Browsing by Author "Martinez-Valdebenito, Constanza"

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    A 19 Year Analysis of Small Mammals Associated with Human Hantavirus Cases in Chile
    (2019) Torres-Perez, Fernando; Eduardo Palma, R.; Boric-Bargetto, Dusan; Vial, Cecilia; Ferres, Marcela; Vial, Pablo A.; Martinez-Valdebenito, Constanza; Pavletic, Carlos; Parra, Alonso; Marquet, Pablo A.; Mertz, Gregory J.
    Small mammals present in areas where hantavirus cardiopulmonary syndrome (HCPS) cases had occurred in central and southern Chile were captured and analyzed to evaluate the abundance of rodents and seroprevalence rates of antibodies to Andes orthohantavirus (ANDV). Sampling areas ranged from the Coquimbo to Aysen regions (30-45 degrees S approx.) regions. Ninety-two sites in peridomestic and countryside areas were evaluated in 19 years of sampling. An antibody against ANDV was detected by strip immunoassay in 58 of 1847 specimens captured using Sherman traps. Of the eleven species of rodents sampled, Abrothrix olivacea, Oligoryzomys longicaudatus and Abrothrix hirta were the most frequently trapped. O. longicaudatus had the highest seropositivity rate, and by logistic regression analysis, O. longicaudatus of at least 60 g had 80% or higher probability to be seropositive. Sex, age and wounds were significantly related to seropositivity only for O. longicaudatus. Across administrative regions, the highest seropositivity was found in the El Maule region (34.8-36.2 degrees S), and the highest number of HCPS cases was registered in the Aysen region. Our results highlight the importance of long term and geographically extended studies, particularly for highly fluctuating pathogens and their reservoirs, to understand the implications of the dynamics and transmission of zoonotic diseases in human populations.
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    Association of single-nucleotide polymorphisms in IL28B, but not TNF-alpha, with severity of disease caused by andes virus
    (2015) Angulo, Jenniffer; Pino, Karla; Echeverria-Chagas, Natalia; Marco, Claudia; Martinez-Valdebenito, Constanza; Galeno, Héctor; Villagra, Eliecer; Vera, Lilian; Lagos, Natalia; Miquel P., Juan Francisco
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    Canine seroprevalence to Orientia species in southern Chile: A cross-sectional survey on the Chiloe A Island
    (2018) Weitzel, Thomas; Jiang, Ju; Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza; Lopez, Javier; Richards, Allen L.; Abarca Villaseca, Katia
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    Characterization of Oral Immunity in Cases and Close Household Contacts Exposed to Andes Orthohantavirus (ANDV)
    (2020) Martinez-Valdebenito, Constanza; Andaur, Camila; Angulo, Jenniffer; Henriquez, Carolina; Ferres, Marcela; Le Corre, Nicole
    Background: Andes orthohantavirus (ANDV) is the sole etiologic agent of Hantavirus Cardiopulmonary Syndrome in Chile and, until now, the only Hantavirus known to be transmitted by person-to-person route. The main risk of person-to-person transmission is to be a sexual partner of an index case, and deep kissing the main mechanism of infection. Experimental reports suggest that ANDV infection can be inhibited by some saliva components. Therefore, some host factors like saliva quality, could help to explain why some individuals do not become infected even though their exposure to the virus is high.
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    Chigger Mites (Acariformes: Trombiculidae) of Chiloe Island, Chile, With Descriptions of Two New Species and New Data on the Genus Herpetacarus
    (2021) Carolina Silva-de La Fuente, Maria; Stekolnikov, Alexandr A.; Weitzel, Thomas; Beltrami, Esperanza; Martinez-Valdebenito, Constanza; Abarca, Katia; Acosta-Jamett, Gerardo
    Three species of chigger mites are recorded in our collections from four species of cricetid rodents on Chiloe Island (southern Chile, Los Lagos Region), an area endemic to scrub typhus (Orientia sp.). Two species are described as new-Herpetacarus (Abonnencia) eloisae sp. nov. and Quadraseta chiloensis sp. nov. One species, Paratrombicula goffi Stekolnikov and Gonzalez-Acuna 2012, is for the first time recorded on a mammal host (one species of cricetid rodent), and its distribution is extended to the Los Lagos Region of Chile. The genus Proschoengastia Vercammen-Grandjean, 1967 is synonymized with the subgenus Herpetacarus (Abonnencia) Vercammen-Grandjean, 1960, and four new combinations are established: Herpetacarus (Abonnencia) herniosa (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) insolita (Brennan and Jones, 1961), comb. nov., Herpetacarus (Abonnencia) macrochaeta (Brennan and Jones, 1961), comb. nov., and Herpetacarus (Abonnencia) antarctica (Stekolnikov and Gonzalez-Acuna, 2015), comb. nov.
