The role of IgA in gastrointestinal helminthiasis: A systematic review.

Immunoglobulin-A (IgA) is an important mediator of immunity and has been associated with protection against several pathogens, although its role in gastrointestinal infections remains unclear. Then, the aim of this systematic review was to synthesize qualitative evidence in respect of IgA as mediator of protective immunity against gastrointestinal helminths. Following recommended guidelines, we searched for articles published between January 1990 and October 2019 that evaluated IgA levels and their association with gastrointestinal helminth infections. Twenty-five articles were included after screening 1,546 titles and abstracts, as well as reading in full 52 selected articles. Consistent associations between higher IgA levels and lower parasitological parameters were only found in mice, rats, and sheep. However, the role of IgA in other host species remains uncertain, making it difficult to create a consensus. Therefore, it is too soon to claim that IgA is an effective protective factor against gastrointestinal helminths, and further studies are still needed.

Intestinal polyparasitism and levels of mucosal anthelmintic SIgA in children from endemic areas in Northeastern Brazil.

Interactions between parasites during co-infections are often complex and can impact immunization and treatment programmes, as well as disease outcomes and morbidity. However, little is known about these interactions and the mechanisms involved. In this study, a coproparasitological survey was carried out in school-age children living in endemic areas of parasitic infection in the state of Sergipe, Northeastern Brazil. Anti-helminth-specific and total secretory immunoglobulin-A (SIgA) levels were measured in stool and saliva samples and were compared in children presenting monoparasitism, polyparasitism (helminths and/or intestinal protozoa) and no infections. The survey showed that protozoa were more prevalent than helminths, and that there was a high frequency of polyparasitism in the studied population, mainly from combinations of protozoan species. Although less frequent, combinations between species of protozoa and helminths were also observed. The levels of salivary SIgA in these co-infected individuals were lower than the average observed in infections with helminths alone. Although the children participating in this survey were asymptomatic, and it was, therefore, not possible to evaluate the impact of salivary SIgA reduction on the diseases, and the study highlights the need for further investigations of co-infections by intestinal parasites and the effects on immune response induced by the interactions between different parasites.

Effect of Aging on Trunk Muscle Function and Its Influence on Falls Among Older Adults.

The objective was to determine whether trunk muscle function is influenced by the aging process and to identify if the trunk can be an important factor in older people's falls over a period of 1 year. The peak torque, rate of torque development, and torque steadiness of the trunk extensors and flexors were compared between a young group, older group (older adults with no episodes of falls), and older faller group (older adults who had suffered at least one fall episode over a period of 1 year) by one-way analysis of variance, followed by the post hoc Tukey test. The adjusted multivariate linear regression was applied to verify the association between the number of falls and the trunk parameters in older adults. The young group showed higher extensors and flexors peak torque and rate of torque development, and lower extensor torque steadiness at 10% when compared with older groups. Only trunk flexor peak torque showed a negative association with the number of future falls (p = .042), but there was no difference in trunk muscle function between the older group and the older faller group.

Melting temperature measurement and mesoscopic evaluation of single, double and triple DNA mismatches.

Unlike the canonical base pairs AT and GC, the molecular properties of mismatches such as hydrogen bonding and stacking interactions are strongly dependent on the identity of the neighbouring base pairs. As a result, due to the sheer number of possible combinations of mismatches and flanking base pairs, only a fraction of these have been studied in varying experiments or theoretical models. Here, we report on the melting temperature measurement and mesoscopic analysis of contiguous DNA mismatches in nearest-neighbours and next-nearest neighbour contexts. A total of 4032 different mismatch combinations, including single, double and triple mismatches were covered. These were compared with 64 sequences containing all combinations of canonical base pairs in the same location under the same conditions. For a substantial number of single mismatch configurations, 15%, the measured melting temperatures were higher than the least stable AT base pair. The mesoscopic calculation, using the Peyrard-Bishop model, was performed on the set of 4096 sequences, and resulted in estimates of on-site and nearest-neighbour interactions that can be correlated to hydrogen bonding and base stacking. Our results confirm many of the known properties of mismatches, including the peculiar sheared stacking of tandem GA mismatches. More intriguingly, it also reveals that a number of mismatches present strong hydrogen bonding when flanked on both sites by other mismatches. To highlight the applicability of our results, we discuss a number of practical situations such as enzyme binding affinities, thymine DNA glycosylase repair activity, and trinucleotide repeat expansions.

