Vaccination of sheep with Quil-A® adjuvant expands the antibody repertoire to the Fasciola MF6p/FhHDM-1 antigen and administered together impair the growth and antigen release of flukes

Combination Adjuvants Enhance Recombinant H5 Hemagglutinin Vaccine Protection Against High-Dose Viral Challenge in Chickens

BACKGROUND

Recombinant avian influenza subunit vaccines often require adjuvants to enhance immune responses. This study aims to evaluate the immune-enhancing potential of seven combination adjuvants in specific pathogen-free (SPF) chickens.

METHODS

SPF chickens were vaccinated with combinations of ISA78VG and adjuvants, including Quil-A, CpG, and monophosphoryl lipid A (MPLA). Their immune responses were assessed using a vaccination and viral challenge protection model.

RESULTS

The combinations of ISA78VG with Quil-A, CpG&MPLA or CpG&Quil-A significantly enhanced antibody responses and provided cross-protection against the H5N8-20135 strain. The ISA78VG&MPLA and ISA78VG&CpG&MPLA combinations induced the stronger IFN-γ production, with CpG further amplifying the immune response. The ISA78VG&Quil-A formulation, in particular, stimulated rapid antibody responses, achieving a 100% seroconversion by day 14 and high titers of hemagglutination inhibition (HI) antibodies against both the recombinant HA antigen and the H5N6-20053 virus.

CONCLUSIONS

The ISA78VG&Quil-A combination is an ideal adjuvant for enhancing the immunogenicity of avian influenza rHA subunit vaccines, offering a promising strategy for H5 subtype vaccine development.

Spatial transcriptomics of a parasitic flatworm provides a molecular map of drug targets and drug resistance genes

The spatial organization of gene expression dictates tissue functions in multicellular parasites. Here, we present the spatial transcriptome of a parasitic flatworm, the common liver fluke Fasciola hepatica. We identify gene expression profiles and marker genes for eight distinct tissues and validate the latter by in situ hybridization. To demonstrate the power of our spatial atlas, we focus on genes with substantial medical importance, including vaccine candidates (Ly6 proteins) and drug resistance genes (glutathione S-transferases, ABC transporters). Several of these genes exhibit unique expression patterns, indicating tissue-specific biological functions. Notably, the prioritization of tegumental protein kinases identifies a PKCβ, for which small-molecule targeting causes parasite death. Our comprehensive gene expression map provides unprecedented molecular insights into the organ systems of this complex parasitic organism, serving as a valuable tool for both basic and applied research.

Production, purification and immunogenicity of Gag virus-like particles carrying SARS-CoV-2 components

The virus-like particle (VLP) platform is a robust inducer of humoral and cellular immune responses; hence, it has been used in vaccine development for several infectious diseases. In the current work, VLPs carrying SARS-CoV-2 Spike (S) protein (Wuhan strain) with an HIV-1 Gag core were produced using suspension HEK 293SF-3F6 cells by transient transfection. The Gag was fused with green fluorescent protein (GFP) for rapid quantification of the VLPs. Five different versions of Gag-Spike VLPs (Gag-S-VLPs) consisting of Gag-S alone or combined with other SARS-CoV-2 components, namely Gag-S-Nucleocapsid (N), Gag-S-Matrix (M), Gag-S-Envelope (E), Gag-S-MEN, along with Gag alone were produced and processed by clarification, nuclease treatment, concentration by tangential flow filtration (TFF) and diafiltration. A pilot mouse study was performed to evaluate the immunogenicity of the Gag-S-VLPs through the measurement of the humoral and/or cellular responses against all the mentioned SARS-CoV-2 components. Antibody response to Spike was observed in all variants. The highest number of Spike-specific IFN-γ + T cells was detected with Gag-S-VLPs. No induction of antigen-specific cellular responses to M, N or E proteins were detected with any of the Gag-S, M, E/or N VLPs tested. Therefore, the Gag-S-VLP, by reason of consistently eliciting strong antigen-specific cellular and antibody responses, was selected for further evaluation. The purification process was improved by replacing the conventional centrifugation by serial microfiltration in the clarification step, followed by Spike-affinity chromatography to get concentrated VLPs with higher purity. Three different doses of Gag-S-VLP in conjunction with two adjuvants (Quil-A or AddaVax) were used to assess the dose-dependent antigen-specific cellular and antibody responses in mice. The Gag-S-VLP adjuvanted with Quil-A resulted in a stronger Spike-specific cellular response compared to that adjuvanted with AddaVax. A strong spike neutralisation activity was observed for all doses, independent of the adjuvant combination.

