Pub Date : 2026-01-26DOI: 10.1016/j.actatropica.2026.107992
Mohamad Al Bannoud , Jorge Luiz Mendes , Rodrigo Seiti Sacay , Tiago Dias Martins , Iara Rocha Antunes Pereira Bresolin , Joana Bratz Lourenço
Dengue remains one of the most critical vector-borne diseases globally, with Brazil consistently reporting the highest incidence in the Americas. The 2024 epidemic was the largest in the country’s history, with São Paulo as its epicenter. This study developed and evaluated a machine learning (ML) framework to forecast dengue under extreme epidemic conditions, focusing on enhancing model robustness when testing data exceed the range of historical observations. A novel virtual data augmentation strategy was introduced to expose models to synthetic large-scale outbreaks and to assess the predictive value of urban incident variables such as flooding and flooded streets. Epidemiological, climatic, and urban incident data from 2014 to 2022 were used for model training, and 2023–mid-2025 for testing. Fourteen ML algorithms were systematically evaluated under multiple preprocessing configurations, including feature scaling, lagged predictors, feature combinations, data augmentation, and feature reduction. Forecasts targeted probable, confirmed, severe, and fatal dengue cases at a one-week horizon. The algorithms AdaBoost and CatBoost achieved the highest predictive accuracy. Virtual data augmentation substantially improved robustness when test values exceeded training maxima, reducing RMSE by up to 80% for probable and confirmed cases, 42% for severe cases, and 53% for deaths compared with models trained on unaugmented data. Flooding-related indicators, especially flooded-street case counts, were among the most influential predictors. The proposed ML framework accurately forecasted dengue incidence and severity during the unprecedented 2024 outbreak. The virtual augmentation method effectively managed distributional shifts and extreme epidemic magnitudes, providing a transferable foundation for early-warning systems and public-health preparedness in urban settings.
{"title":"Machine Learning forecasting of dengue in São Paulo using virtual data augmentation and urban incident predictors: Addressing the exceptional surge of cases in 2024","authors":"Mohamad Al Bannoud , Jorge Luiz Mendes , Rodrigo Seiti Sacay , Tiago Dias Martins , Iara Rocha Antunes Pereira Bresolin , Joana Bratz Lourenço","doi":"10.1016/j.actatropica.2026.107992","DOIUrl":"10.1016/j.actatropica.2026.107992","url":null,"abstract":"<div><div>Dengue remains one of the most critical vector-borne diseases globally, with Brazil consistently reporting the highest incidence in the Americas. The 2024 epidemic was the largest in the country’s history, with São Paulo as its epicenter. This study developed and evaluated a machine learning (ML) framework to forecast dengue under extreme epidemic conditions, focusing on enhancing model robustness when testing data exceed the range of historical observations. A novel virtual data augmentation strategy was introduced to expose models to synthetic large-scale outbreaks and to assess the predictive value of urban incident variables such as flooding and flooded streets. Epidemiological, climatic, and urban incident data from 2014 to 2022 were used for model training, and 2023–mid-2025 for testing. Fourteen ML algorithms were systematically evaluated under multiple preprocessing configurations, including feature scaling, lagged predictors, feature combinations, data augmentation, and feature reduction. Forecasts targeted probable, confirmed, severe, and fatal dengue cases at a one-week horizon. The algorithms AdaBoost and CatBoost achieved the highest predictive accuracy. Virtual data augmentation substantially improved robustness when test values exceeded training maxima, reducing RMSE by up to 80% for probable and confirmed cases, 42% for severe cases, and 53% for deaths compared with models trained on unaugmented data. Flooding-related indicators, especially flooded-street case counts, were among the most influential predictors. The proposed ML framework accurately forecasted dengue incidence and severity during the unprecedented 2024 outbreak. The virtual augmentation method effectively managed distributional shifts and extreme epidemic magnitudes, providing a transferable foundation for early-warning systems and public-health preparedness in urban settings.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107992"},"PeriodicalIF":2.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146071077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aedes aegypti is a primary vector of dengue, chikungunya, Zika, and yellow fever diseases. Despite its global invasion, little is known about how populations from climatically contrasting regions adapt to varied thermal environments. Understanding survival strategies is critical for predicting population dynamics and disease transmission under climate change. To address this gap, we assessed ecological adaptations in terms of development, survival, and wing length, along with molecular variations, in the Thar Desert (Jodhpur) and the east coastal (Kolkata) strains of Ae. aegypti.
Methods
Mosquito eggs (3rd generation) of the coastal and desert Ae. aegypti strains were subjected to 20, 26, 30, and 35 °C to assess the impact on developmental time, survival rate, and wing length. The mitochondrial COI gene was analysed to examine nucleotide sequence variation and protein physicochemical properties.
Results
The desert strain developed faster, but showed inferior survival compared to the coastal strain at all temperatures tested. Temperature also affected wing length in both strains, showing significant differences between strains at 35 °C for males and at 30 °C for females. Wing length of the desert strain was less impacted by temperature increase (30 to 35 °C) compared to the coastal strain for both males and females. The COI gene formed two distinct clades. Three transition nucleotide mutations (Adenosine with Guanosine) altered physicochemical and structural properties of the COI protein (i.e., molecular weight, theoretical isoelectric point, total number of positively charged residues, and the number of atoms). Additionally, the bad angles, instability index, and GRAVY affected the protein.
