Viral Dissemination Research Articles

Online rumors during the COVID-19 pandemic: co-evolution of themes and emotions.

During public health emergencies, online rumors spread widely on social media, causing public information anxiety and emotional fluctuations. Analyzing the co-evolution patterns of online rumor themes and emotions is essential for implementing proactive and precise governance of online rumors during such events. Rumor texts from mainstream fact-checking platforms during the COVID-19 pandemic were collected and analyzed in phases based on the crisis lifecycle theory. The LDA topic model was applied to analyze the distribution of rumor themes at different stages. The Baidu AI Sentiment Analysis API was used to study the emotional tendencies of rumors at different stages. Line graphs were utilized to analyze the co-evolution characteristics of rumor themes and emotions. During the COVID-19 pandemic, the themes of online rumors can be categorized into five types: epidemic prevention and control, panic-inducing, production and livelihood, virus dissemination, and social figures. These themes exhibited repetition and fluctuation at different stages of the pandemic. The emotions embedded in pandemic-related online rumors evolved with the progression of the pandemic. Panic-inducing rumors co-evolved with negative emotions, while epidemic prevention and control rumors co-evolved with positive emotions. The study results help to understand the public's focus and emotional tendencies at different stages of the COVID-19 pandemic, thereby enabling targeted public opinion guidance and crisis management.

Tracing the evolution of the chikungunya virus in Argentina, 2016-2023: independent introductions and prominence of Latin American lineages

ABSTRACT Chikungunya virus (CHIKV) has emerged as a significant public health concern due to its rapid spread and potential for causing debilitating epidemics. In Argentina, the virus has garnered attention since its introduction to the Americas in 2013, due to its growing incidence and impact in neighbouring countries. Here we present a comprehensive analysis of the spatiotemporal dynamics of CHIKV in Argentina, focusing on the evolutionary trajectory of its genetic variants. Through a combination of active surveillance, screening of historical and recent samples, and whole-genome sequencing, we traced the evolutionary history of CHIKV lineages circulating within the country. Our results reveal that two distinct genotypes circulated in Argentina: The Asian lineage during the 2016 epidemic and the ECSA lineage in 2023. This distribution reflects the dominance of particular variants across Latin America. Since 2023, the ECSA lineage has led to a surge in cases throughout the Americas, marking a significant shift. The replacement of lineages in the American region constitutes a major epidemiological event, potentially affecting the dynamics of virus transmission and the clinical outcomes in impacted populations. The spatiotemporal analysis highlights CHIKV's distribution across Argentina and underscores the significant role of human mobility, especially when considering recent epidemics in neighbouring countries such as Paraguay and Uruguay, which have facilitated the spread and introduction of the viral strain into different districts. By integrating epidemiological data with genomic insights, we elucidate the patterns of virus dissemination, highlighting key areas of transmission and potential factors contributing to its spread.

Widening geographic range of Rift Valley fever disease clusters associated with climate change in East Africa

BackgroundRecent epidemiology of Rift Valley fever (RVF) disease in Africa suggests growing frequency and expanding geographic range of small disease clusters in regions that previously had not reported the disease....

The viral protein NS1: a major player in the pathogenesis of orthoflaviviruses

Orthoflaviviruses are enveloped positive-sense RNA viruses comprising numerous human pathogens transmitted by hematophagous arthropods. This includes viruses such as dengue virus, Zika virus, and yellow fever virus. The viral nonstructural protein NS1 plays a central role in the pathogenesis and cycle of these viruses by acting in two different forms: associated with the plasma membrane (NS1m) or secreted outside the cell (NS1s). The versatility of NS1 is evident in its ability to modulate various aspects of the infectious process, from immune evasion to pathogenesis. As an intracellular protein, it disrupts many processes, interfering with signaling pathways and facilitating viral replication in concert with other viral proteins. As a secreted protein, NS1 actively participates in immune evasion, interfering with the host immune system, inhibiting the complement system, facilitating viral dissemination, and disrupting the integrity of endothelial barriers. This review primarily aims to address the role of NS1 in viral pathogenesis associated with orthoflaviviruses.

