Biology subjects

Wallau, G. L.

Publications and source records attributed to Wallau, G. L..

7 recordsLinked to original sources

bioRxiv2025

Viral metagenomics of synanthropic urban bats: a surveillance strategy for uncovering potentially zoonotic viruses

Bats are natural reservoirs for diverse viruses, including coronaviruses, filoviruses, and paramyxoviruses, many leading to zoonotic spillover events and demanding an integrated surveillance. Here, we present a framework that leverages Brazils rabies passive surveillance program to detect bat-borne viruses. Using an algorithm to select representative specimens from 2,422 bats collected across Sao Paulo state, we submitted 150 paired lung and intestine samples to nanopore metagenomic sequencing. We detected 98 viral contigs from 12 families of public health relevance, including Arenaviridae, Coronaviridae, and Paramyxoviridae. Notably, the approach identified a previously unknown filovirus in bats in the Americas, validating the frameworks capacity for epidemic preparedness. These findings reveal an undetected viral diversity and demonstrate how existing animal surveillance can monitor pathogen threats. Crucially, in a workshop involving multisectoral One Health experts in Brazil, this framework was validated as a scalable model for national expansion, adapted for low- and middle-income countries (LMICs). One-sentence summary lineThe study introduces a viral surveillance method using metagenomics in bats, offering a scalable, cost-effective model for operationalizing One Health surveillance, especially relevant to low- and middle-income countries.

genomics↗

bioRxiv2024

Design of nanobody targeting SARS-CoV-2 spike glycoprotein using CDR-grafting assisted by molecular simulation and machine learning

The design of proteins capable to effectively bind to specific protein targets is crucial for developing therapies, diagnostics, and vaccine candidates for viral infections. Here, we introduce a complementarity-determining regions (CDRs)-grafting approach for designing nanobodies (Nbs) that target specific epitopes, with the aid of computer simulation and machine learning. As a proof-of-concept, we designed, evaluated, and characterized a high-affinity Nb against the spike protein of SARS-CoV-2, the causative agent of the COVID-19 pandemic. The designed Nb, referred to as Nb Ab.2, was synthesized and displayed high-affinity for both the purified receptor-binding domain protein and to the virus-like particle, demonstrating affinities of 9 nM and 60 nM, respectively, as measured with microscale thermophoresis. Circular dichroism showed the designed proteins structural integrity and its proper folding, whereas molecular dynamics simulations provided insights into the internal dynamics of Nb Ab.2. This study shows that our computational pipeline can be used to efficiently design high affinity Nbs with diagnostic and prophylactic potential, which can be tailored to tackle different viral targets. Author summaryIn this study, we present a pipeline for designing a high-affinity nanobody (Nb) targeting the SARS-CoV-2 spike protein using enhanced sampling molecular dynamics simulations and CDR-grafting. To address the challenges of CDR grafting in Nbs, including the need for structural similarity between the CDR motif of interest and the scaffold region, we utilized the Nb scaffold cAbBCII10, known for its versatility in accommodating various CDRs. We generated a library based on the cAbBCII10 framework with diverse, unrelated CDRs and applied machine learning to identify the most promising candidates. Our approach enabled successful engineering of a Nb that binds to the SARS-CoV-2 spike protein with high affinity, demonstrating the effectiveness of our design pipeline for potential therapeutic applications.

biophysics↗

bioRxiv2024

Long term co-circulation of multiple arboviruses in southeast Australia revealed by xeno-monitoring of mosquitoes and metatranscriptomics

Arbovirus surveillance of wild-caught mosquitoes is an affordable and sensitive means of monitoring virus transmission dynamics at various spatial-temporal scales, and emergence and re-emergence during epidemic and interepidemic periods. A variety of molecular diagnostics for arbovirus screening of mosquitoes (known as xeno-monitoring) are available, but most provide limited information about virus diversity. PCR-based screening coupled with metatranscriptomics is an increasingly affordable and sensitive pipeline for integrating complete viral genome sequencing into surveillance programs. This enables large-scale, high-throughput arbovirus screening from diverse samples. We collected mosquitoes in CO2-baited light traps from five urban parks in Brisbane from March 2021 to May 2022. Mosquito pools of [≤]200 specimens were screened for alphaviruses and flaviviruses using virus genus-specific primers and reverse transcription quantitative PCR (qRT-PCR). A subset of virus-positive samples was then processed using a mosquito-specific ribosomal RNA depletion method and then sequenced on the Illumina NextSeq. Overall, 54,670 mosquitoes, representing 26 species were screened in 382 pools. Thirty detections of arboviruses were made in 28 pools. Twenty of these positive pools were further characterised using meta-transcriptomics generating 18 full-length genomes. These full-length sequences belonged to four medically relevant arboviruses: Barmah Forest, Ross River, Sindbis-like and Stratford viruses. Phylogenetic and evolutionary analyses revealed the evolutionary progression of arbovirus lineages over the last 100 years, highlighting long-distance dispersal across the Australian continent and continuous circulation characterised by constant turnover of virus lineages.

genomics↗

bioRxiv2024

Simultaneous circulation and coinfection of Dengue clades and serotypes in Southern Brazil

