Prepared from H5N1 Virus of Clade 2.2.1.2 in Chickens

Highly pathogenic Avian Influenza (HPAI) viruses continue to cause severe economic losses in poultry species worldwide. HPAI virus of subtype H5N1 was reported in Egypt in 2006, and despite vaccination efforts, the virus has become endemic. The current study aims to evaluate the efficacy of a virus-like particle (VLP) based vaccine in vivo using specific pathogen-free (SPF) chickens. The vaccine was prepared from the HPAI H5N1 virus of clade 2.2.1.2 using the baculovirus expression system. The VLPs were quantitated and characterized, including electron microscopy. In addition, the protection level of the VLPs was evaluated by using two different regimens, including one dose and two-dose vaccinated groups, which gave up to 70% and 100% protection level, respectively. The results of this study emphasize the potential usefulness of the VLPs-based vaccine as an alternative vaccine candidate for the control of AIV infection in poultry.

Discovery of Oligosaccharide Antigens for Semi-Synthetic Glycoconjugate Vaccine Leads against Streptococcus suis Serotypes 2, 3, 9 and 14*

Streptococcus suis bacteria are one of the most serious health problems for pigs and an emerging zoonotic agent in humans working in the swine industry. S. suis bacteria express capsular polysaccharides (CPS) a major bacterial virulence factor that define the serotypes. Oligosaccharides resembling the CPS of S. suis serotypes 2, 3, 9, and 14 have been synthesized, glycans related to serotypes 2 and 9 were placed on glycan array surfaces to screen blood from infected pigs. Lead antigens for the development of semi-synthetic S. suis serotypes 2 and 9 glycoconjugate veterinary vaccines were identified in this way.

The effect of bovine vaccines against respiratory viruses administered either intranasal or intramuscular on broncho-alveolar fluid cells of heifers

Background

The knowledge on bovine vaccines against respiratory viruses on bronchoalveolar fluid cells is scarce.

Objective

To compare the effects of a commercial intranasal (IN) and intramuscular (IM) vaccine against bovine respiratory disease (BRD) complex viruses on bronchoalveolar fluid cells of healthy heifers.

Methods

21 healthy heifers were assigned to three treatment groups: control (CO, N = 7), intranasally vaccinated (IN) (n = 7), and intramuscularly vaccinated (IM) (n = 7). The IN group received 1 mL of the commercial vaccine in each nostril once containing attenuated BoHV-1, bPIV-3, and BRSV. The IM group was vaccinated with two doses of 2 mL with an interval of 21 days of the commercial vaccine containing attenuated BoHV-1, bPIV-3, and BRSV plus inactivated BVDV. At day 0 (D0), before the first vaccine dose, and at D3, D7, and D21, after the last vaccine dose, airway bronchoscopy was performed to observe local irritation and collect bronchoalveolar lavage fluid (BALF). The bronchoalveolar count, cytological evaluation, bronchoalveolar cell oxidative metabolism, and total bronchoalveolar IgA and IgG were measured.

Results

The IN vaccine increased neutrophil cellularity at D7 and D21 and total IgA at D3 in BALF. Total IgA in BALF also increased at D3 and oxidative metabolism of bronchoalveolar cells at D21 lowered compared to the CO group. Following IM vaccination there was no alteration of immunoglobulins or cell oxidative metabolism in BALF. Both vaccines reduced the number of alveolar macrophages.

Conclusion

Both vaccines induced bronchoalveolar inflammation during the establishment of the vaccine immunity, which was more expressive in the IN protocol.

Mapping Biomolecular Sequences: Graphical Representations - their Origins, Applications and Future Prospects

The exponential growth in the depositories of biological sequence data have generated an urgent need to store, retrieve and analyse the data efficiently and effectively for which the standard practice of using alignment procedures are not adequate due to high demand on computing resources and time. Graphical representation of sequences has become one of the most popular alignment-free strategies to analyse the biological sequences where each basic unit of the sequences - the bases adenine, cytosine, guanine and thymine for DNA/RNA, and the 20 amino acids for proteins - are plotted on a multi-dimensional grid. The resulting curve in 2D and 3D space and the implied graph in higher dimensions provide a perception of the underlying information of the sequences through visual inspection; numerical analyses, in geometrical or matrix terms, of the plots provide a measure of comparison between sequences and thus enable study of sequence hierarchies. The new approach has also enabled studies of comparisons of DNA sequences over many thousands of bases and provided new insights into the structure of the base compositions of DNA sequences In this article we review in brief the origins and applications of graphical representations and highlight the future perspectives in this field.