Conclusion
This study provides a comparative analysis linking life-history traits with genetic variation in Aedes aegypti mosquitoes from climatically distinct regions of India. Temperature affects the survival, developmental rates, and wing length of genetically varied Ae. aegypti from different ecological areas. This may refine the understanding of population dynamics and management.
{"title":"Thermal stress responses on developmental time, survival, and wing morphometrics in desert and coastal strains of Aedes aegypti (Diptera: Culicidae) from India","authors":"Sushmita Swain , Gaurav Sharma , Rakesh Kumar Samantaray , Devi Shankar Suman","doi":"10.1016/j.actatropica.2026.107994","DOIUrl":"10.1016/j.actatropica.2026.107994","url":null,"abstract":"<div><h3>Background</h3><div><em>Aedes aegypti</em> is a primary vector of dengue, chikungunya, Zika, and yellow fever diseases. Despite its global invasion, little is known about how populations from climatically contrasting regions adapt to varied thermal environments. Understanding survival strategies is critical for predicting population dynamics and disease transmission under climate change. To address this gap, we assessed ecological adaptations in terms of development, survival, and wing length, along with molecular variations, in the Thar Desert (Jodhpur) and the east coastal (Kolkata) strains of <em>Ae. aegypti</em>.</div></div><div><h3>Methods</h3><div>Mosquito eggs (3rd generation) of the coastal and desert <em>Ae. aegypti</em> strains were subjected to 20, 26, 30, and 35 °C to assess the impact on developmental time, survival rate, and wing length. The mitochondrial COI gene was analysed to examine nucleotide sequence variation and protein physicochemical properties.</div></div><div><h3>Results</h3><div>The desert strain developed faster, but showed inferior survival compared to the coastal strain at all temperatures tested. Temperature also affected wing length in both strains, showing significant differences between strains at 35 °C for males and at 30 °C for females. Wing length of the desert strain was less impacted by temperature increase (30 to 35 °C) compared to the coastal strain for both males and females. The COI gene formed two distinct clades. Three transition nucleotide mutations (Adenosine with Guanosine) altered physicochemical and structural properties of the COI protein (<em>i.e.</em>, molecular weight, theoretical isoelectric point, total number of positively charged residues, and the number of atoms). Additionally, the bad angles, instability index, and GRAVY affected the protein.</div></div><div><h3>Conclusion</h3><div>This study provides a comparative analysis linking life-history traits with genetic variation in <em>Aedes aegypti</em> mosquitoes from climatically distinct regions of India. Temperature affects the survival, developmental rates, and wing length of genetically varied <em>Ae. aegypti</em> from different ecological areas. This may refine the understanding of population dynamics and management.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107994"},"PeriodicalIF":2.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146117093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1016/j.actatropica.2026.107995
Daniel Marcos J. Agostinho , José Vitorino dos Santos , Mariana Boité , Elisa Cupolillo , Matheus Nobrega Luques , Clarissa R. Damaso , Ulisses Gazos Lopes
Sand fly vectors harbor and transmit Leishmania parasites and other pathogens, including arboviruses, to vertebrate hosts. The geographical distribution of phleboviruses transmitted by sand flies in areas affected by leishmaniasis has prompted research into coinfection in vectors and in Leishmania reservoirs in Europe and Africa. Despite the widespread occurrence of canine visceral Leishmaniasis in Brazil and the identification of several viruses carried by sand flies, the issue of coinfection remains unclear. We developed an RT-PCR-based assay to detect segmented (−) RNA arboviruses from the families Phenuiviridae and Peribunyaviridae in the Americas. This assay was based on a phylogenetic analysis of the genomes of 29 American species within these families. We processed serum and bone marrow samples from 25 dogs with confirmed cases of visceral leishmaniasis in Rio de Janeiro City, Brazil. Samples from two of the dogs were amplified using a set of primers tailored to the predicted amplicon size. DNA sequencing analysis revealed a high identity to members of the Peribunyaviridae family, specifically within the genus Pacuvirus. We successfully cultivated the virus from one of the samples and sequenced its genome, confirming the identification of a virus belonging to the species Pacuvirus pacuiense or a closely related variant. The implications of our results are discussed.