Changes in the epidemiological profile of intestinal parasites after a school-based large-scale treatment for soil-transmitted helminths in a community in northeastern Brazil: Epidemiological profile after large-scale school-based treatment for STH.

Intestinal parasites cause a significant public health problem worldwide due to the associated morbidities, mainly in infected school-aged children (SAC). The strategy of large-scale deworming in SAC to control the transmission of soil-transmitted helminths (STH) has been advocated by the World Health Organization and was recently adopted in Brazil; however, the long-term effects of mass deworming on the larger parasitological profile have been less studied. After a five-year period of school-based large-scale treatment for STH using an annual single dose of albendazole in a community of Sergipe state, Brazil, a marked reduction in prevalence was observed (15.4%% vs.7.4% for Ascaris sp., 6.0%%  vs. 0.4% for hookworm, and 12.8%%  vs. 4.5%% for Trichuris trichiura), with the exception of Strongyloides stercoralis, which had no statistically significant change in prevalence. There was, however, an increase in the prevalence of intestinal protozoans, specifically Entamoeba histolytica/E. dispar (0.0%% vs. 36.0%), Blastocystis hominis (0.0%%  vs. 40.1%), and Giardia duodenalis (5.6%% vs. 14.5%). Although the findings showed a dramatic reduction in the prevalence of STH after four rounds of preventive chemotherapy, there was an increase in intestinal protozoan infections, indicating a change in the epidemiological profile.

Protocolo de Controle de tronco em Ambiente Aquático para Crianças com Paralisia Cerebral: Ensaio Clínico Randomizado / Protocol of Control of Trunk in Aquatic Environment for Children with Cerebral Palsy: Randomized Clinical Trial

Objetivos: Avaliar os efeitos de um protocolo de controle de tronco em ambiente aquático e sua repercussão na funcionalidade de indivíduos com paralisia cerebral (PC) diparéticoespástico, classificados no nível IV do GMFCS (Gross Motor Function Classification System). Métodos: ensaio clínico controlado, randomizado, cego, descritivo-analítico, quantitativo. Foram triados 92 prontuários, 24 crianças foram incluídas e 22 finalizaram o estudo. Os pacientes foram alocados em grupo controle (GC), que realizou terapias convencionais e grupo intervenção (GI) que realizou o protocolo de exercícios aquáticos. Os grupos foram avaliados pré e pós-intervenção através da Trunk Control Measurement Scale (TCMS), Pediatric Reach Test (PRT), Eletromiografia de Superfície (EMG) dos músculos reto abdominal e latíssimo do dorso. Para análises estatísticas foram utilizados o teste de Kolmogorov-Smirnov no momento pré e pós intervenção, teste de Mann-Whitney para a análise intragrupo e teste de Wilcoxon para análise intergrupo. A Correlação de Spearman foi utilizada para observar o grau de associação entre duas variáveis. Foi considerado um intervalo de confiança (IC) de 95%, nível de significância de p<0,05. Resultados: na análise intragrupo constatou-se melhora no item reação de equilíbrio da TCMS, GI (p=0,019) e o GC (p=0,004). No PRT, GC apresentou maior deslocamento pós-intervenção (p=0,006) que o GI. No item 07 da TCMS houve melhora da ativação muscular do reto abdominal (RA) do GI (p=0,047). Conclusão: No presente estudo, observou-se que a fisioterapia aquática trouxe resultados positivos e ganhos motores relacionados ao controle de tronco e funcionalidade para crianças com paralisia cerebral diparética espásticas GMFCS nível IV. (AU)

