Biology subjects

Castillo, J. A.

Publications and source records attributed to Castillo, J. A..

4 recordsLinked to original sources

bioRxiv2026

A TLR2-associated entry pathway promotes productive dengue virus serotype 2 infection and inflammatory responses in classical monocytes

Severe dengue is characterized by systemic inflammation and vascular leakage. Recent evidence indicates that Toll-like receptor 2 (TLR2) supports early steps of dengue virus (DENV) infection in monocytes, whereas intracellular viral RNA sensing drives much of the subsequent inflammatory response. However, whether this entry-associated function of TLR2 differs among human monocyte subsets remains unknown. Here, we investigated how the TLR2 axis regulates DENV serotype 2 (DENV2) infection and inflammatory output in purified primary human monocytes and sorted monocyte subsets. Blocking TLR2 at the cell surface or targeting its intracellular TIR domain reduced virus-cell association, productive infection, and the release of inflammatory and antiviral mediators. Among TLR2-associated receptors, CD14 and, to a lesser extent, CD36 contributed to efficient infection, whereas TLR1, TLR6, and TLR10 were dispensable under the conditions tested. Notably, TLR2 blockade reduced viral production and cytokine release in CD16- classical monocytes but not in pooled CD16+ monocytes, identifying a subset-specific dependence on the TLR2 axis. TLR3 contributed to inflammatory and antiviral responses without affecting viral replication, consistent with post-entry recognition of viral RNA. Finally, blocking the TLR2 axis during monocyte infection prevented the loss of endothelial barrier integrity induced by monocyte-derived soluble mediators. Together, these findings identify a TLR2-associated entry route that preferentially supports productive DENV2 infection in classical monocytes and thereby enables RNA-sensor-dependent inflammatory responses that compromise endothelial function.

microbiology↗

bioRxiv2025

Evolutionary origin and demographic trajectory of tomato spotted wilt virus (Orthotospovirus tomatomaculae)

Tomato spotted wilt orthotospovirus (TSWV) is a harmful pathogen that causes severe disease in tomato, pepper, and other horticultural and agronomic crops. The genome comprises three linear ssRNA molecules (segments L, M, and S) unequally packed in nucleocapsids. Although the genome structure and molecular mechanism of infection are well understood, the evolutionary dynamics require further analysis to know what we seek in this study: to determine the most probable viral ancestor, the date of divergence, the ancestral geographical source of dispersal, and the demographic history of TSWV. We employed the Bayesian framework to analyze whole genome sequences of 136 isolates of TSWV obtained from different sites worldwide and with a sampling window of 35 years. In independent analyses, we performed phylodynamic estimations with segment L, M, and S sequence data. Our results showed that the clock rates of different genome segments ranged from 1.678x10-4 to 2.444x10-4 substitutions/site/year. Likewise, the time to the most recent common ancestor shows variations according to the dataset used for the inferences; however, the most probable date of TSWV divergence is around 1768 CE. Our phylogeographic exploration showed concordant results for the three genomic segments analyzed; that is, the TSWV population originated in South Korea and, from there, early expanded to Europe and then to North America and other continents. Past population dynamics analysis showed that the virus experienced two major population expansions that coincided with the increase of the agricultural frontier and the emergence of new species of insect vectors.

evolutionary biology↗

bioRxiv2018

Candidate genes under balancing selection in a plant bacterial pathogen

Plant pathogens are under significant selective pressure by the plant host. Consequently, they are expected to have adapted to this condition or contribute to evading plant defenses. In order to acquire long-term fitness, plant bacterial pathogens are usually forced to maintain advantageous genetic diversity in populations. This strategy ensures that different alleles in the pathogens gene pool are maintained in a population at frequencies larger than expected under neutral evolution. This selective process, known as balancing selection, is the subject of this work in the context of a common plant bacterial pathogen. We performed a genome-wide scan of Ralstonia solanacearum, an aggressive plant bacterial pathogen that shows broad host range and causes a devastating disease called bacterial wilt. Using a sliding window approach, we analyzed 57 genomes from three phylotypes of R. solanacearum to detect signatures of balancing selection. A total of 161 windows showed extreme values in three summary statistics of population genetics: Tajimas D, Wattersons {theta} and Fu & Lis D*. We discarded any confounding effects due to demographic events by means of coalescent simulations of genetic data. The prospective windows correspond to 78 genes that map in any of the two main replicons of R. solanacearum. The candidate genes under balancing selection are related to primary metabolism (51.3%) or directly associated to virulence (48.7%), being involved in key functions targeted to dismantle plant defenses or to participate in critical stages in the pathogenic process. These genes are useful to understand and monitor the evolution of bacterial pathogen populations and emerge as potential candidates for future treatments to induce specific plant immune responses.

microbiology↗

bioRxiv2017

Barcoding analysis of HIV drug resistance mutations using Oxford Nanopore MinION (ONT) sequencing

Determination of HIV drug resistance (HIVDR) is becoming an integral baseline HIV evaluation for newly infected subjects, as the level of pre-treatment resistance is increasing worldwide. Until now, the gold standard for monitoring ART mutations is the Sanger sequencing method, however, next-generation sequencing technologies (NGS) because high-throughput capability, are gaining attention as a method for detection of HIVDR. In the present work, we evaluated the use of the Oxford Nanopore Technologies (ONT) MinION as an alternative method for detection of drug resistance mutations in pre-treatment HIV positive subjects.\n\nWe evaluate 36 samples taken during November 2016 from treatment naive subjects with age greater than 18 years old, who went to the lab for their first HIV monitoring. To evaluate the agreement between Sanger and MinION generated sequences, we aligned the sequences ([~]1200bp) with muscle v. 3.8.31. Then we counted the differences and calculated the p-distance of the obtained sequences, comparing paired sequences and grouping Sanger and MinION obtained sequences. The percentage of similarity among each sequence was also evaluated.\n\nAll samples were submitted to the Standford University HIV drug resistance database (HIVdb version 8.4). Then we compared the resistance predictions obtained from the sequences generated by Sanger and MinION methods.\n\nResults: The median of available pores was 1314 for the first run, 1215 for the second run, and 536 for the third run. After 3 hours with SQK-NSK007 a total of 18803 2D reads were base-called and in 16577 reads (88%) a barcode was detected.\n\nComparing the nucleotide differences of each sample, we observed that 23 (74%) samples had identical sequence, for the other samples the percentage of identity among each analyzed sequence was greater than 95%. A good positive predictive value (100%) in the estimation of drug resistance mutations in the groups of protease inhibitors (PI), nucleoside reverse transcriptase inhibitors (NRTIs), and non-nucleoside reverse transcriptase inhibitors (NNRTIs).\n\nWe present an approach for the analysis of HIV reads generated with MinION ONT, further studies are guaranteed before the application of this methodology in clinical settings to assess its suitability for HIVDR testing.

genomics↗