Th1 and Th2 indices of the immune response in pigs vaccinated against Taenia solium cysticercosis suggest various host immune strategies against the parasite

Evaluating the modulation of peripheral immune profile in people living with HIV and (Neuro)cysticercosis

BACKGROUND

The parasitic infection caused by Taenia solium represents a significant public health concern in developing countries. Larval invasion of body tissues leads to cysticercosis (CC), while central nervous system (CNS) involvement results in neurocysticercosis (NCC). Both conditions exhibit diverse clinical manifestations, and the potential impact of concomitant HIV infection especially prevalent in sub-Saharan Africa on peripheral and CNS immune responses remains poorly understood. This study aimed to identify the potential impact of HIV coinfection in CC and NCC patients.

METHODOLOGY

A nested study within a cross-sectional analysis in two Tanzanian regions was performed and 234 participants (110 HIV+ and 124 HIV-) were tested for cysticercosis antibodies, antigens, CD4 counts and serum Th1 and Th2 cytokines via multiplex bead-based immunoassay. 127 cysticercosis seropositive individuals underwent cranial computed tomography (CCT) and clinical symptoms were assessed. Multiple regression analyses were performed to identify factors associated with cytokine modulation due to HIV in CC and NCC patients.

RESULTS

Serologically, 18.8% tested positive for cysticercosis antibodies, with no significant difference HIV+ and HIV+. A significantly higher rate of cysticercosis antigen positivity was found in HIV+ individuals (43.6%) compared to HIV- (28.2%) (p = 0.016). CCT scans revealed that overall 10.3% had active brain cysts (NCC+). Our study found no significant changes in the overall cytokine profiles between HIV+ and HIV- participants coinfected CC and NCC, except for IL-5 which was elevated in HIV+ individuals with cysticercosis. Furthermore, HIV infection in general was associated with increased levels of pro-and some anti-inflammatory cytokines e.g. TNF-α, IL-8, and IFN-γ. However, based on the interaction analyses, no cytokine changes were observed due to HIV in CC or NCC patients.

CONCLUSIONS

In conclusion, while HIV infection itself significantly modulates levels of key cytokines such as TNF-α, IL-8, and IFN-γ, it does not modulate any cytokine changes due to CC or NCC. This underscores the dominant influence of HIV on the immune system and highlights the importance of effective antiretroviral therapy in managing immune responses in individuals coinfected with HIV and CC/NCC.

GK1 Improves the Immune Response Induced by Dendritic Cells of BALB/c Mice Infected with Leishmania mexicana Promastigotes

PURPOSE

Dendritic cells (DCs) are the most potent antigen-presenting cells (APCs), and their capacity to activate the immune response has been widely used in immunotherapies against different diseases, predominantly cancer. However, they have not been so widely used in immunotherapies against infectious diseases. Leishmania mexicana is the causative agent of cutaneous leishmaniasis in Mexico, which can result in localized cutaneous leishmaniasis (LCL) and diffuse cutaneous leishmaniasis (DCL). DCL is characterized by the incapability of the immune response to control the parasite, which thus disseminates to all teguments. Treatments against DCL have shown low efficacy, which is a reason why alternative therapies such as immunotherapies are promising. One adjuvant that has proven its effectiveness in immunotherapies against some cancers and infections is GK1, a component of the SPVac vaccine against porcine cysticercosis. GK1 has the capacity to elicit proinflammatory cytokines and chemokines from DCs and macrophages.

METHODS

We pulsed bone marrow-derived dendritic cells (BMDCs) with GK1 and a lysate obtained from L. mexicana promastigotes and tested the efficacy of this combination against the infection of susceptible mice with L. mexicana.

RESULTS

We found that BMDCs stimulated with GK1 and a lysate of L. mexicana promastigotes secreted IFN-γ and IL-12, and when they were adoptively transferred to BALB/c mice which were then infected with L. mexicana promastigotes, there was a reduction in the size of the lesion and in the parasite load.

CONCLUSIONS

The adjuvant properties of GK1 along with parasite antigens may have a protective effect against the infection of BALB/c mice with L. mexicana.