Neuropathological lesions in intravenous BCG-stimulated K18-hACE2 mice challenged with SARS-CoV-2

In the wake of the COVID-19 pandemic caused by SARS-CoV-2, questions emerged about the potential effects of Bacillus Calmette-Guérin (BCG) vaccine on the immune response to SARS-CoV-2 infection, including the neurodegenerative diseases it may contribute to. To explore this, an experimental study was carried out in BCG-stimulated and non-stimulated k18-hACE2 mice challenged with SARS-CoV-2. Viral loads in tissues determined by RT-qPCR, histopathology in brain and lungs, immunohistochemical study in brain (IHC) as well as mortality rates, clinical signs and plasma inflammatory and coagulation biomarkers were assessed. Our results showed BCG-SARS-CoV-2 challenged mice presented higher viral loads in the brain and an increased frequency of neuroinvasion, with the greatest differences observed between groups at 3–4 days post-infection (dpi). Histopathological examination showed a higher severity of brain lesions in BCG-SARS-CoV-2 challenged mice, mainly consisting of neuroinflammation, increased glial cell population and neuronal degeneration, from 5 dpi onwards. This group also presented higher interstitial pneumonia and vascular thrombosis in lungs (3–4 dpi), BCG-SARS-CoV-2 mice showed higher values for TNF-α and D-dimer values, while iNOS values were higher in SARS-CoV-2 mice at 3–4 dpi. Results presented in this study indicate that BCG stimulation could have intensified the inflammatory and neurodegenerative lesions promoting virus neuroinvasion and dissemination in this experimental model. Although k18-hACE2 mice show higher hACE2 expression and neurodissemination, this study suggests that, although the benefits of BCG on enhancing heterologous protection against pathogens and tumour cells have been broadly demonstrated, potential adverse outcomes due to the non-specific effects of BCG should be considered.

A novel collocation method with a coronavirus optimization algorithm for the optimal control of COVID-19: A case study of Wuhan, China

In this study, we develop a numerical optimization approach to address the challenge of optimal control in the spread of COVID-19. We evaluate the impact of various control strategies aimed at reducing the number of exposed and infectious individuals. Our novel approach employs Legendre wavelets, their derivative operational matrix, and a collocation method to transform the COVID-19 transmission optimal control model into a nonlinear programming (NLP) problem. To solve this problem, we employ a coronavirus optimization algorithm (COVIDOA) to determine the optimal control, state variables, and objective value. We investigate three control plans for this highly contagious disease, focusing on individual protection, rapid detection and treatment, detection with delay in treatment, and environmental viral dispersion as time-based control functions. These strategies are applied within an SEIR-type control model specific to COVID-19 in China, designed to mitigate disease spread. Lastly, we analyze the effects of various parameters within the COVID-19 spread model. Our numerical results highlight the significant impact of strategies that minimize the number of exposed and infectious individuals, particularly those related to rapid detection, detection delay, and environmental viral dispersion, in controlling and preventing the transmission of the COVID-19 virus.

Dengue virus exploits autophagy vesicles and secretory pathways to promote transmission by human dendritic cells.

Dengue virus (DENV), transmitted by infected mosquitoes, is a major public health concern, with approximately half the world's population at risk for infection. Recent decades have increasing incidence of dengue-associated disease alongside growing frequency of outbreaks. Although promising progress has been made in anti-DENV immunizations, post-infection treatment remains limited to non-specific supportive treatments. Development of antiviral therapeutics is thus required to limit DENV dissemination in humans and to help control the severity of outbreaks. Dendritic cells (DCs) are amongst the first cells to encounter DENV upon injection into the human skin mucosa, and thereafter promote systemic viral dissemination to additional human target cells. Autophagy is a vesicle trafficking pathway involving the formation of cytosolic autophagosomes, and recent reports have highlighted the extensive manipulation of autophagy by flaviviruses, including DENV, for viral replication. However, the temporal profiling and function of autophagy activity in DENV infection and transmission by human primary DCs remains poorly understood. Herein, we demonstrate that mechanisms of autophagosome formation and extracellular vesicle (EV) release have a pro-viral role in DC-mediated DENV transmission. We show that DENV exploits early-stage canonical autophagy to establish infection in primary human DCs. DENV replication enhanced autophagosome formation in primary human DCs, and intrinsically-heightened autophagosome biogenesis correlated with relatively higher rates of DC susceptibility to DENV. Furthermore, our data suggest that viral replication intermediates co-localize with autophagosomes, while productive DENV infection introduces a block at the late degradative stages of autophagy in infected DCs but not in uninfected bystander cells. Notably, we identify for the first time that approximately one-fourth of DC-derived CD9/CD81/CD63+ EVs co-express canonical autophagy marker LC3, and demonstrate that DC-derived EV populations are an alternative, cell-free mechanism by which DCs promote DENV transmission to additional target sites. Taken together, our study highlights intersections between autophagy and secretory pathways during viral infection, and puts forward autophagosome accumulation and viral RNA-laden EVs as host determinants of DC-mediated DENV infection in humans. Host-directed therapeutics targeting autophagy and exocytosis pathways thus have potential to enhance DC-driven resistance to DENV acquisition and thereby limit viral dissemination by initial human target cells following mosquito-to-human transmission of DENV.