Fasciolosis: pathogenesis, host-parasite interactions, and implication in vaccine development

Fasciola hepatica is distributed worldwide, causing substantial economic losses in the animal husbandry industry. Human fasciolosis is an emerging zoonosis in Andean America, Asia, and Africa. The control of the disease, both in humans and animals, is based on using anthelmintic drugs, which has resulted in increased resistance to the most effective anthelmintics, such as triclabendazole, in many countries. This, together with the concerns about drug residues in food and the environment, has increased the interest in preventive measures such as a vaccine to help control the disease in endemic areas. Despite important efforts over the past two decades and the work carried out with numerous vaccine candidates, none of them has demonstrated consistent and reproducible protection in target species. This is at least in part due to the high immunomodulation capacity of the parasite, making ineffective the host response in susceptible species such as ruminants. It is widely accepted that a deeper knowledge of the host-parasite interactions is needed for a more rational design of vaccine candidates. In recent years, the use of emerging technologies has notably increased the amount of data about these interactions. In the present study, current knowledge of host-parasite interactions and their implication in Fasciola hepatica vaccine development is reviewed.

Fasciola hepatica antioxidant and protease-inhibitor cocktail recombinant vaccines administered five times elicit potent and sustained immune responses in sheep but do not confer protection

Our laboratory's vaccine development strategy against the livestock parasite Fasciola hepatica centres around disrupting key biological processes by combining groups of antigens with similar/complementary functional actions into a single vaccine cocktail. In this study the focus was on antioxidant protein vaccines and a protease inhibitor vaccine aimed at disrupting the parasite's ability to defend against oxidative stress and protease-inhibitor balance, respectively. Two combinations of recombinantly expressed antioxidants were assessed, namely peroxiredoxin (rFhPrx), thioredoxin (rFhTrx) and thioredoxin-glutathione reductase (rFhTGR) (Group 1) and rFhPrx, rFhTrx, and two superoxide dismutases (rFhSOD1 and rFhSOD3) (Group 2). The protease inhibitor vaccine cocktail included representatives of each of the key secreted protease inhibitor families, namely a Kunitz-type inhibitor (rFhKT1), a serpin (rFhSrp1) and a stefin, (rFhStf1) (Group 3). The vaccine combinations were formulated in adjuvant Montanide 61VG administered at five timepoints; two before experimental challenge with 60 F. hepatica metacercariae and three after infection. The vaccine combinations did not reduce the liver fluke burden, and only Group 2 displayed a marginal reduction in egg viability (8.2%). Despite previous results showing an effect of liver fluke vaccines on overall weight gain in infected animals, no significant (P value >0.05) impact on weight gain was observed in this study. Antibodies were elicited against all the vaccine antigens within the cocktails and were maintained at high levels to the end of the trial, due to our strategy of continuing vaccine administration after infection. However, these responses were not boosted by the challenge F. hepatica infection. A comparative analysis with previous vaccine data using a protease inhibitor vaccine found no repeat of the promising outcomes associated with this vaccine, indicating that the addition of rFhSrp1 to the vaccine cocktail did not improve vaccine efficacy. Assessment of liver pathology across the two trials using a modified liver enzyme score (glutamate dehydrogenase to platelet ratio) at eight weeks post infection suggests an association with liver fluke burden above 45 flukes, which could be used to predict liver pathology in future trials. The results reported in this study highlight the ambiguousness in liver fluke vaccine development and the difficulty in obtaining consistent and repeatable protection. This work stresses the need for repetition of trials and the use of sufficiently sized groups to assess vaccine efficacy with adequate statistical power.

