HORMAZABAL CASTILLO, JUAN PATRICIO

Preferred name
HORMAZABAL CASTILLO, JUAN PATRICIO
Main Affiliation
Email
jhormazabal@udd.cl
ORCID
0000-0003-0726-2778
Scopus Author ID
57225278430
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    Traceable and Biocompatible Carbon Dots from Simple Precursors: A Pre-Deployment Safety Baseline
    (MDPI AG, 2025-11-20)
    Christian Silva-Sanzana
    ;
    Plinio Innocenzi
    ;
    Luca Malfatti
    ;
    Federico Fiori
    ;
    Francisca Blanco-Herrera
    <jats:p>Carbon dots (CDs) are promising for agro-environmental applications; however, clear connections between synthesis, photophysical properties, size, and biosafety are often not well established. In this study, we map these relationships for glucose–arginine CDs (GA-CDs). By using microwave and hydrothermal routes at precursor ratios of 1:3, 1:9, and 1:15, we produced sub-10 nm nanoparticles (analyzed by dynamic light scattering and atomic force microscopy) that exhibit tunable absorption and emission properties, as well as surface properties (demonstrated through UV–Vis spectroscopy, 3D photoluminescence, and FTIR analysis). The hydrothermal 1:9 condition yielded the narrowest size distribution and red-shifted photoluminescence. Across biological models spanning plants, insects, plant-growth-promoting bacteria (PGPR), and human cells, GA-CDs were well tolerated, with no adverse changes detected in plant stress markers, aphid feeding behavior or fecundity, or PGPR growth. In A549 cells, viability remained stable up to a concentration of 0.125 mg mL−1, while exposure to 0.5 mg mL−1 reduced viability, establishing a practical operating range. These results provide a clearer picture of how the structure and properties of carbon dots derived from arginine and glucose are correlated to their safety. The GA-CDs are, therefore, useful, and traceable tools for agro-environmental research. The findings support their use as biocompatible nanomaterials for studying interactions among plants, insects, and microbes in agriculture.</jats:p>
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    Immunization and SARS-CoV-2 Antibody Seroprevalence in a Country with High Vaccination Coverage: Lessons from Chile
    (2022)
    AGUILERA SANHUEZA, XIMENA PAZ  
    ;
    Gloria Icaza
    ;
    GONZALEZ WIEDMAIER, CLAUDIA MARTA  
    ;
    RUBILAR RAMIREZ, PAOLA  
    ;
    APABLAZA SALINAS, MAURICIO IVÁN  
    <jats:p>Chile is among the most successful nations worldwide in terms of its COVID-19 vaccine rollout. By 31 December 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using different COVID-19 vaccines. In this context, we aimed to estimate the prevalence of anti-SARS-CoV-2 antibodies following the infection and vaccination campaign. Using a three-stage stratified sampling, we performed a population-based cross-sectional serosurvey based on a representative sample of three Chilean cities. Selected participants were blood-sampled on-site and answered a short COVID-19 and vaccination history questionnaire using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. We recruited 2198 individuals aged 7–93 between 5 October and 25 November 2021; 2132 individuals received COVID-19 vaccinations (97%), 67 (3.1%) received one dose, 2065 (93.9%) received two doses, and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR = 674.6, 154.8–2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. We found a seroprevalence close to 100%, primarily due to the successful vaccination program, which strongly emphasizes universal access.</jats:p>
      6Scopus© Citations 13
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      2Scopus© Citations 3
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    SARS-CoV-2 infectivity and antigenic evasion: spotlight on isolated Omicron sub-lineages
    (2024)
    Aldo Barrera
    ;
    Constanza Martínez-Valdebenito
    ;
    Jenniffer Angulo
    ;
    Carlos Palma
    ;
    HORMAZABAL CASTILLO, JUAN PATRICIO  
    <jats:p>Since the SARS-CoV-2 outbreak in 2019, a diversity of viral genomic variants has emerged and spread globally due to increased transmissibility, pathogenicity, and immune evasion. By the first trimester of 2023 in Chile, as in most countries, BQ and XBB were the predominant circulating sub-lineages of Omicron. The molecular and antigenic characteristics of these variants have been mainly determined using non-authentic spike pseudoviruses, which is often described as a limitation. Additionally, few comparative studies using isolates from recent Omicron sub-lineages have been conducted. In this study, we isolated SARS-CoV-2 variants from clinical samples, including the ancestral B.1.1, Delta, Omicron BA.1, and sub-lineages of BA.2 and BA.5. We assessed their infectivity through cell culture infections and their antibody evasion using neutralization assays. We observed variations in viral plaque size, cell morphology, and