Objectives: To evaluate the effects of a trunk control protocol in the aquatic environment and its impact on the functionality of individuals with spastic diparesis type of CP (Cerebral Palsy) classified as level IV on GMFCS. Methods: A quantitative, controlled clinical trial, randomized, blind, of descriptive and analytical character. 92 records were screened, 24 children were enrolled and 22 completed the study. Patients were allocated in control group (CG), which held conventional therapies and intervention group (IG) which performed the aquatic exercise protocol. Groups were evaluated pre and post intervention through Trunk Control Measurement Scale (TCMS), Pediatric Reach Test (PRT), Surface Electromyography (EMG) of rectus abdominis and latissimus dorsi muscles. For statistical analysis, it was used the Kolmogorov-Smirnov test for pre and post intervention analysis, Mann-Whitney and Wilcoxon test for intragroup and intergroup analysis, respectively. Spearman correlation was used to observe the rate of association between two variables. A confidence interval (CI) of 95% was considered, level of significance of p <0.05. Results: Intragroup analysis showed improvement in TCMS equilibrium reactions item in GI (p = 0.019) and CG (p = 0.004). In the PRT, GC presented greater post-intervention displacement (p = 0.006) than the GI. In item 07 of the TCMS there was improvement of rectus abdominis muscle activation in GI (p = 0.047). Conclusion: In the present study there were positive results and motor gains on trunk control and functionality for individuals with spastic diparesis type of CP classified as level IV on GMFCS after aquatic therapy intervention. (AU)

Gender Identity and Sexual Function in 46,XX Patients with Congenital Adrenal Hyperplasia Raised as Males.

In individuals with congenital adrenal hyperplasia (CAH) and 46,XX karyotype, androgens produced by the adrenal glands during the intrauterine development promote virilization of the genitals, which may even result in the development of a well-formed penis. Some of these children with late diagnosis are registered as males after birth. After obtaining approval from the internal review board, we evaluated gender identity and sexual function in four 46,XX severely virilized patients with CAH, who were originally registered and raised as males, assisted in our Disorders of Sexual Development Clinic. The evaluation consisted of questionnaires to assess gender identity and sexual activity and interview with the multidisciplinary team that provides care for these patients. The patients underwent surgery to remove uterus, ovaries, and remaining vaginal structures, in addition to implantation of testicular prosthesis and correction of hypospadias, when necessary. All four patients have developed a clear male gender identity, and when evaluated for sexual activity, they have reported having erections, libido, orgasms, and sexual attraction to women only. Two of these 4 patients had satisfactory sexual intercourses when assessed using the International Index of Erectile Function questionnaire. The other two patients who never had sexual intercourse reported not having a partner for sexual activity; one is 18 years old, and the other is 14 years old. This study showed that this group of 46,XX severely virilized patients with CAH, registered and raised as males, adapted well to the assigned male gender, with satisfactory sexual function in patients who had sexual intercourse.

Modeling mutant/wild-type interactions to ascertain pathogenicity of PROKR2 missense variants in patients with isolated GnRH deficiency.

A major challenge in human genetics is the validation of pathogenicity of heterozygous missense variants. This problem is well-illustrated by PROKR2 variants associated with Isolated GnRH Deficiency (IGD). Homozygous, loss of function variants in PROKR2 was initially implicated in autosomal recessive IGD; however, most IGD-associated PROKR2 variants are heterozygous. Moreover, while IGD patient cohorts are enriched for PROKR2 missense variants similar rare variants are also found in normal individuals. To elucidate the pathogenic mechanisms distinguishing IGD-associated PROKR2 variants from rare variants in controls, we assessed 59 variants using three approaches: (i) in silico prediction, (ii) traditional in vitro functional assays across three signaling pathways with mutant-alone transfections, and (iii) modified in vitro assays with mutant and wild-type expression constructs co-transfected to model in vivo heterozygosity. We found that neither in silico analyses nor traditional in vitro assessments of mutants transfected alone could distinguish IGD variants from control variants. However, in vitro co-transfections revealed that 15/34 IGD variants caused loss-of-function (LoF), including 3 novel dominant-negatives, while only 4/25 control variants caused LoF. Surprisingly, 19 IGD-associated variants were benign or exhibited LoF that could be rescued by WT co-transfection. Overall, variants that were LoF in ≥ 2 signaling assays under co-transfection conditions were more likely to be disease-associated than benign or 'rescuable' variants. Our findings suggest that in vitro modeling of WT/Mutant interactions increases the resolution for identifying causal variants, uncovers novel dominant negative mutations, and provides new insights into the pathogenic mechanisms underlying heterozygous PROKR2 variants.

