Search

Domestic animals can share viral pathogens with humans, acting mainly as a bridge host. The Orthopoxvirus genus hosts important zoonotic species that have emerged in urban areas worldwide. Nevertheless, the role of companion animals, such as dogs and cats, in the circulation of orthopoxviruses in urban areas remains poorly understood. Therefore, the objective of this study was to evaluate the presence of neutralizing anti-orthopoxvirus antibodies in serum samples from owned dogs from three municipalities in Minas Gerais, as well as the presence of the C11R and A56R orthopoxviruses genes. The presence of neutralizing antibodies was detected in 14.3% of the animals investigated. However, no sample was positive for the presence of the genes investigated. Further study of the population of dogs in urban areas may prove a valuable tool for understanding the spread of orthopoxviruses in urbanized areas of Brazil.

Recombination plays a crucial role in the evolution of SARS-CoV-2. The Omicron XBB* recombinant lineages are a noteworthy example, as they have been the dominant SARS-CoV-2 variant worldwide in the first half of 2023. Since November 2023, a new recombinant lineage between Omicron subvariants XBB and BA.2.86, designated XDR, has been detected mainly in Brazil. In this study, we reconstructed the spatiotemporal dynamics and estimated the absolute and relative transmissibility of the XDR lineage. The XDR lineage displayed a recombination breakpoint in the ORF1a-coding region, and the most closely related sequences to the 5' and 3' ends of the recombinant correspond to JD.1.1 and JN.1.1 lineages, respectively. The first XDR sequences were detected in November 2023 in the Northeastern Brazilian region, and their prevalence rapidly surged from <1% to 25% by February 2024. The Bayesian phylogeographic analysis supports that the XDR lineage likely emerged in the Northeastern Brazilian region around late October 2023 and rapidly disseminated within and outside Brazilian borders from mid-November onward. The median effective reproductive number of the XDR lineage in Brazil during the initial expansion phase was estimated to be around 1.5, and the average relative instantaneous reproduction numbers of XDR and JN* lineages were estimated to be 1.37 and 1.29 higher than that of co-circulating XBB* lineages. In summary, these findings support that the recombinant lineage XDR arose in the Northeastern Brazilian region in October 2023, shortly after the first detection of JN.1 sequences in the country. In Brazil, the XDR lineage exhibited a higher transmissibility level than its parental XBB.* lineages and is spreading at a rate similar to or slightly faster than the JN.1* lineages.IMPORTANCEThis study highlights the emergence and rapid dissemination of the recombinant SARS-CoV-2 XDR lineage, derived from the Omicron lineages JD.1.1 and JN.1.1. The XDR lineage exhibited equivalent transmissibility to its JN.1* parental lineages and quickly spread across Brazil in late 2023. The findings underscore the critical role of real-time genomic surveillance in detecting novel variants with higher transmission potential. By utilizing phylogenetic and epidemiological methods, this research provides important insights into the molecular dynamics of XDR, which could inform public health responses and vaccine composition updates. The study's significance lies in its ability to document the impact of recombination on viral evolution, offering valuable information to the field of virology and pandemic preparedness., Competing Interests: The authors declare no conflict of interest.

The global number of COVID-19 deaths has reached 7 million, with 4% of these deaths occurring in children and adolescents. In Brazil, around 1500 children up to 11 years old died from the disease. The most common symptoms in children are respiratory, potentially progressing to severe illnesses, such as severe acute respiratory syndrome (SARS) and MIS-C. Studies indicate that comorbidities and genetic factors, such as polymorphisms in immune response genes, can influence the severity of COVID-19. This study investigates the occurrence of single-nucleotide polymorphisms (SNPs) in innate immune response genes in children with COVID-19. Seventy-three samples were analyzed from children under 13 years old hospitalized at João Paulo II Children's Hospital due to COVID-19. The evaluated SNPs were tlr8 (1) (rs3764879), tlr8 (2) (rs2407992), tlr7 (rs179008), tlr3 (rs3775291), tirap (rs8177374), and mcp-1 (rs1024611), considering four categories of severity: mild, moderate, severe, and critical COVID-19. To identify the SNPs, PCR and sequencing were performed. The frequencies of the SNPs obtained were not discrepant when compared to the frequencies described in the Global ALFA, Global 1000 Genomes, Global gnomAD, American 1000 Genomes, and American gnomAD databases, except for the SNP in TLR7. Comparing severe and critical cases to mild and moderate cases, we found a higher relative risk associated with mutations in tlr8 (1) , tlr7 , tlr3 , and tirap ( p < 0.05). No association was found for SNPs in tlr8 (2) and mcp-1 . Our analyses suggest an association between SNPs in innate immune response genes and severity of symptoms in children with COVID-19 (or SARS-CoV-2 infected children).

