Acta tropica最新文献

Subtropical Asia has a rich diversity of reptiles and ticks, though the role of reptiles in the sylvatic cycles of medically important ticks in the region is poorly known. Habu vipers (Protobothrops flavoviridis) are widespread and common in the Japanese subtropics but their role as hosts for ticks has not been carefully explored. For 15 months in 2023/24, habu vipers were screened for ticks and were found to be important hosts for immature stages of the tick Amblyomma testudinarium, with a 22% infestation rate. Amblyomma testudinarium was found to have weak attachment site preferences on P. flavoviridis and host body length was found to have no relationship with either the risk of infestation or the tick load in infested snakes. The phenological profile of A. testudinarium was mapped for the first time in the subtropics based on mean tick loads on P. flavoviridis and historical flagging data. March-April were identified as the period of highest activity, May to July was a period of declining activity, August-September was a period of almost complete inactivity, and October to February was a periods of increasing activity. The role of habu vipers in the sylvatic cycle of A. testudinarium in subtropical Asia is discussion. Additionally, the potential of habu vipers to serve as reservoirs of pathogens or as dilution hosts is also explored.

Leishmaniasis is a neglected tropical disease and is one of the major causes of mortality in poverty-stricken areas. A limited chemotherapeutics arsenal is available to tackle this deadly infection. Thus, identifying novel potent scaffolds using innovative strategies is the need of the hour. High-throughput screening (HTS) is a critical technique that can accelerate the process of drug discovery by evaluating millions of drug-like molecules using various automation tools and biological assays. In the present study, we have employed the HTS strategy to identify potent hits against Leishmania donovani sterol C-24 methyltransferase (LdSMT) from the in-house ChemBridge library. Firstly, a robust dataset was prepared with previously reported sterol C-24 methyltransferase inhibitors, belonging to diverse structural classes. Then, ligand-based virtual screening using similarity search was performed to screen the ChemBridge library having ∼20,000 molecules. This computational approach yielded 81 candidate compounds, which were selected for further molecular docking and biological evaluation. Anti-leishmanial assays revealed that out of 81 molecules, seven showed potential parasitic killing. Three molecules namely IIIM-CB-14, IIIM-CB-29, and IIIM-CB-45 were the most potent ones with 50% inhibitory concentration (IC₅₀) of 5.76, 8.08, and 10.64 µg/mL, respectively. SEM analyses suggest that these potent hits cause considerable morphological alterations. ADME studies of the potent hit molecules indicate that all the hits have considerable drug-likeness properties. Further, molecular dynamics studies were also performed to check the stable confirmation of LdSMT protein with the top two hits (IIIM-CB-14 and IIIM-CB-45). Thus, the present study harnesses computational and experimental approaches to unravel potent anti-leishmanial scaffolds.

Estimating the abundance of immature mosquitoes in discarded water-filled tyres is a laborious task due to their shape and size. Our objective was to develop a procedure that allows, by counting individuals in a water sample, to estimate their total abundance. Polynomial functions linking water column height and water volume were fitted for five tyre categories (from cars to tractors) and horizontal/vertical storage positions. A total of 358 discarded water-filled tyres were then surveyed using this method in 16 piles of tyres in temperate Argentina. Tyre capacity was greater in vertical than horizontal position, reaching a maximum of 95.6 L in tractor tyres. In contrast, the volume of water retained under field conditions showed the opposite pattern, being greater in horizontal tyres. Water volume increased significantly across tyre categories in both horizontal (J-T=7306, p<0.001) and vertical (J-T=10792, p<0.001) positions. Most infested tyres (n=150) showed low abundances and a few extremely high values, both for all mosquito species grouped and for Culex pipiens and Aedes aegypti separately. The median abundance of mosquitoes per infested tyre was 35, decreasing to 30 for Cx. pipiens and 17 for Ae. aegypti. These values ​​increased significantly across tyre categories for mosquitoes (J-T=5525, p<0.001) and Cx. pipiens (J-T=2275, p<0.05), but not for Ae. aegypti (J-T=1526, p=0.472). The comparison between vertical and horizontal positions was not significant for both vector species. Our methodological approach could be particularly useful in research addressing the assessment of disease risk associated with mosquito productivity.