Mesoscopic modelling of Cy3 and Cy5 dyes attached to DNA duplexes.

Cy3 and Cy5 dyes linked to the 5' end of a double stranded DNA molecule are known to attach to both strands in a way that is very similar to an additional base pair and has a stabilizing effect on the oligonucleotide. Here we adapt the Peyrard-Bishop mesoscopic model to incorporate cyanine dyes and use the technique of thermal equivalence to obtain the appropriate parameters from existing melting temperatures. We have found that the stacking parameters are in the same range of ordinary AT and CG base pairs, in particular Cy3-A was found to be most rigidly stacked. While the cyanines stabilize the AT hydrogen bonds quite strongly the CG bonds are mostly unaffected.

Reduced frequency of two activating KIR genes in patients with sepsis.

Natural killer (NK) cell activity is regulated by activating and inhibitory signals transduced by killer cell immunoglobulin-like receptors (KIR). Diversity in KIR gene repertoire among individuals may affect disease outcome. Sepsis development and severity may be influenced by genetic factors affecting the immune response. Here, we examined sixteen KIR genes and their human leucocyte antigen (HLA) class I ligands in critical patients, aiming to identify patterns that could be associated with sepsis. Male and female patients (ages ranging between 14 and 94years-old) were included. DNA samples from 211 patients with sepsis and 60 controls (critical care patients with no sepsis) collected between 2004 and 2010 were included and genotyped for KIR genes using the polymerase chain reaction method with sequence-specific oligonucleotide (PCR-SSO), and for HLA genes using the polymerase chain reaction method with sequence-specific primers (PCR-SSP). The frequencies of activating KIR2DS1 and KIR3DS1 in sepsis patients when compared to controls were 41.23% versus 55.00% and 36.49% versus 51.67% (p=0.077 and 0.037 respectively before Bonferroni correction). These results indicate that activating KIR genes 2DS1 and 3DS1 may more prevalent in critical patients without sepsis than in patients with sepsis, suggesting a potential protective role of activating KIR genes in sepsis.

Complete Genome Sequence of Type Strain Campylobacter fetus subsp. fetus ATCC 27374.

Campylobacter fetus subsp. fetus is a zoonotic bacterium important for animal and public health. The complete sequencing and annotation of the genome of the type strain C. fetus subsp. fetus ATCC 27374 are reported here.

New insights into the immunopathology of early Toxocara canis infection in mice.

BACKGROUND: Nematodes of the genus Toxocara are cosmopolitan roundworms frequently found in dogs and cats. Toxocara spp. can accidentally infect humans and cause a zoonosis called human toxocariasis, which is characterized by visceral, ocular or cerebral migration of larval stages of the parasite, without completing its life cycle. In general, chronic nematode infections induce a polarized TH2 immune response. However, during the initial phase of infection, a strong pro-inflammatory response is part of the immunological profile and might determine the outcome and/or pathology of the infection. METHODS: Parasitological aspects and histopathology during larval migration were evaluated after early T. canis experimental infection of BALB/c mice, which were inoculated via the intra-gastric route with a single dose of 1000 fully embryonated eggs. Innate immune responses and systemic cytokine patterns (TH1, TH2, TH17 and regulatory cytokines) were determined at different times after experimental challenge by sandwich ELISA. RESULTS: We found that experimental infection with T. canis induced a mix of innate inflammatory/TH17/TH2 responses during early infection, with a predominance of the latter. The TH2 response was evidenced by significant increases in cytokines such as IL-4, IL-5, IL-13 and IL-33, in addition to increasing levels of IL-6 and IL-17. No significant increases were observed for IL-10, TNF-α or IFN-γ levels. In parallel, parasitological analysis clearly revealed the pattern of larval migration through the mouse organs, starting from the liver in the first 24 h of infection, reaching the peak in the lungs on the 3rd day of infection and finally being found numerously in the brain after 5 days of infection. Peripheral leukocytosis, characterized by early neutrophilia and subsequent eosinophilia, was remarkable during early infection. The tissue damage induced by larvae was evidenced by histopathological analysis of the organs at different time points of infection. In all of the affected organs, larval migration induced intense inflammatory infiltrate and hemorrhage. CONCLUSION: In conclusion, these new insights into early T. canis infection in mice presented here enabled a better understanding of the immunopathological events that might also occur during human toxocariasis, thus contributing to future strategies of diagnosis and control.