{"title":"Development of an RT-PCR assay for American Phlebotomine-transmitted Bunyaviricetes and isolation of Pacuvirus (Peribunyaviridae) in dogs with canine visceral Leishmaniasis in Rio de Janeiro, Brazil","authors":"Daniel Marcos J. Agostinho , José Vitorino dos Santos , Mariana Boité , Elisa Cupolillo , Matheus Nobrega Luques , Clarissa R. Damaso , Ulisses Gazos Lopes","doi":"10.1016/j.actatropica.2026.107995","DOIUrl":"10.1016/j.actatropica.2026.107995","url":null,"abstract":"<div><div>Sand fly vectors harbor and transmit <em>Leishmania</em> parasites and other pathogens, including arboviruses, to vertebrate hosts. The geographical distribution of phleboviruses transmitted by sand flies in areas affected by leishmaniasis has prompted research into coinfection in vectors and in <em>Leishmania</em> reservoirs in Europe and Africa. Despite the widespread occurrence of canine visceral Leishmaniasis in Brazil and the identification of several viruses carried by sand flies, the issue of coinfection remains unclear. We developed an RT-PCR-based assay to detect segmented (−) RNA arboviruses from the families <em>Phenuiviridae</em> and <em>Peribunyaviridae</em> in the Americas. This assay was based on a phylogenetic analysis of the genomes of 29 American species within these families. We processed serum and bone marrow samples from 25 dogs with confirmed cases of visceral leishmaniasis in Rio de Janeiro City, Brazil. Samples from two of the dogs were amplified using a set of primers tailored to the predicted amplicon size. DNA sequencing analysis revealed a high identity to members of the <em>Peribunyaviridae</em> family, specifically within the genus <em>Pacuvirus</em>. We successfully cultivated the virus from one of the samples and sequenced its genome, confirming the identification of a virus belonging to the species <em>Pacuvirus pacuiense</em> or a closely related variant. The implications of our results are discussed.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107995"},"PeriodicalIF":2.5,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146163556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.actatropica.2026.107991
Carlos Tejeda , Natalia Pérez , Francisca Escobar , Daniel Iturra , Brandon Aristizábal , Eduardo Raffo , Manuel Moroni , Miguel Salgado , Felipe A. Hernández
Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne’s disease (paratuberculosis), a chronic enteritis affecting domestic and wild ruminants worldwide. While MAP transmission primarily occurs among livestock, increasing attention has been given to the role of wildlife in the maintenance and spread of this pathogen. Invasive species, such as the American mink (Neogale vison), may serve as unexpected source of infection or mechanical vectors for MAP, especially in regions where wildlife and domestic animals share habitats. In this study, we performed a specific MAP-IS900 real-time PCR assay to detect bacterial DNA in mesenteric lymph nodes (MesLN) (n = 401) and colonic/rectal fecal swabs (n = 346) from minks in Los Ríos region, Chile. We detected MAP DNA in 16 % and 10 % of minks in MesLN and fecal swabs, respectively, while 4 % of minks were MAP qPCR-positive in both MesLN and fecal swab samples. Considering specimens with known sex and age, we detected MAP DNA in 22 % of minks in either MesLN or fecal swabs, where 21 % of males and 22 % of females were MAP qPCR-positives, and 15 % of juveniles, 25 % of subadults, and 21 % of adults were MAP DNA-positive in at least one sample type. Our study is the first report on MAP detection in this non-ruminant carnivore in Chile, raising further questions about interspecies transmission dynamics and the potential environmental dissemination of this bacterial agent. These findings highlight the need for broader surveillance strategies that incorporate wildlife, particularly invasive species, into MAP control programs.
{"title":"Molecular evidence of Mycobacterium avium subspecies paratuberculosis (MAP) shedding in the invasive American mink (Neogale vison) in southern Chile","authors":"Carlos Tejeda , Natalia Pérez , Francisca Escobar , Daniel Iturra , Brandon Aristizábal , Eduardo Raffo , Manuel Moroni , Miguel Salgado , Felipe A. Hernández","doi":"10.1016/j.actatropica.2026.107991","DOIUrl":"10.1016/j.actatropica.2026.107991","url":null,"abstract":"<div><div><em>Mycobacterium avium</em> subsp. <em>paratuberculosis</em> (MAP) is the causative agent of Johne’s disease (paratuberculosis), a chronic enteritis affecting domestic and wild ruminants worldwide. While MAP transmission primarily occurs among livestock, increasing attention has been given to the role of wildlife in the maintenance and spread of this pathogen. Invasive species, such as the American mink (<em>Neogale vison</em>), may serve as unexpected source of infection or mechanical vectors for MAP, especially in regions where wildlife and domestic animals share habitats. In this study, we performed a specific MAP-IS<em>900</em> real-time PCR assay to detect bacterial DNA in mesenteric lymph nodes (MesLN) (<em>n</em> = 401) and colonic/rectal fecal swabs (<em>n</em> = 346) from minks in Los Ríos region, Chile. We detected MAP DNA in 16 % and 10 % of minks in MesLN and fecal swabs, respectively, while 4 % of minks were MAP qPCR-positive in both MesLN and fecal swab samples. Considering specimens with known sex and age, we detected MAP DNA in 22 % of minks in either MesLN or fecal swabs, where 21 % of males and 22 % of females were MAP qPCR-positives, and 15 % of juveniles, 25 % of subadults, and 21 % of adults were MAP DNA-positive in at least one sample type. Our study is the first report on MAP detection in this non-ruminant carnivore in Chile, raising further questions about interspecies transmission dynamics and the potential environmental dissemination of this bacterial agent. These findings highlight the need for broader surveillance strategies that incorporate wildlife, particularly invasive species, into MAP control programs.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107991"},"PeriodicalIF":2.5,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146049509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Blastocystis sp. is a gut protozoan parasite that is associated with gastrointestinal symptoms. Over time, it has garnered controversial findings on having a beneficial or harmful role in the gut microbiota. To date, studies on the interaction between Blastocystis sp. and bacteria remain limited due to challenges in establishing axenic Blastocystis sp. cultures. Although axenization is imperative for Blastocystis sp.