High frequency of Taenia pisiformis metacestodes and high sex-associated susceptibility to cysticercosis in naturally infected wild rabbits

Sexual dimorphism is a well-documented phenomenon observed at all levels of the animal kingdom, with the inclusion of both sexes in clinical trials and basic research becoming mandatory. Regarding parasitosis, in several animal species, the signs and virulence of the disease may change depending on the sex of the affected animal. In the cestodiasis caused by Taenia solium and Taenia crassiceps, females are more susceptible to experimental infection than males. Cysticercosis by Taenia pisiformis in rabbits has acquired relevance due to its economic impact, namely affecting welfare and production. In America, specifically in Mexico, there are no formal reports on the infection with T. pisiformis metacestodes in populations of wild rabbits, despite being the country with more endemic species (about 15 species), among them, the volcanoes rabbits or the endangered teporingo (Romerolagus diazi). In this study, 31 wild rabbits were obtained by hunters of some regions of Morelos state during several hunting seasons, and sex, physiological stage, and number of metacestodes were recorded. A high frequency of infection by T. pisiformis metacestodes (67.7%) was found. Also, a higher susceptibility to this infection was observed in does (80% infected) compared to bucks (40%), finding 84.2% of metacestodes (235 metacestodes) in does and 15.8% of metacestodes (44 metacestodes) in bucks. The percentage of infection was higher in lactating compared with pregnant and non-pregnant does, with metacestodes lodging mainly in the uterus. Increasing our knowledge regarding parasitic infections can help us better understand transmission circles as well as the parasite-host interaction of these increasingly at risk rabbit species.

Host Th1/Th2 immune response to Taenia solium cyst antigens in relation to cyst burden of neurocysticercosis

Neurocysticercosis (NCC), Taenia solium larval infection of the brain, is an important cause of acquired seizures in endemic countries, which relate to number, location and degenerating cysts in the brain. Multicyst infections are common in endemic countries although single-cyst infection prevails in India. Single-cyst infections in an endemic country suggest a role for host immunity limiting the infection. This study examined ex vivo CD4(+) T cells and in vitro Th1 and Th2 cytokine responses to T. solium cyst antigens of peripheral blood mononuclear cells of healthy subjects from endemic and nonendemic regions and of single- and multicyst-infected patients for association with cyst burden of NCC. T. solium cyst antigens elicited a Th1 cytokine response in healthy subjects of T. solium-endemic and T. solium-non-endemic regions and those with single-cyst infections and a Th2 cytokine response from subjects with multicyst neurocysticercosis. Multicyst neurocysticercosis subjects also exhibited low levels of effector memory CD4(+) T cells. Th1 cytokine response of T. solium exposure and low infectious loads may aid in limiting cyst number. Th2 cytokines and low effector T cells may enable multiple-cyst infections to establish and persist.

Regulation of immunity by Taeniids: lessons from animal models and in vitro studies

Taeniidae is the largest family of the Cyclophyllidea order of parasites despite being composed of just two genera: Taenia spp and Echinococcus spp. These parasites are flatworms with a terrestrial life cycle, having an immature or larval stage called metacestode, which develops into the mature form within the intestine of the primary host after being consumed in raw or poorly cooked meat. Consumed eggs hatch into oncospheres, penetrate the intestinal walls and are transported via the bloodstream to later develop into metacestodes within the muscles and internal organs of secondary and sometimes primary hosts, thereby initiating the cycle again. Larval stages of both Taenia spp and Echinococcus spp are well known to produce tissue-dwelling, long-lasting infections; in this stage, these parasites can reach centimetres (macroparasites) and both genera may cause life-threatening diseases in humans. Establishing such long-term infections requires an exceptional ability to modulate host immunity for long periods of time. In this review, we analyse the immunoregulatory mechanisms induced by these tapeworms and their products, mainly discussing the importance of taeniid strategies to successfully colonize their hosts, such as antigen-presenting cell phenotype manipulation and the consequent induction of T-cell anergy, among others.

Mutations in a Highly Conserved Motif of nsp1β Protein Attenuate the Innate Immune Suppression Function of Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein 1β (nsp1β) is a multifunctional viral protein, which is involved in suppressing the host innate immune response and activating a unique -2/-1 programmed ribosomal frameshifting (PRF) signal for the expression of frameshifting products. In this study, site-directed mutagenesis analysis showed that the R128A or R129A mutation introduced into a highly conserved motif ((123)GKYLQRRLQ(131)) reduced the ability of nsp1β to suppress interferon beta (IFN-β) activation and also impaired nsp1β's function as a PRF transactivator. Three recombinant viruses, vR128A, vR129A, and vRR129AA, carrying single or double mutations in the GKYLQRRLQ motif were characterized. In comparison to the wild-type (WT) virus, vR128A and vR129A showed slightly reduced growth abilities, while the vRR129AA mutant had a significantly reduced growth ability in infected cells. Consistent with the attenuated growth phenotype in vitro, pigs infected with nsp1β mutants had lower levels of viremia than did WT virus-infected pigs. Compared to the WT virus in infected cells, all three mutated viruses stimulated high levels of IFN-α expression and exhibited a reduced ability to suppress the mRNA expression of selected interferon-stimulated genes (ISGs). In pigs infected with nsp1β mutants, IFN-α production was increased in the lungs at early time points postinfection, which was correlated with increased innate NK cell function. Furthermore, the augmented innate response was consistent with the increased production of IFN-γ in pigs infected with mutated viruses. These data demonstrate that residues R128 and R129 are critical for nsp1β function and that modifying these key residues in the GKYLQRRLQ motif attenuates virus growth ability and improves the innate and adaptive immune responses in infected animals.