Zoonotic infections (swine-human) caused by influenza A viruses (IAVs) have been reported and linked to close contact between these species. Here, we describe eight human IAV variant infections (6 mild and 2 severe cases, including 1 death) detected in Paraná, Brazil, during 2020-2023. Genomes recovered were closely related to Brazilian swIAVs of three major lineages (1 A.3.3.2/pdm09, 1B/human-like, and H3.1990.5), including three H1N1v, two H1N2v, two H3N2v and one H1v. Five H1v were closely related to pdm09 lineage, one H1v (H1N2v) grouped within 1B.2.3 clade, and the two H3v grouped within a clade composed exclusively of Brazilian H3 swIAV (clade H3.1990.5.1). Internal gene segments were closely related to H1N1pdm09 isolated from pigs. IAV variant rarely result in sustained transmission between people, however the potential to develop such ability is of concern and must not be underestimated. This study brings into focus the need for continuous influenza surveillance and timely risk assessment., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Yellow fever virus (YFV) circulates in a sylvatic cycle between non-human primates (NHPs) and arboreal mosquitoes in Brazil. Passive monitoring of ill or deceased NHPs is a key component of the Brazilian yellow fever (YF) surveillance program. Samples from NHPs carcasses are usually suitable for molecular tests but not for serological assays. As an alternative to the conventional plaque reduction neutralization test (PRNT) based on sera, we tested the utility of liver homogenates from experimentally infected (YFV, Mayaro virus [MAYV], chikungunya virus [CHIKV], or mock) mice to quantify PRNTs. Although homogenates from mock-infected mice showed a low level of nonspecific virus neutralization against all three viruses, homogenates from YFV-, MAYV- and CHIKV-infected mice demonstrated significantly higher levels of virus neutralization compared to controls. Receiver operating characteristic (ROC) curves analyses were performed using the median neutralization values of three technical replicates for each infected group separately or collectively. Results showed scores ≥0.97 (95% CI ≥ 0.89-1.0) for the area under the curve at dilutions 1:20 to 1:80, suggesting that median virus neutralization values effectively differentiated infected mice from controls. Liver homogenates obtained from 25 NHP carcasses (collected during the 2017 YF outbreak in Brazil) were also tested using the adapted PRNT as well as rapid lateral flow tests to investigate anti-YFV IgM. Neutralization activity was detected in six NHP samples that were also positive by PCR and anti-YFV IgM tests and one sample that tested negative by PCR and IgM test. Our results demonstrate the feasibility of using liver homogenates as an alternative approach for serological investigation in viral epidemiologic surveillance., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Costa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Chloroviruses exhibit a close relationship with their hosts with the phenotypic aspect of their ability to form lytic plaques having primarily guided the taxonomy. However, with the isolation of viruses that are only able to complete their replication cycle in one strain of Chlorella variabilis , systematic challenges emerged. In this study, we described the genomic features of 53 new chlorovirus isolates and used them to elucidate part of the evolutionary history and taxonomy of this clade. Our analysis revealed new chloroviruses with the largest genomes to date (>400 kbp) and indicated that four genomic features are statistically different in the viruses that only infect the Syngen 2-3 strain of C. variabilis (OSy viruses). We found large regions of dissimilarity in the genomes of viruses PBCV-1 and OSy-NE5 when compared with the other genomes. These regions contained genes related to the interaction with the host cell machinery and viral capsid proteins, which provided insights into the evolution of the replicative and structural modules in these giant viruses. Phylogenetic analysis using hallmark genes of Nucleocytoviricota revealed that OSy-viruses evolved from the NC64A-viruses, possibly emerging as a result of the strict relationship with their hosts. Merging phylogenetics and nucleotide identity analyses, we propose strategies to demarcate viral species, resulting in seven new species of chloroviruses. Collectively, our results show how genomic data can be used as lines of evidence to demarcate viral species. Using the chloroviruses as a case study, we expect that similar initiatives will emerge using the basis exhibited here.IMPORTANCEChloroviruses are a group of giant viruses with long dsDNA genomes that infect different species of Chlorella- like green algae. They are host-specific, and some isolates can only replicate within a single strain of Chlorella variabilis . The genomics of these viruses is still poorly explored, and the characterization of new isolates provides important data on their genetic diversity and evolution. In this work, we describe 53 new chlorovirus genomes, including many isolated from alkaline lakes for the first time. Through comparative genomics and molecular phylogeny, we provide evidence of genomic gigantism in chloroviruses and show that a subset of viruses became highly specific for their hosts at a particular point in evolutionary history. We propose criteria to demarcate species of chloroviruses, paving the way for an update in the taxonomy of other groups of viruses. This study is a new and important piece in the complex puzzle of giant algal viruses., Competing Interests: The authors declare no conflict of interest.

In the context of the virosphere, viral particles can compete for host cells. In this scenario, some viruses block the entry of exogenous virions upon infecting a cell, a phenomenon known as superinfection inhibition. The molecular mechanisms associated with superinfection inhibition vary depending on the viral species and the host, but generally, blocking superinfection ensures the genetic supremacy of the virus's progeny that first infects the cell. Giant amoeba-infecting viruses have attracted the scientific community's attention due to the complexity of their particles and genomes. However, there are no studies on the occurrence of superinfection and its inhibition induced by giant viruses. This study shows that mimivirus, moumouvirus, and megavirus, exhibit different strategies related to the infection of Acanthamoeba . For the first time, we have reported that mimivirus and moumouvirus induce superinfection inhibition in amoebas. Interestingly, megaviruses do not exhibit this ability, allowing continuous entry of exogenous virions into infected amoebas. Our investigation into the mechanisms behind superinfection blockage reveals that mimivirus and moumouvirus inhibit amoebic phagocytosis, leading to significant changes in the morphology and activity of the host cells. In contrast, megavirus-infected amoebas continue incorporating newly formed virions, negatively affecting the available viral progeny. This effect, however, is reversible with chemical inhibition of phagocytosis. This work contributes to the understanding of superinfection and its inhibition in mimivirus, moumouvirus, and megavirus, demonstrating that despite their evolutionary relatedness, these viruses exhibit profound differences in their interactions with their hosts.IMPORTANCESome viruses block the entry of new virions upon infecting a cell, a phenomenon known as superinfection inhibition. Superinfection inhibition in giant viruses has yet to be studied. This study reveals that even closely related viruses, such as mimivirus, moumouvirus, and megavirus, have different infection strategies for Acanthamoeba . For the first time, we have reported that mimivirus and moumouvirus induce superinfection inhibition in amoebas. In contrast, megaviruses do not exhibit this ability, allowing continuous entry of exogenous virions into infected amoebas. Our investigation shows that mimivirus and moumouvirus inhibit amoebic phagocytosis, causing significant changes in host cell morphology and activity. Megavirus-infected amoebas, however, continue incorporating newly formed viruses, affecting viral progeny. This research enhances our understanding of superinfection inhibition in these viruses, highlighting their differences in host interactions., Competing Interests: The authors declare no conflict of interest.

Background: In response to the coronavirus disease 2019 (Covid-19) pandemic, Brazil authorised the Astra Zeneca/Fiocruz vaccine in January 2021. As the Delta variant emerged in May 2021, interval between vaccine doses was adjusted. By September 2021, the Brazilian National Immunisation Program recommended a booster dose for individuals over 70, and later expanded the recommendation to all adults., Objectives: Assess the equivalence of IgG antibody response against the Covid-19 S protein before and approximately 28 days after the third dose of a Covid-19 recombinant vaccine. Two groups received initial two doses with intervals of eight and 12 weeks., Methods: This is a phase IV clinical study, uncontrolled, non-randomised. The study proposes calculating the ratio of geometric means titres (GMT) 28 days after the third dose, with a target ratio of confidence interval (CI) between 0.77 and 1.3., Findings: In the primary endpoint, there was no equivalence between the eight- and 12-week intervals with a slight variation favouring the eight-week group. Post-third dose, both groups showed increases titres at 28 days, three months, six months and 12 months. Both groups responded similarly to Delta and Omicron BA.1, with a more significant increase for Delta., Main Conclusions: The study showed strong and consistent immune response in all age groups receiving the Covid-19 recombinant vaccine. Third dose elicited an increase in GMT by at least three times aligned with Ministry of Health strategies emphasising Bio-Manguinhos crucial role in pandemic control in the country.