Short Term Safety, Immunogenicity, and Reproductive Effects of Combined Vaccination With Anti-GnRH (Gonacon) and Rabies Vaccines in Female Feral Cats

Overpopulation of free-roaming cats is a major problem leading to negative impacts on animal health and welfare, public nuisance, transmission of zoonotic diseases, and well-documented harm to wildlife. Surgical sterilization had failed to provide a practical solution to free-roaming cats' overpopulation under field conditions; therefore, efficient and safe non-surgical immunocontraception methods are aspired. Rabies is a deadly virus that may infect people and animals. However, the safety and efficacy of combined vaccination with anti-GnRH and rabies vaccines in feral cats, which often suffer from disrupted health conditions and experienced high stress level, has never been studied. Therefore, our objective was to examine the short-term safety and efficacy of anti-GnRH vaccine (Gonacon), in combination with rabies vaccine in female feral cats. Mature feral female cats were captured and divided into the following groups: (I) GonaconX1-Rabies: queens vaccinated with both Gonacon and rabies (n = 5); (II) GonaconX2-Rabies: queens vaccinated twice with Gonacon (3 weeks apart) and with Rabies (n = 4); (III) OVx-Rabies: queens ovariohysterectomized and vaccinated with rabies (n = 4); (IV) Intact-Rabies: queens vaccinated against rabies and remained intact (n = 3). Comprehensive veterinary examinations and blood tests were performed every 2 weeks for 14 weeks. Data were analyzed by Repeated-Measures-ANOVA or Fisher-Exact-Test. There were neither systemic nor local adverse reactions at the vaccination sites. Blood count (PCV, TS, RBC, HGB, HCT, WBC) and chemistry (Total protein, Total globulin, Albumin, Urea, Creatinine, Creatine kinase, Bilirubin, GGT, ALT, AST) analyses revealed no differences among groups. There were no differences in serum rabies antibodies titers among groups, and queens kept a protective titer (>0.5 IU/mL) starting at 2–4 weeks after vaccination. Anti-GnRH antibodies were detected in all Gonacon-vaccinated queens, excluding one queen (GonaconX2-Rabies group). Anti-müllerian hormone serum concentrations reduced significantly after ovariohysterectomy, as well as gradually following vaccination with Gonacon, but it remained high in intact queens. Evaluation of vaginal cytology and ovarian histology suggested that reproductive cyclicity was suppressed in Gonacon-vaccinated queens. Our results support the conclusion that in the short term, the combined vaccination with Gonacon and rabies is safe and effective in female feral cats. However, further long-term studies are warranted to test this immunologic regimen in feral cats.

Immune response in dairy cattle against combined foot and mouth disease and haemorrhagic septicemia vaccine under field conditions

Background

Foot-and-mouth disease (FMD) and Haemorrhagic septicemia (HS) are two important diseases that are known to have caused significant economic losses to the cattle industry. Accordingly, vaccinations have been recognized as an efficient method to control and prevent both of the above-mentioned diseases. This study aimed to determine the immune response to FMD virus antigens and the recombinant outer membrane protein of HS (rOmpH) of Pasteurella multocida in cattle administered as a combination vaccine and compare antibody titers with the two vaccines given independently, under field conditions. Dairy cattle were divided into three groups. Each group was immunized with different vaccine types according to the vaccination program employed in this study. Antibody responses were determined by indirect ELISA, liquid phase blocking ELISA (LPB-ELISA) and viral neutralization test (VNT). Furthermore, the cellular immune responses were measured by lymphocyte proliferation assay (LPA).

Results

The overall antibody titers to HS and FMDV were above cut-off values for the combined FMD-HS vaccine in this study.The mean antibody titer against HS after the first immunization in the combined FMD-HS vaccine groups was higher than in the HS vaccine groups. However, no statistically significant differences (p > 0.05) were observed between groups. Likewise, the antibody titer to the FMDV serotypes O/TAI/189/87 and Asia 1/TAI/85 determined by LPB-ELISA in the combined vaccine were not statistically significantly different when compared to the FMD vaccine groups. However, the mean VNT antibody titer of combined vaccine against serotype O was significantly higher than the VN titer of FMD vaccine groups (p < 0.05). Moreover, the LPA results showed that all vaccinated groups displayed significantly higher than the negative control (p < 0.05). Nevertheless, no differences in the lymphocyte responses were observed in comparisons between the groups (p > 0.05).

Conclusions

The combined FMD-HS vaccine formulated in this study could result in high both antibody and cellular immune responses without antigenic competition. Therefore, the combined FMD-HS vaccine can serve as an alternative vaccine against both HS and FMD in dairy cattle under field conditions.