The combination of vaccines and adjuvants to prevent the occurrence of high incidence of infectious diseases in bovine

As the global population grows, the demand for beef and dairy products is also increasing. The cattle industry is facing tremendous pressures and challenges. The expanding cattle industry has led to an increased risk of disease in cattle. These diseases not only cause economic losses but also pose threats to public health and safety. Hence, ensuring the health of cattle is crucial. Vaccination is one of the most economical and effective methods of preventing bovine infectious diseases. However, there are fewer comprehensive reviews of bovine vaccines available. In addition, the variable nature of bovine infectious diseases will result in weakened or even ineffective immune protection from existing vaccines. This shows that it is crucial to improve overall awareness of bovine vaccines. Adjuvants, which are crucial constituents of vaccines, have a significant role in enhancing vaccine response. This review aims to present the latest advances in bovine vaccines mainly including types of bovine vaccines, current status of development of commonly used vaccines, and vaccine adjuvants. In addition, this review highlights the main challenges and outstanding problems of bovine vaccines and adjuvants in the field of research and applications. This review provides a theoretical and practical basis for the eradication of global bovine infectious diseases.

The trehalose glycolipid C18Brar promotes antibody and T-cell immune responses to Mannheimia haemolytica and Mycoplasma ovipneumoniae whole cell antigens in sheep

Bronchopneumonia is a common respiratory disease in livestock. Mannheimia haemolytica is considered the main causative pathogen leading to lung damage in sheep, with Mycoplasma ovipneumoniae and ParaInfluenza virus type 3, combined with adverse physical and physiological stress, being predisposing factors. A balance of humoral and cellular immunity is thought to be important for protection against developing respiratory disease. In the current study, we compared the ability of the trehalose glycolipid adjuvant C18Brar (C18-alkylated brartemicin analogue) and three commercially available adjuvant systems i.e., Quil-A, Emulsigen-D, and a combination of Quil-A and aluminium hydroxide gel, to stimulate antibody and cellular immune responses to antigens from inactivated whole cells of M. haemolytica and M. ovipneumoniae in sheep. C18Brar and Emulsigen-D induced the strongest antigen-specific antibody responses to both M. haemolytica and M. ovipneumoniae, while C18Brar and Quil-A promoted the strongest antigen-specific IL-17A responses. The expression of genes with known immune functions was determined in antigen-stimulated blood cultures using Nanostring nCounter technology. The expression levels of CD40, IL22, TGFB1, and IL2RA were upregulated in antigen-stimulated blood cultures from animals vaccinated with C18Brar, which is consistent with T-cell activation. Collectively, the results demonstrate that C18Brar can promote both antibody and cellular responses, notably Th17 immune responses in a ruminant species.

Baseline T-lymphocyte and cytokine indices in sheep peripheral blood

Background

Sheep are an important livestock species worldwide and an essential large-animal model for animal husbandry and veterinary research. Understanding fundamental immune indicators, especially T-lymphocyte parameters, is necessary for research on sheep diseases and vaccines, to better understand the immune response to bacteria and viruses for reducing the use of antibiotics and improving the welfare of sheep. We randomly selected 36 sheep of similar ages to analyze cell-related immune indicators in peripheral blood mononuclear cells (PBMCs). The proportions of CD4⁺ and CD8⁺ T cells in PBMCs were detected by flow cytometry. We used Concanavalin A (Con A) and Phorbol-12-myristate-13-acetate (PMA)/Ionomycin to stimulate PBMCs, and measured the expression of IFN-γ, IL-4, and IL-17A using enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISpot). Simultaneously, PMA/Ionomycin/brefeldin A (BFA) was added to PBMCs, then the expression of IFN-γ, IL-4, and IL-17A was detected by flow cytometry after 4 h of culturing. In addition, we observed the proliferation of PBMCs stimulated with Con A for 3, 4, and 5 days.