Background: Household transmission studies seek to understand the transmission dynamics of a pathogen by estimating the risk of infection from household contacts and community exposures. We estimated within/extra-household SARS-CoV-2 infection risk and associated factors in a household cohort study in one of the most vulnerable neighbourhoods in Rio de Janeiro city., Methods: Individuals ≥1 years-old with suspected or confirmed COVID-19 in the past 30 days (index cases) and household members aged ≥1 year were enrolled and followed at 14 and 28 days (study period November/2020-December/2021). RT-PCR testing, COVID-19 symptoms, and SARS-CoV-2 serologies were ascertained in all visits. Chain binomial household transmission models were fitted using data from 2024 individuals (593 households)., Findings: Extra-household infection risk was 74.2% (95% credible interval [CrI] 70.3-77.8), while within-household infection risk was 11.4% (95% CrI 5.7-17.2). Participants reporting having received two doses of a COVID-19 vaccine had lower extra-household (68.9%, 95% CrI 57.3-77.6) and within-household (4.1%, 95% CrI 0.4-16.6) infection risk. Within-household infection risk was higher among participants aged 10-19 years, from overcrowded households, and with low family income. Contrastingly, extra-household infection risk was higher among participants aged 20-29 years, unemployed, and public transportation users., Interpretation: Our study provides important insights into COVID-19 household/community transmission in a vulnerable population that resided in overcrowded households and who struggled to adhere to lockdown policies and social distancing measures. The high extra-household infection risk highlights the extreme social vulnerability of this population. Prioritising vaccination of the most socially vulnerable could protect these individuals and reduce widespread community transmission., Funding: Fundação Oswaldo Cruz, CNPq, FAPERJ, Royal Society, Instituto Serrapilheira, FAPESP., Competing Interests: CJS is a member of PAHO and WHO advisory boards (no payment involved). All other authors declare that they have no competing interests., (© 2024 The Authors.)

Marseilleviruses (MsV) are a group of viruses that compose the Marseilleviridae family within the Nucleocytoviricota phylum. They have been found in different samples, mainly in freshwater. MsV are classically organized into five phylogenetic lineages (A/B/C/D/E), but the current taxonomy does not fully represent all the diversity of the MsV lineages. Here, we describe a novel strain isolated from a Brazilian saltwater sample named Marseillevirus cajuinensis. Based on genomics and phylogenetic analyses, M. cajuinensis exhibits a 380,653-bp genome that encodes 515 open reading frames. Additionally, M. cajuinensis encodes a transfer RNA, a feature that is rarely described for Marseilleviridae. Phylogeny suggests that M. cajuinensis forms a divergent branch within the MsV lineage A. Furthermore, our analysis suggests that the common ancestor for the five classical lineages of MsV diversified into three major groups. The organization of MsV into three main groups is reinforced by a comprehensive analysis of clusters of orthologous groups, sequence identities, and evolutionary distances considering several MsV isolates. Taken together, our results highlight the importance of discovering new viruses to expand the knowledge about known viruses that belong to the same lineages or families. This work proposes a new perspective on the Marseilleviridae lineages organization that could be helpful to a future update in the taxonomy of the Marseilleviridae family., Importance: Marseilleviridae is a family of viruses whose members were mostly isolated from freshwater samples. In this work, we describe the first Marseillevirus isolated from saltwater samples, which we called Marseillevirus cajuinensis . Most of M. cajuinensis genomic features are comparable to other Marseilleviridae members, such as its high number of unknown proteins. On the other hand, M. cajuinensis encodes a transfer RNA, which is a gene category involved in protein translation that is rarely described in this viral family. Additionally, our phylogenetic analyses suggested the existence of, at least, three major Marseilleviridae groups. These observations provide a new perspective on Marseilleviridae lineages organization, which will be valuable in future updates to the taxonomy of the family since the current official classification does not capture all the Marseilleviridae known diversity., Competing Interests: The authors declare no conflict of interest.

The discovery of mimivirus in 2003 prompted the search for novel giant viruses worldwide. Despite increasing interest, the diversity and distribution of giant viruses is barely known. Here, we present data from a 2012-2022 study aimed at prospecting for amoebal viruses in water, soil, mud, and sewage samples across Brazilian biomes, using Acanthamoeba castellanii for isolation. A total of 881 aliquots from 187 samples covering terrestrial and marine Brazilian biomes were processed. Electron microscopy and PCR were used to identify the obtained isolates. Sixty-seven amoebal viruses were isolated, including mimiviruses, marseilleviruses, pandoraviruses, cedratviruses, and yaraviruses. Viruses were isolated from all tested sample types and almost all biomes. In comparison to other similar studies, our work isolated a substantial number of Marseillevirus and cedratvirus representatives. Taken together, our results used a combination of isolation techniques with microscopy, PCR, and sequencing and put highlight on richness of giant virus present in different terrestrial and marine Brazilian biomes., (© 2024. The Author(s).)