High Frequencies of kdr Mutation and Chikungunya Infection in Aedes aegypti Population from Minas Gerais, Brazil.

The Chikungunya virus (CHIKV) presents global health challenges, with Brazil experiencing outbreaks since its introduction in 2014. In 2023, following a CHIKV outbreak in Minas Gerais (MG), social media was used to optimize an entomological survey aimed at identifying vectors and viral lineages and assessing insecticide resistance. Following Instagram posts, residents with suspected CHIKV infection were able to schedule mosquito aspirations. In total, 421 mosquitoes (165 Aedes aegypti and 256 Culex quinquefasciatus) were captured from 40 households in Salinas city (MG) and tested for the Dengue, Zika, and Chikungunya viruses through RT-qPCR. Twelve of 57 pools (10 Ae. aegypti and two Cx. quinquefasciatus) tested positive for CHIKV RNA. Viral RNA was also detected in the heads of nine Ae. aegypti, indicating viral dissemination but not in Cx. quinquefasciatus. Genome sequencing yielded the first near-complete genome from the 2023 outbreak, unveiling that the CHIKV strain belonged to the East/Central/South African (ECSA) genotype. Additionally, genetic analyses revealed high frequencies of kdr alleles, including in CHIKV-infected mosquitoes, suggesting resistance to pyrethroid insecticides in this Ae. aegypti population. Social media was important for guiding mosquito-capture efforts in CHIKV transmission hotspots, thus optimizing the opportunity for viral detection. These findings emphasize the urgent need for innovative vector studies and control strategies, as well as interdisciplinary approaches in public health interventions.

Exosomes as Conduits: Facilitating Hepatitis B Virus-Independent Hepatitis D Virus Transmission and Propagation in Hepatocytes.

A number of research studies, including ours, have spotlighted exosomes as critical facilitators of viral dissemination. While hepatitis B virus (HBV) transmission through exosomes has been studied, the focus on its satellite virus, the hepatitis delta virus (HDV), has been unexplored in this context. HDV, although being a defective virus, can replicate its genome autonomously within hepatocytes, independently of HBV. Investigations on Huh7 cells revealed an intriguing phenomenon: the HDV proteins, S-HDAg and L-HDAg, are transmitted between cells without a complete viral structure. Detailed analysis further revealed that the expression of these proteins not only bolstered exosome secretion but also ensured their enrichment within these vesicles. Our experimental approach utilized transfection of various plasmids to examine the role of HDV RNA and proteins in the process. One salient finding was the differential propagation of the HDV proteins S-HDAg and L-HDAg, suggesting intricate molecular mechanisms behind their transmission. Notably, the purity of our exosome preparations was monitored using markers such as TSG101 and CD81. Importantly, these exosomes were found to carry both HDV RNA and proteins, highlighting their role in HDV dissemination. This novel study underscores the role of exosomes in mediating the transmission of HDV components between hepatocytes independent of HBV. These revelations about the exosomal pathway of HDV transmission provide a foundation for the development of innovative therapeutic strategies against HDV infections.

Natural IgG protects against early dissemination of vesicular stomatitis virus

Neonatal Fc receptor (FcRn) recycles immunoglobulin G, and inhibition of FcRn is used clinically for treatment of autoimmune diseases. In this work, using the vesicular stomatitis virus (VSV) mouse infection model system, we determined the role of FcRn during virus infection. While induction of neutralizing antibodies and long-term protection of these antibodies was hardly affected in FcRn deficient mice, FcRn deficiency limited the amount of natural IgG (VSV-specific) antibodies. Lack of natural antibodies (nAbs) limited early control of VSV in macrophages, accelerated propagation of virus in several organs, led to the spread of VSV to the neural tissue resulting in fatal outcomes. Adoptive transfer of natural IgG into FcRn deficient mice limited early propagation of VSV in FcRn deficient mice and enhanced survival of FcRn knockout mice. In line with this, vaccination of FcRn mice with very low dose of VSV prior to infection similarly prevented death after infection. In conclusion we determined the importance of nAbs during VSV infection. Lack of FcRn limited nAbs and thereby enhanced the susceptibility to virus infection.

Dynamics and Control Strategies for SLBRS Model of Computer Viruses Based on Complex Networks

Dynamics and Control Strategies for SLBRS Model of Computer Viruses Based on Complex Networks

Ecological Requirements for Abundance and Dispersion of Brazilian Yellow Fever Vectors in Tropical Areas.

