Use of Veterinary Vaccines for Livestock as a Strategy to Control Foodborne Parasitic Diseases

Insights into the epidemiology, pathogenesis, and differential diagnosis of schistosomiasis

Schistosomiasis is a neglected tropical disease that is prevalent in low- and middle-income countries. There are five human pathogenic species, of which Schistosoma haematobium, Schistosoma mansoni and Schistosoma japonicum are the most prevalent worldwide and cause the greatest burden of disease in terms of mortality and morbidity. In addition, hybrid schistosomes have been identified through molecular analysis. Human infection occurs when cercariae, the larval form of the parasite, penetrate the skin of people while bathing in contaminated waters such as lakes and rivers. Schistosomiasis can cause both urogenital and intestinal symptoms. Urogenital symptoms include haematuria, bladder fibrosis, kidney damage, and an increased risk of bladder cancer. Intestinal symptoms may include abdominal pain, sometimes accompanied by diarrhoea and blood in the stool. Schistosomiasis affects more than 250 million people and causes approximately 70 million Disability-Adjusted Life Years (DALYs), mainly in Africa, South America, and Asia. To control infection, it is essential to establish sensitive and specific diagnostic tests for epidemiological surveillance and morbidity reduction. This review provides an overview of schistosomiasis, with a focus on available diagnostic tools for Schistosoma spp. Current molecular detection methods and progress in the development of new diagnostics for schistosomiasis infection are also discussed.

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.

Global prevalence and risk factors of Enterocytozoon bieneusi infection in humans: a systematic review and meta-analysis

Enterocytozoon bieneusi is one of the most important zoonotic pathogens. In this study, we present a systematic review and meta-analysis of the prevalence of human E. bieneusi infection in endemic regions and analyze the various potential risk factors. A total of 75 studies were included. Among 31,644 individuals tested, 2,291 (6.59%) were E. bieneusi-positive. The highest prevalence of E. bieneusi in the male population was 5.50%. The prevalence of E. bieneusi in different age groups was varied, with 10.97% in teenagers. The prevalence of E. bieneusi in asymptomatic patients (6.49%) is significantly lower than that in HIV-infected patients (11.49%), and in patients with diarrheal symptoms (16.45%). Rural areas had a higher rate (7.58%) than urban ones. The prevalence of E. bieneusi in humans was the highest (6.42%) at altitudes <10 m. Moreover, the temperate zone marine climate (13.55%) had the highest prevalence. A total of 69 genotypes of E. bieneusi have been found in humans. This is the first global study regarding E. bieneusi prevalence in humans. Not only people with low immunity (such as the elderly, children, people with HIV, etc.), but also people in Europe in temperate marine climates should exercise caution to prevent infection with E. bieneusi during contact process with animals.

China's prevention and control experience of echinococcosis: A 19-year retrospective

Echinococcosis poses a significant threat to public health. The Chinese government has implemented prevention and control measures to mitigate the impact of the disease. By analyzing data from the Chinese Center for Disease Control and Prevention and the State Council of the People's Republic of China, we found that implementation of these measures has reduced the infection rate by nearly 50% between 2004 to 2022 (from 0.3975 to 0.1944 per 100,000 person-years). Nonetheless, some regions still bear a significant disease burden, and lack of detailed information limites further evaluation of the effects on both alveolar and cystic echinococcosis. Our analysis supports the continuing implementation of these measures and suggests that enhanced wildlife management, case-based strategies, and surveillance systems will facilitate disease control.

Knowledge, perceptions, and practices around zoonotic diseases among actors in the livestock trade in the Lake Victoria crescent ecosystem in East Africa

Background

Zoonotic diseases such as anthrax, rabies, brucellosis, and Rift Valley fever pose a direct threat to health and undercut livelihoods in the communities in which they occur. A combination of anthropogenic and animal activities like migration and interaction with wildlife and their respective parasites and vectors drives the emergence and re-emergence of zoonotic diseases. Consequently, One Health interdisciplinary approaches that incorporate social scientists can provide key insights into complex local perceptions. The approach calls for collaboration between the human and animal health sectors, including the sharing of disease surveillance data necessary to alleviate disease impacts. Livestock traders interact closely with livestock, which puts them at elevated risk of infection and creates conditions by which they may spread zoonotic disease. It is thus essential to examine practices among actors involved in the livestock trade to understand the most appropriate ways to mitigate these risks.