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    Comparison of VSV Pseudovirus and Focus Reduction Neutralization Assays for Measurement of Anti-Andes orthohantavirusNeutralizing Antibodies in Patient Samples
    (2020) Vial, Cecilia; Whitaker, Annalis; Wilhelm, Jan; Ovalle, Jimena; Perez, Ruth; Valdivieso, Francisca; Ferres, Marcela; Martinez-Valdebenito, Constanza; Eisenhauer, Philip; Mertz, Gregory J.; Hooper, Jay W.; Botten, Jason W.; Vial, Pablo A.
    Andes orthohantavirus(ANDV) is the etiologic agent of hantavirus cardiopulmonary syndrome (HCPS), which has a case fatality rate around 35%, with no effective treatment or vaccine available. ANDV neutralizing antibody (NAb) measurements are important for the evaluation of the immune response following infection, vaccination, or passive administration of investigational monoclonal or polyclonal antibodies. The standard assay for NAb measurement is a focus reduction neutralization test (FRNT) featuring live ANDV and must be completed under biosafety level (BSL)-3 conditions. In this study, we compared neutralization assays featuring infectious ANDV or vesicular stomatitis virus (VSV) pseudovirions decorated with ANDV glycoproteins for their ability to measure anti-ANDV NAbs from patient samples. Our studies demonstrate that VSV pseudovirions effectively measure NAb from clinical samples and have greater sensitivity compared to FRNT with live ANDV. Importantly, the pseudovirus assay requires less labor and sample materials and can be conducted at BSL-2.
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    Development of a New Genus-Specific Quantitative Real-Time PCR Assay for the Diagnosis of Scrub Typhus in South America
    (2022) Jiang, Ju; Martinez-Valdebenito, Constanza; Weitzel, Thomas; Farris, Christina M.; Acosta-Jamett, Gerardo; Abarca, Katia; Richards, Allen L.
    Scrub typhus is a potentially severe rickettsiosis, caused by Orientia tsutsugamushi in the Asia-Pacific region. Recently, however, two distinct pathogens, "Candidatus Orientia chuto" and "Candidatus Orientia chiloensis", have been discovered in the Middle East and South America, respectively. Since the novel pathogens differ significantly from O. tsutsugamushi, many established diagnostic methods are unreliable. This work describes the development and validation of a new quantitative real-time PCR (qPCR) assay (Orien16S) for the detection of all known Orientia species. Based on a 94 bp sequence of the 16S rRNA gene (rrs), Orien16S recognized DNA samples from O. tsutsugamushi (n = 41), Ca. O. chiloensis (n = 5), and Ca. O. chuto (n = 1), but was negative for DNA preparations from closely related rickettsiae and other members of the order Rickettsiales (n = 22) as well as unrelated bacterial species (n = 11). After its implementation in Chile, the assay was verified, correctly identifying all tested eschar and buffy coat samples (n = 28) of clinical suspected cases. Furthermore, Orien16S detected Orientia DNA in trombiculid mites collected in endemic regions in southern Chile. The presented novel qPCR assay provides a useful tool for detecting Orientia and diagnosing scrub typhus from all geographical regions.