Dengue is an arthropod-borne virus with worldwide urban transmission mediated by anthropophilic vectors of the genus Aedes. Currently, there is a substantial genotype diversity that belongs to at least four known serotypes. Tropical regions, where several serotypes cocirculate in the population, are hyperendemic, driving multiple outbreaks with variable disease manifestations. Notably, the Dengue virus burden is increasing in subtropical and temperate regions of the globe due to climatic changes associated with new outbreaks in naive and previously unaffected human populations. The introduction and endemic transmission of different clades and serotypes in these regions is highly concerning due to the known and still unknown consequences of Dengue infection on populations with diverse genetic backgrounds. Here, we characterized the coinfection of different Dengue clades and serotypes in Rio Grande do Sul, Brazils southernmost and subtropical state, by combining serotype-specific RT-PCR and deep sequencing. We found five coinfected patients in four municipalities where these clades and serotypes circulated simultaneously. Our data suggests that coinfection events account for a minority of total cases, but these findings may reflect the early transmission phases of some Dengue clades. Hence, close monitoring is warranted to evaluate coinfection rates and associated clinical consequences as clade prevalence changes.

genomics↗

bioRxiv2022

Incipient parallel evolution of SARS-CoV-2 Deltacron variant in South Brazil

With the coexistence of multiple lineages and increased international travel, recombination and gene flow are likely to become increasingly important in the adaptive evolution of SARS-CoV-2. This could result in the incipient parallel evolution of multiple recombinant lineages. However, identifying recombinant lineages is challenging, and the true extent of recombinant evolution in SARS-CoV-2 may be underestimated. This study describes the first SARS-CoV-2 Deltacron recombinant case identified in Brazil. We demonstrate that the recombination breakpoint is at the beginning of Spike gene (S). The 5' genome portion (circa 22 kb) resembles the AY.101 lineage (VOC Delta), and the 3' genome portion (circa 8 kb nucleotides) is most similar to the BA.1.1 lineage (VOC Omicron). Furthermore, evolutionary genomic analyses indicate that the new strain emerged after a single recombination event between lineages of diverse geographical locations in December 2021 in South Brazil. This Deltacron, named AYBA-RS, is one out of almost 30 recombinants described this year. The submission of only four sequences in the GISAID database suggests that this Brazilian lineage had a minor epidemiological impact. On the other hand, the recent emergence of this and various other Deltacron recombinant lineages (i.e., XD, XF, and XS) suggests that gene flow and recombination may play an increasingly important role in the COVID-19 pandemic. We explain the evolutionary and population genetic theory that support this assertion, and we conclude that this stresses the need for continued genomic and epidemiological surveillance. This is particularly important for countries where multiple variants are present, as well as for countries that receive significant inbound international travel.

evolutionary biology↗

bioRxiv2022

Ancient origin of Jingchuvirales derived glycoproteins integrated in arthropod genomes

Endogenous virus elements (EVEs) are viral-derived sequences integrated into their host genomes. EVEs of the Jingchuvirales order were detected in a wide range of insect genomes covering several distantly related families and Jingchuvirales-derived glycoproteins were recently associated by our group with the origin of a putative new retrovirus based on a glycoprotein captured by a mosquito retrotransposon. But, except for mosquitoes, there is a lack of a more detailed understanding of the endogenization mechanism, timing and frequency per viral lineages. Here we screened Jingchuvirales glycoprotein-derived EVEs (Jg-EVEs) in eukaryotic genomes. We found six distinct endogenization events of Jg-EVEs, that belong to two out of five known Jingchuvirales families (Chuviridae and Natareviridae). For seven arthropod families bearing Jg-EVEs there is no register of bona fide circulating chuvirus infection. Hence, our results show that Jingchuvirales viruses infected or still infect these host families, expanding their known host range. We estimated that two endogenization events occurred in the ancestors of the Myrmicinae-Ponerinae subfamilies (Pteromalidae - Hymenoptera order) around 155[~]54.8 MyA and Bombus genus (Hemiptera order) around (36[~]2 MyA). Although we found abundant evidence of LTR-Gypsy retrotransposons fragments associated with the glycoprotein in Hymenoptera and other insect orders, there is no evidence of potential functional glycoprotein capture. Our results show that the widespread distribution of Jingchuvirales glycoproteins in extant Arhtropods is a result of multiple ancient endogenization events and that these viruses fossils are being vertically inherited for millions of years through the Arthropods evolutionary tree. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=142 HEIGHT=200 SRC="FIGDIR/small/497255v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@194f47org.highwire.dtl.DTLVardef@1a3dd24org.highwire.dtl.DTLVardef@10b77bdorg.highwire.dtl.DTLVardef@1e21ffb_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2021

A potential SARS-CoV-2 variant of interest (VOI) harboring mutation E484K in the Spike protein was identified within lineage B.1.1.33 circulating in Brazil

The SARS-CoV-2 epidemic in Brazil was dominated by two lineages designated as B.1.1.28 and B.1.1.33. Two SARS-CoV-2 variants harboring mutations at the receptor-binding domain of the Spike (S) protein, designated as lineages P.1 and P.2, evolved within lineage B.1.1.28 and are rapidly spreading in Brazil. Lineage P.1 is considered a Variant of Concern (VOC) because of the presence of multiple mutations in the S protein (including K417T, E484K, N501Y), while lineage P.2 only harbors mutation S:E484K and is considered a Variant of Interest (VOI). Here we report the identification of a new SARS-CoV-2 VOI within lineage B.1.1.33 that also harbors mutation S:E484K and was detected in Brazil between November 2020 and February 2021. This VOI displayed four non-synonymous lineage-defining mutations (NSP3:A1711V, NSP6:F36L, S:E484K, and NS7b:E33A) and was designated as lineage N.9. The VOI N.9 probably emerged in August 2020 and has spread across different Brazilian states from the Southeast, South, North and Northeast regions.

microbiology↗