Methods

A qualitative study was conducted among the actors in the livestock trade in Busia County on their knowledge and perceptions of zoonotic diseases and practices that may contribute to the spread, control, and prevention of zoonotic disease transmission. A thematic analysis framework was used to categorize and synthesize data from in-depth interviews (IDIs), key informant interviews (KIIs), and structured observations.

Results

Whereas participants could list livestock diseases, they could not identify which ones were zoonoses, demonstrating insufficient knowledge of zoonosis. They identify sick animals by checking for dropped ears, excess mucus production, diarrhea, bloody urinal discharge, and general animal activity levels. To prevent the spread of these diseases, they wash their animals, isolate sick animals from the rest of the stock, and vaccinate their animals. They seek help from animal health professionals for sick animals as part of curative practices. This shows that they perceive the diseases as serious and that they need to be attended to by professionals. The results also show that they perceive animals from outside the region to be more vulnerable to diseases compared to those from within. The actors in the livestock trade engage in practices like skinning dead animals before burying them; to them, this is a normal practice. Some also consume dead carcasses. These increase the risk of zoonotic disease transmission.

Conclusion

The actors involved in the livestock trade are critical in the prevention and elimination of zoonotic diseases; hence, they need to be involved when developing intervention programs and policies for animal health extension services. Training them as a continuum of animal health workers blends lay and professional knowledge, which, alongside their intense contact with large numbers of animals, becomes a critical disease surveillance tool. Increasing awareness of zoonoses by using multi-disciplinary teams with social scientists is urgently needed so that practices like skinning dead animals before disposing of them and consumption of dead carcasses can be minimized.

Proteomics Applications in Toxoplasma gondii: Unveiling the Host-Parasite Interactions and Therapeutic Target Discovery

Toxoplasma gondii, a protozoan parasite with the ability to infect various warm-blooded vertebrates, including humans, is the causative agent of toxoplasmosis. This infection poses significant risks, leading to severe complications in immunocompromised individuals and potentially affecting the fetus through congenital transmission. A comprehensive understanding of the intricate molecular interactions between T. gondii and its host is pivotal for the development of effective therapeutic strategies. This review emphasizes the crucial role of proteomics in T. gondii research, with a specific focus on host-parasite interactions, post-translational modifications (PTMs), PTM crosstalk, and ongoing efforts in drug discovery. Additionally, we provide an overview of recent advancements in proteomics techniques, encompassing interactome sample preparation methods such as BioID (BirA*-mediated proximity-dependent biotin identification), APEX (ascorbate peroxidase-mediated proximity labeling), and Y2H (yeast two hybrid), as well as various proteomics approaches, including single-cell analysis, DIA (data-independent acquisition), targeted, top-down, and plasma proteomics. Furthermore, we discuss bioinformatics and the integration of proteomics with other omics technologies, highlighting its potential in unraveling the intricate mechanisms of T. gondii pathogenesis and identifying novel therapeutic targets.

Evaluation of livestock farmers' knowledge, attitudes and practices regarding the use of veterinary vaccines in Southwest Ethiopia

BACKGROUND

The utilization of veterinary vaccines plays a vital role in preventing and managing animal diseases. However, the success of vaccination programmes relies on livestock farmers' understanding, perspectives and behaviours regarding their application. Therefore, this study aims to evaluate the knowledge, attitudes and practices of livestock farmers in Southwest Ethiopia regarding the use of veterinary vaccines.

METHODS

The study followed a cross-sectional design conducted between October 2021 and October 2022. A sample of 476 livestock-owning farmers, including those who raise dairy cattle, beef cattle and poultry, were interviewed from the districts of Shei Bench, Semen Bench, Sheko and Yeki.