IMPORTANCE

PRRSV infection induces poor antiviral innate IFN and cytokine responses, which results in weak adaptive immunity. One of the strategies in next-generation vaccine construction is to manipulate viral proteins/genetic elements involved in antagonizing the host immune response. PRRSV nsp1β was identified to be a strong innate immune antagonist. In this study, two basic amino acids, R128 and R129, in a highly conserved GKYLQRRLQ motif were determined to be critical for nsp1β function. Mutations introduced into these two residues attenuated virus growth and improved the innate and adaptive immune responses of infected animals. Technologies developed in this study could be broadly applied to current commercial PRRSV modified live-virus (MLV) vaccines and other candidate vaccines.

Immunology of Taenia solium taeniasis and human cysticercosis

The life cycle of Taenia solium, the pork tapeworm, is continuously closed in many rural settings in developing countries when free roaming pigs ingest human stools containing T. solium eggs and develop cysticercosis, and humans ingest pork infected with cystic larvae and develop intestinal taeniasis, or may also accidentally acquire cysticercosis by faecal-oral contamination. Cysticercosis of the human nervous system, neurocysticercosis, is a major cause of seizures and other neurological morbidity in most of the world. The dynamics of exposure, infection and disease as well as the location of parasites result in a complex interaction which involves immune evasion mechanisms and involutive or progressive disease along time. Moreover, existing data are limited by the relative lack of animal models. This manuscript revises the available information on the immunology of human taeniasis and cysticercosis.

Genome-wide association study for cytokines and immunoglobulin G in swine

Increased disease resistance through improved immune capacity would be beneficial for the welfare and productivity of farm animals. To identify genomic regions responsible for immune capacity traits in swine, a genome-wide association study was conducted. In total, 675 pigs were included. At 21 days of age, all piglets were vaccinated with modified live classical swine fever vaccine. Blood samples were sampled when the piglets were 20 and 35 days of age, respectively. Four traits, including Interferon-gamma (IFN-γ) and Interleukin 10 (IL-10) levels, the ratio of IFN-γ to IL-10 and Immunoglobulin G (IgG) blocking percentage to CSFV in serum were measured. All the samples were genotyped for 62,163 single nucleotide polymorphisms (SNP) using the Illumina porcineSNP60k BeadChip. After quality control, 46,079 SNPs were selected for association tests based on a single-locus regression model. To tackle the issue of multiple testing, 10,000 permutations were performed to determine the chromosome-wise and genome-wise significance level. In total, 32 SNPs with chromosome-wise significance level (including 4 SNPs with genome-wise significance level) were identified. These SNPs account for 3.23% to 13.81% of the total phenotypic variance individually. For the four traits, the numbers of significant SNPs range from 5 to 15, which jointly account for 37.52%, 82.94%, 26.74% and 24.16% of the total phenotypic variance of IFN-γ, IL-10, IFN-γ/IL-10, and IgG, respectively. Several significant SNPs are located within the QTL regions reported in previous studies. Furthermore, several significant SNPs fall into the regions which harbour a number of known immunity-related genes. Results herein lay a preliminary foundation for further identifying the causal mutations affecting swine immune capacity in follow-up studies.

Development of the S3Pvac vaccine against porcine Taenia solium cysticercosis: a historical review

Herein we present a review of our research dealing with vaccination against experimental and naturally acquired porcine Taenia solium cysticercosis using Taenia crassiceps-derived antigens. Results strongly support that the different versions of S3Pvac vaccine are indeed effective against porcine T. solium cysticercosis. Immunological results related to vaccination prove that protection is at least partially mediated by specific immunity. The data also support the validity of T. crassiceps murine cysticercosis as an effective tool to identify vaccine candidates against some metacestode infections.