In the Americas, wild yellow fever (WYF) is an infectious disease that is highly lethal for some non-human primate species and non-vaccinated people. Specifically, in the Brazilian Atlantic Forest, Haemagogus leucocelaenus and Haemagogus janthinomys mosquitoes act as the major vectors. Despite transmission risk being related to vector densities, little is known about how landscape structure affects vector abundance and movement. To fill these gaps, we used vector abundance data and a model-selection approach to assess how landscape structure affects vector abundance, aiming to identify connecting elements for virus dispersion in the state of São Paulo, Brazil. Our findings show that Hg. leucocelaenus and Hg. janthinomys abundances, in highly degraded and fragmented landscapes, are mainly affected by increases in forest cover at scales of 2.0 and 2.5 km, respectively. Fragmented landscapes provide ecological corridors for vector dispersion, which, along with high vector abundance, promotes the creation of risk areas for WYF virus spread, especially along the border with Minas Gerais state, the upper edges of the Serra do Mar, in the Serra da Cantareira, and in areas of the metropolitan regions of São Paulo and Campinas.

Mapping the Proposed Caribbean Zoonotic (Swine Influenza) Epidemic of 1493 As a Geographic Model of Infectious Virus Dispersion

This paper investigates the proposed 1493 zoonotic (swine influenza) pandemic that swept through the Spanish colony at La Isabela, Hispaniola. Primary and secondary accounts of the malady describe the attributed symptoms as summarized in the work of Guerra (1988) and attempt to predict the geographic spread of the zoonosis as a series of four expanding regional stages, beginning at La Isabela and nearby Indigenous villages, moving outward along known valley pathways, engulfing northern Hispaniola, and finally transporting the infectious disease to the nearby islands of Cuba, Puerto Rico, Jamaica, and the Bahama Archipelago, with the possibility of spreading to the Lesser Antilles, the eastern coast of Yucatan and Honduras, and the northern coast of South America. This proposed geographic virus dispersion model includes a series of island maps that locate selected archeological sites of known villages along with suggested travel times, providing a historical record of viral spread tracing.

A multi-species, multi-pathogen avian viral disease outbreak event: Investigating potential for virus transmission at the wild bird – poultry interface

ABSTRACT A free-range organic broiler (Gallus gallus domesticus) premises in Staffordshire was infected by high pathogenicity avian influenza virus (HPAIV) H5N8 during the 2020–2021 epizootic in the United Kingdom (UK). Following initial confirmation of the infection in poultry, multiple wild bird species were seen scavenging on chicken carcasses. Detected dead wild birds were subsequently demonstrated to have been infected and succumbed to HPAIV H5N8. Initially, scavenging species, magpie (Pica pica) and raven (Corvus corax) were found dead on the premises but over the following days, buzzards (Buteo buteo) were also found dead within the local area with positive detection of HPAIV in submitted carcasses. The subacute nature of microscopic lesions within a buzzard was consistent with the timeframe of infection. Finally, a considerable number of free-living pheasants (Phasianus colchicus) were also found dead in the surrounding area, with carcasses having higher viral antigen loads compared to infected chickens. Limited virus dissemination was observed in the carcasses of the magpie, raven, and buzzard. Further, an avirulent avian paramyxovirus type 1 (APMV-1) was detected within poultry samples as well as in the viscera of a magpie infected with HPAIV. Immunohistochemistry did not reveal colocalization of avian paramyxovirus antigens with lesions, supporting an avirulent APMV-1 infection. Overall, this case highlights scenarios in which bi-directional transmission of avian viral diseases between commercial and wild bird species may occur. It also underlines the importance of bio separation and reduced access when infection pressure from HPAIV is high.

Contemporary Strategies for Managing and Controlling Viral Outbreaks: An Overview

Viruses are notorious for causing a significant array of infectious diseases, rendering them a prominent contributor to global morbidity and mortality rates. Throughout history, various regions have experienced outbreaks, epidemics, and pandemics, resulting in significant mortality rates. The Influenza virus gave rise to highly fatal outbreaks that disseminated on a global scale, subsequently resulting in a pandemic during the initial decades of the 20th century. This catastrophic event led to >75 million fatalities, accompanied by a substantial incidence of illnesses. In addition to the development of efficacious treatments for viral diseases, it is imperative to establish and implement various preventive measures to mitigate the transmission of diseases within both local and global populations. Furthermore, it is critical to implement proven conventional and contemporary strategies for managing viral infections, alongside bolstered surveillance systems. Viruses employ diverse modes of transmission, encompassing respiratory, oral-fecal, blood-borne, and vector-borne pathways. Consequently, effective measures to mitigate viral dissemination must be tailored to address each distinct route of transmission. This review discusses the existing strategies employed to mitigate the transmission and containment of viral outbreaks, as well as the dissemination of the disease within a sizable population, intending to reduce their detrimental and fatal impacts on a community.