Results

The proportions of CD4⁺ T lymphocytes (18.70 ± 4.21%) and CD8⁺ T lymphocytes (8.70 ± 3.65%) were generally consistent among individuals, with a CD4/CD8 ratio of 2.40 ± 0.79. PBMCs produced high levels of IFN-γ, IL-4, and IL-17A after stimulation with PMA/Ionomycin and Con A. Furthermore, PMA/Ionomycin stimulation of PBMC yielded significantly higher cytokine levels than Con A stimulation. Flow cytometry showed that the level of IFN-γ (51.49 ± 11.54%) in CD8⁺ T lymphocytes was significantly (p < 0.001) higher than that in CD4⁺ T lymphocytes (14.29 ± 3.26%); IL-4 (16.13 ± 6.81%) in CD4⁺ T lymphocytes was significantly (p < 0.001) higher than that in CD8⁺ T lymphocytes (1.84 ± 1.33%), There was no difference in IL-17A between CD4⁺ (2.83 ± 0.98%) and CD8⁺ T lymphocytes (1.34 ± 0.67%). The proliferation of total lymphocytes, CD4⁺ T lymphocytes, and CD8⁺ T lymphocytes continued to increase between days 3 and 5; however, there were no significant differences in proliferation between the cell types during the stimulation period.

Conclusions

Evaluating primary sheep immune indicators, especially T lymphocytes, is significant for studying cellular immunity. This study provided valuable data and theoretical support for assessing the immune response of sheep to pathogens and improving sheep welfare.

Vaccination with cathepsin L phage-exposed mimotopes, single or in combination, reduce size, fluke burden, egg production and viability in sheep experimentally infected with Fasciola hepatica

Fascioliasis is a worldwide emergent zoonotic disease that significantly constrains the productivity of livestock. In this study, fluke burdens, liver fluke size and biomass, faecal eggs counts, serum levels of hepatic enzymes and immune response were assessed in sheep vaccinated with peptide mimotopes of cathepsin L and infected with metacercariae. A total of 25 sheep were allocated randomly into five groups of five animals each, and experimental groups were immunised with 1 × 10¹³ filamentous phage particles of cathepsin L1 (CL1) (TPWKDKQ), CL2 (YGSCFLR) and mixtures of CL1 + CL2 mimotopes, in combination with Quil A adjuvant, and wild-type M13KE phage in a two-vaccination scheme on weeks 0 and 4. The control group received phosphate-buffered saline. All groups were challenged with 300 metacercariae two weeks after the last immunisation and euthanised 16 weeks later. The CL1 vaccine was estimated to provide 57.58% protection compared with the control group; no effect was observed in animals immunised with CL2 and CL1 + CL2 (33.14% and 11.63%, respectively). However, animals receiving CL2 had a significant reduction in parasite egg output. Vaccinated animals showed a significant reduction in fluke length and width and wet weights. In the CL1 group, there was a significant reduction in the total biomass of parasites recovered. Egg development was divided into seven stages: dead, empty, unembryonated, cell division, eyespot, hatched and hatching. The highest percentage of developmental stages was detected for vaccinated sheep administered CL1 + CL2 with cell division, and the lowest percentage was observed in the hatching stage. Furthermore, a significant difference in all developmental stages was observed between vaccinated animals and the control group (P < 0.01). The levels of anti-phage total IgG in immune sera increased significantly at four weeks after immunisation and were always significantly higher for cathepsin L vaccine group than in the challenged control group. Total IgG was inversely and significantly correlated with worm burden in the CL1 group.