The immune response to parasitic helminths of veterinary importance and its potential manipulation for future vaccine control strategies

Despite the increasing knowledge of the immunobiology and epidemiology of parasitic helminths of the gastrointestinal system and the cardiorespiratory system, complications arising from infections of animals and humans with these parasites are a major clinical and economic problem. This has been attributed to the high incidence of these parasites, the widespread emergence of multi-drug resistant parasite strains and the lack of effective vaccines. Efforts to develop and produce vaccines against virtually all helminths (with the exception of Dictyocaulus viviparus and some cestode species) have been hindered by the complexity of the host-parasite relationship, and incomplete understanding of the molecular and immune regulatory pathways associated with the development of protective immunity against helminths. Novel genomic and proteomic technologies have provided opportunities for the discovery and characterisation of effector mechanisms and molecules that govern the host-parasite interactions in these two body systems. Such knowledge provided clues on how appropriate and protective responses are elicited against helminths and, thus, may lead to the development of effective therapeutic strategies. Here, we review advances in the immune response to selected helminths of animal health significance, and subsequent vaccine potential. The topics addressed are important for understanding how helminths interact with host immune defences and also are relevant for understanding the pathogenesis of diseases caused by helminths.

Mapping quantitative trait loci for cytokines in the pig

Increased disease resistance through improved general immune capacity would be beneficial for the welfare and productivity of farm animals. Cytokines are essential diagnostic parameters in veterinary practice. To identify quantitative trait loci (QTL) for cytokine levels in serum in the pig, Interferon-gamma (IFN-γ) and Interleukin 10 (IL-10) levels and the ratio of IFN-γ to IL-10 were measured in a composite pig population, before and after challenge with modified live CSF (classical swine fever) vaccine. Through interval mapping using the variance component approach and the permutation test, 11 QTL (five for IFN-γ, two for IL-10 and four for the ratio of IFN-γ to IL-10) with significance levels of P < 0.10 were identified, of which five were significant at the P < 0.05 level. The most significant QTL (P < 0.01) was found on chromosome 16, with effect on the ratio of IFN-γ to IL-10. Within these QTL regions, a number of known genes were revealed and their potential relationships to the studied traits were discussed. Some of these genes may serve as candidate genes for these traits in swine.

Renewed hope for a vaccine against the intestinal adult Taenia solium

Review of experimental and observational evidence about various cestode infections of mammalian hosts revives hope for the development of an effective vaccine against adult intestinal tapeworms, the central protagonists in their transmission dynamics. As for Taenia solium, there are abundant immunological data regarding cysticercosis in humans and pigs, but information about human taeniasis is scarce. A single publication reporting protection against T. solium taeniasis by experimental primo infection and by vaccination of an experimental foster host, the immunocompetent female hamster, kindles the hope of a vaccine against the tapeworm to be used in humans, its only natural definitive host.

Characterization of S3Pvac anti-cysticercosis vaccine components: implications for the development of an anti-cestodiasis vaccine

Background

Cysticercosis and hydatidosis seriously affect human health and are responsible for considerable economic loss in animal husbandry in non-developed and developed countries. S3Pvac and EG95 are the only field trial-tested vaccine candidates against cysticercosis and hydatidosis, respectively. S3Pvac is composed of three peptides (KETc1, GK1 and KETc12), originally identified in a Taenia crassiceps cDNA library. S3Pvac synthetically and recombinantly expressed is effective against experimentally and naturally acquired cysticercosis.

Methodology/Principal Findings

In this study, the homologous sequences of two of the S3Pvac peptides, GK1 and KETc1, were identified and further characterized in Taenia crassiceps WFU, Taenia solium, Taenia saginata, Echinococcus granulosus and Echinococcus multilocularis. Comparisons of the nucleotide and amino acid sequences coding for KETc1 and GK1 revealed significant homologies in these species. The predicted secondary structure of GK1 is almost identical between the species, while some differences were observed in the C terminal region of KETc1 according to 3D modeling. A KETc1 variant with a deletion of three C-terminal amino acids protected to the same extent against experimental murine cysticercosis as the entire peptide. On the contrary, immunization with the truncated GK1 failed to induce protection. Immunolocalization studies revealed the non stage-specificity of the two S3Pvac epitopes and their persistence in the larval tegument of all species and in Taenia adult tapeworms.