RESULTS

The findings revealed that participants from Sheko, who had a poultry farm, were college graduates and resided in an urban area, were more likely to have good knowledge of veterinary vaccines. Similarly, participants who were male, from Semen Bench, had a poultry farm and had a high school education, exhibited a positive attitude towards veterinary vaccines. Furthermore, being male, from Semen Bench, having a poultry farm, and having a high school education were associated with increased veterinary vaccine use.

CONCLUSION

This study highlights the importance of addressing gender differences and tailoring interventions based on geography and farming conditions in the area. These measures are crucial to improve practices related to veterinary vaccines for enhanced animal health and productivity. Prioritizing education, veterinary services and information dissemination is vital. However, further research and targeted interventions are needed to better comprehend underlying factors and implement effective strategies for diverse communities in different areas.

Screening of lipid-A related genes and development of low-endotoxicity live-attenuated Salmonella gallinarum by arnT deletion that elicits immune responses and protection against fowl typhoid in chickens

In the present study, lipid-A gene mutants of Salmonella gallinarum (SG) were screened, and the arnT mutant exhibited optimal acidic and oxidative-stress and macrophage-survival. Modifying lipid-A by arnT-deletion resulted in significantly reduced endotoxicity, virulence, and mortality. Therefore, the arnT-deleted vaccine-candidate strain JOL2841 was constructed and demonstrated to be safe due to appropriate clearance by the chicken immune system. The reduced-endotoxicity of JOL2841 was evident from the downregulation of TNFα and IL-1β inflammatory cytokines, no inflammatory signs in organ gross-examination, and histopathological analysis. The IgY and IgA antibody titres, CD4, and CD8 T-cell population improvements, and IL-4, IL-2, and INFγ expression decipher the profound Th2 and Th1 immunogenicity. Consequently, JOL2841 exhibited prominent protection against wild-type SG challenge, as revealed by organ pathogen-load determination, organ gross-examination, and histopathological examination. Overall, the study represented the first report of arnT deficient SG resulted in negligible endotoxicity, low-virulence, safety and coordinated elicitation of humoral and cell-mediated immune response in chickens.

Universal Tick Vaccines: Candidates and Remaining Challenges

Recent advancements in molecular biology, particularly regarding massively parallel sequencing technologies, have enabled scientists to gain more insight into the physiology of ticks. While there has been progress in identifying tick proteins and the pathways they are involved in, the specificities of tick-host interaction at the molecular level are not yet fully understood. Indeed, the development of effective commercial tick vaccines has been slower than expected. While omics studies have pointed to some potential vaccine immunogens, selecting suitable antigens for a multi-antigenic vaccine is very complex due to the participation of redundant molecules in biological pathways. The expansion of ticks and their pathogens into new territories and exposure to new hosts makes it necessary to evaluate vaccine efficacy in unusual and non-domestic host species. This situation makes ticks and tick-borne diseases an increasing threat to animal and human health globally, demanding an urgent availability of vaccines against multiple tick species and their pathogens. This review discusses the challenges and advancements in the search for universal tick vaccines, including promising new antigen candidates, and indicates future directions in this crucial research field.

In Vitro Transcriptional Response of Eimeria tenella to Toltrazuril Reveals That Oxidative Stress and Autophagy Contribute to Its Anticoccidial Effect

Intestinal coccidiosis is a common parasitic disease in livestock, caused by the infection of Eimeria and Cystoisospora parasites, which results in great economic losses to animal husbandry. Triazine compounds, such as toltrazuril and diclazuril, are widely used in the treatment and chemoprophylaxis of coccidiosis. Unfortunately, widespread drug resistance has compromised their effectiveness. Most studies have focused on prophylaxis and therapeutics with toltrazuril in flocks, while a comprehensive understanding of how toltrazuril treatment alters the transcriptome of E. tenella remains unknown. In this study, merozoites of E. tenella were treated in vitro with 0.5 μg/mL toltrazuril for 0, 1, 2 and 4 h, respectively. The gene transcription profiles were then compared by high-throughput sequencing. Our results showed that protein hydrolysis genes were significantly upregulated after drug treatment, while cell cycle-related genes were significantly downregulated, suggesting that toltrazuril may affect parasite division. The expression of redox-related genes was upregulated and elevated levels of ROS and autophagosomes were detected in the parasite after toltrazuril treatment, suggesting that toltrazuril may cause oxidative stress to parasite cells and lead to its autophagy. Our results provide basic knowledge of the response of Eimeria genes to toltrazuril and further analysis of the identified transcriptional changes can provide useful information for a better understanding of the mechanism of action of toltrazuril against Eimeria.

