Identification of novel genetic loci and candidate genes for progressive ethanol consumption in diversity outbred mice.

Mouse behavioral genetic mapping studies can identify genomic intervals modulating complex traits under well-controlled environmental conditions and have been used to study ethanol behaviors to aid in understanding genetic risk and the neurobiology of alcohol use disorder (AUD). However, historically such studies have produced large confidence intervals, thus complicating identification of potential causal candidate genes. Diversity Outbred (DO) mice offer the ability to perform high-resolution quantitative trait loci (QTL) mapping on a very genetically diverse background, thus facilitating identification of candidate genes. Here, we studied a population of 636 male DO mice with four weeks of intermittent ethanol access via a three-bottle choice procedure, producing a progressive ethanol consumption phenotype. QTL analysis identified 3 significant (Chrs 3, 4, and 12) and 13 suggestive loci for ethanol-drinking behaviors with narrow confidence intervals (1-4 Mbp for significant QTLs). Results suggested that genetic influences on initial versus progressive ethanol consumption were localized to different genomic intervals. A defined set of positional candidate genes were prioritized using haplotype analysis, identified coding polymorphisms, prefrontal cortex transcriptomics data, human GWAS data and prior rodent gene set data for ethanol or other misused substances. These candidates included Car8, the lone gene with a significant cis-eQTL within a Chr 4 QTL for week four ethanol consumption. These results represent the highest-resolution genetic mapping of ethanol consumption behaviors in mice to date, providing identification of novel loci and candidate genes for study in relation to the neurobiology of AUD.

Identification of ethanol analgesia quantitative trait loci and candidate genes in BXD recombinant inbred mouse lines.

Alcohol consumption produces acute analgesic effects, and people experiencing pain conditions may drink alcohol to alleviate discomfort. However, tolerance to the analgesic properties of alcohol could prompt escalating consumption and dependence. Both nociception and alcohol-induced analgesia are under significant genetic control. Understanding the genetic architecture of these processes could inform better treatment options for people with pain conditions. This study aims to identify quantitative trait loci (QTL) driving variation in ethanol-induced analgesia across BXD recombinant inbred mouse lines. Male and female mice from 62 BXD strains received ethanol or saline oral gavage for five days and were tested for hot plate (HP) latency at baseline, Day 1, and Day 5. QTL mapping of HP phenotypes identified a significant provisional QTL on chromosome 17 for Day 1 HP latency in mice receiving ethanol. An additional highly suggestive QTL was present on chromosome 9 for the difference in pre- and post-ethanol thermal nociception. Candidate genes within QTL support intervals were provisionally identified using HP phenotypic correlations to transcriptomic database, expression QTL analysis, and other bioinformatics inquiries. The combined behavioral and bioinformatic analyses yielded strong ethanol analgesia candidate genes, specifically Myo6. Thus, the results of this genetic study of ethanol-induced analgesia in BXD mouse strains may contribute significantly to our understanding of the molecular basis for individual variation in the analgesic response to acute ethanol.

A selective GSK3ß inhibitor, tideglusib, decreases intermittent access and binge ethanol self-administration in C57BL/6J mice.

Over 10% of the US population over 12 years old meets criteria for Alcohol Use Disorder (AUD), yet few effective, long-term treatments are currently available. Glycogen synthase kinase 3 beta (GSK3ß) has been implicated in ethanol behaviors and poses as a potential therapeutic target in the treatment of AUD. Here we investigate the role of tideglusib, a selective GSK3ß inhibitor, in ethanol consumption and other behaviors. We have shown tideglusib decreases ethanol consumption in both a model of daily, progressive ethanol intake (two-bottle choice, intermittent ethanol access) and binge-like drinking behavior (drinking-in-the-dark) without effecting water intake. Further, we have shown tideglusib to have no effect on ethanol pharmacokinetics, taste preference, or anxiety-like behavior, though there was a transient increase in total locomotion following treatment. Additionally, we assessed liver health following treatment via serum levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase and showed no effect on aminotransferase levels though there was a decrease in alkaline phosphatase. RNA sequencing studies revealed a role of GSK3ß inhibition via tideglusib on the canonical Wnt signaling pathway, suggesting tideglusib may carry out its effects on ethanol consumption through effects on ß-catenin binding to the transcription factors TCF3 and LEF1. The data presented here further implicate GSK3ß in alcohol consumption and support the use of tideglusib as a potential therapeutic in the treatment of AUD.