Orpheoviruses, cedratviruses, and pithoviruses are large DNA viruses that cluster together taxonomically within the order Pimascovirales of the phylum Nucleocytoviricota. However, they were not classified previously by the International Committee on Taxonomy of Viruses (ICTV). Here, we present a comprehensive analysis of the gene content, morphology, and phylogenomics of these viruses, providing data that underpinned the recent proposal to establish new taxa for their initial classification. The new taxonomy, which has now been ratified by the ICTV, includes the family Orpheoviridae and genus Alphaorpheovirus, the family Pithoviridae and genus Alphapithovirus, and the family Cedratviridae and genus Alphacedratvirus, aiming to formally catalogue the isolates covered in this study. Additionally, as per the newly adopted rules, we applied standardized binomial names for the virus species created to classify isolates with complete genome sequences available in public databases at the time of the proposal. The specific epithet of each virus species was chosen as a reference to the location where the exemplar virus was isolated., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Aims: The present study aimed to use a conventional and metagenomic approach to investigate the microbiological diversity of water bodies in a network of drainage channels and rivers located in the central area of the city of Belém, northern Brazil, which is considered one of the largest cities in the Brazilian Amazon., Methods and Results: In eight of the analyzed points, both bacterial and viral microbiological indicators of environmental contamination-physical-chemical and metals-were assessed. The bacterial resistance genes, drug resistance mechanisms, and viral viability in the environment were also assessed. A total of 473 families of bacteria and 83 families of viruses were identified. Based on the analysis of metals, the levels of three metals (Cd, Fe, and Mn) were found to be above the recommended acceptable level by local legislation. The levels of the following three physicochemical parameters were also higher than recommended: biochemical oxygen demand, dissolved oxygen, and turbidity. Sixty-three bacterial resistance genes that conferred resistance to 13 different classes of antimicrobials were identified. Further, five mechanisms of antimicrobial resistance were identified and viral viability in the environment was confirmed., Conclusions: Intense human actions combined with a lack of public policies and poor environmental education of the population cause environmental degradation, especially in water bodies. Thus, urgent interventions are warranted to restore the quality of this precious and scarce asset worldwide., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)

Zika virus (ZIKV), an arbovirus from the Flaviviridae family, is the causative agent of Zika fever, a mild and frequent oligosymptomatic disease in humans. Nonetheless, on rare occasions, ZIKV infection can be associated with Guillain-Barré Syndrome (GBS), and severe congenital complications, such as microcephaly. The oligosymptomatic disease, however, presents symptoms that are quite similar to those observed in infections caused by other frequent co-circulating arboviruses, including dengue virus (DENV). Moreover, the antigenic similarity between ZIKV and DENV, and even with other members of the Flaviviridae family, complicates serological testing due to the high cross-reactivity of antibodies. Here, we designed, produced in a prokaryotic expression system, and purified three multiepitope proteins (ZIKV-1, ZIKV-2, and ZIKV-3) for differential diagnosis of Zika. The proteins were evaluated as antigens in ELISA tests for the detection of anti-ZIKV IgG using ZIKV- and DENV-positive human sera. The recombinant proteins were able to bind and detect anti-ZIKV antibodies without cross-reactivity with DENV-positive sera and showed no reactivity with Chikungunya virus (CHIKV)- positive sera. ZIKV-1, ZIKV-2, and ZIKV-3 proteins presented 81.6%, 95%, and 66% sensitivity and 97%, 96%, and 84% specificity, respectively. Our results demonstrate the potential of the designed and expressed antigens in the development of specific diagnostic tests for the detection of IgG antibodies against ZIKV, especially in regions with the circulation of multiple arboviruses., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Pereira et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The SARS-CoV-2 P.1 variant, responsible for an outbreak in Manaus, Brazil, is distinguished by 12 amino acid differences in the S protein, potentially increasing its ACE-2 affinity and immune evasion capability. We investigated the innate immune response of this variant compared to the original B.1 strain, particularly concerning cytokine production. Blood samples from three severe COVID-19 patients were analyzed post-infection with both strains. Results showed no significant difference in cytokine production of mononuclear cells and neutrophils for either variant. While B.1 had higher cytopathogenicity, neither showed viral replication in mononuclear cells. Structural analyses of the S protein highlighted physicochemical variations, which might be linked to the differences in infectivity between the strains. Our studies point to the increased infectivity of P.1 could stem from altered immunogenicity and receptor-binding affinity.

Objective: Assess the level of measles vaccine-induced neutralizing antibodies against the D8 genotype and the persistence of humoral and cell-mediated immunity in children who received their first dose of the measles, mumps, and rubella vaccine eight years previously., Methods: Measles-specific IgG and neutralizing antibodies were determined in serum using ELISA and plaque reduction neutralization test, respectively. Cellular response was evaluated from peripheral blood mononuclear cells (PBMC). IFN-γ-secreting cells, memory B and T cells, and immunological mediators were assayed by ELISpot, flow cytometry, and multiplex liquid microarray assay, respectively., Results: Antibody concentrations declined over time; however, the vaccine-induced neutralizing antibodies' effect against D8 and vaccinal genotypes persisted. PBMC stimulated with the vaccine virus exhibited specific IFN- γ-measles-secreting responses in most participants. Participants with high levels of neutralizing antibodies showed a higher proportion of activated B cells compared to participants with low levels of neutralizing antibodies, while proportions of memory CD4+ and CD8+ T cells were similar between these groups. PBMC supernatant cytokine levels showed a significant difference between stimulated and non-stimulated conditions for IL-2, TNF-α, IL-10, and CXCL10., Conclusion: Despite the decline in antibody concentrations over time, the participants still demonstrated neutralizing capacity against the measles D8 genotype five to eight years after the second dose of the measles, mumps, and rubella vaccine. Additionally, most of the enrolled children exhibited cell-mediated immunity responses to measles virus stimulation., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: LKL, EMS, MLSM, JRX, AMVS, JGM, and NSA are employees of the Immunobiological Technology Institute/Oswaldo CruzFoundation (Bio-Manguinhos/Fiocruz), Marketing Authorization Holder of themeasles, mumps, and rubella vaccine used inthe Brazilian healthcare system.The other authors declare that they have no known competing financial interests or personal relationships that might have influenced the work reported in this article., (Copyright © 2024. Published by Elsevier Ltd.)