The characterization of non-retroviral integrated RNA virus sequences (NIRVS) in mosquitoes has emerged as a significant area of research that could yield insight into virus-host interactions. This study aimed to characterize NIRVS in the Anopheles darlingi reference genome and identify putative transcribed NIRVS in field-collected mosquitoes from Colombia. The An. darlingi reference genome was analyzed to identify and characterize NIRVS by conducting a BLAST query with all the virus sequences previously identified in arthropods available in the NCBI-virus repository. In addition, An. darlingi field-collected mosquitoes were examined for NIRVS using a metatranscriptomic approach. As a result, 44 NIRVS were identified in the An. darlingi genome, constituting integrations of negative single-stranded RNA viruses (ssRNA-) from the families Rhabdoviridae, Chuviridae and Phasmaviridae, and integrations of double-stranded RNA viruses (dsRNA) from the families Partitiviridae and Sedoreoviridae. These NIRVS were not randomly distributed but clustered in specific regions of the genome enriched with BEL/Pao and Ty3/Gypsy long terminal repeat elements. Furthermore, putative NIRVS-like sequences were present in the transcriptomic data from all the Colombian An. darlingi natural populations. This study is significant as it represents the first identification of NIRVS in the most important malaria vector of the Neotropics. The findings help in understanding the intricate relationship between the mosquito and its virome, and the regulation of viruses' mechanisms in the Anopheles genus.

Accurate counting of mosquito larval populations is essential for maintaining optimal conditions and population control within rearing facilities, assessing disease transmission risks, and implementing effective vector control measures. While existing methods for counting mosquito larvae have faced challenges such as the impact on larval mortality rate, multiple parameters adjustment and limitations in availability and affordability, recent advancements in artificial intelligence, particularly in AI-driven visual analysis, hold promise for addressing these issues. Here, we introduce LarvaeCountAI, an open-source convolutional neural network (CNN)-based tool designed to automatically count Culex annulirostris mosquito larvae from videos captured in laboratory environments. LarvaeCountAI does not require videos to be recorded using an advanced setup; it can count larvae with high accuracy from videos captured using a simple setup mainly consisting of a camera and commonly used plastic trays. Using the videos enables LarvaeCountAI to capitalise on the continuous movement of larvae, enhancing the likelihood of accurately counting a greater number of larvae. LarvaeCountAI adopts a non-invasive approach, where larvae are simply placed in trays and imaged, minimising any potential impact on larval mortality. This approach addresses the limitations associated with previous methods involving mechanical machines, which often increase the risk of larval mortality as larvae pass through multiple sections for counting purposes. The performance of LarvaeCountAI was tested using 10 video samples. Validation results demonstrated the excellent performance of LarvaeCountAI, with an accuracy ranging from 96.25 % to 99.13 % across 10 test videos and an average accuracy of 97.88 %. LarvaeCountAI represents a remarkable advancement in mosquito surveillance technology, offering a robust and efficient solution for monitoring larval populations. LarvaeCountAI can contribute to developing effective strategies for reducing disease transmission and safeguarding public health by providing timely and accurate data on mosquito larvae abundance.

Toxoplasmosis remains a challenge for both public health and animal husbandry which created a constant demand to develop novel compounds using innovative methods. To join this relentless quest for an ideal chemotherapeutic agent, herein, we developed newly synthesized isatin-1,2,3-triazole derivatives. Three compounds (5a, 5b and 5c) were synthesized, characterized, and loaded on chitosan nanoparticles (CNPs) and then evaluated accordingly. Initially, a molecular docking study was carried out which revealed the effective interaction with the target enzymes; purine nucleoside phosphorylase (PNPase) and T. gondii calcium-dependent protein kinase-1 (TgCDPK1). This was further substantiated by in vivo evaluation of the three compounds (5a-c) and their nanoformulae (5a-CNPs, 5b-CNPs, and 5c-CNPs) against acute Toxoplasma gondii infection in murine model. It is worthy of note that all tested compounds and their nanoformulae produced a significant reduction of parasite burden in both peritoneal fluid and liver impression smear and profound ultrastructural alterations, detected by scanning electron microscopy, compared to the infected non-treated control. The nanoformula 5c-CNPs yielded the most outstanding results with the highest tachyzoite reduction percentage in both peritoneal fluid (98.1%) and liver impression smear (95.3%). Furthermore, the serum levels of liver enzymes (aspartate transaminase (AST) and alanine transaminase (ALT), and renal function tests (urea and creatinine) in mice were within normal limits which makes them more appealing candidates with proven safety. To the best of our knowledge, the present work is the first in silico and in vivo study proving the anti-Toxoplasma effect of isatin-1,2,3- triazoles which paves the way for further development of isatin and triazole-based leads for the treatment of toxoplasmosis.