Surgical incision pain induced an increase in alcohol consumption in mice.

INTRODUCTION: Large population-based studies have suggested a link between increased alcohol use and reduced pain. In addition, these studies suggest that higher levels of pain intensity are associated with an increase in alcohol consumption and rates of hazardous drinking which potentiates the risk of developing alcohol use disorders (AUD). The mechanisms and determinants of the alcohol-pain interaction can be studied in preclinical studies. METHODS: The overall goal of this study is to use animal models to explore the impact of acute postoperative pain on alcohol intake. To achieve this, we characterized the timeline and levels of alcohol intake and preference in mice after laparotomy in the 2-bottle choice paradigm. RESULTS: Our results show that laparotomy surgery increased alcohol intake and preference in male mice but not females in the 2-bottle choice and 3-bottle choice assays. In addition, ketoprofen administration blocked the increase in alcohol consumption in male mice after laparotomy. We also found that changes in alcohol initial sensitivity and acute functional tolerance, using loss of righting reflex (LORR) response, occur after surgery in mice. CONCLUSION: Taken together, these findings suggests that sex, pain and alcohol sensitivity-related factors may modulate the relationship between alcohol consumption and pain.

Comparative genomics of Leishmania donovani progeny from genetic crosses in two sand fly species and impact on the diversity of diagnostic and vaccine candidates.

Sand fly transmitted Leishmania species are responsible for severe, wide ranging, visceral and cutaneous leishmaniases. Genetic exchange can occur among natural Leishmania populations and hybrids can now be produced experimentally, with limitations. Feeding Phlebotomus orientalis or Phlebotomus argentipes on two strains of Leishmania donovani yielded hybrid progeny, selected using double drug resistance and fluorescence markers. Fluorescence activated cell sorting of cultured clones derived from these hybrids indicated diploid progeny. Multilocus sequence typing of the clones showed hybridisation and nuclear heterozygosity, although with inheritance of single haplotypes in a kinetoplastid target. Comparative genomics showed diversity of clonal progeny between single chromosomes, and extraordinary heterozygosity across all 36 chromosomes. Diversity between progeny was seen for the HASPB antigen, which has been noted previously as having implications for design of a therapeutic vaccine. Genomic diversity seen among Leishmania strains and hybrid progeny is of great importance in understanding the epidemiology and control of leishmaniasis. As an outcome of this study we strongly recommend that wider biological archives of different Leishmania species from endemic regions should be established and made available for comparative genomics. However, in parallel, performance of genetic crosses and genomic comparisons should give fundamental insight into the specificity, diversity and limitations of candidate diagnostics, vaccines and drugs, for targeted control of leishmaniasis.

Adolescent social housing protects against adult emotional and cognitive deficits and alters the PFC and NAc transcriptome in male and female C57BL/6J mice.

Introduction: Adolescence is a critical period in cognitive and emotional development, characterized by high levels of social interaction and increases in risk-taking behavior including binge drinking. Adolescent exposure to social stress and binge ethanol have individually been associated with the development of social, emotional, and cognitive deficits, as well as increased risk for alcohol use disorder. Disruption of cortical development by early life social stress and/or binge drinking may partly underlie these enduring emotional, cognitive, and behavioral effects. The study goal is to implement a novel neighbor housing environment to identify the effects of adolescent neighbor housing and/or binge ethanol drinking on (1) a battery of emotional and cognitive tasks (2) adult ethanol drinking behavior, and (3) the nucleus accumbens and prefrontal cortex transcriptome. Methods: Adolescent male and female C57BL/6J mice were single or neighbor housed with or without access to intermittent ethanol. One cohort underwent behavioral testing during adulthood to determine social preference, expression of anxiety-like behavior, cognitive performance, and patterns of ethanol intake. The second cohort was sacrificed in late adolescence and brain tissue was used for transcriptomics analysis. Results: As adults, single housed mice displayed decreased social interaction, deficits in the novel object recognition task, and increased anxiety-like behavior, relative to neighbor-housed mice. There was no effect of housing condition on adolescent or adult ethanol consumption. Adolescent ethanol exposure did not alter adult ethanol intake. Transcriptomics analysis revealed that adolescent housing condition and ethanol exposure resulted in differential expression of genes related to synaptic plasticity in the nucleus accumbens and genes related to methylation, the extracellular matrix and inflammation in the prefrontal cortex. Discussion: The behavioral results indicate that social interaction during adolescence via the neighbor housing model may protect against emotional, social, and cognitive deficits. In addition, the transcriptomics results suggest that these behavioral alterations may be mediated in part by dysregulation of transcription in the frontal cortex or the nucleus accumbens.