Introduction: A lateral flow rapid diagnostic test (RDT) enables detection of measles specific immunoglobulin M (IgM) antibody in serum, capillary blood, and oral fluid with accuracy consistent with enzyme immunoassay (EIA). The objectives of the study were: 1) to assess measles RDT inter-reader agreement between two clinic staff; 2) to assess the sensitivity and specificity of the measles RDT relative to standard surveillance testing in a low transmission setting; 3) to evaluate the knowledge, attitudes, and practices of staff in clinics using the RDT; and 4) to assess the impact of RDT testing on the measles public health response in Malaysia., Materials and Methods: The clinic-based prospective evaluation included all suspected measles cases captured by routine measles surveillance at 34 purposely selected clinics in 15 health districts in Malaysia between September 2019 and June 2020, following day-long regional trainings on RDT use. Following informed consent, four specimens were collected from each suspected case, including those routinely collected for standard surveillance [serum for EIA and throat swabs for quantitative reverse transcriptase polymerase chain reaction (RT-qPCR)] together with capillary blood and oral fluid tested with RDTs during the study. RDT impact was evaluated by comparing the rapidity of measles public health response between the pre-RDT implementation (December 2018 to August 2019) and RDT implementation periods (September 2019 to June 2020). To assess knowledge, attitudes, and practices of RDT use, staff involved in the public health management of measles at the selected sites were surveyed., Results: Among the 436 suspect cases, agreement of direct visual readings of measles RDT devices between two health clinic staff was 99% for capillary blood (k = 0.94) and 97% for oral fluid (k = 0.90) specimens. Of the total, 45 (10%) were positive by measles IgM EIA (n = 44, including five also positive by RT-qPCR) or RT-qPCR only (n = 1), and 38 were positive by RDT (using either capillary blood or oral fluid). Using measles IgM EIA or RT-qPCR as reference, RDT sensitivity using capillary blood was 43% (95% CI: 30%-58%) and specificity was 98% (95% CI: 96%-99%); using oral fluid, sensitivity (26%, 95% CI: 15%-40%) and specificity (97%, 95% CI: 94%-98%) were lower. Nine months after training, RDT knowledge was high among staff involved with the public health management of measles (average quiz score of 80%) and was highest among those who received formal training (88%), followed by those trained during supervisory visits (83%). During the RDT implementation period, the number of days from case confirmation until initiation of public response decreased by about 5 days., Conclusion: The measles IgM RDT shows >95% inter-reader agreement, high retention of RDT knowledge, and a more rapid public health response. However, despite ≥95% RDT specificity using capillary blood or oral fluid, RDT sensitivity was <45%. Higher-powered studies using highly specific IgM assays and systematic RT-qPCR for case confirmation are needed to establish the role of RDT in measles elimination settings., Competing Interests: During the project, LW and DWB were supported in part by Bill & Melinda Gates grant number OPP1066619 to develop the measles IgM RDT and the ‘Oralight’ oral fluid collection device. The ‘Oralight’ oral fluid collection device is the subject of patent application PCT/GB2015/051155 by Public Health England (PHE; now UKHSA), with priority date 17 April 2014, and currently undergoing patent prosecution in US, Japan, Canada, Australia, India and Europe. The rapid diagnostic test has been licensed non-exclusively from UKHSA to Global Access Diagnostics (GADx) Ltd, England. A modified version of this device is being developed for regulatory approval and commercialization by GADx and Diatropix, a not-for-profit initiative of Institut Pasteur de Dakar, Senegal, with funding from Bill & Melinda Gates Foundation, Seattle, WA (grant number INV-003213). LW is employed by UKHSA that has been sub-contracted by Institut Pasteur de Dakar to support the technical transfer of measles RDT technology from UKHSA to GADx, and DWB holds a fellowship at Fiocruz in Brazil funded with this grant support. These circumstances do not alter our adherence to PLOS ONE policies on sharing data and materials. All other authors declared that no competing interests exist. Besides the BMGF grant, there was no other external funding received for this study. BMGF had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Herpes simplex virus 1 (HSV-1) or simplexvirus humanalpha 1 is a neurotropic virus that is responsible for orofacial infections in humans. More than 70% of the world's population may have seropositivity for HSV-1, and this virus is a leading cause of sporadic lethal encephalitis in humans. The role of toll-like receptors (TLRs) in defending against HSV-1 infection has been explored, including the consequences of lacking these receptors or other proteins in the TLR pathway. Cell and mouse models have been used to study the importance of these receptors in combating HSV-1, how they relate to the innate immune response, and how they participate in the orchestration of the adaptive immune response. Myeloid differentiation factor 88 (MyD88) is a protein involved in the downstream activation of TLRs and plays a crucial role in this signaling. Mice with functional MyD88 or TLR2 and TLR9 can survive HSV-1 infection. However, they can develop encephalitis and face a 100% mortality rate in a dose-dependent manner when MyD88 or TLR2 plus TLR9 proteins are non-functional. In TLR2/9 knockout mice, an increase in chemokines and decreases in nitric oxide (NO), interferon (IFN) gamma, and interleukin 1 (IL-1) levels in the trigeminal ganglia (TG) have been correlated with mortality., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

The SARS-CoV-2 XBB is a group of highly immune-evasive lineages of the Omicron variant of concern that emerged by recombining BA.2-descendent lineages and spread worldwide during 2023. In this study, we combine SARS-CoV-2 genomic data ( n = 11,065 sequences) with epidemiological data of severe acute respiratory infection (SARI) cases collected in Brazil between October 2022 and July 2023 to reconstruct the space-time dynamics and epidemiologic impact of XBB dissemination in the country. Our analyses revealed that the introduction and local emergence of lineages carrying convergent mutations within the Spike protein, especially F486P, F456L, and L455F, propelled the spread of XBB* lineages in Brazil. The average relative instantaneous reproduction numbers of XBB* + F486P, XBB* + F486P + F456L, and XBB* + F486P + F456L + L455F lineages in Brazil were estimated to be 1.24, 1.33, and 1.48 higher than that of other co-circulating lineages (mainly BQ.1*/BE*), respectively. Despite such a growth advantage, the dissemination of these XBB* lineages had a reduced impact on Brazil's epidemiological scenario concerning previous Omicron subvariants. The peak number of SARI cases from SARS-CoV-2 during the XBB wave was approximately 90%, 80%, and 70% lower than that observed during the previous BA.1*, BA.5*, and BQ.1* waves, respectively. These findings revealed the emergence of multiple XBB lineages with progressively increasing growth advantage, yet with relatively limited epidemiological impact in Brazil throughout 2023. The XBB* + F486P + F456L + L455F lineages stand out for their heightened transmissibility, warranting close monitoring in the months ahead., Importance: Brazil was one the most affected countries by the SARS-CoV-2 pandemic, with more than 700,000 deaths by mid-2023. This study reconstructs the dissemination of the virus in the country in the first half of 2023, a period characterized by the dissemination of descendants of XBB.1, a recombinant of Omicron BA.2 lineages evolved in late 2022. The analysis supports that XBB dissemination was marked by the continuous emergence of indigenous lineages bearing similar mutations in key sites of their Spike protein, a process followed by continuous increments in transmissibility, and without repercussions in the incidence of severe cases. Thus, the results suggest that the epidemiological impact of the spread of a SARS-CoV-2 variant is influenced by an intricate interplay of factors that extend beyond the virus's transmissibility alone. The study also underlines the need for SARS-CoV-2 genomic surveillance that allows the monitoring of its ever-shifting composition., Competing Interests: The authors declare no conflict of interest.

