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Background: Strongyloides stercoralis is a soil-transmitted intestinal nematode with a complex life cycle that primarily affects humans, non-human primates, dogs, and occasionally cats. This study presents, to the best of our knowledge, the first case of S. stercoralis infection and its genotyping in a domestic dog from Argentina., Methods: The patient was a female wired-haired Teckel dog exhibiting recurrent coughing. Coproparasitological analysis using the Baermann technique revealed the presence of rhabditiform larvae morphologically compatible with S. stercoralis. To confirm this finding, molecular diagnosis (18S ribosomal RNA) and analysis of the cox1 gene were performed., Results: We identified a haplotype (HP20) that has previously only been related to S. stercoralis infection in dogs, but was found in the present study to be highly related to the haplotype (HP16) of a zoonotic variant and divergent from those previously described from human patients in Argentina. Furthermore, unlike in human cases following treatment with ivermectin, the dog was negative after moxidectin treatment according to polymerase chain reaction of the sampled faeces., Conclusions: This case report shows the importance of further investigation into potential transmission events and prevalences of S. stercoralis in dogs and humans in South America. The results reported here should also encourage future work that examines different scenarios of infection with S. stercoralis in dogs and humans with the aim of integrating clinical management, diagnosis, treatment and follow-up strategies in the quest for new approaches for the treatment of this disease in animals and humans. The findings support the adoption of a One Health approach, which recognizes the interconnectedness between animal and human health, in addressing parasitic infections such as strongyloidiasis., (© 2023. The Author(s).)

Background: Chagas disease is a lifelong infection caused by the protozoa Trypanosoma cruzi endemic in Latin-America and emergent worldwide. Decades after primary infection, 20-30% of infected people develop chronic Chagas cardiomyopathy (CCC) while the others remain asymptomatic. CCC pathogenesis is complex but associated with sustained pro-inflammatory response leading to tissue damage. Hence, levels of IL-10 could have a determinant role in CCC etiology. Studies with Latin-American populations have addressed the association of genetic variants of IL-10 and the risk of developing CCC with inconsistent results. We carried out a case control study to explore the association between IL-10-1082G>A (rs18008969), -819C>T (rs1800871), -592A>C (rs1800872) polymorphisms and CCC in a population attending a hospital in Buenos Aires Argentina. Next, a systematic review of the literature and a meta-analysis were conducted combining present and previous studies to further study this association., Methods: Our case control study included 122 individuals with chronic T. cruzi infection including 64 patients with any degree of CCC and 58 asymptomatic individuals. Genotyping of IL-10 -1082G>A, -819C>T, -592A>C polymorphisms was performed by capillary sequencing of the region spanning the three polymorphic sites and univariate and multivariate statistical analysis was undertaken. Databases in English, Spanish and Portuguese language were searched for papers related to these polymorphisms and Chagas disease up to December 2021. A metanalysis of the selected literature and our study was performed based on the random effect model., Results: In our cohort, we found a significant association between TT genotype of -819 rs1800871 and AA genotype of -592 rs1800872 with CCC under the codominant (OR=5.00; 95%CI=1.12-23.87 P=0,04) and the recessive models (OR=5.37; 95%CI=1.12-25.68; P=0,03). Of the genotypes conformed by the three polymorphic positions, the homozygous genotype ATA was significantly associated with increased risk of CCC. The results of the meta-analysis of 754 cases and 385 controls showed that the TT genotype of -819C>T was associated with increased CCC risk according to the dominant model (OR=1.13; 95% CI=1.02-1.25; P=0,03)., Conclusion: The genotype TT at -819 rs1800871 contributes to the genetic susceptibility to CCC making this polymorphism a suitable candidate to be included in a panel of predictive biomarkers of disease progression., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Grijalva, Gallo Vaulet, Agüero, Toledano, Risso, Quarroz Braghini, Sosa, Ruybal, Repetto and Alba Soto.)