cytotoxicity upon infection in Vero E6-TMPRSS2 cells for each variant compared to the ancestral B.1.1 virus. BA.2-derived sub-variants, such as XBB.1.5, showed attenuated viral replication, while BA.5-derived variants, such as BQ.1.1, exhibited replication rates similar to the ancestral SARS-CoV-2 virus. Similar trends were observed in intestinal Caco-2 cells, except for Delta. Antibody neutralization experiments using sera from individuals infected during the first COVID-19 wave (FWI) showed a consistent but moderate reduction in neutralization against Omicron sub-lineages. Interestingly, despite being less prevalent, BQ.1.1 showed a 6.1-fold greater escape from neutralization than XBB.1.5. Neutralization patterns were similar when tested against sera from individuals vaccinated with 3xBNT162b2 (PPP) or Coronavac-Coronavac-BNT162b2 (CCP) schedules. However, CCP sera showed 2.3-fold higher neutralization against XBB.1.5 than FWI and PPP sera. This study provides new insights into the differences between BA.2 and BA.5-derived variants, leading to their eventual outcompetition. Our analysis offers important evidence regarding the balance between infectivity and antigenic escape that drives the evolution of second-generation SARS-CoV-2 variants in the population.</jats:p>
      5Scopus© Citations 4
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      2Scopus© Citations 61
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    Scopus© Citations 16  8
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    Evaluation of the Immune Response Induced by CoronaVac 28-Day Schedule Vaccination in a Healthy Population Group
    (2022)
    Alejandro Escobar
    ;
    Felipe E. Reyes-López
    ;
    Mónica L. Acevedo
    ;
    Luis Alonso-Palomares
    ;
    Fernando Valiente-Echeverría
    <jats:p>CoronaVac vaccine from Sinovac Life Science is currently being used in several countries. In Chile, the effectiveness of preventing hospitalization is higher than 80% with a vaccination schedule. However, to date, there are no data about immune response induction or specific memory. For this reason, we recruited 15 volunteers without previous suspected/diagnosed COVID-19 and with negative PCR over time to evaluate the immune response to CoronaVac 28 and 90 days after the second immunization (dpi). The CoronaVac administration induces total and neutralizing anti-spike antibodies in all vaccinated volunteers at 28 and 90 dpi. Furthermore, using ELISpot analysis to assay cellular immune responses against SARS-CoV-2 spike protein, we found an increase in IFN-gamma- and Granzyme B-producing cells in vaccinated volunteers at 28 and 90 dpi. Together, our results indicate that CoronaVac induces a robust humoral immune response and cellular immune memory of at least 90 dpi.</jats:p>
      23Scopus© Citations 19
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    KFERQ-selective protein autophagy in Caenorhabditis elegans depends on LMP-1
    (Public Library of Science (PLoS), 2025-09-02)
    Alicia N. Minniti
    ;
    María Gallardo-Campos
    ;
    HORMAZABAL CASTILLO, JUAN PATRICIO  
    ;
    NUÑEZ VASQUEZ, GONZALO ESTEBAN  
    ;
    Carlos F. Lagos
    Mammalian cells exhibit three autophagy mechanisms: macroautophagy, microautophagy (MIA), and chaperone-mediated autophagy (CMA), each employing unique mechanisms for transporting cellular material to the lysosome for degradation. MIA involves the engulfment of proteins via lysosomes/late endosomes through membrane invagination, while CMA directly imports cytosolic proteins into lysosomes, selectively targeting those harboring the KFERQ pentapeptide motif, helped by the chaperone HSC70. Despite the identification of several genetic markers of these pathways, our understanding of the underlying mechanisms, particularly in MIA and CMA, remains limited. To study CMA in vivo we designed a photoactivatable CMA reporter consisting of a plasmid encoding the KFERQ consensus signal for CMA targeting. We generated transgenic <jats:italic><jats:italic>C. elegans</jats:italic></jats:italic> strains with diverse genetic backgrounds to analyze the role of known molecular components of CMA in mammals. Additionally, we conducted an in-silico analysis of the structural interaction between <jats:italic><jats:italic>C. elegans</jats:italic></jats:italic> LMP-1 or LMP-2 proteins with the HSP-1 chaperone. Results: Our study shows a significant alteration in the distribution pattern of the KFERQ reporter in muscle cells upon induction of selective autophagy (CMA or MIA). We found that the reporter localized into lysosomes only during starvation, which abrogated in the absence of LMP-1. This study validates CMA in <jats:italic><jats:italic>C. elegans</jats:italic></jats:italic> and provides the development of a new tool for understanding selective autophagy mechanisms and their potential implications in various organisms.
      1Scopus© Citations 2