COX-2 rs20417 Polymorphism Is Associated with Stroke and White Matter Disease.

BACKGROUND: To investigate the effect of COX-2 polymorphism and its product, prostaglandin E2 (PGE2), on stroke risk in an endemic area for Chagas disease. In a separate cohort, to investigate the effect of COX-2 polymorphisms on the total burden of cerebral white matter disease. METHODS: Cases were outpatients with ischemic stroke; controls were stroke-free subjects from 2 outpatient clinics (heart failure and caregivers of a movement disorders clinic). We extracted DNA from total blood to investigate the rs20417 COX-2 polymorphism. Serologic tests (Enzime-linked immunosorbent assay) were performed to confirm Trypanosoma cruzi infection and to quantify PGE2 levels. In the Boston cohort, white matter hyperintensity volume (WMHv) was quantified on the admission brain magnetic resonance images of subjects with ischemic stroke, who also donated DNA for the COX-2 gene region analysis. RESULTS: We studied 44 patients with stroke and 96 controls (46 with heart failure and 50 caregivers) in the Brazilian cohort; and 788 stroke patients (302 cardioembolic and 486 noncardioembolic) in the Boston cohort. In the Brazilian cohort, rs20417 polymorphism was associated with both stroke (P = 5 × 10(-6)) and decreased PGE2 levels (P = 4 × 10(-5)); similarly, Chagas was associated with stroke (P = 4 × 10(-3)) and decreased PGE2 levels (P = 7 × 10(-3)). In the Boston cohort, rs20417 polymorphism was associated with increased WMHv among noncardioembolic (P = .037), but not among cardioembolic stroke patients. CONCLUSIONS: Variation in COX-2 gene is associated with both symptomatic and silent brain cerebrovascular disease. This candidate gene region should be tested in population-based samples.

Comparative genomics of the major fungal agents of human and animal Sporotrichosis: Sporothrix schenckii and Sporothrix brasiliensis.

BACKGROUND: The fungal genus Sporothrix includes at least four human pathogenic species. One of these species, S. brasiliensis, is the causal agent of a major ongoing zoonotic outbreak of sporotrichosis in Brazil. Elsewhere, sapronoses are caused by S. schenckii and S. globosa. The major aims on this comparative genomic study are: 1) to explore the presence of virulence factors in S. schenckii and S. brasiliensis; 2) to compare S. brasiliensis, which is cat-transmitted and infects both humans and cats with S. schenckii, mainly a human pathogen; 3) to compare these two species to other human pathogens (Onygenales) with similar thermo-dimorphic behavior and to other plant-associated Sordariomycetes. RESULTS: The genomes of S. schenckii and S. brasiliensis were pyrosequenced to 17x and 20x coverage comprising a total of 32.3 Mb and 33.2 Mb, respectively. Pair-wise genome alignments revealed that the two species are highly syntenic showing 97.5% average sequence identity. Phylogenomic analysis reveals that both species diverged about 3.8-4.9 MYA suggesting a recent event of speciation. Transposable elements comprise respectively 0.34% and 0.62% of the S. schenckii and S. brasiliensis genomes and expansions of Gypsy-like elements was observed reflecting the accumulation of repetitive elements in the S. brasiliensis genome. Mitochondrial genomic comparisons showed the presence of group-I intron encoding homing endonucleases (HE's) exclusively in S. brasiliensis. Analysis of protein family expansions and contractions in the Sporothrix lineage revealed expansion of LysM domain-containing proteins, small GTPases, PKS type1 and leucin-rich proteins. In contrast, a lack of polysaccharide lyase genes that are associated with decay of plants was observed when compared to other Sordariomycetes and dimorphic fungal pathogens, suggesting evolutionary adaptations from a plant pathogenic or saprobic to an animal pathogenic life style. CONCLUSIONS: Comparative genomic data suggest a unique ecological shift in the Sporothrix lineage from plant-association to mammalian parasitism, which contributes to the understanding of how environmental interactions may shape fungal virulence. . Moreover, the striking differences found in comparison with other dimorphic fungi revealed that dimorphism in these close relatives of plant-associated Sordariomycetes is a case of convergent evolution, stressing the importance of this morphogenetic change in fungal pathogenesis.