This study analysed Strongyloides stercoralis genetic variability based on a 404 bp region of the cox1 gene from Latin-American samples in a clinical context including epidemiological, diagnosis and follow-up variables. A prospective, descriptive, observational study was conducted to evaluate clinical and parasitological evolution after ivermectin treatment of 41 patients infected with S. stercoralis. Reactivation of the disease was defined both by clinical symptoms appearance and/or direct larvae detection 30 days after treatment or later. We described 10 haplotypes organized in two clusters. Most frequent variants were also described in the Asian continent in human (HP24 and HP93) and canine (HP24) samples. Clinical presentation (intestinal, severe, cutaneous and asymptomatic), immunological status and eosinophil count were not associated with specific haplotypes or clusters. Nevertheless, presence of cluster 1 haplotypes during diagnosis increased the risk of reactivation with an odds ratio (OR) of 7.51 [confidence interval (CI) 95% 1.38–44.29, P = 0.026]. In contrast, reactivation probability was 83 times lower if cluster 2 (I152V mutation) was detected (OR = 0.17, CI 95% 0.02–0.80, P = 0.02). This is the first analysis of S. stercoralis cox1 diversity in the clinical context. Determination of clusters during the diagnosis could facilitate and improve the design of follow-up strategies to prevent severe reactivations of this chronic disease.

Ancylostoma caninum is a zoonotic nematode which is able to affect animals and humans. Diagnosis in the definitive host and environmental detection are key to prevent its dissemination and achieve control. Herein, a new coprological LAMP method for the detection of A. caninum (Copro-LAMPAc) DNA was developed. DNA extraction was performed using a low-cost method and a fragment of the cox -1 gene was used for primer design. The analytical sensitivity, evaluated with serial dilutions of genomic DNA from A. caninum adult worms, was 100 fg. A specificity of 100% was obtained using genomic DNA from the host and other pathogens. The Copro-LAMPAc was evaluated using environmental canine fecal samples. When compared with gold standard optical microscopy in epidemiological studies, it proved to be more sensitive. This new LAMP assay can provide an alternative protocol for screening and identification of A. caninum for epidemiological studies in endemic areas., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Avila, Risso, Cabrera, Ruybal, Repetto, Butti, Trangoni, Santillán, Pérez and Periago.)

Toxocariasis is a zoonotic disease caused mainly by Toxocara canis and Toxocara cati and diagnosis in dogs and cats is an important tool for its control. For this reason, a new coprological loop-mediated isothermal amplification (LAMP) assay was developed for the simultaneous detection of these species. The primer set was designed on a region of the mitochondrial cox-1 gene. Amplification conditions were evaluated using a temperature gradient (52°C to 68°C), different incubation times (15–120 min), and different concentrations of malachite green dye (0.004–0.4% w/v). The analytical sensitivity was evaluated with serial dilutions of genomic DNA from T. canis and T. cati adult worms, and with serial dilutions of DNA extracted from feces using a low-cost in-house method. The specificity was evaluated using genomic DNA from Canis lupus familiaris, Felis catus, Escherichia coli, Toxascaris leonina, Ancylostoma caninum, Echinococcus granulosus sensu stricto and Taenia hydatigena. The LAMP assay applied to environmental fecal samples from an endemic area showed an analytical sensitivity of 10–100 fg of genomic DNA and 10−5 serial dilutions of DNA extracted from feces using the low-cost in-house method; with a specificity of 100%. Additionally, the total development of the assay was carried out in a basic laboratory and per-reaction reagent cost decreased by ~80%. This new, low-cost tool can help identify the most common agents of toxocariasis in endemic areas in order to manage prevention strategies without having to rely on a laboratory with sophisticated equipment.

Background: Strongyloides stercoralis affects 30-100 million people worldwide. The first-line therapy is ivermectin. Cure is defined as the absence of larvae by parasitological methods 1 year after treatment. To date, no longitudinal parasitological studies for longer periods of time have been conducted to confirm its cure. Here, we evaluated treatment response in long-term follow-up patients with chronic infection using parasitological and molecular methods for larvae or DNA detection., Methods: A prospective, descriptive, observational study was conducted between January 2009 and September 2015 in Buenos Aires, Argentina. Twenty-one patients with S. stercoralis diagnosis were evaluated 30, 60, and 90 days as well as 1, 2, 3, and/or 4 years after treatment by conventional methods (fresh stool, Ritchie method, agar plate culture), S. stercoralis-specific polymerase chain reaction (PCR) in stool DNA, and eosinophil values., Results: During follow-up, larvae were detected by conventional methods in 14 of 21 patients. This parasitological reactivation was observed starting 30 days posttreatment (dpt) and then at different times since 90 dpt. Eosinophil values decreased (P = .001) 30 days after treatment, but their levels were neither associated with nor predicted these reactivations. However, S. stercoralis DNA was detected by PCR in all patients, both in their first and subsequent stool samples, thus reflecting the poor efficacy of ivermectin at eradicating parasite from host tissues. Asymptomatic eosinophilia was the most frequent clinical form among chronically infected patients., Conclusions: These results suggest that the parasitological cure is unlikely. Strongyloidiasis must be considered a chronic infection and ivermectin administration schedules should be reevaluated.

Infection with oncogenic human papillomavirus induces deregulation of cellular redox homeostasis. Virus replication and papillomavirus-induced cell transformation require persistent expression of viral oncoproteins E7 and E6 that must retain their functionality in a persistent oxidative environment. Here, we dissected the molecular mechanisms by which E7 oncoprotein can sense and manage the potentially harmful oxidative environment of the papillomavirus-infected cell. The carboxy terminal domain of E7 protein from most of the 79 papillomavirus viral types of alpha genus, which encloses all the tumorigenic viral types, is a cysteine rich domain that contains two classes of cysteines: strictly conserved low reactive Zn +2 binding and degenerate reactive cysteine residues that can sense reactive oxygen species (ROS). Based on experimental data obtained from E7 proteins from the prototypical viral types 16, 18 and 11, we identified a couple of low pKa nucleophilic cysteines that can form a disulfide bridge upon the exposure to ROS and regulate the cytoplasm to nucleus transport. From sequence analysis and phylogenetic reconstruction of redox sensing states we propose that reactive cysteine acquisition through evolution leads to three separate E7s protein families that differ in the ROS sensing mechanism: non ROS-sensitive E7s; ROS-sensitive E7s using only a single or multiple reactive cysteine sensing mechanisms and ROS-sensitive E7s using a reactive-resolutive cysteine couple sensing mechanism., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Trypanosoma cruzi the agent of Chagas disease is a monophyletic but heterogeneous group conformed by several Discrete Typing Units (DTUs) named TcI to TcVI characterized by genetic markers. The trans-sialidase (TS) is a virulence factor involved in cell invasion and pathogenesis that is differentially expressed in aggressive and less virulent parasite stocks. Genes encoding TS-related proteins are included in a large family divided in several groups but only one of them contains TS genes. Two closely related genes differing in a T/C transition encode the enzymatically active TS (aTS) and a lectin-like TS (iTS). We quantified the aTS/iTS genes from TcII and TcVI aggressive and TcI low virulent strains and found variable aTS number (1-32) per haploid genome. In spite of being low TS enzyme-expressers, TcI strains carry 28-32 aTS gene copies. The intriguing absence of iTS genes in TcI strains together with the presence of aTS/iTS in TcII and TcVI strains (virulent) were observed. Moreover, after sequencing aTS/iTS from 38 isolates collected along the Americas encompassing all DTUs, the persistent absence of the iTS gene in TcI, TcIII and TcIV was found. In addition, the sequence clustering together with T/C transition analysis correlated to DTUs of T. cruzi. The consistence of TS results with both evolutionary genome models proposed for T. cruzi, namely the "Two Hybridization" and the "Three Ancestor" was discussed and reviewed to fit present findings. Parasite stocks to attempt genetic KO or to assay the involvement of iTS in parasite biology and virulence are finally available.

Genotyping studies show a polarized geographic distribution of Trypanosoma cruzi lineages in humans. Here, we assessed their distribution along Latin America through an immunological approach we designated Western blot (WB) assay with Trypomastigote small-surface antigen (TSSA) I and TSSA II (TSSA-WB). These antigens are expressed by T. cruzi I (TCI; now TcI) and T. cruzi II (TCII; reclassified as TcII to TcVI) parasites. TSSA-WB showed good concordance with genotyping tests. An unexpected frequency of TSSA II recognition was observed in Colombia, Venezuela, and Mexico (northern region of Latin America). In Argentina and Paraguay (southern region), immunophenotyping confirmed the already reported TCII (TcII to TcVI) dominance. The lineage distribution between these regions showed significant difference but not among countries within them (except for Colombia and Venezuela). TSSA-WB shows TCII emergence in the northern region where TCI was reported as dominant or even as the unique T. cruzi lineage infecting humans.