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    Differential neutralizing antibody responses elicited by CoronaVac and BNT162b2 against SARS-CoV-2 Lambda in Chile
    (2022) Acevedo, Monica L.; Gaete-Argel, Aracelly; Alonso-Palomares, Luis; de Oca, Marco Montes; Bustamante, Andres; Gaggero, Aldo; Paredes, Fabio; Cortes, Claudia P.; Pantano, Sergio; Martinez-Valdebenito, Constanza; Angulo, Jenniffer; Le Corre, Nicole; Ferres, Marcela; Navarrete, Marcelo A.; Valiente-Echeverria, Fernando; Soto-Rifo, Ricardo
    The SARS-CoV-2 Lambda variant has been prevalent in Latin America. An analysis of the neutralization capacity of antibodies elicited by CoronaVac and BNT162b2 against SARS-CoV-2 Lambda in plasma from healthcare workers and patients in Chile reveals that BNT162b2 elicits higher neutralizing antibody titres than CoronaVac.
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    Eco-epidemiology of rodent-associated trombiculid mites and infection with Orientia spp. in Southern Chile
    (2023) Silva de la Fuente, Maria Carolina; Perez, Caricia; Martinez-Valdebenito, Constanza; Perez, Ruth; Vial, Cecilia; Stekolnikov, Alexandr; Abarca, Katia; Weitzel, Thomas; Acosta-Jamett, Gerardo
    BackgroundScrub typhus is a potentially severe infection caused by bacteria of the genus Orientia, endemic in Asia-Pacific and recently discovered in southern Chile. The presented study aimed to determine the prevalence and species richness of rodent-associated trombiculid mites and their infection with Orientia spp. in different areas of two regions in southern Chile. Methodology/Principal findingsDuring summer 2020, trombiculid mites were collected from rodents captured in three areas in southern Chile known to be endemic for scrub typhus (Cochamo and Chiloe Island in the Los Lagos Region and Tortel in the Aysen Region). A total of 132 rodents belonging to five species were captured using Sherman-like traps; 89.4% were infested with trombiculids. Mite specimens were morphologically identified and subsequently tested by Orientia-specific qPCR. Six mite species were identified. Among chigger-infested rodents, 33.9% carried Orientia-positive mites; this rate was higher in Tortel (63.8%) than in Cochamo (45.0%) and Chiloe Island (2.0%). The analysis of individual mites (n = 901) revealed that 31.2% of Herpetacarus antarctica samples (n = 202) were positive for Orientia DNA; the prevalence was 7.0% in Paratrombicula neuquenensis (n = 213), 6.9% in Herpetacarus eloisae (n = 144), 3.6% in Argentinacarus expansus (n = 55), and 0% in Paratrombicula goffi (n = 110) and Quadraseta chiloensis (n = 177). The southernmost site (Tortel) showed the highest rates of trombiculid infestation, trombiculid load, and Orientia infection in the captured rodents. Conclusions/SignificanceOur study provides new insights into the trombiculid fauna and prevalence of Orientia in mites collected from wild rodents in southern Chile. Orientia DNA was detected in four of the six mite species. Rates of infestation, mite loads, and Orientia prevalences differed geographically and were highest in the Aysen Region. Our data improve our knowledge on possible vectors of scrub typhus and their distribution in Chile.
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    Rickettsia felis in Rhipicephalus sanguineus from Two Distant Chilean Cities
    (2013) Abarca, Katia; Lopez, Javier; Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza
    Introduction: Rickettsia felis is an emerging agent considered a human threat; although its natural reservoir and agent of transmission is the cat flea, it has been also found in other vectors. R. felis has been identified in Chile in cat fleas and in one specimen of Rhipicephalus sanguineus collected in the Metropolitan Region. The objective of this study was to detect the presence of Rickettsia spp. in R. sanguineus from dogs of two different and distant geographical areas in Chile.
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    Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloe Island and molecular evidence of infection with Orientia species
    (2020) Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza; Beltrami, Esperanza; Carolina Silva-de La Fuente, Maria; Jiang, Ju; Richards, Allen L.; Weitzel, Thomas; Abarca, Katia
    Background
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    Monkeypox Virus in Wastewater Samples from Santiago Metropolitan Region, Chile
    (2023) Ampuero, Manuel; Martinez-Valdebenito, Constanza; Ferres, Marcela; Soto-Rifo, Ricardo; Gaggero, Aldo
    Sewage surveillance provides useful epidemiologic and public health information on viral infections at the population level. We detected monkeypox virus DNA from sewage samples covering 85% of the population in Santiago Metropolitan Region, Chile. We also isolated infective viruses from those samples. Wastewater surveillance could complement clinical surveillance for monkeypox virus.