Terrain-aware semantic mapping for cooperative subterranean exploration.

Navigation over torturous terrain such as those in natural subterranean environments presents a significant challenge to field robots. The diversity of hazards, from large boulders to muddy or even partially submerged Earth, eludes complete definition. The challenge is amplified if the presence and nature of these hazards must be shared among multiple agents that are operating in the same space. Furthermore, highly efficient mapping and robust navigation solutions are absolutely critical to operations such as semi-autonomous search and rescue. We propose an efficient and modular framework for semantic grid mapping of subterranean environments. Our approach encodes occupancy and traversability information, as well as the presence of stairways, into a grid map that is distributed amongst a robot fleet despite bandwidth constraints. We demonstrate that the mapping method enables safe and enduring exploration of subterranean environments. The performance of the system is showcased in high-fidelity simulations, physical experiments, and Team MARBLE's entry in the DARPA Subterranean Challenge which received third place.

Case-only exome variation analysis of severe alcohol dependence using a multivariate hierarchical gene clustering approach.

BACKGROUND: Variation in genes involved in ethanol metabolism has been shown to influence risk for alcohol dependence (AD) including protective loss of function alleles in ethanol metabolizing genes. We therefore hypothesized that people with severe AD would exhibit different patterns of rare functional variation in genes with strong prior evidence for influencing ethanol metabolism and response when compared to genes not meeting these criteria. OBJECTIVE: Leverage a novel case only design and Whole Exome Sequencing (WES) of severe AD cases from the island of Ireland to quantify differences in functional variation between genes associated with ethanol metabolism and/or response and their matched control genes. METHODS: First, three sets of ethanol related genes were identified including those a) involved in alcohol metabolism in humans b) showing altered expression in mouse brain after alcohol exposure, and altering ethanol behavioral responses in invertebrate models. These genes of interest (GOI) sets were matched to control gene sets using multivariate hierarchical clustering of gene-level summary features from gnomAD. Using WES data from 190 individuals with severe AD, GOI were compared to matched control genes using logistic regression to detect aggregate differences in abundance of loss of function, missense, and synonymous variants, respectively. RESULTS: Three non-independent sets of 10, 117, and 359 genes were queried against control gene sets of 139, 1522, and 3360 matched genes, respectively. Significant differences were not detected in the number of functional variants in the primary set of ethanol-metabolizing genes. In both the mouse expression and invertebrate sets, we observed an increased number of synonymous variants in GOI over matched control genes. Post-hoc simulations showed the estimated effects sizes observed are unlikely to be under-estimated. CONCLUSION: The proposed method demonstrates a computationally viable and statistically appropriate approach for genetic analysis of case-only data for hypothesized gene sets supported by empirical evidence.

A comparative 'omics' approach for prediction of candidate Strongyloides stercoralis diagnostic coproantigens.

Human infection with the intestinal nematode Strongyloides stercoralis is persistent unless effectively treated, and potentially fatal in immunosuppressed individuals. Epidemiological data are lacking, partially due to inadequate diagnosis. A rapid antigen detection test is a priority for population surveillance, validating cure after treatment, and for screening prior to immunosuppression. We used a targeted analysis of open access 'omics' data sets and used online predictors to identify S. stercoralis proteins that are predicted to be present in infected stool, Strongyloides-specific, and antigenic. Transcriptomic data from gut and non-gut dwelling life cycle stages of S. stercoralis revealed 328 proteins that are differentially expressed. Strongyloides ratti proteomic data for excreted and secreted (E/S) proteins were matched to S. stercoralis, giving 1,057 orthologues. Five parasitism-associated protein families (SCP/TAPS, prolyl oligopeptidase, transthyretin-like, aspartic peptidase, acetylcholinesterase) were compared phylogenetically between S. stercoralis and outgroups, and proteins with least homology to the outgroups were selected. Proteins that overlapped between the transcriptomic and proteomic datasets were analysed by multiple sequence alignment, epitope prediction and 3D structure modelling to reveal S. stercoralis candidate peptide/protein coproantigens. We describe 22 candidates from seven genes, across all five protein families for further investigation as potential S. stercoralis diagnostic coproantigens, identified using open access data and freely-available protein analysis tools. This powerful approach can be applied to many parasitic infections with 'omic' data to accelerate development of specific diagnostic assays for laboratory or point-of-care field application.