Characterising the mucosal and systemic immune responses to experimental human hookworm infection.

The mucosal cytokine response of healthy humans to parasitic helminths has never been reported. We investigated the systemic and mucosal cytokine responses to hookworm infection in experimentally infected, previously hookworm naive individuals from non-endemic areas. We collected both peripheral blood and duodenal biopsies to assess the systemic immune response, as well as the response at the site of adult worm establishment. Our results show that experimental hookworm infection leads to a strong systemic and mucosal Th2 (IL-4, IL-5, IL-9 and IL-13) and regulatory (IL-10 and TGF-ß) response, with some evidence of a Th1 (IFN-γ and IL-2) response. Despite upregulation after patency of both IL-15 and ALDH1A2, a known Th17-inducing combination in inflammatory diseases, we saw no evidence of a Th17 (IL-17) response. Moreover, we observed strong suppression of mucosal IL-23 and upregulation of IL-22 during established hookworm infection, suggesting a potential mechanism by which Th17 responses are suppressed, and highlighting the potential that hookworms and their secreted proteins offer as therapeutics for human inflammatory diseases.

Evidence for reductive genome evolution and lateral acquisition of virulence functions in two Corynebacterium pseudotuberculosis strains.

BACKGROUND: Corynebacterium pseudotuberculosis, a gram-positive, facultative intracellular pathogen, is the etiologic agent of the disease known as caseous lymphadenitis (CL). CL mainly affects small ruminants, such as goats and sheep; it also causes infections in humans, though rarely. This species is distributed worldwide, but it has the most serious economic impact in Oceania, Africa and South America. Although C. pseudotuberculosis causes major health and productivity problems for livestock, little is known about the molecular basis of its pathogenicity. METHODOLOGY AND FINDINGS: We characterized two C. pseudotuberculosis genomes (Cp1002, isolated from goats; and CpC231, isolated from sheep). Analysis of the predicted genomes showed high similarity in genomic architecture, gene content and genetic order. When C. pseudotuberculosis was compared with other Corynebacterium species, it became evident that this pathogenic species has lost numerous genes, resulting in one of the smallest genomes in the genus. Other differences that could be part of the adaptation to pathogenicity include a lower GC content, of about 52%, and a reduced gene repertoire. The C. pseudotuberculosis genome also includes seven putative pathogenicity islands, which contain several classical virulence factors, including genes for fimbrial subunits, adhesion factors, iron uptake and secreted toxins. Additionally, all of the virulence factors in the islands have characteristics that indicate horizontal transfer. CONCLUSIONS: These particular genome characteristics of C. pseudotuberculosis, as well as its acquired virulence factors in pathogenicity islands, provide evidence of its lifestyle and of the pathogenicity pathways used by this pathogen in the infection process. All genomes cited in this study are available in the NCBI Genbank database (http://www.ncbi.nlm.nih.gov/genbank/) under accession numbers CP001809 and CP001829.