Conclusions/Significance

These results indicate that GK1 and KETc1 may be considered candidates to be included in the formulation of a multivalent and multistage vaccine against these cestodiases because of their enhancing effects on other available vaccine candidates.

The immune response in Taenia solium cysticercosis: protection and injury

This article reviews current knowledge on the innate and acquired immune responses in human Taenia solium neurocysticercosis, highlighting the conditions that appear to be favourable for the survival or destruction of the parasite and for the benefit or injury to its host.

Making sense of apparently conflicting data: Stress and immunity in swine and cattle1

Stress is generally considered to suppress the immune system and may lead to an increase in the occurrence of disease in the presence of a pathogen. The immune system is ordinarily brought back to a baseline response level after immune challenge through homeostatic processes, in part regulated by the hypothalamic-pituitary-axis. Often, findings reported from various studies investigating the effects of stress on the immune system are conflicting and difficult to reconcile into a cohesive and comprehensible set of universally applicable theories. These discrepancies may be partly explained by the types and durations of the stressors, the aspect(s) of immune system measured, genetics, and social status. A particular stressor may enhance cell-mediated immune responses while suppressing humoral responses or vice versa, thus disrupting the balance between these components of the immune system. How farm animals perceive their environment depends not only on traditional environmental stressors (e.g., heat, cold, humidity, pollutants), but also on aspects of their social environment. Dominant animals may have enhanced immune activation, whereas subordinates have suppression of the same immune component in response to the same stressor. This could explain why individual animals within a group respond differently to stressors and disease challenges. A better understanding of the consequences and complex interactions between social and environmental stressors for innate and adaptive immune traits must be developed so we can more fully understand the effects of stress on immunity in livestock. Once these complex relationships are better understood, more effective interventions can be designed to improve animal health and well-being.

Improvement of the synthetic tri-peptide vaccine (S3Pvac) against porcine Taenia solium cysticercosis in search of a more effective, inexpensive and manageable vaccine

Vaccination of pigs may curtail Taenia solium transmission by reducing the number of cysticerci, the precursors of adult intestinal tapeworms in humans. Several antigen preparations induce protection against porcine cysticercosis in experimental settings but only one subunit vaccine (S3Pvac) has been tested and proved effective in the field against naturally acquired disease. Besides improving of the vaccine's effectiveness, significant reductions in production costs and in the logistics of its administration are necessary for the feasibility of nationwide control programs. This review highlights the development of several versions of S3Pvac aimed to increase effectiveness, reduce costs and increase feasibility by novel delivery systems and alternative routes of administration.

Therapeutic capacity of the synthetic peptide-based vaccine against Taenia solium cysticercosis in pigs

The S3Pvac synthetic vaccine composed of three peptides (GK1, KETc1 and KETc12) effectively protect against pig cysticercosis. Preliminary results point to an additional cysticidal capacity induced by S3Pvac or GK1 immunization. Herein, clear evidences of the cysticidal effect of S3Pvac but not of GK1 are presented. S3Pvac immunization of already experimentally infected pigs induced a reduction in the parasite load, in the vesicular cysticerci and in their viability. It also substantially increases the percent of histological damaged cysticerci more importantly in muscles than in brains, with a concomitant reduction in the antibody levels. Thus, S3Pvac represents a powerful means of controlling cysticercosis infection in pigs.

Recombinant bacteriophage-based multiepitope vaccine against Taenia solium pig cysticercosis

The aim of this study was to test the capacity of recombinant phages to deliver antigens for vaccination against porcine cysticercosis. Thus, three peptides (KETc1, KETc12, GK1) and a recombinant antigen KETc7, previously proven to induce high levels of protection against pig cysticercosis, were expressed on the surface of the M13 bacteriophage at multiple copies. The pool of these four recombinant phages induced high levels of protection against an experimental murine cysticercosis. The immunogenicity of the phage vaccine preparation was therefore, tested in pigs, the natural host of Taenia solium. Subcutaneous or oral vaccination with these phages induced antigen-specific cellular immune responses in pigs. Preliminary data also points to the protective capacity of this recombinant phage vaccine against pig cysticercosis. The immunogenicity of these recombinant phages, together with the low cost of their production, make them a realistic candidate to be tested in pigs as an anti-cysticercus phage vaccine for field trials. This is the first report describing the application of a filamentous bacteriophage as a vaccine in large animals such as pigs, the only intermediate hosts of T. solium, a parasite of major medical importance in developing countries. The potential application of phages as a modern platform for vaccines for human and animal diseases is discussed.