Identification of candidate genes for nicotine withdrawal in C57BL/6J × DBA/2J recombinant inbred mice.

Nicotine is the reinforcing ingredient in tobacco. Following chronic exposure, sudden cessation of nicotine use produces negative symptoms of withdrawal that contribute to dependence. The molecular mechanisms underlying nicotine withdrawal behaviors, however, are poorly understood. Using recombinant inbred mice, chronic nicotine was delivered by minipump and withdrawal induced using mecamylamine. Somatic signs of withdrawal, and anxiety-like behavior using elevated plus maze, were then assessed. Interval mapping was used to identify associations between genetic variation and withdrawal behaviors, and with basal gene expression. Differential gene expression following nicotine exposure and withdrawal was also assessed in progenitor mice using microarrays. Quantitative trait loci mapping identified chromosome intervals with significant genetic associations to somatic signs of withdrawal or withdrawal-induced anxiety-like behavior. Using bioinformatics, and association with basal gene expression in nucleus accumbens, we implicated Rb1, Bnip3l, Pnma2, Itm2b, and Kif13b as candidate genes for somatic signs of withdrawal, and Galr1, which showed trans-regulation from a region of chromosome 14 that was associated with somatic signs of withdrawal. Candidate genes within the chromosome 9 region associated with anxiety-like withdrawal behavior included Dixdc1, Ncam1, and Sorl1. Bioinformatics identified six genes that were also significantly associated with nicotine or alcohol traits in recent human genome-wide association studies. Withdrawal-associated somatic signs and anxiety-like behavior had strong non-overlapping genetic associations, respectively, with regions of chromosome 14 and chromosome 9. Genetic, behavioral and gene expression correlations, and bioinformatics analysis identified several candidate genes that may represent novel molecular targets for modulating nicotine withdrawal symptoms.

Thermal antinociceptive responses to alcohol in DBA/2J and C57BL/6J inbred male and female mouse strains.

BACKGROUND: The phenomenon of alcohol analgesia and tolerance can facilitate misuse and lead to the development of alcohol use disorder (AUD). Numerous alcohol-induced behaviors are genetically influenced; however, it is unknown if alcohol analgesia has a genetic contribution. Rodent studies have shown that alcohol responses differ vastly between two widely studied inbred strains of mice, C57BL/6 J (B6) and DBA/2 J (D2). Here, we used B6 and D2 mice as an initial behavioral genetic analysis of acute alcohol-induced antinociception. METHODS: The antinociceptive effect of orally-administered alcohol was characterized using the hot plate test in B6 and D2 mice of both sexes. Using the opioid receptor antagonist naloxone, the involvement of the opioid system was assessed. Locomotor activity and blood alcohol concentrations were also measured. Ovariectomized mice were used to evaluate the influence of ovarian sex hormones on alcohol-induced antinociception. RESULTS: Alcohol induced an antinociceptive effect in B6 and D2 male mice in a time- and dose-dependent manner. In addition, D2 male mice were more sensitive to the antinociceptive effect of alcohol than B6 male mice. However, locomotion is not impeded by the tested doses of alcohol in B6 mice. Female D2 and B6 mice failed to show significant antinociceptive effects in alcohol dose-response studies. In addition, alcohol-induced antinociception was still not evident in ovariectomized female mice. Male mice of both strains developed tolerance to this effect after repeated administration of alcohol. Strain differences were found in blood alcohol concentration. Finally, no difference was found in the blockade of alcohol antinociception by 2 mg/kg naloxone. CONCLUSION: Our results indicate that the antinociceptive effects of alcohol in the hot plate test are influenced by strain and sex. These findings support further genetic analysis of alcohol-induced antinociception to identify operative mechanisms and better assess the contribution of this phenotype to AUD.

Effect of Workpiece/Tool Heat Transfer and Friction Coefficients on Accuracy of Simulated Temperatures and Torques in a Friction Stir Welding Plunge.

Friction stir process models are typically validated by tuning heat transfer and friction coefficients until measured temperatures in either the tool or workpiece, but rarely in both, match simulated results. A three-dimensional finite element model for a tool plunge in an AA 6061-T6 is validated for temperature predictions in both the tool and workpiece using a friction coefficient that varies with time. Peak workpiece temperatures were within 1.5% of experimental temperatures and tool temperatures were off by 80 °C. The sensitivity of the predicted temperatures with respect to the workpiece/tool heat transfer coefficient was shown to be high for the tool and low for the workpiece, while the spindle torque was slightly underpredicted in the best case. These results show that workpiece/tool interface properties must be tuned by considering predictions on both sides of the heat generation interface in order to ensure a reliable process simulation.