Potency testing for the experimental Na-GST-1 hookworm vaccine.

Over the next decade, a new generation of vaccines will target the neglected tropical diseases (NTDs). The goal of most NTD vaccines will be to reduce the morbidity and decrease the chronic debilitating nature of these often-forgotten infections – outcomes that are hard to measure in the traditional potency testing paradigm. The absence of measurable correlates of protection, a lack of permissive animal models for lethal infection, and a lack of clinical indications that do not include the induction of sterilizing immunity required us to reconsider the traditional bioassay methods for determining vaccine potency. Owing to these limitations, potency assay design for NTD vaccines will increasingly rely on a paradigm where potency testing is one among many tools to ensure that a manufacturing process yields a product of consistent quality. Herein, we discuss the evolution of our thinking regarding the design of a potency assay along these newly defined lines and its application to the release of the experimental Necator americanus-glutathione-S- transferase-1 (Na-GST-1) vaccine to prevent human hookworm infection. We discuss the necessary steps to accomplish the design and implementation of such a new potency assay as a resource for the burgeoning NTD vaccine community. Our experience is that much of the existing information is proprietary and needs to be pulled together in a single source to aid in our overall understanding of potency testing.

Neutralizing antibodies to the hookworm hemoglobinase Na-APR-1: implications for a multivalent vaccine against hookworm infection and schistosomiasis.

The aspartic protease of Necator americanus, Na-APR-1, is a vaccine antigen that induces antibodies that neutralize hemoglobin proteolysis in the gut of the worm. To define the epitopes recognized by these antibodies, monoclonal antibodies (mAbs) were raised and assessed for neutralizing activity. Three immunoglobulin (Ig) G1 mAbs bound to the intestine of N. americanus and inhibited Na-APR-1 enzymatic activity. Overlapping fragments of Na-APR-1 were expressed, and one (APR-1/5B) was recognized by all 3 mAbs; the epitope was further characterized as AGPKAQVEAIQKY (A(291)Y). This same peptide with a Phe/Tyr(303) substitution was recognized by mAbs in APR-1 orthologues from Ancylostoma species hookworms. IgG from humans infected with hookworms did not recognize A(291)Y but, rather, recognized the S(107)L epitope. APR-1/5B was fused to other helminth vaccine antigens, including Schistosoma mansoni Sm-TSP-2 and N. americanus Na-GST-1; antibodies against both chimeras neutralized the enzymatic activity of Na-APR-1. These findings support the incorporation of Na-APR-1 into a multivalent vaccine against hookworm and/or schistosomiasis.

Molecular cloning, biochemical characterization, and partial protective immunity of the heme-binding glutathione S-transferases from the human hookworm Necator americanus.

Hookworm glutathione S-transferases (GSTs) are critical for parasite blood feeding and survival and represent potential targets for vaccination. Three cDNAs, each encoding a full-length GST protein from the human hookworm Necator americanus (and designated Na-GST-1, Na-GST-2, and Na-GST-3, respectively) were isolated from cDNA based on their sequence similarity to Ac-GST-1, a GST from the dog hookworm Ancylostoma caninum. The open reading frames of the three N. americanus GSTs each contain 206 amino acids with 51% to 69% sequence identity between each other and Ac-GST-1. Sequence alignment with GSTs from other organisms shows that the three Na-GSTs belong to a nematode-specific nu-class GST family. All three Na-GSTs, when expressed in Pichia pastoris, exhibited low lipid peroxidase and glutathione-conjugating enzymatic activities but high heme-binding capacities, and they may be involved in the detoxification and/or transport of heme. In two separate vaccine trials, recombinant Na-GST-1 formulated with Alhydrogel elicited 32 and 39% reductions in adult hookworm burdens (P < 0.05) following N. americanus larval challenge relative to the results for a group immunized with Alhydrogel alone. In contrast, no protection was observed in vaccine trials with Na-GST-2 or Na-GST-3. On the basis of these and other preclinical data, Na-GST-1 is under possible consideration for further vaccine development.