-bacteria interaction, the process is time-consuming. This study evaluates alternative approaches to study Blastocystis sp.-bacteria associations when axenization is unfeasible in a limited timeframe. Blastocystis sp. cells were purified using mechanical (Lymphopure-density gradient centrifugation) and chemical (antibiotic cocktail treatment) purification methods and subsequently assessed by establishing a growth profile of purified Blastocystis sp. cells co-cultured with Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa at varying concentrations. Our results demonstrated that both purification methods successfully reduced bacterial load. However, mechanical purification was able to reduce the bacterial load to a greater extent across both isolates compared to chemical purification. Growth of Blastocystis sp. in co-cultures varied according to the bacterial species and their respective concentrations. The symptomatic Blastocystis sp. isolate generally peaked at lower bacterial concentrations compared to the asymptomatic Blastocystis sp. isolate, implicating an isolate-specific association with bacteria. This observation is more apparent in mechanically purified co-cultures. Our findings suggest that mechanical purification can be a feasible time-saving alternative to axenization. Our preliminary data hypothesizes that Blastocystis sp.-bacteria association is influenced by the status of the protozoan isolate, bacterial concentration, and purification methods.
{"title":"The association of Blastocystis sp. ST3 with gram negative bacteria is altered by short-term purification strategies","authors":"Sheivanya Gayatrri Kuppusamy , Suresh Kumar Govind , Chandramathi Samudi Raju , Freddy Franklin , Christina Parvinder Kaur , Arutchelvan Rajamanikam","doi":"10.1016/j.actatropica.2026.107990","DOIUrl":"10.1016/j.actatropica.2026.107990","url":null,"abstract":"<div><div><em>Blastocystis</em> sp. is a gut protozoan parasite that is associated with gastrointestinal symptoms. Over time, it has garnered controversial findings on having a beneficial or harmful role in the gut microbiota. To date, studies on the interaction between <em>Blastocystis sp</em>. and bacteria remain limited due to challenges in establishing axenic <em>Blastocystis</em> sp. cultures. Although axenization is imperative for <em>Blastocystis sp</em>.-bacteria interaction, the process is time-consuming. This study evaluates alternative approaches to study <em>Blastocystis</em> sp.-bacteria associations when axenization is unfeasible in a limited timeframe. <em>Blastocystis</em> sp. cells were purified using mechanical (Lymphopure-density gradient centrifugation) and chemical (antibiotic cocktail treatment) purification methods and subsequently assessed by establishing a growth profile of purified <em>Blastocystis</em> sp. cells co-cultured with <em>Escherichia coli, Klebsiella pneumoniae</em> and <em>Pseudomonas aeruginosa</em> at varying concentrations. Our results demonstrated that both purification methods successfully reduced bacterial load. However, mechanical purification was able to reduce the bacterial load to a greater extent across both isolates compared to chemical purification. Growth of <em>Blastocystis sp</em>. in co-cultures varied according to the bacterial species and their respective concentrations. The symptomatic <em>Blastocystis</em> sp. isolate generally peaked at lower bacterial concentrations compared to the asymptomatic <em>Blastocystis sp</em>. isolate, implicating an isolate-specific association with bacteria. This observation is more apparent in mechanically purified co-cultures. Our findings suggest that mechanical purification can be a feasible time-saving alternative to axenization. Our preliminary data hypothesizes that <em>Blastocystis</em> sp.-bacteria association is influenced by the status of the protozoan isolate, bacterial concentration, and purification methods.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107990"},"PeriodicalIF":2.5,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146045955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-20DOI: 10.1016/j.actatropica.2026.107987
Adiba, Alia Uzma, Mustafeez Mujtaba Babar, Muhammad Armaghan Khalid, Muhammad Tariq Navid, Liaqat Ali, Deeba Amraiz
Dengue virus (DENV) poses a significant global health burden, affecting many countries and regions worldwide, with no specific antiviral therapy currently available. The NS2B/NS3 protease is a crucial enzyme in viral replication, making it a promising target for the development of antiviral drugs. Drug repurposing offers a rapid and cost-efficient strategy by evaluating FDA-approved compounds for new antiviral indications. The present study aimed to identify potent inhibitors of DENV-2 NS2B/NS3 protease with an integrated in silico and in vitro analysis. Molecular docking was used to screen a library of 3109 FDA-approved drugs in the ZINC database with PyRx software. The three hits, Simeprevir, Saquinavir, and Dolutegravir were subsequently evaluated for their cytotoxicity and antiviral activity in Vero cells, using MTT and infectivity-based assays, respectively. MD simulations confirmed stable binding of Dolutegravir, Saquinavir, and Simeprevir with DENV NS2B/NS3 protease. Although dolutegravir displayed a slightly lower docking affinity, the compound demonstrated the lowest cytotoxicity with CC₅₀ 133.7 µg/mL (318.8 µM), and slightly enhanced antiviral activity with IC₅₀ 22.5 µg/mL (53.7 µM) among the tested compounds. Saquinavir showed CC₅₀ of 118.6 µg/mL (176.8 µM)) and an IC₅₀ 25.0 µg/mL (37.3 µM) and Simeprevir exhibited CC₅₀ 80.9 µg/mL (107.9 µM) with an IC₅₀ 20.0 µg/mL (26.7 µM). This study reflects on the potential of Dolutegravir as a dengue protease inhibitor and also indicates the efficacy of drug repurposing as a drug discovery strategy in the paradigm of antiviral discovery. Dolutegravir was identified as a potential candidate against DENV-2, and additional research is needed with molecular dynamics, mechanistic inquiry, and in vivo support investigation.