Linear and conformational determinants of visceral leishmaniasis diagnostic antigens rK28 and rK39.

BACKGROUND: Recombinant antigens rK39 (based on kinesin sequence) and rK28 (comprising kinesin and HASPB sequences) are a mainstay of serological diagnosis for visceral leishmaniasis (VL). However, their key epitopes and the significance of their structural conformation are not clearly defined, particularly in relation to reported cross-reactivity with sera from patients with malaria, schistosomiasis, and tuberculosis. METHODS: To assess the effect of conformation on antigenicity with Sudanese VL sera, antigens rK39 and rK28 were heat-denatured at 95 °C for 10 min and then assayed by enzyme-linked immunosorbent assay (ELISA). Amino acid sequences of rK39 and rK28 were submitted to NCBI BLASTp to assess homology with Plasmodium, Schistosoma, and Mycobacterium. RESULTS: Heat denaturation significantly diminished the antigenicity of rK39 compared to non-denatured antigen (P = 0.001), but not for rK28 (P = 0.275). In BLASTp searches, HASPB sequences from rK28 had similarities with sequences from Plasmodium, encompassing software-predicted B-cell epitopes. CONCLUSIONS: The antigenicity of rK39 appears to be dependent on structural conformation, whereas that of rK28 depends on linear sequence. HASPB sequence homology with Plasmodium may be responsible for the reported cross-reactivity of rK28 with malaria sera. Further work is warranted to refine the specificity of these antigens.

Digital Image Correlation Characterization and Formability Analysis of Aluminum Alloy TWB during Forming.

The formability of aluminum alloy 5754-O tailor-welded blanks prepared by friction stir welding was studied experimentally. The strain evolution and deformation during limiting dome height experiments were studied using digital image correlation and the ARAMIS software. The influence of the sheet thickness of the base materials on the punch loading, fracture strain and formability were investigated experimentally. It was found that the punch loading, fracture strain and limiting dome height values increase with the increasing sheet thickness of the base materials. A linear relationship between the limiting dome height value and the sheet thickness was demonstrated. An increase of 16.8% in the fracture strain of aluminum tailor-welded blanks was observed for an increase of 36% in sheet thickness. This paper provides a methodology for experimentally determining the forming limits of aluminum alloy tailor-welded blanks accurately.

Microevolution of Trypanosoma cruzi reveals hybridization and clonal mechanisms driving rapid genome diversification.

Protozoa and fungi are known to have extraordinarily diverse mechanisms of genetic exchange. However, the presence and epidemiological relevance of genetic exchange in Trypanosoma cruzi, the agent of Chagas disease, has been controversial and debated for many years. Field studies have identified both predominantly clonal and sexually recombining natural populations. Two of six natural T. cruzi lineages (TcV and TcVI) show hybrid mosaicism, using analysis of single-gene locus markers. The formation of hybrid strains in vitro has been achieved and this provides a framework to study the mechanisms and adaptive significance of genetic exchange. Using whole genome sequencing of a set of experimental hybrids strains, we have confirmed that hybrid formation initially results in tetraploid parasites. The hybrid progeny showed novel mutations that were not attributable to either (diploid) parent showing an increase in amino acid changes. In long-term culture, up to 800 generations, there was a variable but gradual erosion of progeny genomes towards triploidy, yet retention of elevated copy number was observed at several core housekeeping loci. Our findings indicate hybrid formation by fusion of diploid T. cruzi, followed by sporadic genome erosion, but with substantial potential for adaptive evolution, as has been described as a genetic feature of other organisms, such as some fungi.

Congenital Chagas disease in Santa Cruz Department, Bolivia, is dominated by Trypanosoma cruzi lineage V.

