Spatiotemporal transmission of SARS-CoV-2 lineages during 2020-2021 in Pernambuco - Brazil (preprint)

In recent years, the SARS-CoV-2 viruses emerged and spread around the world, leaving a large death toll and long-lasting impact on survivors. As of January 2023, Brazil is still among the countries with the highest number of registered deaths. This continental-size and pluralistic country experienced a heterogenous implementation of non-pharmacological and pharmacological interventions which, associated with large socioeconomic differences between the country regions, has led to distinct virus spread dynamics across the country. Here we investigate the spatiotemporal dispersion of emerging SARS-CoV-2 lineages and its dynamics in distinct epidemiological scenarios in the first two years of the pandemics in the Pernambuco state (Northeast Brazil). We generated a total of 1389 new SARS-CoV-2 genomes from June 2020 to August 2021 covering all major regions of the state. This sampling captured the arrival, communitary transmission and the circulation of the B1.1, B.1.1.28 and B.1.1.33 lineages in the first eight months of the pandemics, the emergence of the former variant of interest P.2 and the emergence and fast replacement of all previous variants by the more transmissible variant of concern P.1 (Gamma) lineage. Based on the incidence and lineage spread pattern we observed that there was an East-to-West to inner state pattern of transmission which is in agreement with the transmission of more populous metropolitan areas to medium and small size country-side cities in the state. Such transmission patterns may be partially explained by the main routes of traffic across municipalities in the state. Nevertheless, inter-state traffic was also another important source of lineage introduction and spread into the state. Our results highlight that the fine grained intrastate analysis of lineages and incidence spread can provide actionable insights for planning future non-pharmacological intervention for air-borne transmissible human pathogens.

Real-life evaluation of a rapid antigen test (DPP SARS-CoV-2 Antigen) for COVID-19 diagnosis of primary healthcare patients, in the context of the Omicron-dominant wave in Brazil (preprint)

Rapid antigen tests play an important role in the monitoring and mitigation of the COVID-19 pandemic, as it provides an easy, fast and efficient diagnosis with minimum infrastructure requirements. However, as new variants of concern continue to emerge, mutations in the virus genome may impair the recognition of the mutated antigen by the tests. Therefore, it is essential to re-assess the test's sensitivity as the virus mutation profile undergoes significant changes. Here, we prospectively accessed the performance of the DPP SARS-CoV-2 Antigen test in the context of an omicron-dominant real-life setting. We evaluated 347 unselected individuals (all-comers) from a public testing center in Brazil, performing the rapid antigen test diagnosis at point-of-care with fresh samples. The combinatory result from two distinct RT-qPCR methods was employed as reference and 13 samples with discordant PCR results were excluded. The assessment of the rapid test in 67 PCR-positive and 265 negative samples revealed an overall sensitivity of 80.5%, specificity of 99.2% and positive/negative predictive values higher than 95%. However, we observed that the sensitivity was dependent on the viral load (sensitivity in Ct<31 = 93.7%; Ct>31 = 47.4%). Furthermore, we were able to confirm that the positive samples evaluated in the study were Omicron (BA.1/BA.1.1) by whole-genome sequencing (n=40) and multiplex RT-qPCR (n=17). Altogether, the data obtained from a real-life prospective cohort supports that the rapid antigen test sensitivity for the Omicron remains high and underscores the reliability of the test for COVID-19 diagnosis in a setting with high disease prevalence and limited PCR testing capability.

Phylogenetic-based inference reveals distinct transmission dynamics of SARS-CoV-2 variant of concern Gamma and lineage P.2 in Brazil (preprint)

The COVID-19 epidemic in Brazil experienced two major country-wide lineage replacements, the first driven by the lineage P.2, formerly classified as variant of interest (VOI) Zeta in late 2020 and the second by the variant of concern (VOC) Gamma in early 2021. To better understand how these SARS-CoV-2 lineage turnovers occurred in Brazil, we analyzed 11,724 high-quality SARS-CoV-2 whole genomes of samples collected in different country regions between September 2020 and April 2021. Our findings indicate that the spatial dispersion of both variants in Brazil was driven by short and long-distance viral transmission. The lineage P.2 harboring Spike mutation E484K probably emerged around late July 2020 in the Rio de Janeiro (RJ) state, which contributed with most (~50%) inter-state viral disseminations, and only became locally established in most Brazilian states by October 2020. The VOC Gamma probably arose in November 2020 in the Amazonas (AM) state, which was responsible for 60-70% of the inter-state viral dissemination, and the earliest timing of community transmission of this VOC in many Brazilian states was already traced to December 2020. We estimate that variant Gamma was 1.56-3.06 more transmissible than variant P.2 co-circulating in RJ and that the median effective reproductive number (Re) of Gamma in RJ and SP states (Re = 1.59-1.91) was lower than in AM (Re = 3.55). In summary, although the epicenter of the lineage P.2 dissemination in Brazil was the heavily interconnected Southeastern region, it displayed a slower rate of spatial spread than the VOC Gamma originated in the more isolated Northern Brazilian region. Our findings also support that the VOC Gamma was more transmissible than lineage P.2, although the viral Re of the VOC varied according to the geographic context.

ViralFlow: an automated workflow for SARS-CoV-2 genome assembly, lineage assignment, mutations and intrahost variants detection (preprint)

The COVID-19 pandemic, a disease caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), emerged in 2019 and quickly spread worldwide. Genomic surveillance has become the gold standard methodology to monitor and study this emerging virus. The current deluge of SARS-CoV-2 genomic data being generated worldwide has put additional pressure on the urgent need for streamlined bioinformatics workflows for data analysis. Here, we describe a workflow developed by our group to process and analyze large-scale SARS-CoV-2 Illumina amplicon sequencing data. This workflow automates all the steps involved in SARS-CoV-2 genomic analysis: data processing, genome assembly, PANGO lineage assignment, mutation analysis and the screening of intrahost variants. The workflow presented here (https://github.com/dezordi/ViralFlow) is available through Docker or Singularity images, allowing implementation in laptops for small scale analyses or in high processing capacity servers or clusters. Moreover, the low requirements for memory and CPU cores makes it a versatile tool for SARS-CoV-2 genomic analysis.

Unusual SARS-CoV-2 intra-host diversity reveals lineages superinfection (preprint)

The SARS-CoV-2 has infected almost 200 million people worldwide by July 2021 and the pandemic has been characterized by infection waves of viral lineages showing distinct fitness profiles. The simultaneous infection of a single individual by two distinct SARS-CoV-2 lineages provides a window of opportunity for viral recombination and the emergence of new lineages with differential phenotype. Several hundred SARS-CoV-2 lineages are currently well characterized but two main factors have precluded major coinfection/codetection analysis thus far: i) the low diversity of SARS-CoV-2 lineages during the first year of the pandemic which limited the identification of lineage defining mutations necessary to distinguish coinfecting viral lineages; and the ii) limited availability of raw sequencing data where abundance and distribution of intrasample/intrahost variability can be accessed. Here, we have put together a large sequencing dataset from Brazilian samples covering a period of 18 May 2020 to 30 April 2021 and probed it for unexpected patterns of high intrasample/intrahost variability. It enabled us to detect nine cases of SARS-CoV-2 coinfection with well characterized lineage-defining mutations. In addition, we matched these SARS-CoV-2 coinfections with spatio-temporal epidemiological data confirming their plausibility with the co-circulating lineages at the timeframe investigated. These coinfections represent around 0.61% of all samples investigated. Although our data suggests that coinfection with distinct SARS-CoV-2 lineages is a rare phenomenon, it is likely an underestimation and coinfection rates warrants further investigation. DATA SUMMARYThe raw fastq data of codetection cases are deposited on gisaid.org and correlated to gisaid codes: EPI_ISL_1068258, EPI_ISL_2491769, EPI_ISL_2491781, EPI_ISL_2645599, EPI_ISL_2661789, EPI_ISL_2661931, EPI_ISL_2677092, EPI_ISL_2777552, EPI_ISL_3869215. Supplementary data are available on https://doi.org/10.6084/m9.figshare.16570602.v1. The workflow code used in this study is publicly available on: https://github.com/dezordi/IAM_SARSCOV2.

Identification of SARS-CoV-2 P.1-related lineages in Brazil provides new insights about the mechanisms of emergence of Variants of Concern (preprint)

One of the most remarkable features of the SARS-CoV-2 Variants of Concern (VOC) is the unusually large number of mutations they carry. However, the specific factors that drove the emergence of such variants since the second half of 2020 are not fully resolved. In this study, we described a new SARS-CoV-2 lineage provisionally designated as P.1-like-II that, as well as the previously described lineage P.1-like-I, shares several lineage-defining mutations with the VOC P.1 circulating in Brazil. Reconstructions of P.1 ancestor sequences demonstrate that the entire constellation of mutations that define the VOC P.1 did not accumulate within a single long-term infected individual, but was acquired by sequential addition during interhost transmissions. Our evolutionary analyses further estimate that P.1-ancestors strains carrying half of the P.1-lineage-defining mutations, including those at the receptor-binding domain of the Spike protein, circulated cryptically in the Amazonas state since August 2020. This evolutionary pattern is consistent with the hypothesis that partial human population immunity acquired from natural SARS-CoV-2 infections during the first half of 2020 might have been the major driving force behind natural selection that allowed VOCs' emergence and worldwide spread. These findings also support a long lag-time between the emergence of variants with key mutations of concern and expansion of the VOC P.1 in Brazil.

The ongoing evolution of variants of concern and interest of SARS-CoV-2 in Brazil revealed by convergent indels in the amino (N)-terminal domain of the Spike protein (preprint)

Mutations at both the receptor-binding domain (RBD) and the amino (N)-terminal domain (NTD) of the SARS-CoV-2 Spike (S) glycoprotein can alter its antigenicity and promote immune escape. We identified that SARS-CoV-2 lineages circulating in Brazil with mutations of concern in the RBD independently acquired convergent deletions and insertions in the NTD of the S protein, which altered the NTD antigenic-supersite and other predicted epitopes at this region. These findings support that the ongoing widespread transmission of SARS-CoV-2 in Brazil is generating new viral lineages that might be more resistant to neutralization than parental variants of concern.

Multiple introductions followed by ongoing community spread of SARS-CoV-2 at one of the largest metropolitan areas in the Northeast of Brazil (preprint)

The emergence of SARS-CoV-2 in the human population has caused a huge pandemic that is still unfolding in many countries around the world. Multiple epicenters of the pandemic have emerged since the first pneumonia cases in Wuhan, first in Italy followed by the USA and Brazil. Up to now, Brazil is the second most affected country, however, genomic sequences of SARS-CoV-2 strains circulating in the country are restricted to some highly impacted states. Although the Pernambuco state, located in the Northeast Region, is the sixth most affected brazilian state and the second considering lethality rate, there is a lack of high quality genomic sequences from the strains circulating in this region. Here, we sequenced 38 strains of SARS-CoV-2 from patients presenting Covid-19 symptoms. Phylogenetic reconstructions revealed that three lineages were circulating in the state and 36 samples belong to B1.1 lineage. We detected two introductions from European countries and five clades, corroborating the community spread of the virus between different municipalities of the state. Finally, we detected that all except one strain showed the D614G spike protein amino acid change that may impact virus infectivity in human cells. Our study brought new light to the spread of SARS-CoV-2 strains in one of the most heavily impacted states of Brazil.