{"title":"Repurposing of FDA-approved drugs to identify potential ns2b/ns3 protease inhibitors against dengue virus: In silico and in vitro evaluation","authors":"Adiba, Alia Uzma, Mustafeez Mujtaba Babar, Muhammad Armaghan Khalid, Muhammad Tariq Navid, Liaqat Ali, Deeba Amraiz","doi":"10.1016/j.actatropica.2026.107987","DOIUrl":"10.1016/j.actatropica.2026.107987","url":null,"abstract":"<div><div>Dengue virus (DENV) poses a significant global health burden, affecting many countries and regions worldwide, with no specific antiviral therapy currently available. The NS2B/NS3 protease is a crucial enzyme in viral replication, making it a promising target for the development of antiviral drugs. Drug repurposing offers a rapid and cost-efficient strategy by evaluating FDA-approved compounds for new antiviral indications. The present study aimed to identify potent inhibitors of DENV-2 NS2B/NS3 protease with an integrated <em>in silico</em> and <em>in vitro</em> analysis. Molecular docking was used to screen a library of 3109 FDA-approved drugs in the ZINC database with PyRx software. The three hits, Simeprevir, Saquinavir, and Dolutegravir were subsequently evaluated for their cytotoxicity and antiviral activity in Vero cells, using MTT and infectivity-based assays, respectively. MD simulations confirmed stable binding of Dolutegravir, Saquinavir, and Simeprevir with DENV NS2B/NS3 protease. Although dolutegravir displayed a slightly lower docking affinity, the compound demonstrated the lowest cytotoxicity with CC₅₀ 133.7 µg/mL (318.8 µM), and slightly enhanced antiviral activity with IC₅₀ 22.5 µg/mL (53.7 µM) among the tested compounds. Saquinavir showed CC₅₀ of 118.6 µg/mL (176.8 µM)) and an IC₅₀ 25.0 µg/mL (37.3 µM) and Simeprevir exhibited CC₅₀ 80.9 µg/mL (107.9 µM) with an IC₅₀ 20.0 µg/mL (26.7 µM). This study reflects on the potential of Dolutegravir as a dengue protease inhibitor and also indicates the efficacy of drug repurposing as a drug discovery strategy in the paradigm of antiviral discovery. Dolutegravir was identified as a potential candidate against DENV-2, and additional research is needed with molecular dynamics, mechanistic inquiry, and <em>in vivo</em> support investigation.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"274 ","pages":"Article 107987"},"PeriodicalIF":2.5,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.actatropica.2026.107985
Nalia Mekarnia , Pénélope Gillard , Benjamin Aubry , Antoine Huguenin , Philippe M. Loiseau , Jérôme Depaquit
Cutaneous leishmaniasis (CL), a neglected disease prevalent in 88 countries, is commonly caused by Leishmania (L.) major in the Old World, posing significant public health concerns. Isolation from sand flies or infected mammals and in vitro cultivation of Leishmania parasites are critical for epidemiological studies, but these cultures are often compromised by bacterial and fungal contamination, especially when outsourced from vector digestive tracts. While the Leishmania parasite’s natural resistance to antibiotics simplifies bacterial control, most antifungals also inhibit the parasites growth, complicating efforts to manage fungal contamination. This study aimed to identify antifungal agents that could protect Leishmania cultures from yeast contamination with minimal impact on parasite growth. Five antifungal drugs: griseofulvin (GRF), caspofungin diacetate (CSF), 5-fluorocytosine (5-FC), po(ly)vidone-iodine (PVI), and undecylenic acid (UCA) were assessed in vitro for their effects on promastigote forms of L. major. The IC50 values indicated strong antileishmanial activity for 5-FC, GRF, UCA, and PVI (<13 µM), whereas CSF exhibited higher IC50 value (17 µM), suggesting relatively lower toxicity to the parasites. Under continuous CSF exposure, L. major promastigotes demonstrated substantial survival, with only a modest reduction in maximum parasite growth curves (peak of 2.65 × 10⁶ parasites/mL) compared to untreated controls (4.31 × 10⁶ parasites/mL maximum growth). These findings suggest that caspofungin diacetate could be used in the field to decontaminate Leishmania cultures from yeasts without significant parasite loss, facilitating L. major isolation and epidemiological investigations in endemic regions.