BACKGROUND: This study identified Trypanosoma cruzi discrete typing units (DTUs) in maternal and infant specimens collected from two hospitals in Bolivia, using conventional genotyping and DTU-specific serotyping. METHODS: Specimens from 142 mothers were used, including 24 seronegative and 118 seropositive individuals; 29 women transmitted T. cruzi to their infants. Maternal and infant parasite loads were determined by quantitative real-time PCR. Maternal sera were tested with an in-house parasite lysate ELISA and serotyped by a lineage-specific peptide ELISA, targeting the trypomastigote small surface antigen (TSSA). Trypanosoma cruzi genotypes in infected infants were determined by a triple PCR-RFLP assay. RESULTS: All infant specimens were genotyped as TcV. Maternal parasite loads and absorbance values by the lysate ELISA were significantly higher for transmitters compared with non-transmitters. Among seropositive mothers, 65.3% had positive results by the TSSA II/V/VI peptide ELISA. No significant difference in reactivity to TSSA II/V/VI was observed for transmitters compared with non-transmitters (79.3% vs 60.7%, respectively). CONCLUSIONS: Our findings reinforce the difficulty in obtaining sufficient sample numbers and parasite DNA to investigate the interaction between parasite genetics and the risk of congenital transmission and argue for the inclusion of DTU-specific serotyping in prospective studies.

Chloride intracellular channel 4 (CLIC4) expression profile in the mouse medial prefrontal cortex and its regulation by ethanol.

BACKGROUND: Chloride intracellular channel 4 (CLIC4) is a multifunctional metamorphic protein for which a growing body of evidence supports a major role in the brain's molecular and behavioral responses to ethanol (EtOH). Although key to understanding the functional biology underlying this role, little is known about the cellular and subcellular expression patterns of CLIC4 in brain and how they are affected by EtOH. METHODS: We used qRT-PCR to assess Clic4 mRNA expression in the medial prefrontal cortex (mPFC) of C57BL/6J mice in the absence and presence of acute EtOH exposure. Two complementary immunohistochemical techniques were employed to assess the subcellular localization of the CLIC4 protein and its pattern of expression across brain cell types in the mPFC in the absence and presence of acute EtOH. RESULTS: Through immunohistochemical and stereological techniques, we show that CLIC4 protein is robustly expressed by oligodendrocytes (most abundant), microglia, and astrocytes, with minimal expression in neurons. Following acute EtOH exposure, we observed a rapid increase in Clic4 mRNA expression in female but not male mice and an overall increase in the number of oligodendrocytes and astrocytes expressing the CLIC4 protein. CONCLUSIONS: These findings suggest that Clic4 functions as an early response gene for acute EtOH in brain, which likely underlies its ability to modulate EtOH behavior. Our results also suggest that the role of CLIC4 in the brain's response to EtOH is mediated through oligodendrocytes.

Assessing antibody decline after chemotherapy of early chronic Chagas disease patients.

BACKGROUND: Chagas disease remains a significant public health problem in Latin America. There are only two chemotherapy drugs, nifurtimox and benznidazole, and both may have severe side effects. After complete chemotherapy of acute cases, seropositive diagnosis may revert to negative. However, there are no definitive parasitological or serological biomarkers of cure. METHODS: Following a pilot study with seven Bolivian migrants to Spain, we tested 71 serum samples from chronic patients (mean age 12.6 years) inhabiting the Argentine Chaco region. Benznidazole chemotherapy (5-8 mg/kg day, twice daily for 60 days) was administered during 2011-2016. Subsequently, pre-and post-chemotherapy serum samples were analysed in pairs by IgG1 and IgG ELISA using two different antigens and Chagas Sero K-SeT rapid diagnostic tests (RDT). Molecular diagnosis by kDNA-PCR was applied to post-treatment samples. RESULTS: Pilot data demonstrated IgG1 antibody decline in three of seven patients from Bolivia 1 year post-treatment. All Argentine patients in 2017 (averaging 5 years post-treatment), except one, were positive by conventional serology. All were kDNA-PCR-negative. Most (91.5%) pre-treatment samples were positive by the Chagas Sero K-SeT RDT, confirming the predominance of TcII/V/VI. IgG1 and IgG of Argentine patients showed significant decline in antibody titres post-chemotherapy, with either lysate (IgG, P = 0.0001, IgG1, P = 0.0001) or TcII/V/VI peptide antigen (IgG, P = 0.0001, IgG1, P = 0.0001). IgG1 decline was more discriminative than IgG. Antibody decline after treatment was also detected by the RDT. Incomplete treatment was associated with high IgG1 post-treatment titres against lysate (P = 0.013), as were IgG post-treatment titres to TcII/V/VI peptide (P = 0.0001). High pre-treatment IgG1 with lysate was associated with Qom ethnicity (P = 0.045). No associations were found between gender, age, body mass index and pre- or post-treatment antibody titres. CONCLUSIONS: We show that following chemotherapy of early chronic Chagas disease, significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure. We show that following chemotherapy of early chronic Chagas disease, a significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure.