A DNA intercalating dye-based RT-qPCR alternative to diagnose SARS-CoV-2.

Early detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been proven crucial during the efforts to mitigate the effects of the COVID-19 pandemic. Several diagnostic methods have emerged in the past few months, each with different shortcomings and limitations. The current gold standard, RT-qPCR using fluorescent probes, relies on demanding equipment requirements plus the high costs of the probes and specific reaction mixes. To broaden the possibilities of reagents and thermocyclers that could be allocated towards this task, we have optimized an alternative strategy for RT-qPCR diagnosis. This is based on a widely used DNA-intercalating dye and can be implemented with several different qPCR reagents and instruments. Remarkably, the proposed qPCR method performs similarly to the broadly used TaqMan-based detection, in terms of specificity and sensitivity, thus representing a reliable tool. We think that, through enabling the use of vast range of thermocycler models and laboratory facilities for SARS-CoV-2 diagnosis, the alternative proposed here can increase dramatically the testing capability, especially in countries with limited access to costly technology and reagents.

Surveillance of antiviral resistance markers in Argentina: detection of E119V neuraminidase mutation in a post-treatment immunocompromised patient.

Although vaccines are the best means of protection against influenza, neuraminidase inhibitors are currently the main antiviral treatment available to control severe influenza cases. One of the most frequent substitutions in the neuraminidase (NA) protein of influenza A(H3N2) viruses during or soon after oseltamivir administration is E119V mutation. We describe the emergence of a mixed viral population with the E119E/V mutation in the NA protein sequence in a post-treatment influenza sample collected from an immunocompromised patient in Argentina. This substitution was identified by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) protocol and was confirmed by direct Sanger sequencing of the original sample. In 2014, out of 1140 influenza samples received at the National Influenza Centre, 888 samples (78%) were A(H3N2) strains, 244 (21.3%) were type B strains, and 8 (0.7%) were A(H1N1)pdm09 strains. Out of 888 A(H3N2) samples, 842 were tested for the E119V substitution by quantitative RT-PCR: 841 A(H3N2) samples had the wild-type E119 genotype and in one sample, a mixture of viral E119/ V119 subpopulations was detected. Influenza virus surveillance and antiviral resistance studies can lead to better decisions in health policies and help in medical treatment planning, especially for severe cases and immunocompromised patients.

Comorbidity and high viral load linked to clinical presentation of respiratory human bocavirus infection.

Human bocavirus (HBoV) is a new parvovirus associated with acute respiratory tract infection (ARTI). In order to evaluate HBoV significance as an agent of acute respiratory disease, we screened 1,135 respiratory samples from children and adults with and without symptoms during two complete calendar years. HBoV1 prevalence in patients with ARTI was 6.33 % in 2011 and 11.64 % in 2012, including neonatal and adult patients. HBoV1 was also detected in 3.77 % of asymptomatic individuals. The co-detection rate was 78.1 %. Among children, 87 % were clinically diagnosed with lower respiratory infection (no significant differences between patients with and without coinfection), and 31 % exhibited comorbidities. Pediatric patients with comorbidities were significantly older than patients without comorbidities. Patients with ARTI had either high or low viral load, while controls had only low viral load, but there were no clinical differences between patients with high or low viral load. In conclusion, we present evidence of the pathogenic potential of HBoV1 in young children with ARTI. Since patients with HBoV1-single infection are not significantly different from those with coinfection with respect to clinical features, the virus can be as pathogenic by itself as other respiratory agents are. Furthermore, an association between high HBoV1 load and disease could not be demonstrated in this study, but all asymptomatic individuals had low viral loads. Also, children with comorbidities are susceptible to HBoV1 infection at older ages than previously healthy children. Thus, the clinical presentation of infection may occur depending on both viral load and the particular interaction between the HBoV1 and the host.

A Gamma-adapted subunit vaccine induces broadly neutralizing antibodies against SARS-CoV-2 variants and protects mice from infection.

In the context of continuous emergence of SARS-CoV-2 variants of concern (VOCs), one strategy to prevent the severe outcomes of COVID-19 is developing safe and effective broad-spectrum vaccines. Here, we present preclinical studies of a RBD vaccine derived from the Gamma SARS-CoV-2 variant adjuvanted with Alum. The Gamma-adapted RBD vaccine is more immunogenic than the Ancestral RBD vaccine in terms of inducing broader neutralizing antibodies. The Gamma RBD presents more immunogenic B-cell restricted epitopes and induces a higher proportion of specific-B cells and plasmablasts than the Ancestral RBD version. The Gamma-adapted vaccine induces antigen specific T cell immune responses and confers protection against Ancestral and Omicron BA.5 SARS-CoV-2 challenge in mice. Moreover, the Gamma RBD vaccine induces higher and broader neutralizing antibody activity than homologous booster vaccination in mice previously primed with different SARS-CoV-2 vaccine platforms. Our study indicates that the adjuvanted Gamma RBD vaccine is highly immunogenic and a broad-spectrum vaccine candidate.

Addressing pandemic-wide systematic errors in the SARS-CoV-2 phylogeny.

The SARS-CoV-2 genome occupies a unique place in infection biology - it is the most highly sequenced genome on earth (making up over 20% of public sequencing datasets) with fine scale information on sampling date and geography, and has been subject to unprecedented intense analysis. As a result, these phylogenetic data are an incredibly valuable resource for science and public health. However, the vast majority of the data was sequenced by tiling amplicons across the full genome, with amplicon schemes that changed over the pandemic as mutations in the viral genome interacted with primer binding sites. In combination with the disparate set of genome assembly workflows and lack of consistent quality control (QC) processes, the current genomes have many systematic errors that have evolved with the virus and amplicon schemes. These errors have significant impacts on the phylogeny, and therefore over the last few years, many thousands of hours of researchers time has been spent in "eyeballing" trees, looking for artefacts, and then patching the tree. Given the huge value of this dataset, we therefore set out to reprocess the complete set of public raw sequence data in a rigorous amplicon-aware manner, and build a cleaner phylogeny. Here we provide a global tree of 3,960,704 samples, built from a consistently assembled set of high quality consensus sequences from all available public data as of March 2023, viewable at https://viridian.taxonium.org. Each genome was constructed using a novel assembly tool called Viridian (https://github.com/iqbal-lab-org/viridian), developed specifically to process amplicon sequence data, eliminating artefactual errors and mask the genome at low quality positions. We provide simulation and empirical validation of the methodology, and quantify the improvement in the phylogeny. Phase 2 of our project will address the fact that the data in the public archives is heavily geographically biased towards the Global North. We therefore have contributed new raw data to ENA/SRA from many countries including Ghana, Thailand, Laos, Sri Lanka, India, Argentina and Singapore. We will incorporate these, along with all public raw data submitted between March 2023 and the current day, into an updated set of assemblies, and phylogeny. We hope the tree, consensus sequences and Viridian will be a valuable resource for researchers.

Cross-protection and cross-neutralization capacity of ancestral and VOC-matched SARS-CoV-2 adenoviral vector-based vaccines.

COVID-19 vaccines were originally designed based on the ancestral Spike protein, but immune escape of emergent Variants of Concern (VOC) jeopardized their efficacy, warranting variant-proof vaccines. Here, we used preclinical rodent models to establish the cross-protective and cross-neutralizing capacity of adenoviral-vectored vaccines expressing VOC-matched Spike. CoroVaxG.3-D.FR, matched to Delta Plus Spike, displayed the highest levels of nAb to the matched VOC and mismatched variants. Cross-protection against viral infection in aged K18-hACE2 mice showed dramatic differences among the different vaccines. While Delta-targeted vaccines fully protected mice from a challenge with Gamma, a Gamma-based vaccine offered only partial protection to Delta challenge. Administration of CorovaxG.3-D.FR in a prime/boost regimen showed that a booster was able to increase the neutralizing capacity of the sera against all variants and fully protect aged K18-hACE2 mice against Omicron BA.1, as a BA.1-targeted vaccine did. The neutralizing capacity of the sera diminished in all cases against Omicron BA.2 and BA.5. Altogether, the data demonstrate that a booster with a vaccine based on an antigenically distant variant, such as Delta or BA.1, has the potential to protect from a wider range of SARS-CoV-2 lineages, although careful surveillance of breakthrough infections will help to evaluate combination vaccines targeting antigenically divergent variants yet to emerge.

Evaluation of RT-qPCR and Loop-Mediated Isothermal Amplification (LAMP) Assays for the Detection of SARS-CoV-2 in Argentina.