{"title":"Improving Leishmania isolation in field conditions: Efficacy of caspofungin against yeasts contamination","authors":"Nalia Mekarnia , Pénélope Gillard , Benjamin Aubry , Antoine Huguenin , Philippe M. Loiseau , Jérôme Depaquit","doi":"10.1016/j.actatropica.2026.107985","DOIUrl":"10.1016/j.actatropica.2026.107985","url":null,"abstract":"<div><div>Cutaneous leishmaniasis (CL), a neglected disease prevalent in 88 countries, is commonly caused by <em>Leishmania (L.) major</em> in the Old World, posing significant public health concerns. Isolation from sand flies or infected mammals and <em>in vitro</em> cultivation of <em>Leishmania</em> parasites are critical for epidemiological studies, but these cultures are often compromised by bacterial and fungal contamination, especially when outsourced from vector digestive tracts. While the <em>Leishmania</em> parasite’s natural resistance to antibiotics simplifies bacterial control, most antifungals also inhibit the parasites growth, complicating efforts to manage fungal contamination. This study aimed to identify antifungal agents that could protect <em>Leishmania</em> cultures from yeast contamination with minimal impact on parasite growth. Five antifungal drugs: griseofulvin (GRF), caspofungin diacetate (CSF), 5-fluorocytosine (5-FC), po(ly)vidone-iodine (PVI), and undecylenic acid (UCA) were assessed <em>in vitro</em> for their effects on promastigote forms of <em>L. major</em>. The IC<sub>50</sub> values indicated strong antileishmanial activity for 5-FC, GRF, UCA, and PVI (<13 µM), whereas CSF exhibited higher IC<sub>50</sub> value (17 µM), suggesting relatively lower toxicity to the parasites. Under continuous CSF exposure, <em>L. major</em> promastigotes demonstrated substantial survival, with only a modest reduction in maximum parasite growth curves (peak of 2.65 × 10⁶ parasites/mL) compared to untreated controls (4.31 × 10⁶ parasites/mL maximum growth). These findings suggest that caspofungin diacetate could be used in the field to decontaminate <em>Leishmania</em> cultures from yeasts without significant parasite loss, facilitating <em>L. major</em> isolation and epidemiological investigations in endemic regions.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"275 ","pages":"Article 107985"},"PeriodicalIF":2.5,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146002830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.actatropica.2026.107984
Estefania Grostieta , Beatriz Salceda-Sánchez , Héctor M. Zazueta-Islas , Miguel Tenchipe-Márquez , Laura V. Mondragon-Peña , Joselin Benítez , Paola Yesenia García Castillo , Carlos I. Miranda-Caballero , Gabriela Aguilar-Tipacamú , Miguel A. Alonso-Diaz , Roger I. Rodríguez-Vivas , Jorge L. Chagoya- Fuentes , Edelmira Jácome-Sosa , Herón Huerta , Ingeborg Becker , Sokani Sánchez-Montes
For over 80 years, the genus Coxiella was considered monotypic, comprising only Coxiella burnetii, the aetiological agent of Q fever. Recent studies, however, have revealed several candidate species and genetic lineages associated with ticks, many of which act as endosymbionts that are essential for tick development. This association is particularly notable in the members of the Rhipicephalus sanguineus complex, where Candidatus Coxiella massiliensis (zoonotic) and Candidatus Coxiella mudrowiae (unknown pathogenicity) have been described. Given the close relationship between these ticks, domestic dogs, and humans, active surveillance for Coxiella species of medical and veterinary importance is crucial.
This study evaluated the presence and diversity of Coxiella species in 812 hard ticks: Amblyomma mixtum (n = 23), Rhipicephalus linnaei (n = 762), and R. sanguineus sensu stricto (n = 27) collected from December 2018 to November 2024 parasitizing dogs (n = 418), humans (n = 18), cattle (n = 4), and one cat across 17 states of Mexico.
A fragment (∼1500 base pair) of the Coxiella 16S ribosomal DNA (rDNA) gene was amplified, sequenced, and analysed phylogenetically. Additionally, published records of Coxiella endosymbionts associated with ticks parasitising dogs were compiled. Of 812 samples, 188 tested positive, revealing three Coxiella lineages closely related to known endosymbionts of Rhipicephalus and Amblyomma ticks. A review of 25 studies from across the globe identified four Coxiella taxa in 23 tick species from dogs across 19 countries. This is the first report of Coxiella lineages in dog-associated ticks in Mexico. Our findings expand the known diversity of the genus in the Neotropical region and underscore the need for further research to clarify their ecological roles and potential health implications.