Yellow fever (YF) presents a wide spectrum of severity, with clinical manifestations in humans ranging from febrile and self-limited to fatal cases. Although YF is an old disease for which an effective and safe vaccine exists, little is known about the viral- and host-specific mechanisms that contribute to liver pathology. Several studies have demonstrated that oxidative stress triggered by viral infections contributes to pathogenesis. We evaluated whether yellow fever virus (YFV), when infecting human hepatocytes cells, could trigger an imbalance in redox homeostasis, culminating in oxidative stress. YFV infection resulted in a significant increase in reactive oxygen species (ROS) levels from 2 to 4 days post infection (dpi). When measuring oxidative parameters at 4 dpi, YFV infection caused oxidative damage to lipids, proteins, and DNA, evidenced by an increase in lipid peroxidation/8-isoprostane, carbonyl protein, and 8-hydroxy-2'-deoxyguanosine, respectively. Furthermore, there was a significant reduction in the activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), in addition to a reduction in the ratio of reduced to oxidized glutathione (GSH/GSSG), indicating a pro-oxidant environment. However, no changes were observed in the enzymatic activity of the enzyme catalase (CAT) or in the gene expression of SOD isoforms (1/2/3), CAT, or GPx. Therefore, our results show that YFV infection generates an imbalance in redox homeostasis, with the overproduction of ROS and depletion of antioxidant enzymes, which induces oxidative damage to cellular constituents. Moreover, as it has been demonstrated that oxidative stress is a conspicuous event in YFV infection, therapeutic strategies based on antioxidant biopharmaceuticals may be new targets for the treatment of YF., Competing Interests: Declaration of competing interest The authors declare that is no conflict of interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Latin America and Caribbean (LAC) regions were an important epicenter of the COVID-19 pandemic and SARS-CoV-2 evolution. Through the COVID-19 Genomic Surveillance Regional Network (COVIGEN), LAC countries produced an important number of genomic sequencing data that made possible an enhanced SARS-CoV-2 genomic surveillance capacity in the Americas, paving the way for characterization of emerging variants and helping to guide the public health response. In this study we analyzed approximately 300,000 SARS-CoV-2 sequences generated between February 2020 and March 2022 by multiple genomic surveillance efforts in LAC and reconstructed the diffusion patterns of the main variants of concern (VOCs) and of interest (VOIs) possibly originated in the Region. Our phylogenetic analysis revealed that the spread of variants Gamma, Lambda and Mu reflects human mobility patterns due to variations of international air passenger transportation and gradual lifting of social distance measures previously implemented in countries. Our results highlight the potential of genetic data to reconstruct viral spread and unveil preferential routes of viral migrations that are shaped by human mobility patterns., (© 2024. The Author(s).)

Since the Orthoflavivirus zikaense (ZIKV) has been considered a risk for Zika congenital syndrome development, developing a safe and effective vaccine has become a high priority. Numerous research groups have developed strategies to prevent ZIKV infection and have identified the domain III of the ZIKV envelope protein (zEDIII) as a promising target. Subunit antigens are often poorly immunogenic, necessitating the use of adjuvants and/or delivery systems to induce optimal immune responses. The subject of nanotechnology has substantial expansion in recent years in terms of research and applications. Nanoparticles could be used as drug delivery systems and to increase the immunogenicity and stability of a given antigen. This work aims to characterize and validate the potential of a vaccine formulation composed of domain zEDIII and bovine serum albumin nanoparticles containing polyinosinic-polycytidylic acid (NPPI). NPPI were uptake in vitro by immature bone marrow dendritic cells and histological analysis of the skin of mice treated with NPPI showed an increase in cellularity. Immunization assay showed that mice immunized with zEDIII in the presence of NPPI produced neutralizing antibodies. Through the passive transfer of sera from immunized mice to ZIKV-infected neonatal mice, it was demonstrated that these antibodies provide protection, mitigating weight loss, clinical or neurological signs induced by infection, and significantly increased survival rates. Protection was further substantiated by the reduction in the number of viable infectious ZIKV, as well as a decrease in inflammatory cytokines and tissue alterations in the brains of infected mice. Taken together, data presented in this study shows that NPPI + zEDIII is a promising vaccine candidate for ZIKV., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study compares the effects of virus-cell interactions among SARS-CoV-2 variants of concern (VOCs) isolated in Brazil in 2021, hypothesizing a correlation between cellular alterations and mortality and between viral load and transmissibility. For this purpose, reference isolates of Alpha, Gamma, Zeta, and Delta variants were inoculated into monolayers of Vero-E6 cells. Viral RNA was quantified in cell supernatants by RT‒PCR, and infected cells were analyzed by Transmission Electron Microscopy (TEM) for qualitative and quantitative evaluation of cellular changes 24, 48, and 72 hours postinfection (hpi). Ultrastructural analyses showed that all variants of SARS-CoV-2 altered the structure and function of mitochondria, nucleus, and rough endoplasmic reticulum of cells. Monolayers infected with the Delta variant showed the highest number of modified cells and the greatest statistically significant differences compared to those of other variants. Viral particles were observed in the cytosol and the cell membrane in 100 % of the cells at 48 hpi. Alpha showed the highest mean particle diameter (79 nm), and Gamma and Delta were the smallest (75 nm). Alpha and Gamma had the highest particle frequency per field at 48 hpi, while the same was observed for Zeta and Delta at 72 hpi and 24 hpi, respectively. The cycle threshold of viral RNA varied among the target protein, VOC, and time of infection. The findings presented here demonstrate that all four VOCs evaluated caused ultrastructural changes in Vero-E6 cells, which were more prominent when infection occured with the Delta variant., Competing Interests: Conflicts of interest The authors declare no have conflicts of interest., (Copyright © 2023 Sociedade Brasileira de Infectologia. Published by Elsevier España, S.L.U. All rights reserved.)