Our aim was to evaluate the analytical and clinical performance of the SARS-CoV-2 molecular detection kits used in Argentina. Nine real-time reverse-transcription polymerase chain reaction (RT-qPCR) and three reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assays were evaluated using the World Health Organization (WHO) recommended test as reference method. A secondary standard calibrated for the E, N and RdRp genes against the Pan American Health Organization-World Health Organization-International Standard was used to calculate the limit of detection (LoD). A panel of artificial clinical samples, 32 positive and 30 negative for SARS-CoV-2, were analyzed to estimate the kappa concordance (κ) and the diagnostic performance. Differences among the LoD values for the target genes amplified by each kit were >1 log copies/reaction. The κ for the RT-qPCR kits was greater than 0.9, whereas that for the RT-LAMP assays ranged from 0.75 to 0.93. The clinical performance of RT-qPCR kits showed 100% specificity and high sensitivity, although with variations according to the gene analyzed. The E and N genes provided greater clinical sensitivity, whereas the RdRp gene increased the clinical specificity. The RT-LAMP assays revealed a variable diagnostic performance. The information provided can be useful to choose the most appropriate diagnostic test and may contribute to the establishment of a consensus in the diagnosis of SARS-CoV-2 in Argentina and the region.

A combined approach of MALDI-TOF mass spectrometry and multivariate analysis as a potential tool for the detection of SARS-CoV-2 virus in nasopharyngeal swabs.

Coronavirus disease 2019, known as COVID-19, is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The early, sensitive and specific detection of SARS-CoV-2 virus is widely recognized as the critical point in responding to the ongoing outbreak. Currently, the diagnosis is based on molecular real time RT-PCR techniques, although their implementation is being threatened due to the extraordinary demand for supplies worldwide. That is why the development of alternative and / or complementary tests becomes so relevant. Here, we exploit the potential of mass spectrometry technology combined with machine learning algorithms, for the detection of COVID-19 positive and negative protein profiles directly from nasopharyngeal swabs samples. According to the preliminary results obtained, accuracy = 67.66 %, sensitivity = 61.76 %, specificity = 71.72 %, and although these parameters still need to be improved to be used as a screening technique, mass spectrometry-based methods coupled with multivariate analysis showed that it is an interesting tool that deserves to be explored as a complementary diagnostic approach due to the low cost and fast performance. However, further steps, such as the analysis of a large number of samples, should be taken in consideration to determine the applicability of the method developed.

Development of a hyperimmune equine serum therapy for COVID-19 in Argentina.

The disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date. Equine polyclonal antibodies (EpAbs) put forward a sound alternative. The new generation of processed and purified EpAbs containing highly purified F(ab')2 fragments demonstrated to be safe and well tolerated. EpAbs are easy to manufacture allowing a fast development and scaling up for a treatment. Based on these ideas, we present a new therapeutic product obtained after immunization of horses with the receptor-binding domain of the viral Spike glycoprotein. Our product shows around 50 times more potency in in vitro seroneutralization assays than the average of convalescent plasma. This result may allow us to test the safety and efficacy of this product in a phase 2/3 clinical trial to be conducted in July 2020 in the metropolitan area of Buenos Aires, Argentina.

La enfermedad denominada COVID-19 es causada por el coronavirus SARS-CoV-2 y es actualmente considerada una pandemia a nivel global. El desarrollo de vacunas es sin duda la mejor estrategia a largo plazo, pero debido a la emergencia sanitaria, existe una necesidad urgente de encontrar soluciones rápidas y efectivas para el tratamiento de la enfermedad. Hasta la fecha, el uso de plasma de convalecientes es la única inmunoterapia disponible para pacientes hospitalizados con COVID-19. El uso de anticuerpos policlonales equinos (EpAbs) es otra alternativa terapéutica interesante. La nueva generación de EpAbs incluyen el procesamiento y purificación de los mismos y la obtención de fragmentos F(ab')2 con alta pureza y un excelente perfil de seguridad en humanos. Los EpAbs son fáciles de producir, lo cual permite el desarrollo rápido y la elaboración a gran escala de un producto terapéutico. En este trabajo mostramos el desarrollo de un suero terapéutico obtenido luego de la inmunización de caballos utilizando el receptor-binding domain de la glicoproteína Spike del virus. Nuestro producto mostró ser alrededor de 50 veces más potente en ensayos de seroneutralización in vitro que el promedio de los plasmas de convalecientes. Estos resultados nos permitirían testear la seguridad y eficacia de nuestro producto en ensayos clínicos de fase 2/3 a realizarse a partir de julio de 2020 en la zona metropolitana de Buenos Aires, Argentina.

Development of a hyperimmune equine serum therapy for COVID-19 in Argentina

The disease named COVID-19, caused by the SARS-CoV-2 coronavirus, is currently generating a global pandemic. Vaccine development is no doubt the best long-term immunological approach, but in the current epidemiologic and health emergency there is a need for rapid and effective solutions. Convalescent plasma is the only antibody-based therapy available for COVID-19 patients to date. Equine polyclonal antibodies (EpAbs) put forward a sound alternative. The new generation of processed and purified EpAbs containing highly purified F(ab’)2 fragments demonstrated to be safe and well tolerated. EpAbs are easy to manufacture allowing a fast development and scaling up for a treatment. Based on these ideas, we present a new therapeutic product obtained after immunization of horses with the receptor-binding domain of the viral Spike glycoprotein. Our product shows around 50 times more potency in in vitro seroneutralization assays than the average of convalescent plasma. This result may allow us to test the safety and efficacy of this product in a phase 2/3 clinical trial to be conducted in July 2020 in the metropolitan area of Buenos Aires, Argentina.

La enfermedad denominada COVID-19 es causada por el coronavirus SARS-CoV-2 y es actualmente considerada una pandemia a nivel global. El desarrollo de vacunas es sin duda la mejor estrategia a largo plazo, pero debido a la emergencia sanitaria, existe una necesidad urgente de encontrar soluciones rápidas y efectivas para el tratamiento de la enfermedad. Hasta la fecha, el uso de plasma de convalecientes es la única inmunoterapia disponible para pacientes hospitalizados con COVID-19. El uso de anticuerpos policlonales equinos (EpAbs) es otra alternativa terapéutica interesante. La nueva generación de EpAbs incluyen el procesamiento y purificación de los mismos y la obtención de fragmentos F(ab’)2 con alta pureza y un excelente perfil de seguridad en humanos. Los EpAbs son fáciles de producir, lo cual permite el desarrollo rápido y la elaboración a gran escala de un producto terapéutico. En este trabajo mostramos el desarrollo de un suero terapéutico obtenido luego de la inmunización de caballos utilizando el receptor-binding domain de la glicoproteína Spike del virus. Nuestro producto mostró ser alrededor de 50 veces más potente en ensayos de seroneutralización in vitro que el promedio de los plasmas de convalecientes. Estos resultados nos permitirían testear la seguridad y eficacia de nuestro producto en ensayos clínicos de fase 2/3 a realizarse a partir de julio de 2020 en la zona metropolitana de Buenos Aires, Argentina.

Antigenic and genomic characterization of human influenza A and B viruses circulating in Argentina after the introduction of influenza A(H1N1)pdm09.

This study was conducted as part of the Argentinean Influenza and other Respiratory Viruses Surveillance Network, in the context of the Global Influenza Surveillance carried out by the World Health Organization (WHO). The objective was to study the activity and the antigenic and genomic characteristics of circulating viruses for three consecutive seasons (2010, 2011 and 2012) in order to investigate the emergence of influenza viral variants. During the study period, influenza virus circulation was detected from January to December. Influenza A and B, and all current subtypes of human influenza viruses, were present each year. Throughout the 2010 post-pandemic season, influenza A(H1N1)pdm09, unexpectedly, almost disappeared. The haemagglutinin (HA) of the A(H1N1)pdm09 viruses studied were segregated in a different genetic group to those identified during the 2009 pandemic, although they were still antigenically closely related to the vaccine strain A/California/07/2009. Influenza A(H3N2) viruses were the predominant strains circulating during the 2011 season, accounting for nearly 76 % of influenza viruses identified. That year, all HA sequences of the A(H3N2) viruses tested fell into the A/Victoria/208/2009 genetic clade, but remained antigenically related to A/Perth/16/2009 (reference vaccine recommended for this three-year period). A(H3N2) viruses isolated in 2012 were antigenically closely related to A/Victoria/361/2011, recommended by the WHO as the H3 component for the 2013 Southern Hemisphere formulation. B viruses belonging to the B/Victoria lineage circulated in 2010. A mixed circulation of viral variants of both B/Victoria and B/Yamagata lineages was detected in 2012, with the former being predominant. A(H1N1)pdm09 viruses remained antigenically closely related to the vaccine virus A/California/7/2009; A(H3N2) viruses continually evolved into new antigenic clusters and both B lineages, B/Victoria/2/87-like and B/Yamagata/16/88-like viruses, were observed during the study period. The virological surveillance showed that the majority of the circulating strains during the study period were antigenically related to the corresponding Southern Hemisphere vaccine strains except for the 2012 A(H3N2) viruses.

