Coronavirus persistence in human respiratory tract and cell culture: An overview

ABSTRACT Emerging human coronaviruses, including the recently identified SARS-CoV-2, are relevant respiratory pathogens due to their potential to cause epidemics with high case fatality rates, although endemic coronaviruses are also important for immunocompromised patients. Long-term coronavirus infections had been described mainly in experimental models, but it is currently evident that SARS-CoV-2 genomic-RNA can persist for many weeks in the respiratory tract of some individuals clinically recovered from coronavirus infectious disease-19 (COVID-19), despite a lack of isolation of infectious virus. It is still not clear whether persistence of such viral RNA may be pathogenic for the host and related to long-term sequelae. In this review, we summarize evidence of SARS-CoV-2 RNA persistence in respiratory samples besides results obtained from cell culture and histopathology describing long-term coronavirus infection. We also comment on potential mechanisms of coronavirus persistence and relevance for pathogenesis.

Antifúngicos poliénicos. Mecanismo de acción y aplicaciones / Polyenic Antifungals. Action Mechanisms and their Applications

Resumen: Los primeros compuestos con actividad antifúngica específica fueron identificados a mediados del siglo pasado como un producto del metabolismo secundario de bacterias del orden Actinomycetales, y su uso en la clínica redujo de manera importante la morbilidad y la mortalidad relacionadas con infecciones severas por hongos de varios géneros. Muchos de estos compuestos biosintéticos se caracterizan por tener una estructura química de tipo poliénico, con un número variable de dobles enlaces carbono-carbono. Actualmente, además de los fármacos poliénicos, existe otro tipo de compuestos con actividad antimicótica, como los azoles, que se utilizan con mayor frecuencia y que presentan menor toxicidad en los pacientes; sin embargo, se han documentado casos de falla terapéutica con tales compuestos, por lo que el uso de los poliénicos se ha mantenido como la mejor alternativa en esos casos. El presente trabajo brinda información acerca de las propiedades y las aplicaciones de los antifúngicos poliénicos teniendo como modelo a la anfotericina B.

Abstract The first compounds with specific antifungal activity were identified in the middle of the last century as a product of the secondary metabolism of bacteria of the order Actinomycetales, and their clinical use significantly diminished the morbidity and mortality associated with severe fungal infections. Many of such biosynthetic compounds are characterized by a chemical polygenic structure, with a variable number of carbon-carbon double bonds. Currently, besides polygenic antimycotics, there are other antifungal agents, such as the azole compounds, that have less toxicity in patients; however, cases of therapeutic failure with such compounds have been documented, therefore, the use of polygenics is still the best alternative in such cases. This review presents data about the properties and applications of antifungal-polygenic compounds using amphotericin B as a model.