Immunogenicity of peptide-based vaccine composed of epitopes from Echinococcus granulosus rEg.P29

Echinococcus granulosus is one of the main causes of economic loss in the livestock industry because of its food-borne transmission. Cutting off the transmission route is a valid prevention method, and vaccines are the most effective means of controlling and eliminating infectious diseases. However, no human-related vaccine has been yet marketed. As a genetic engineering vaccine, recombinant protein P29 of E. granulosus (rEg.P29) could provide protection against deadly challenges. In this study, we generated peptide vaccines (rEg.P29_T , rEg.P29_B , and rEg.P29_T+B ) based on rEg.P29 and an immunized model was established by subcutaneous immunization. Further evaluation showed that peptide vaccine immunization in mice induced T helper type 1 (Th1)-mediated cellular immune responses, leading to high levels of rEg.P29 or rEg.P29_B -specific antibodies. In addition, rEg.P29_T+B immunization can induce a higher antibody and cytokine production level than single-epitope vaccines, and immune memory is also longer. Collectively, these results suggest that rEg.P29_T+B has the potential to be developed as an efficient subunit vaccine for use in areas where E. granulosus is endemic.

Is the incidence of congenital toxoplasmosis declining?

Prenatal infection with the protozoan parasite Toxoplasma gondii can cause congenital toxoplasmosis (CT), an often fatal or lifelong-disabling condition. Several studies of human populations have reported temporal decreases in seroprevalence, suggesting declining CT incidence. However, the consistency of this trend among diverse populations remains unclear, as does its implication for prenatal screening programmes, the major intervention against CT. Using temporally resolved data on the seroprevalence of T. gondii in various countries, we discuss how the parasite's changing epidemiology may affect trends in CT incidence in varying and counterintuitive ways. We argue that parasite stage-specific serology could be helpful for understanding underlying causes of secular changes in seroprevalence. Furthermore, we highlight the importance of updating cost-effectiveness estimates of screening programmes, accounting for neuropsychiatric sequelae.

Oral immunization of mice with recombinant Lactobacillus plantarum expressing a Trichinella spiralis galectin induces an immune protection against larval challenge

BACKGROUND

Trichinella spiralis is an important foodborne parasite that presents a severe threat to food safety. The development of an anti-Trichinella vaccine is an important step towards controlling Trichinella infection in food animals and thus ensure meat safety. Trichinella spiralis galectin (Tsgal) is a novel protein that has been identified on the surface of this nematode. Recombinant Tsgal (rTsgal) was found to participate in larval invasion of intestinal epithelium cells (IECs), whereas anti-rTsgal antibodies impeded the invasion.

METHODS

The rTsgal/pSIP409- pgsA' plasmid was constructed and transferred into Lactobacillus plantarum strain NC8, following which the in vitro biological properties of rTsgal/NC8 were determined. Five groups of mice were orally immunized three times, with a 2-week interval between immunizations, with recombinant NC8-Tsgal, recombinant NC8-Tsgal + α-lactose, empty NC8, α-lactose only or phosphate-buffered saline (PBS), respectively. The vaccinated mice were infected orally with T. spiralis larvae 2 weeks following the last vaccination. Systemic and intestinal local mucosal immune responses and protection were also assessed, as were pathological changes in murine intestine and skeletal muscle.

RESULTS

rTsgal was expressed on the surface of NC8-Tsgal. Oral immunization of mice with rTsgal vaccine induced specific forms of serum immunoglobulin G (IgG), namely IgG1/IgG2a, as well as IgA and gut mucosal secretion IgA (sIgA). The levels of interferon gamma and interleukin-4 secreted by cells of the spleen, mesenteric lymph nodes, Peyer's patches and intestinal lamina propria were significantly elevated at 2-6 weeks after immunization, and continued to rise following challenge. Immunization of mice with the oral rTsgal vaccine produced a significant immune protection against T. spiralis challenge, as demonstrated by a 57.28% reduction in the intestinal adult worm burden and a 53.30% reduction in muscle larval burden, compared to the PBS control group. Immunization with oral rTsgal vaccine also ameliorated intestinal inflammation, as demonstrated by a distinct reduction in the number of gut epithelial goblet cells and mucin 2 expression level in T. spiralis-infected mice. Oral administration of lactose alone also reduced adult worm and larval burdens and relieved partially inflammation of intestine and muscles.

