Ascaris lumbricoides and Necator americanus are soil-transmitted parasites with global geographic distribution, and they represent some of the most common and neglected infections in the world. Periodic treatment with mass drug administration (MDA) in endemic areas is the recommended action put forth by the World Health Organization. However, MDA can cause the selection of subpopulations that possess the genetic ability to overcome the mechanism of drug action. In fact, beta-tubulin gene mutations (codons 167, 198 and 200) are correlated with benzimidazole resistance in nematodes of veterinary importance. It is possible that these SNPs also have strong correlation with treatment resistance in the human geohelminths A. lumbricoides, Trichuris trichiura and hookworms. Here, we aimed to investigate the presence of some of these canonical molecular markers associated with parasite resistance to benzimidazole in N. americanus and A. lumbricoides collected from six Brazilian states. Nested-PCR and PCR-RFLP were used to detect mutations at codons 167 and 198 in 601 individual eggs of A. lumbricoides collected from 62 human stool samples; however, no mutations were found. Codons 198 and 200 were tested in 552 N. americanus eggs collected from 48 patients using the same methodology, which presented a relative frequency of 1.4% and 1.1%, respectively. The presence of these SNPs in N. americanus eggs is an important finding, indicating that with high benzimidazole drug pressure there is potential for benzimidazole resistance to be selected in this hookworm. However, at these low frequencies it does not indicate that there is at present any benzimidazole resistance problem. This is the first systematic study performed in South America, and the study yielded a landscape of the genetic variants in the beta-tubulin gene and anthelmintic resistance to soil-transmitted parasites detected by a simple, rapid and affordable genotyping assay of individual eggs.

SUMMARYSchistosoma mansoni is a blood fluke parasite responsible for schistosomiasis. The best long-term strategy to control schistosomiasis is through immunization combined with drug treatment. In this study, we cloned, expressed and purified SmTSP-2 fused to the N-and C-terminal halves of Sm29 and tested these chimeras as vaccine candidates using an adjuvant approved to be used in humans. The results demonstrated that vaccination with SmTSP-2 fused to N-or C-terminus of Sm29-induced reduction in worm burden and liver pathology when compared to control animals. Additionally, we detected high levels of mouse-specific IgG, IgG1 and IgG2a against both chimeras and significant amounts of IFN-c and TNF-a and no IL-4. Finally, studies with sera from patients resistant to infection and living in schistosomiasis endemic areas revealed high levels of specific IgG to both chimeras when compared to healthy individuals. In conclusion, SmTSP-2/Sm29 chimeras tested here induced partial protection against infection and might be a potential vaccine candidate.

BackgroundBlomia tropicalis is a dust mite and an important source of allergens in tropical regions. Up to now, the assays to diagnose atopy to this mite use whole body extract as antigens. However, anti-B. tropicalis IgE antibodies cross-react with Ascaris lumbricoides antigens, hindering the diagnosis of allergy to this mite. In this study, B. tropicalis recombinant allergens were evaluated with the purpose of developing an immunodiagnostic assay for allergy to this mite with greater specificity than those commercially available.MethodsTwo B. tropicalis allergens (Blo t 5 and Blo t 21) were cloned into a plasmidial expression vector, expressed in Escherichia coli and purified by affinity chromatography. Sixty-three sera containing anti-B. tropicalis extract (BtE) IgE antibodies were used to investigate IgE reactivity to the recombinant Blot 5 and 21 allergens. Inhibition assays with 20 sera pre-adsorbed with A. lumbricoides extract were performed using rBlo t 5, rBlo t 21, and BtE as antigens. All the assays were carried using indirect ELISA.ResultsEighty-two point nine percent and 80.0% of the sera with anti-BtE antibodies from 35 children reacted with rBlo t 5 and rBlo t 21, respectively, whereas 92.8% and 89.3% of the 28 sera with anti-BtE antibodies from adult asthma patients reacted with the same allergens, and 96.4% of these sera reacted with a mixture of rBlo t 5 and rBlo t 21. In an inhibition ELISA, the absorption of sera by A. lumbricoides extract affected less the reaction with rBlo t 5 and rBlo t 21 than with BtE.ConclusionsThe rBlo t 5 and rBlo t 21 allergens contain important epitopes recognized by IgE antibodies of individuals allergic to B. tropicalis antigens. Moreover, the assays using the recombinant allergens had lower IgE cross-reactivity with A. lumbricoides antigens, a fact which would confers higher specificity to serodiagnostic assays than the crude mite extract. However, additional recombinant allergens should be evaluated in order to reach the same sensitivity of the commercially available assays based on mite extract.

Allergic diseases are considered a major problem for healthcare systems in both developed and developing countries. House dust mites are well-known triggers of allergic manifestations. While the Dermatophagoides genus is widely distributed globally, Blomia tropicalis is the most prominent mite species in the tropical and subtropical regions of the world. Over the last decades, an increase in sensitization rates to B. tropicalis has been reported, leading to increased research efforts on Blomia allergens. In fact, 8 new allergens have been identified and characterized to different degrees. Here, we provide an overview of recent developments concerning the identification and production of recombinant Blomia allergens, as well as their structural and immunological characterization. Although considerable progress has been achieved, detailed molecule-based studies are still needed to better define the clinical relevance of Blomia allergens. Thus, the establishment of a well-standardized and fully characterized panel of allergens remains a challenge for the development of better diagnosis and therapy of allergic diseases induced by B. tropicalis.