Yellow fever virus (YFV) is the agent of yellow fever (YF), which affects both humans and non-human primates (NHP). Neotropical NHP are highly susceptible to YFV and considered sentinels for YFV circulation. Brazil faced a significant YF outbreak in 2017-2018, with over 2000 human cases and 2000 epizootics cases, mainly in the State of Minas Gerais, Brazil. This study aimed to investigate whether YFV circulation persisted in NHP after the human outbreak had subsided. To this end, NHP carcass samples collected in Minas Gerais from 2021 to 2023 were screened for YFV. RNA was extracted from tissue fragments and used in RT-qPCR targeting the YFV 5'UTR. Liver and lung samples from 166 animals were tested, and the detection of the β-actin mRNA was used to ensure adequacy of RNA isolation. YFV RNA was detected in the liver of 18 NHP carcasses collected mainly from urban areas in 2021 and 2022. YFV positive NHP were mostly represented by Callithrix, from 5 out of the 12 grouped municipalities (mesoregions) in Minas Gerais state. These findings reveal the continued YFV circulation in NHP in urban areas of Minas Gerais during 2021 and 2022, with the attendant risk of re-establishing the urban YFV cycle.

Importance: Giant viruses are noteworthy not only due to their enormous particles but also because of their gigantic genomes. In this context, a fundamental question has persisted: how did these genomes evolve? Here we present the discovery of cedratvirus pambiensis, featuring the largest genome ever described for a cedratvirus. Our data suggest that the larger size of the genome can be attributed to an unprecedented number of duplicated genes. Further investigation of this phenomenon in other viruses has illuminated gene duplication as a key evolutionary mechanism driving genome expansion in diverse giant viruses. Although gene duplication has been described as a recurrent event in cellular organisms, our data highlights its potential as a pivotal event in the evolution of gigantic viral genomes., Competing Interests: The authors declare no conflict of interest.

Numerous Antarctic species are recognized as reservoirs for various pathogens, and their migratory behavior allows them to reach the Brazilian coast, potentially contributing to the emergence and circulation of new infectious diseases. To address the potential zoonotic risks, we conducted surveillance of influenza A virus (IAV) and coronaviruses (CoVs) in the Antarctic Peninsula, specifically focusing on different bird and mammal species in the region. During the summer of 2021/2022, as part of the Brazilian Antarctic Expedition, we collected and examined a total of 315 fecal samples to target these respiratory viruses. Although we did not detect the viruses of interest during this particular expedition, previous research conducted by our team has shown the presence of the H11N2 subtype of influenza A virus in penguin fecal samples from the same region. Given the continuous emergence of new viral strains worldwide, it is crucial to maintain active surveillance in the area, contributing to strengthening integrated One Health surveillance efforts.

Mutations in the SARS-CoV-2 genome can alter the virus' fitness, leading to the emergence of variants of concern (VOC). In Brazil, the Gamma variant dominated the pandemic in the first half of 2021, and from June onwards, the first cases of Delta infection were documented. Here, we investigate the introduction and dispersal of the Delta variant in the RS state by sequencing 1077 SARS-CoV-2-positive samples from June to October 2021. Of these samples, 34.7% were identified as Gamma and 65.3% as Delta. Notably, 99.2% of Delta sequences were clustered within the 21J lineage, forming a significant Brazilian clade. The estimated clock rate was 5.97 × 10 -4 substitutions per site per year. The Delta variant was first reported on 17 June in the Vinhedos Basalto microregion and rapidly spread, accounting for over 70% of cases within nine weeks. Despite this, the number of cases and deaths remained stable, possibly due to vaccination, prior infections, and the continued mandatory mask use. In conclusion, our study provides insights into the Delta variant circulating in the RS state, highlighting the importance of genomic surveillance for monitoring viral evolution, even when the impact of new variants may be less severe in a given region.