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    SARS-CoV-2 infectivity and antigenic evasion: spotlight on isolated Omicron sub-lineages
    (2024) Barrera, Aldo; Martinez-Valdebenito, Constanza; Angulo, Jenniffer; Palma, Carlos; Hormazabal, Juan; Vial, Cecilia; Aguilera, Ximena; Castillo-Torres, Pablo; Pardo-Roa, Catalina; Balcells, Maria Elvira; Nervi, Bruno; Le Corre, Nicole; Ferres, Marcela
    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.
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    Scrub Typhus in Continental Chile, 2016-2018
    (2019) Weitzel, Thomas; Martinez-Valdebenito, Constanza; Acosta-Jamett, Gerardo; Jiang, Ju; Richards, Allen L.; Abarca, Katia
    Endemic scrub typhus was recently detected on Chiloe Island in southern Chile. We report a series of cases, acquired over a wide geographical range in continental Chile during 2016-2018, demonstrating that this emerging rickettsial infection is also found on the mainland of South America.
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    Scrub Typhus Outbreak - Los Lagos Region, Chile, January-February 2023
    (2023) Weitzel, Thomas; Martinez-Valdebenito, Constanza; Acosta-Jamett, Gerardo; Abarca, Katia
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    Viral shedding and viraemia of Andes virus during acute hantavirus infection: a prospective study
    (2024) Ferres, Marcela; Martinez-Valdebenito, Constanza; Henriquez, Carolina; Marco, Claudia; Angulo, Jenniffer; Barrera, Aldo; Palma, Carlos; Pinto, Gonzalo Barriga; Cuiza, Analia; Ferreira, Leonila; Rioseco, Maria Luisa; Calvo, Mario; Fritz, Ricardo; Bravo, Sebastian; Bruhn, Alejandro; Graf, Jeronimo; Llancaqueo, Alvaro; Rivera, Gonzalo; Cerda, Carolina; Tischler, Nicole; Valdivieso, Francisca; Vial, Pablo; Mertz, Gregory; Vial, Cecilia; Le Corre, Nicole
    Background Andes virus (ANDV) is a zoonotic Orthohantavirus leading to hantavirus cardiopulmonary syndrome. Although most transmissions occur through environmental exposure to rodent faeces and urine, rare person -toperson transmission has been documented, mainly for close contacts. This study investigates the presence and infectivity of ANDV in body fluids from confirmed cases and the duration of viraemia. Methods In this prospective study, 131 participants with confirmed ANDV infection were enrolled in Chile in a prospective study between 2008 and 2022. Clinical samples (buffy coat, plasma, gingival crevicular fluid [GCF], saliva, nasopharyngeal swabs [NPS], and urine) were collected weekly for 3 weeks together with clinical and epidemiological data. Samples were categorised as acute or convalescent (up to and after 16 days following onset of symptoms). Infectivity of positive fluids was assessed after the culture of samples on Vero E6 cells and use of flow cytometry assays to determine the production of ANDV nucleoprotein. Findings ANDV RNA was detected in 100% of buffy coats during acute phase, declining to 95% by day 17, and to 93% between days 23-29. ANDV RNA in GCF and saliva decreased from 30% and 12%, respectively, during the acute phase, to 12% and 11% during the convalescent phase. Successful infectivity assays of RT-qPCR-positive fluids, including GCF, saliva, NPS, and urine, were observed in 18 (42%) of 43 samples obtained during the acute phase of infection. After re -culture, the capacity to infect Vero E6 cells was maintained in 16 (89%) of 18 samples. Severity was associated with the presence of ANDV RNA in one or more fluids besides blood (odds ratio 258 [95% CI 142-518]). Interpretation ANDV infection is a systemic and viraemic infection, that affects various organs. The presence of infectious particles in body fluids contributes to our understanding of potential mechanisms for person -to -person transmission, supporting the development of preventive strategies. Detection of ANDV RNA in additional fluids at hospital admission is a predictor of disease severity. Funding National Institutes of Health and Agencia de Investigaci & oacute;n y Desarrollo. Copyright (c) 2024 Elsevier Ltd. All rights reserved.