CONCLUSIONS

Immunization with oral rTsgal vaccine triggered an obvious gut local mucosal sIgA response and specific systemic Th1/Th2 immune response, as well as an evident protective immunity against T. spiralis challenge. Oral rTsgal vaccine provided a prospective approach for control of T. spiralis infection.

Toxoplasma gondii: the kitty litter parasite

Toxoplasma gondii is considered the most successful parasite by some, and yet, it is likely that you haven't even heard of it.

Toxoplasmosis vaccines: what we have and where to go?

Despite recent major advances in developing effective vaccines against toxoplasmosis, finding new protective vaccination strategies remains a challenging and elusive goal as it is critical to prevent the disease. Over the past few years, various experimental approaches have shown that developing an effective vaccine against T. gondii is achievable. However, more remains unknown due to its complicated life cycle, difficulties in clinical translation, and lack of a standardized platform. This minireview summarizes the recent advances in the development of T. gondii vaccines and the main obstacles to developing a safe, effective and durable T. gondii vaccine. The successes and failures in developing and testing vaccine candidates for the T. gondii vaccine are also discussed, which may facilitate the future development of T. gondii vaccines.

Identification of B‐cell dominant epitopes in the recombinant protein P29 from Echinococcus granulosus

Introduction

Echinococcus granulosus (E. granulosus) causes a hazardous zoonotic parasitic disease. This parasite can occupy the liver and several areas of the body, causing incurable damage. Our previous studies have provided evidence that the recombinant protein P29 (rEg.P29) exhibit immune protection in sheep and mice against pathological damage induced by E. granulosus, showing its potential as candidate for vaccine development. However, information on the B‐cell epitopes of rEg.P29 has not yet been reported.

Methods

Immunological model was established in mice with rEg.P29. SDS‐PAGE and Western blot were used to identify protein. Screening for B‐cell dominant epitope peptides of rEg.P29 by enzyme‐linked immunosorbent assay (ELISA) and immune serum. Dominant epitopes were validated using ELISA and flow cytometry. Multiple sequence alignment analysis was performed using BLAST and UniProt.

Results

Immunization with rEg.P29 induced intense and persistent antibody responses, and the epitope of the dominant antigen of B cells are identified as rEg.P29_166–185 (LKNAKTAEQKAKWEAEVRKD). Anti‐rEg.P29_166–185‐specific antibodies lack epitopes against IgA, IgE, and IgG3, compared to anti‐rEg.P29‐specific antibodies. However, anti‐rEg.P29_166–185 IgG showed comparatively higher titers, as determined among those peptides by endpoint titration. In addition, rEg.P29 and rEg.P29_166–185 promote B‐cell activation and proliferation in vitro. The dominant epitopes are relatively conserved in different subtypes of the rEg.P29 sequence.

Conclusion

rEg.P29_166–185 can act as a dominant B‐cell epitope for rEg.P29 and promote cell activation and proliferation in the same way as rEg.P29.

Vaccines as a Strategy to Control Trichinellosis

Trichinellosis caused by Trichinella spiralis is a worldwide food-borne parasitic zoonosis. Several approaches have been performed to control T. spiralis infection, including veterinary vaccines, which contribute to improving animal health and increasing public health by preventing the transmission of trichinellosis from animals to humans. In the past several decades, many vaccine studies have been performed in effort to control T. spiralis infection by reducing the muscle larvae and adult worms burden. Various candidate antigens, selected from excretory-secretory (ES) products and different functional proteins involved in the process of establishing infection have been investigated in rodent or swine models to explore their protective effect against T. spiralis infection. Moreover, different types of vaccines have been developed to improve the protective effect against T. spiralis infection in rodent or swine models, such as live attenuated vaccines, natural antigen vaccines, recombinant protein vaccines, DNA vaccines, and synthesized epitope vaccines. However, few studies of T. spiralis vaccines have been performed in pigs, and future research should focus on exploring the protective effect of different types of vaccines in swine models. Here, we present an overview of the strategies for the development of effective T. spiralis vaccines and summarize the factors of influencing the effectiveness of vaccines. We also discuss several propositions in improving the effectiveness of vaccines and may provide a route map for future T. spiralis vaccines development.

