Coronavirus pathogenesis in mice explains the SARS-CoV-2 multi-organ spread by red blood cell hitch-hiking (preprint)

SARS-CoV-2 infection causes a multisystemic disease that affects numerous organs beyond the respiratory system. Thus, it is well known that COVID-19 is associated with a wide range of hematological disorders; however, it remains unclear how the SARS-CoV-2 virus is able to navigate from tissue to tissue. In this work, we performed a comprehensive analysis of the pleiotropic effects of a prototypical coronavirus in its natural host, the validated preclinical model of murine hepatitis virus (MHV). Throughout this study we compared our results with the real-world data from COVID-19 patients (including autopsies). Thus, the presence of viral RNA was only detected in less than 25% of the human serum samples, whereas all had multiple positive nasal swabs for SARS-CoV-2. Notably, we found viral RNA not only in lungs, but also in heart and kidney of deceased COVID-19 patients. Subsequently, we investigated the association between viral organotropism and clinical manifestations employing the MHV murine model. Results from RT-qPCR and viral infectivity showcased the presence of viral RNA and infectious particles in multiple organs including liver, lung, brain, heart, kidney, spleen and pancreas, and even the blood of infected mice. Surprisingly, when comparing plasma and red blood cells (RBCs)-enriched fraction, higher viral load levels were detected in RBCs, with decreased RBC count, and hematocrit and hemoglobin levels in infected mice. Next, we treated infected mice with hemin triggering more aggressive symptoms. Strikingly, when combining hemin treatment with chloroquine (a compound that known to interact with the heme group and induces a conformational change in its structure) the infection and its clinical manifestations were distinctly attenuated. Computational docking suggested that heme is able to bind to MHV Spike protein in a similar way to the one, experimentally observed for SARS-CoV-2. Overall, our results lead to a global perspective of COVID-19 beyond the canonical focus on the respiratory system, and strongly support the multi-organ extent of coronavirus infection through specific interactions with RBC hemoproteins.

¿What did we learn from Convalescent plasma treatment in a COVID-19 patient two-time kidney transplanted? A case report from the viral and immune response evolution perspective (preprint)

Background: COVID-19, an infectious disease caused by SARS-CoV-2 virus, can provoke a vast range of clinical manifestations, ranging from asymptomatic to potentially life-threatening complications. At the beginning, convalescent plasma therapy has been proposed as an effective alternative to treat severe cases. The aim of this study was to follow over time a two-time renal transplanted COVID-19 severe patient treated with convalescent plasma from an immunological and virologic perspective.Case presentation: A 42-year-old female patient, two-time kidney transplanted was hospitalized with COVID-19. Due to worsening of respiratory symptoms, she was admitted to the intensive care unit where she received two doses of convalescent plasma. Conclusion: We analyzed the dynamics of viral load in nasopharyngeal swab, saliva and tracheal aspirate samples, before and after convalescent plasma transfusion. Pro-inflammatory cytokines and antibody titers were also measured in serum samples. A post-treatment decrease in viral load was observed to be sharp in saliva and nasopharyngeal swab samples, and slight in tracheal aspirate samples. Furthermore, we evidenced an increase of antibody titers post transfusion, accompanied with a decrease of several cytokines responsible of the cytokine storm.

Emergence and spread of a B.1.1.28-derived lineage with Q675H and Q677H Spike mutations in Uruguay (preprint)

Uruguay was able to control the viral dissemination during the first nine months of the SARS-CoV-2 pandemic. Unfortunately, towards the end of 2020, the number of daily new cases exponentially increased. We previously identified a B.1.1.28 sublineage carrying mutations Q675H+Q677H in the viral Spike, with local transmission in Rocha, a department bordering Brazil. To understand whether these B.1.1.28+Q675H+Q677H sequences were part of an emergent SARS-CoV-2 lineage broadly disseminated in Uruguay, herein we analyzed the country-wide genetic diversity of viruses between November, 2020 and April, 2021. Our findings support that B.1.1.28+Q675H+Q677H probably arose around November 2020, in Montevideo, Uruguay's capital department. This clade spread to other Uruguayan departments, with evidence of further local transmission clusters. It also spread to the USA and Spain. The Q675H and Q677H mutations are in the proximity of the polybasic cleavage site at the S1/S2 boundary and also arose independently in many SARS-CoV-2 lineages circulating worldwide. Although in Uruguay the B.1.1.28+Q675H+Q677H lineage was dominated by the VOC P.1 since April 2021, the monitoring of the concurrent emergence of Q675H+Q677H in VOIs and/or VOCs should be of worldwide interest.

Implementation of a qPCR assay coupled with genomic surveillance for real-time monitoring of SARS-CoV-2 variants of concern. (preprint)

We developed a genomic surveillance program for real-time monitoring of SARS-CoV-2 variants of concern in Uruguay. Here, we present the first results, including the proposed qPCR-VOC method, the general workflow and the report of the introduction and community transmission of the VOC P.1 in Uruguay in multiple independent events.

An effective COVID-19 response in South America: the Uruguayan Conundrum (preprint)

Background: South America has become the new epicenter of the COVID-19 pandemic with more than 1.1M reported cases and >50,000 deaths (June 2020). Conversely, Uruguay stands out as an outlier managing this health crisis with remarkable success. Methods: We developed a molecular diagnostic test to detect SARS-CoV-2. This methodology was transferred to research institutes, public hospitals and academic laboratories all around the country, creating a COVID-19 diagnostic lab network. Uruguay also implemented active epidemiological surveillance following the Test, Trace and Isolate (TETRIS) strategy coupled to real-time genomic epidemiology. Results: Three months after the first cases were detected, the number of positive individuals reached 826 (23 deaths, 112 active cases and 691 recovered). The Uruguayan strategy was based in a close synergy established between the national health authorities and the scientific community. In turn, academia rapidly responded to develop national RT-qPCR tests. Consequently, Uruguay was able to perform ~1,000 molecular tests per day in a matter of weeks. The COVID-19 diagnostic lab network performed more than 54% of the molecular tests in the country. This, together with real-time genomics, were instrumental to implement the TETRIS strategy, helping to contain domestic transmission of the main outbreaks registered so far. Conclusions: Uruguay has successfully navigated the first trimester of the COVID-19 health crisis in South America. A rapid response by the scientific community to increase testing capacity, together with national health authorities seeking out the support from the academia were fundamental to successfully contain, until now, the COVID-19 outbreak in the country.

Evaluation Of SYBR Green Real Time PCR For Detecting SARS-CoV-2 From Clinical Samples (preprint)

The pandemic caused by SARS-CoV-2 has triggered an extraordinary collapse of healthcare systems and hundred thousand of deaths worldwide. Following the declaration of the outbreak as a Public Health Emergency of International Concern by the World Health Organization (WHO) on January 30th, 2020, it has become imperative to develop diagnostic tools to reliably detect the virus in infected patients. Several methods based on real time reverse transcription polymerase chain reaction (RT-qPCR) for the detection of SARS-CoV-2 genomic RNA have been developed. In addition, these methods have been recommended by the WHO for laboratory diagnosis. Since all these protocols are based on the use of fluorogenic probes and one-step reagents (cDNA synthesis followed by PCR amplification in the same tube), these techniques can be difficult to perform given the limited supply of reagents in low and middle income countries. In the interest of economy, time and availability of chemicals and consumables, the SYBR Green-based detection was implemented to establish a convenient assay. Therefore, we adapted one of WHO recommended Taqman-based one-step real time PCR protocols (from the University of Hong Kong) to SYBR Green. Our results suggest that SYBR-Green detection represents a reliable cost-effective alternative to increase the testing capacity.