Efficacy of a multivalent vaccine against Fasciola hepatica infection in sheep

In this work we report the protection found in a vaccination trial performed in sheep with two different vaccines composed each one by a cocktail of antigens (rCL1, rPrx, rHDM and rLAP) formulated in two different adjuvants (Montanide ISA 61 VG (G1) and Alhydrogel®(G2)). The parameters of protection tested were fluke burden, faecal egg count and evaluation of hepatic lesions. In vaccinated group 1 we found a significant decrease in fluke burden in comparison to both unimmunised and infected control group (37.2%; p = 0.002) and to vaccinated group 2 (Alhydrogel®) (27.08%; p = 0.016). The lower fluke burden found in G1 was accompanied by a decrease in egg output of 28.71% in comparison with the infected control group. Additionally, gross hepatic lesions found in vaccine 1 group showed a significant decrease (p = 0.03) in comparison with unimmunised-infected group. The serological study showed the highest level for both IgG1 and IgG2 in animals from group 1. All these data support the hypothesis of protection found in vaccine 1 group.

Phage display-based vaccine with cathepsin L and excretory-secretory products mimotopes of Fasciola hepatica induces protective cellular and humoral immune responses in sheep

Fasciolosis is a foodborne zoonotic disease that affects grazing animals and causes substantial economic losses worldwide. Excretory/secretory (E/S) products and cathepsin L mimotopes from Fasciola hepatica were used to immunise experimentally infected sheep against liver flukes. The level of protection was measured in terms of fluke burden, morphometric measurements and faecal egg counts, as well as the humoral and cellular immune responses elicited. Five groups of 5 sheep each were immunised with 1 × 10¹³ phage particles of cathepsin L1 (group 1: SGTFLFS), cathepsin L1 (group 2: WHVPRTWWVLPP) and immunodominant E/S product (group 3) mimotopes with Quil A adjuvant, and wild-type M13KE phage (group 4) at the beginning and as a booster two weeks later. The control group received phosphate-buff ;ered saline. All groups were challenged with 300 metacercariae at week four and slaughtered 18 weeks later. The mean fluke burdens after challenge were reduced by 52.39 % and 67.17 % in sheep vaccinated with E/S products (group 3) and cathepsin L1 (group 1: SGTFLFS), respectively; no eff ;ect was observed in animals inoculated with cathepsin L1 (group 2: WHVPRTWWVLPP). Animals vaccinated showed a significant reduction in fluke length and width, wet weights and egg output Sheep immunised with phage-displayed mimotopes induced the development of specific IgG1 and IgG2, indicating a mixed Th1/Th2 immune response. Measurement of cytokine levels revealed higher levels of IFN-γ as well as lower production of IL-4 in sheep vaccinated with the mimotope peptide of F. hepatica. Fluke-specific production of IFN-γ in immunised animals was significantly correlated with fluke burden (P < 0.01). As helminth infection progressed, increased levels of IL-4 were evident in the wild-type M13KE phage (group 4) and the control groups (group 5), accompanied by a downregulation of IFN-γ production. Vaccinated animals with cathepsin L1 (group 1: SGTFLFS) showed that amino acids located in the middle (⁶⁴SG⁶⁵) of the linear sequence and C-terminal end (³¹⁴TFLFS³¹⁸) were associated with significant protection.