Foodborne Parasitic Diseases in the Neotropics - A Review

Within the Universal Declaration of Human Rights, it is stated that everyone has the right to an adequate standard of living, which ensures, as well as their family, health and well-being, and food, thereby ensuring adequate nutrition. One of the major threats to overcome this is to ensure food security, which becomes particularly challenging in developing countries due to the high incidence of parasitic diseases. The World Health Organization (WHO), considers it one of the main causes of morbidity, closely linked to poverty and related to inadequate personal hygiene, consumption of raw food, lack of sanitary services, limited access to drinking water and fecal contamination in the environment. It is estimated that more than a fifth of the world’s population is infected by one or several intestinal parasites, and that in many countries of Central and South America the average percentage of infected people is 45%, being Taenia solium, Echinococcus granulosus, Toxoplasma gondii, Cryptosporidium spp, Entamoeba histolytica, Trichinella spiralis, Ascaris spp, Trypanosoma cruzi and Fasciola hepatica some of the most important ones in the neotropics. One of the main reasons why these diseases are diffi cult to control is t he ignorance of their lifecycles, as well as symptoms and current epidemiology of the disease, which contributes to a late or erroneous diagnosis. The present work aims to discuss and make public the current knowledge as well as the general characteristics of these diseases to the general audience.

Chemical Conjugation Strategies for the Development of Protein-Based Subunit Nanovaccines

The production of subunit nanovaccines relies heavily on the development of a vaccine delivery system that is safe and efficient at delivering antigens to the target site. Nanoparticles have been extensively investigated for vaccine delivery over the years, as they often possess self-adjuvanting properties. The conjugation of antigens to nanoparticles by covalent bonds ensures co-delivery of these components to the same subset of immune cells in order to trigger the desired immune responses. Herein, we review covalent conjugation strategies for grafting protein or peptide antigens onto other molecules or nanoparticles to obtain subunit nanovaccines. We also discuss the advantages of chemical conjugation in developing these vaccines.

Heat Shock Proteins 90 kDa: Immunomodulators and Adjuvants in Vaccine Design Against Infectious Diseases

Heat shock proteins 90 kDa (Hsp90s) were originally identified as stress-responsive proteins and described to participate in several homeostatic processes. Additionally, extracellular Hsp90s have the ability to bind to surface receptors and activate cellular functions related to immune response (cytokine secretion, cell maturation, and antigen presentation), making them very attractive to be studied as immunomodulators. In this context, Hsp90s are proposed as new adjuvants in the design of novel vaccine formulations that require the induction of a cell-mediated immune response to prevent infectious diseases. In this review, we summarized the adjuvant properties of Hsp90s when they are either alone, complexed, or fused to a peptide to add light to the knowledge of Hsp90s as carriers and adjuvants in the design of vaccines against infectious diseases. Besides, we also discuss the mechanisms by which Hsp90s activate and modulate professional antigen-presenting cells.

Immunomodulation and Immune Escape Strategies of Gastrointestinal Helminths and Schistosomes

Parasitic worms (helminths) developed various immunoregulatory mechanisms to counteract the immune system of their host. The increasing identification and characterization of helminth-derived factors with strong immune modulatory activity provides novel insights into immune escape strategies of helminths. Such factors might be good targets to enhance anti-helminthic immune responses. In addition, immunosuppressive helminth-derived factors could be useful to develop new therapeutic strategies for treatment of chronic inflammatory conditions. This review will take an in depth look at the effects of immunomodulatory molecules produced by different helminths with a focus on schistosomes and mouse models of hookworm infections.