{"title":"Molecular detection of Coxiella endosymbionts associated with ixodid ticks recovered from animals and man in Mexico: Phylogeography and haplotype diversity analysis","authors":"Estefania Grostieta , Beatriz Salceda-Sánchez , Héctor M. Zazueta-Islas , Miguel Tenchipe-Márquez , Laura V. Mondragon-Peña , Joselin Benítez , Paola Yesenia García Castillo , Carlos I. Miranda-Caballero , Gabriela Aguilar-Tipacamú , Miguel A. Alonso-Diaz , Roger I. Rodríguez-Vivas , Jorge L. Chagoya- Fuentes , Edelmira Jácome-Sosa , Herón Huerta , Ingeborg Becker , Sokani Sánchez-Montes","doi":"10.1016/j.actatropica.2026.107984","DOIUrl":"10.1016/j.actatropica.2026.107984","url":null,"abstract":"<div><div>For over 80 years, the genus <em>Coxiella</em> was considered monotypic, comprising only <em>Coxiella burnetii</em>, the aetiological agent of Q fever. Recent studies, however, have revealed several candidate species and genetic lineages associated with ticks, many of which act as endosymbionts that are essential for tick development. This association is particularly notable in the members of the <em>Rhipicephalus sanguineus</em> complex, where <em>Candidatus</em> Coxiella massiliensis (zoonotic) and <em>Candidatus</em> Coxiella mudrowiae (unknown pathogenicity) have been described. Given the close relationship between these ticks, domestic dogs, and humans, active surveillance for <em>Coxiella</em> species of medical and veterinary importance is crucial.</div><div>This study evaluated the presence and diversity of <em>Coxiella</em> species in 812 hard ticks: <em>Amblyomma mixtum</em> (<em>n</em> = 23), <em>Rhipicephalus linnaei</em> (<em>n</em> = 762), and <em>R. sanguineus</em> sensu stricto (<em>n</em> = 27) collected from December 2018 to November 2024 parasitizing dogs (<em>n</em> = 418), humans (<em>n</em> = 18), cattle (<em>n</em> = 4), and one cat across 17 states of Mexico.</div><div>A fragment (∼1500 base pair) of the <em>Coxiella</em> 16S ribosomal DNA (rDNA) gene was amplified, sequenced, and analysed phylogenetically. Additionally, published records of <em>Coxiella</em> endosymbionts associated with ticks parasitising dogs were compiled. Of 812 samples, 188 tested positive, revealing three <em>Coxiella</em> lineages closely related to known endosymbionts of <em>Rhipicephalus</em> and <em>Amblyomma</em> ticks. A review of 25 studies from across the globe identified four <em>Coxiella</em> taxa in 23 tick species from dogs across 19 countries. This is the first report of <em>Coxiella</em> lineages in dog-associated ticks in Mexico. Our findings expand the known diversity of the genus in the Neotropical region and underscore the need for further research to clarify their ecological roles and potential health implications.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"274 ","pages":"Article 107984"},"PeriodicalIF":2.5,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146002889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-17DOI: 10.1016/j.actatropica.2026.107986
Yani Zhang, Yuanfeng Wang, Tianmeng Song, Yichen Zhao, Zhenchao Zhang, Xiaowei Tian, Shuai Wang, Zhenke Yang, Xuefang Mei
Blastocystis hominis (B. hominis), one of the most common intestinal protozoa infecting humans worldwide, is associated with gastrointestinal disorders, yet it remains unclear whether it secretes virulence factors that interact with villin, a key cytoskeletal protein essential for brush border homeostasis and epithelial barrier function. In this study, we constructed a high-quality normalized full-length B. hominis cDNA library (capacity 5.2 × 10⁶ CFU; recombination rate 95.8%) and performed yeast two-hybrid screening using villin as bait. Thirty initial positive clones were obtained, and sequencing combined with BLAST identified 24 unique prey proteins. Among these, 11 were in-frame (ORF-true), 8 proteins were selected for pairwise verification, and 6 proteins were ultimately confirmed to specifically interact with villin, including pyridine nucleotide transhydrogenase (XP_014525634), an ATP/GTP-binding protein-like molecule (OAO14457), and four hypothetical proteins (XP_012896330, XP_012895057, XP_012893676, XP_012894607). GO and KEGG analyses performed on the 24 prey proteins indicated enrichment in cellular metabolic processes and membrane-associated pathways. These findings identify multiple B. hominis proteins capable of interacting with villin, provide new insights into parasite-induced epithelial damage, and offer potential biomarkers and candidate targets for drug and vaccine development against blastocystosis.
