Browsing by Author "Tischler, Nicole D."

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    A rapid method for infectivity titration of Andes hantavirus using flow cytometry
    (2013) Barriga, Gonzalo P.; Martínez Valdebenito, Constanza; Galeno, Héctor; Ferrés Garrido, Marcela Viviana; Lozach, Pierre Yves; Tischler, Nicole D.
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    Andes Virus Antigens Are Shed in Urine of Patients with Acute Hantavirus Cardiopulmonary Syndrome
    (AMER SOC MICROBIOLOGY, 2009) Godoy, Paula; Marsac, Delphine; Stefas, Elias; Ferrer, Pablo; Tischler, Nicole D.; Pino, Karla; Ramdohr, Pablo; Vial, Pablo; Valenzuela, Pablo D. T.; Ferres, Marcela; Veas, Francisco; Lopez Lastra, Marcelo
    Hantavirus cardiopulmonary syndrome (HCPS) is a highly pathogenic emerging disease (40% case fatality rate) caused by New World hantaviruses. Hantavirus infections are transmitted to humans mainly by inhalation of virus-contaminated aerosol particles of rodent excreta and secretions. At present, there are no antiviral drugs or immunotherapeutic agents available for the treatment of hantaviral infection, and the survival rates for infected patients hinge largely on early virus recognition and hospital admission and aggressive pulmonary and hemodynamic support. In this study, we show that Andes virus (ANDV) interacts with human apolipoprotein H (ApoH) and that ApoH-coated magnetic beads or ApoH-coated enzyme-linked immunosorbent assay plates can be used to capture and concentrate the virus from complex biological mixtures, such as serum and urine, allowing it to be detected by both immunological and molecular approaches. In addition, we report that ANDV-antigens and infectious virus are shed in urine of HCPS patients.
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    Induction of SARS-CoV-2 neutralizing antibodies by CoronaVac and BNT162b2 vaccines in naive and previously infected individuals
    (2022) Muena, Nicolas A.; Garcia-Salum, Tamara; Pardo-Roa, Catalina; Jose Avendano, Maria; Serrano, Eileen F.; Levican, Jorge; Almonacid, Leonardo, I; Valenzuela, Gonzalo; Poblete, Estefany; Strohmeier, Shirin; Salinas, Erick; Munoz, Andres; Haslwanter, Denise; Dieterle, Maria Eugenia; Jangra, Rohit K.; Chandran, Kartik; Gonzalez, Claudia; Riquelme, Arnoldo; Krammer, Florian; Tischler, Nicole D.; Medina, Rafael A.
    Interpretation The decay of nAbs titres in previously infected individuals over time indicates that vaccination is needed to boost humoral memory responses. Immunization of naydve individuals with two doses of CoronaVac induced nAbs titres that were significantly lower to that of convalescent patients, and similar to vaccination with one dose of BTN162b2. The real life effectiveness for CoronaVac in Chile was higher than estimated; indicating that lower titres and additional cellular immune responses induced by CoronaVac might afford protection in a highly immunized population. Nevertheless, the lower nAb titre induced by two doses of CoronaVac as compared to the BTN162b2 vaccine in naydve individuals, highlights the need of booster immunizations over time to maintain protec-tive levels of antibody, particularly with the emergence of new SARS-CoV-2 variants. Funding FONDECYT 1161971, 1212023, 1181799, FONDECYT Postdoctorado 3190706 and 3190648, ANID Becas/ Doctorado Nacional 21212258, PIA ACT 1408, CONICYT REDES180170, Centro Ciencia & Vida, FB210008, Finan-ciamiento Basal para Centros Cient?ficos y Tecnol?ogicos de Excelencia grants from the Agencia Nacional de Inves-tigaci?on y Desarrollo (ANID) of Chile; NIH-NIAD grants U19AI135972, R01AI132633 and contracts HHSN272201400008C and 75N93019C00051; the JPB Foundation, the Open Philanthropy Project grant 2020-215611 (5384); and by anonymous donors. The funders had no role in study design, data collection and analysis, deci-sion to publish, or preparation of the manuscript. Copyright (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
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    Long-lasting neutralizing antibody responses in SARS-CoV-2 seropositive individuals are robustly boosted by immunization with the CoronaVac and BNT162b2 vaccines
    (2021) Muena, Nicolás A.; García Salum, Tamara Cristal; Pardo Roa, Catalina; Serrano García, Eileen Francisca; Levicán Asenjo, Jorge Enrique; Avendaño, María José; Almonacid Cárdenas, Leonardo Iván; Valenzuela Galaz, Gonzalo Hernán; Poblete Cárdenas, Estefany Aracely; Strohmeier, Shirin; Salinas Ortíz, Erick David; Haslwanter, Denise; Dieterle, Maria Eugenia; Jangra, Rohit K.; Chandran, Kartik; González, Claudia; Riquelme Pérez, Arnoldo Javier; Krammer, Florian; Tischler, Nicole D.; Medina, Rafael
    The durability of circulating neutralizing antibody (nAb) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and their boosting by vaccination remains to be defined. We show that outpatient and hospitalized SARS-CoV-2 seropositive individuals mount a robust neutralizing antibody (nAb) response that peaks at days 23 and 27 post-symptom onset, respectively. Although nAb titers remained higher in hospitalized patients, both study groups showed long-lasting nAb responses that can persist for up to 12 months after natural infection. These nAb responses in previously seropositive individuals can be significantly boosted through immunization with two doses of the CoronaVac (Sinovac) or one dose of the BNT162b2 (BioNTech/Pfizer) vaccines, suggesting a substantial induction of B cell memory responses. Noteworthy, three obese previously seropositive individuals failed to mount a booster response upon vaccination, warranting further studies in this population. Immunization of naïve individuals with two doses of the CoronaVac vaccine or one dose of the BNT162b2 vaccine elicited similar levels of nAbs compared to seropositive individuals 4.2 to 13.3 months post-infection with SARS-CoV-2. Thus, this preliminary evidence suggests that both, seropositive and naïve individuals, require two doses of CoronaVac to ensure the induction of robust nAb titers.
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    The Andes Hantavirus NSs Protein Is Expressed from the Viral Small mRNA by a Leaky Scanning Mechanism
    (AMER SOC MICROBIOLOGY, 2012) Vera Otarola, Jorge; Solis, Loretto; Soto Rifo, Ricardo; Ricci, Emiliano P.; Pino, Karla; Tischler, Nicole D.; Ohlmann, Theophile; Darlix, Jean Luc; Lopez Lastra, Marcelo
    The small mRNA (SmRNA) of all Bunyaviridae encodes the nucleocapsid (N) protein. In 4 out of 5 genera in the Bunyaviridae, the smRNA encodes an additional nonstructural protein denominated NSs. In this study, we show that Andes hantavirus (ANDV) SmRNA encodes an NSs protein. Data show that the NSs protein is expressed in the context of an ANDV infection. Additionally, our results suggest that translation initiation from the NSs initiation codon is mediated by ribosomal subunits that have bypassed the upstream N protein initiation codon through a leaky scanning mechanism.