Rol del virus sincicial respiratorio en una cohorte de adultos mayores / Respiratory Syncytial Virus in the elderly adults

El rol de los virus respiratorios distintos de influenza en las infecciones respiratorias agudas en los adultos mayores ha sido probablemente subestimado. En los últimos años, los avances en técnicas moleculares de diagnóstico han hecho posible la identificación rápida del virus sincicial respiratorio humano (HRSV). Realizamos un estudio prospectivo observacional para evaluar el rol del HRSV en mayores de 65 años que se hospitalizaron por infecciones respiratorias en nuestra institución, ubicada en la ciudad de La Plata, provincia de Buenos Aires. Fueron reclutados 124 pacientes y el HRSV se detectó en 13, influenza B en 9 e influenza A en 8. La presentación clínica más frecuente de los The role of respiratory viruses other than influenza in acute respiratory tract infections among elderly adults has probably been underestimated. Recent advances in molecular diagnosis have made the rapid identification of human respiratory syncitial virus HRSV infection possible. We conducted a prospective observational study to evaluate the role of HRSV in elderly patients (>65 years of age) hospitalized for acute respiratory infections. A total of 124 patients were recruited, HRSV infection was identified in 13 patients, Influenza B in 9 patients and influenza A in 8 patients. The most frequent clinical presentation was bronchospasm and the infection was prevalent in patients with comorbidities. HRSV infections accounted for an important number of hospital admissions and has been associated with high mortality rates (23%). pacientes con HRSV fue el broncoespasmo y afectó principalmente a personas con comorbilidades. HRSV fue responsable de un número importante de internaciones por enfermedad respiratoria aguda en mayores de 65 años en nuestra institución y se asoció a mortalidad elevada (23%).

The role of respiratory viruses other than influenza in acute respiratory tract infections among elderly adults has probably been underestimated. Recent advances in molecular diagnosis have made the rapid identification of human respiratory syncitial virus HRSV infection possible. We conducted a prospective observational study to evaluate the role of HRSV in elderly patients (>65 years of age) hospitalized for acute respiratory infections. A total of 124 patients were recruited, HRSV infection was identified in 13 patients, Influenza B in 9 patients and influenza A in 8 patients. The most frequent clinical presentation was bronchospasm and the infection was prevalent in patients with comorbidities. HRSV infections accounted for an important number of hospital admissions and has been associated with high mortality rates (23%).

Surveillance of antiviral resistance markers in Argentina: detection of E119V neuraminidase mutation in a post-treatment immunocompromised patient

Although vaccines are the best means of protection against influenza, neuraminidase inhibitors are currently the main antiviral treatment available to control severe influenza cases. One of the most frequent substitutions in the neuraminidase (NA) protein of influenza A(H3N2) viruses during or soon after oseltamivir administration is E119V mutation. We describe the emergence of a mixed viral population with the E119E/V mutation in the NA protein sequence in a post-treatment influenza sample collected from an immunocompromised patient in Argentina. This substitution was identified by a real-time reverse transcriptase polymerase chain reaction (RT-PCR) protocol and was confirmed by direct Sanger sequencing of the original sample. In 2014, out of 1140 influenza samples received at the National Influenza Centre, 888 samples (78%) were A(H3N2) strains, 244 (21.3%) were type B strains, and 8 (0.7%) were A(H1N1)pdm09 strains. Out of 888 A(H3N2) samples, 842 were tested for the E119V substitution by quantitative RT-PCR: 841 A(H3N2) samples had the wild-type E119 genotype and in one sample, a mixture of viral E119/ V119 subpopulations was detected. Influenza virus surveillance and antiviral resistance studies can lead to better decisions in health policies and help in medical treatment planning, especially for severe cases and immunocompromised patients.