Chitin is a biopolymer profusely present in nature and of pivotal importance as a structural component in cells. It is degraded by chitinases, enzymes naturally produced by different organisms. Chitinases are proteins enrolled in many cellular mechanisms, including the remodeling process of the fungal cell wall, the cell growth process, the autolysis of filamentous fungi, and cell separation of yeasts, among others. These enzymes also have properties with different biotechnological applications. They are used to produce polymers, for biological control, biofilm formation, and as antitumor and anti-inflammatory target molecules. Chitinases are classified into different glycoside hydrolase (GH) families and are widespread in microorganisms, including viruses. Among them, the GH18 family is highly predominant in the viral genomes, being present and active enzymes in baculoviruses and nucleocytoplasmic large DNA viruses (NCLDV), especially chloroviruses from the Phycodnaviridae family. These viral enzymes contain one or more GH domains and seem to be involved during the viral replication cycle. Curiously, only a few DNA viruses have these enzymes, and studying their properties could be a key feature for biological and biotechnological novelties. Here, we provide an overview of viral chitinases and their probable function in viral infection, showing evidence of at least two distinct origins for these enzymes. Finally, we discuss how these enzymes can be applied as biotechnological tools and what one can expect for the coming years on these GHs., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Immunological and cytotoxic mediators are induced in natural infection and are essential for the effectiveness of vaccination. Vaccination is useful to prevent the spread of SARS-CoV-2 and limit the morbidity/mortality of COVID-19. ChAdOx1 nCoV-19 is one of the most widespread vaccines in the world. We compared the detection of anti-S1 SARS-CoV2 IgG and the profile of inflammatory and cytotoxic responses of patients who developed different clinical outcomes of COVID-19 with individuals previously exposed or not to the virus received the first and booster doses of ChAdOx1 nCoV-19. Plasma from 35 patients with COVID-19 and 11 vaccinated were evaluated by multiplex assay. Here, no vaccinated subjects had serious adverse effects. Those vaccinated with a booster dose had higher anti-S1 IgG than mild/moderate and recovered patients. Critically ill and deceased patients had IgG levels like those immunized. By univariate analysis, IL-2, IL-17, and perforin do not differentiate between patients and vaccinated individuals. Granzyme A increased at dose 1, while patients had their levels reduced. High levels of granulysin, sFas, and IL-6 were detected in the deaths, but after vaccination, all were declined. The multivariate analysis supports the role of IL-6 and granulysin as associated and non-confounding variables related to the worst clinical outcome of COVID-19, but not sFas. Our data confirm the ability of the ChAdOx1 vaccine to produce specific antibody levels up to booster time. Furthermore, our data suggest that the vaccine can regulate both the hyper-production and the kinetics of the production of inflammatory and cytotoxic mediators involved in the cytokine storm, such as granulysin and IL-6., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The capsid has a central role in viruses' life cycle. Although one of its major functions is to protect the viral genome, the capsid may be composed of elements that, at some point, promote interaction with host cells and trigger infection. Considering the scenario of multiple origins of viruses along the viral evolution, a substantial number of capsid shapes, sizes, and symmetries have been described. In this context, capsids of giant viruses (GV) that infect protists have drawn the attention of the scientific community, especially in the last 20 years, specifically for having bacterial-like dimensions with hundreds of different proteins and exclusive features. For instance, the surface fibrils present on the mimivirus capsid are one of the most intriguing features of the known virosphere. They are 150-nm-long structures attached to a 450-nm capsid, resulting in a particle with a hairy appearance. Surface fibrils have also been described in the capsids of other nucleocytoviruses, although they may differ substantially among them. In this mini review for non-experts, we compile the most important available information on surface fibrils of nucleocytoviruses, discussing their putative functions, composition, length, organization, and origins., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Large DNA viruses in the phylum Nucleocytoviricota, sometimes referred to as "giant viruses" owing to their large genomes and virions, have been the subject of burgeoning interest over the last decade. Here, we describe recently adopted taxonomic updates for giant viruses within the order Imitervirales. The families Allomimiviridae, Mesomimiviridae, and Schizomimiviridae have been created to accommodate the increasing diversity of mimivirus relatives that have sometimes been referred to in the literature as "extended Mimiviridae". In addition, the subfamilies Aliimimivirinae, Megamimivirinae, and Klosneuvirinae have been established to refer to subgroups of the Mimiviridae. Binomial names have also been adopted for all recognized species in the order. For example, Acanthamoeba polyphaga mimivirus is now classified in the species Mimivirus bradfordmassiliense., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

New variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged, imposing the need for periodic booster doses. However, whether booster doses should be applied to the entire population or groups, and the booster doses interval, remains unclear. In this study, we evaluated humoral reactivity kinetics from before the first dose to 180 days after the third booster dose in different schedules in a well-controlled health worker cohort. Among the 2,506 employees, the first 500 vaccinated health workers were invited to participate. The third booster dose was administered 8 months after the first dose. Among the invited participants, 470 were included in the study; 258 received inactivated vaccine CoronaVac (VAC group) and 212 received viral vector vaccine ChAdOx1 (AZV group). The groups were homogeneous in terms of age and sex. 347 participants were followed up after the booster dose with AZV or BNT162b2 (Pfizer, BNT group): 63 with VAC/AZV, 117 with VAC/BNT, 72 with the AZV/AZV and 95 with AZV/BNT schedules. Blood samples were collected immediately before, 28 days after each dose and 180 days after the primary vaccination and booster dose. Anti-SARS-CoV-2 antibodies were measured by chemiluminescence and plaque reduction neutralization test (PRNT). Plasma immune mediators were quantified using a multiplex immunoassay. Geometric mean of antibodies increased 28 days after the second dose with 100 % seroconversion rate in both groups and decreased 180 days after the first dose. In the baseline-seropositive VAC group, the levels of plasma immune mediators increased after the second dose. Booster dose was applied at 4-6 months after the primary vaccination. Heterologous booster in VAC or AZV primary vaccinees were effective maintaining the titers of anti-SARS-CoV-2 antibodies even after 6 months of follow-up. The heterologous schedule induced higher and stable antibody reactivity, even after 180 days, protecting to ancestral (Wuhan), Delta, and Omicron variants., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Background: There is interest in lingering non-specific symptoms after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, referred to as Long coronavirus disease 2019 (Long COVID-19). It remains unknown whether the risk of Long COVID-19 is associated with pre-existing comorbidities or initial COVID-19 severity, including infections due to new Omicron lineages which predominated in 2023., Objectives: The aim of this case report was to characterize the clinical features of acute XBB.1.5 infection followed by Long COVID-19., Methods: We followed a 73-year old female resident of Rio de Janeiro with laboratory-confirmed SARS-CoV-2 during acute infection and subsequent months. The SARS-CoV-2 lineage was determined by genome sequencing., Findings: The participant denied comorbidities and had completed a two-dose vaccination schedule followed by two booster doses eight months prior to SARS-CoV-2 infection. Primary infection by viral lineage XBB.1.5. was clinically mild, but the participant subsequently reported persistent fatigue., Main Conclusions: This case demonstrates that Long COVID-19 may develop even after mild disease due to SARS-CoV-2 in fully vaccinated and boosted individuals without comorbidities. Continued monitoring of new SARS-CoV-2 lineages and associated clinical outcomes is warranted. Measures to prevent infection should continue to be implemented including development of new vaccines and antivirals effective against novel variants.

The phylum Nucleocytoviricota includes the largest and most complex viruses known. These "giant viruses" have a long evolutionary history that dates back to the early diversification of eukaryotes, and over time they have evolved elaborate strategies for manipulating the physiology of their hosts during infection. One of the most captivating of these mechanisms involves the use of genes acquired from the host-referred to here as viral homologs or "virologs"-as a means of promoting viral propagation. The best-known examples of these are involved in mimicry, in which viral machinery "imitates" immunomodulatory elements in the vertebrate defense system. But recent findings have highlighted a vast and rapidly expanding array of other virologs that include many genes not typically found in viruses, such as those involved in translation, central carbon metabolism, cytoskeletal structure, nutrient transport, vesicular trafficking, and light harvesting. Unraveling the roles of virologs during infection as well as the evolutionary pathways through which complex functional repertoires are acquired by viruses are important frontiers at the forefront of giant virus research., (© The Author(s) 2023. Published by Oxford University Press on behalf of FEMS.)