During the acute phase of Trypanosoma cruzi infection, strong haematological and immune system alterations are observed. The parasite expresses trans-sialidase, a virulence factor responsible for the sialylation of its surface glycoconjugates. This enzyme is also shed to the bloodstream where it is associated with immune system alterations triggered during the infection. During experimental and human infections, the host elicits antibodies able to neutralize the enzyme activity that would be responsible for restricting systemic trans-sialidase to the early steps of the infection, when major immune alterations are induced. The actual relevance of these antibodies was tested by passive transference of monoclonal neutralizing antibodies in acute infection models displaying extreme sensitivity to the infection. Mice were inoculated with virulent parasite strains that induce high parasitaemia, early mortality and strong immune tissue abnormalities. The trans-sialidase-neutralizing antibodies were able to preserve B cell areas both in ganglia and spleen as well as the thymus architecture even in these extreme models. Although no differences between control and treated mice regarding animal survival were found, a major role for the humoral response in controlling the damage of the immune system induced by a systemically distributed virulence factor was defined in an infection with a eukaryotic pathogen.

The trans-sialidase, a modified sialidase that transfers sialyl residues among macromolecules, is a unique enzymatic activity expressed by some parasitic trypanosomes being essential for their survival in the mammalian host and/or in the insect vector. The enzyme from Trypanosoma cruzi, the agent of Chagas disease, is found in blood and able to act far from the infection site by inducing apoptosis in cells from the immune system. A central and still unsolved question is whether trans-sialidase-mediated addition or removal of sialic acid to/from host acceptor molecules is the event associated with the apoptosis induced by the enzyme. Here we show that lactitol, a competitive inhibitor that precluded the transference of the sialyl residue to endogenous acceptors but not the hydrolase activity of the enzyme, prevented ex vivo and in vivo the apoptosis caused by the trans-sialidase. By lectin histochemistry, the transference of sialyl residue to the cell surface was demonstrated in vivo and found associated with the apoptosis induction. The sialylation of the CD43 mucin, a key molecule involved in trans-sialidase-apoptotic process, was readily detected and also prevented by lactitol on thymocytes. Therefore, lesions induced by trans-sialidase on the immune system are due to the sialylation of endogenous acceptor molecules.

The clinical outcome of Chagas disease is highly variable, mainly because of the heterogeneity of Trypanosoma cruzi, a parasite for which 2 major phylogenetic groups (I and II) were recently defined. Epidemiological and immunological data indicate that the prevalence of T. cruzi II in patients living in the southern cone of South America correlates with the alterations caused by Chagas disease. We report here that infection with T. cruzi II isolates induces 100% mortality in mice, in contrast to infection with T. cruzi I isolates, in which almost all mice enter the chronic phase even when a 1000-fold higher inoculum is administered. Trypomastigotes from T. cruzi II strains express and shed significantly higher amounts of trans-sialidase than do those from the T. cruzi I lineage. Disorganization of the thymus histoarchitecture associated with the circulating enzyme was observed after infection with T. cruzi II strains, in contrast to transient thymus lesions found in mice infected with T. cruzi I strains. Therefore, trans-sialidase becomes the first T. cruzi virulence factor identified that is differentially expressed by the main parasite groups and that contributes to their contrasting behaviors.

The study of antibody avidity changes during infection has improved the understanding of the pathologic processes involved in several infectious diseases. In some infections, like toxoplasmosis, this information is being used for diagnostic purposes. Results of the evolution of antibody avidity for different specific antigens in Trypanosome cruzi-infected rats are presented. A Western blotting technique, combined with avidity analysis to identify antigens that elicit high-avidity antibodies, is suggested. In this system, antibodies showed high avidity values only during the chronic phase of infection and only in relation to antibodies against 21-, 33-, 41-, 42-, 56-, 58-, 66-, and 72-kDa antigens. Finally, a 97-kDa T. cruzi antigen, which was recognized by high-avidity antibodies and occurred in noninfected rats, was identified. These results allow us to evaluate the different antigens in chagasic infection. Our results show that with the correct choice of antigen it is possible to detect differences in maturation of antibodies and to discriminate, in an experimental model, between recent (acute) and chronic infections.