{"title":"Identification of villin-interacting virulence factors of Blastocystis hominis using yeast two-hybrid screening","authors":"Yani Zhang, Yuanfeng Wang, Tianmeng Song, Yichen Zhao, Zhenchao Zhang, Xiaowei Tian, Shuai Wang, Zhenke Yang, Xuefang Mei","doi":"10.1016/j.actatropica.2026.107986","DOIUrl":"10.1016/j.actatropica.2026.107986","url":null,"abstract":"<div><div><em>Blastocystis hominis</em> (<em>B. hominis</em>), one of the most common intestinal protozoa infecting humans worldwide, is associated with gastrointestinal disorders, yet it remains unclear whether it secretes virulence factors that interact with villin, a key cytoskeletal protein essential for brush border homeostasis and epithelial barrier function. In this study, we constructed a high-quality normalized full-length <em>B. hominis</em> cDNA library (capacity 5.2 × 10⁶ CFU; recombination rate 95.8%) and performed yeast two-hybrid screening using villin as bait. Thirty initial positive clones were obtained, and sequencing combined with BLAST identified 24 unique prey proteins. Among these, 11 were in-frame (ORF-true), 8 proteins were selected for pairwise verification, and 6 proteins were ultimately confirmed to specifically interact with villin, including pyridine nucleotide transhydrogenase (XP_014525634), an ATP/GTP-binding protein-like molecule (OAO14457), and four hypothetical proteins (XP_012896330, XP_012895057, XP_012893676, XP_012894607). GO and KEGG analyses performed on the 24 prey proteins indicated enrichment in cellular metabolic processes and membrane-associated pathways. These findings identify multiple <em>B. hominis</em> proteins capable of interacting with villin, provide new insights into parasite-induced epithelial damage, and offer potential biomarkers and candidate targets for drug and vaccine development against blastocystosis.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"274 ","pages":"Article 107986"},"PeriodicalIF":2.5,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146002827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Timely serodiagnosis of Toxoplasma gondii is critical for HIV/AIDS patients, in whom latent infection can reactivate into life-threatening toxoplasmic encephalitis. This study aimed to evaluate the diagnostic performance of a novel recombinant T. gondii matrix antigen 1 (TgMAG1)-based indirect ELISA and a commercial latex agglutination test (LAT) for detecting anti-T. gondii IgG in HIV/AIDS patients, using the Sabin-Feldman dye test (DT) as the reference standard. A secondary objective was to determine the current prevalence of latent toxoplasmosis in this population in Thailand. We conducted a comparative serological evaluation using 348 residual clinical specimens collected from 2016 to 2019 from HIV/AIDS patients. All samples were tested using the in-house TgMAG1 ELISA, a commercial LAT, and the DT. The sensitivity, specificity, and agreement (kappa statistic) of each index test were calculated against the DT. The DT identified a T. gondii seroprevalence of 12.36% (43/348; 95% CI: 8.94–16.64). Compared to the DT, the TgMAG1-ELISA demonstrated a sensitivity of 72.09% and a specificity of 93.11%, with moderate agreement (κ = 0.598). The LAT showed a similar sensitivity of 69.76% but a higher specificity of 97.04%, achieving substantial agreement with the DT (κ = 0.696). In conclusion, both the TgMAG1-based ELISA and LAT demonstrated high specificity but moderate sensitivity compared to the reference standard. Consequently, while these assays are valuable screening tools in settings lacking the DT, their results require careful interpretation and potential confirmation in high-risk populations.
{"title":"Evaluation of recombinant Toxoplasma gondii matrix antigen MAG1 for toxoplasmosis screening in HIV/AIDS patients","authors":"Ruenruetai Udonsom , Charoonluk Jirapattharasate , Supaluk Popruk , Sumonmal Uttayamakul , Intira Tantawiwattananon , Manas Kotepui , Sukhontha Siri , Hirotake Mori , Yoshifumi Nishikawa , Aongart Mahittikorn","doi":"10.1016/j.actatropica.2026.107983","DOIUrl":"10.1016/j.actatropica.2026.107983","url":null,"abstract":"<div><div>Timely serodiagnosis of <em>Toxoplasma gondii</em> is critical for HIV/AIDS patients, in whom latent infection can reactivate into life-threatening toxoplasmic encephalitis. This study aimed to evaluate the diagnostic performance of a novel recombinant <em>T. gondii</em> matrix antigen 1 (TgMAG1)-based indirect ELISA and a commercial latex agglutination test (LAT) for detecting anti-<em>T. gondii</em> IgG in HIV/AIDS patients, using the Sabin-Feldman dye test (DT) as the reference standard. A secondary objective was to determine the current prevalence of latent toxoplasmosis in this population in Thailand. We conducted a comparative serological evaluation using 348 residual clinical specimens collected from 2016 to 2019 from HIV/AIDS patients. All samples were tested using the in-house TgMAG1 ELISA, a commercial LAT, and the DT. The sensitivity, specificity, and agreement (kappa statistic) of each index test were calculated against the DT. The DT identified a <em>T. gondii</em> seroprevalence of 12.36% (43/348; 95% CI: 8.94–16.64). Compared to the DT, the TgMAG1-ELISA demonstrated a sensitivity of 72.09% and a specificity of 93.11%, with moderate agreement (κ = 0.598). The LAT showed a similar sensitivity of 69.76% but a higher specificity of 97.04%, achieving substantial agreement with the DT (κ = 0.696). In conclusion, both the TgMAG1-based ELISA and LAT demonstrated high specificity but moderate sensitivity compared to the reference standard. Consequently, while these assays are valuable screening tools in settings lacking the DT, their results require careful interpretation and potential confirmation in high-risk populations.</div></div>","PeriodicalId":7240,"journal":{"name":"Acta tropica","volume":"274 ","pages":"Article 107983"},"PeriodicalIF":2.5,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145994070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}