Characterization of two putative Dichelobacter nodosus footrot vaccine antigens identifies the first lysozyme inhibitor in the genus

The Gram-negative anaerobic bacterium Dichelobacter nodosus (Dn) causes footrot in ruminants, a debilitating and highly contagious disease that results in necrotic hooves and significant economic losses in agriculture. Vaccination with crude whole-cell vaccine mixed with multiple recombinant fimbrial proteins can provide protection during species-specific outbreaks, but subunit vaccines containing broadly cross-protective antigens are desirable. We have investigated two D. nodosus candidate vaccine antigens. Macrophage Infectivity Potentiator Dn-MIP (DNO_0012, DNO_RS00050) and Adhesin Complex Protein Dn-ACP (DNO_0725, DNO_RS06795) are highly conserved amongst ~170 D. nodosus isolates in the https://pubmlst.org/dnodosus/ database. We describe the presence of two homologous ACP domains in Dn-ACP with potent C-type lysozyme inhibitor function, and homology of Dn-MIP to other putative cell-surface and membrane-anchored MIP virulence factors. Immunization of mice with recombinant proteins with a variety of adjuvants induced antibodies that recognised both proteins in D. nodosus. Notably, immunization with fimbrial-whole-cell Footvax vaccine induced anti-Dn-ACP and anti-Dn-MIP antibodies. Although all adjuvants induced high titre antibody responses, only antisera to rDn-ACP-QuilA and rDn-ACP-Al(OH)₃ significantly prevented rDn-ACP protein from inhibiting lysozyme activity in vitro. Therefore, a vaccine incorporating rDn-ACP in particular could contribute to protection by enabling normal innate immune lysozyme function to aid bacterial clearance.

Liposomes used as a vaccine adjuvant-delivery system: From basics to clinical immunization

Liposomes are widely utilized as a carrier to improve therapeutic efficacy of agents thanks to their merits of high loading capacity, targeting delivery, reliable protection of agents, good biocompatibility, versatile structure modification and adjustable characteristics, such as size, surface charge, membrane flexibility and the agent loading mode. In particular, in recent years, through modification with immunopotentiators and targeting molecules, and in combination with innovative immunization devices, liposomes are rapidly developed as a multifunctional vaccine adjuvant-delivery system (VADS) that has a high capability in inducing desired immunoresponses, as they can target immune cells and even cellular organelles, engender lysosome escape, and promote Ag cross-presentation, thus enormously enhancing vaccination efficacy. Moreover, after decades of development, several products developed on liposome VADS have already been authorized for clinical immunization and are showing great advantages over conventional vaccines. This article describes in depth some critical issues relevant to the development of liposomes as a VADS, including principles underlying immunization, physicochemical properties of liposomes as the immunity-influencing factors, functional material modification to enhance immunostimulatory functions, the state-of-the-art liposome VADSs, as well as the marketed vaccines based on a liposome VADS. Therefore, this article provides a comprehensive reference to the development of novel liposome vaccines.

Low allelic diversity in vaccine candidates genes from different locations sustain hope for Fasciola hepatica immunization

Fasciola hepatica is a trematode parasite that causes fasciolosis in animals and humans. Fasciolosis is usually treated with triclabendazole, although drug-resistant parasites have been described in several geographical locations. An alternative to drug treatment would be the use of a vaccine, although vaccination studies that have been performed mainly in ruminants over the last 30 years, show high variability in the achieved protection and are not yet ready for commercialisation. Since F. hepatica exhibits a high degree of genomic polymorphism, variation in vaccine efficacy could be attributed, at least partially, to phenotypic differences in vaccine candidate sequences amongst parasites used in the challenge infections. To begin to address this issue, a collection of F. hepatica isolates from geographically dispersed regions, as well as parasites obtained from vaccination trials performed against a field isolate from Uruguay and the experimentally maintained South Gloucester isolate (Ridgeway Research, UK), were compiled to establish a F. hepatica Biobank. These collected isolates were used for the genetic analysis of several vaccine candidates that are important in host-parasite interactions and are the focus of the H2020 PARAGONE vaccine project (https://www.paragoneh2020.eu/), namely FhCL1, FhCL2, FhPrx, FhLAP and FhHDM. Our results show that F. hepatica exhibits a high level of conservation in the sequences encoding each of these proteins. The consequential low variability in these vaccine candidates amongst parasites from different geographical regions reinforces the idea that they would be suitable immunogens against liver fluke isolates worldwide.