The High Capacity of Brazilian Aedes aegypti Populations to Transmit a Locally Circulating Lineage of Chikungunya Virus.

The incidence of chikungunya has dramatically surged worldwide in recent decades, imposing an expanding burden on public health. In recent years, South America, particularly Brazil, has experienced outbreaks that have ravaged populations following the rapid dissemination of the chikungunya virus (CHIKV), which was first detected in 2014. The primary vector for CHIKV transmission is the urban mosquito species Aedes aegypti, which is highly prevalent throughout Brazil. However, the impact of the locally circulating CHIKV genotypes and specific combinations of local mosquito populations on vector competence remains unexplored. Here, we experimentally analyzed and compared the infectivity and transmissibility of the CHIKV-ECSA lineage recently isolated in Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected AG129 mice for blood feeding, all the mosquito populations displayed high infection rates and dissemination efficiency. Furthermore, we observed that all the populations were highly efficient in transmitting CHIKV to a vertebrate host (naïve AG129 mice) as early as eight days post-infection. These results demonstrate the high capacity of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage. This observation could help to explain the high prevalence of the CHIKV-ECSA lineage over the Asian lineage, which was also detected in Brazil in 2014. However, further studies comparing both lineages are necessary to gain a better understanding of the vector's importance in the epidemiology of CHIKV in the Americas.

In Ovo Models to Predict Virulence of Highly Pathogenic Avian Influenza H5-Viruses for Chickens and Ducks.

Highly pathogenic avian influenza (HPAI) H5-viruses are circulating in wild birds and are repeatedly introduced to poultry causing outbreaks in the Netherlands since 2014. The largest epizootic ever recorded in Europe was caused by HPAI H5N1 clade 2.3.4.4b viruses in the period 2021-2022. The recent H5-clade 2.3.4.4 viruses were found to differ in their virulence for chickens and ducks. Viruses causing only mild disease may remain undetected, increasing the risk of virus spread to other farms, wild birds and mammals. We developed in ovo models to determine the virulence of HPAI viruses for chickens and ducks, which are fast and have low costs. The virulence of five contemporary H5-viruses was compared studying replication rate, average time to death and virus spread in the embryo. Remarkable differences in virulence were observed between H5-viruses and between poultry species. The H5N1-2021 virus was found to have a fast replication rate in both the chicken and duck in ovo models, but a slower systemic virus dissemination compared to three other H5-clade 2.3.4.4b viruses. The results show the potential of in ovo models to quickly determine the virulence of novel HPAI viruses, and study potential virulence factors which can help to better guide the surveillance in poultry.

Infection, dissemination, and transmission of lumpy skin disease virus in Aedes aegypti (Linnaeus), Culex tritaeniorhynchus (Giles), and Culex quinquefasciatus (Say) mosquitoes

Lumpy skin disease virus (LSDV) is a transboundary viral disease in cattle and water buffaloes. Although this Poxvirus is supposedly transmitted by mechanical vectors, only a few studies have investigated the role of local vectors in the transmission of LSDV. This study examined the infection, dissemination, and transmission rates of LSDV in Aedes aegypti, Culex tritaeniorhynchus, and Culex quinquefasciatus following artificial membrane feeding of 102.7, 103.7, 104.7 TCID50/mL LSDV in sheep blood. The results demonstrated that these mosquito species were susceptible to LSDV, with Cx tritaeniorhynchus exhibiting significantly different characteristics from Ae. aegypti and Cx. quinquefasciatus. These three mosquito species were susceptible to LSDV. Ae. aegypti showed it as early as 2 days post-infection (dpi), indicating swift dissemination in this particular species. The extrinsic incubation period (EIP) of LSDV in Cx. tritaeniorhynchus and Cx. quinquefasciatus was 8 and 14 dpi, respectively. Ingestion of different viral titers in blood did not affect the infection, dissemination, or transmission rates of Cx. tritaeniorhynchus and Cx. quinquefasciatus. All rates remained consistently high at 8–14 dpi for Cx. tritaeniorhynchus. In all three species, LSDV remained detectable until 14 dpi. The present findings indicate that, Ae. aegypti, Cx. tritaeniorhynchus, and Cx. quinquefasciatus may act as vectors during the LSDV outbreak; their involvement may extend beyond being solely mechanical vectors.

Kaposi’s Varicelliform Eruption in a Patient with Darier’s Disease: A Rare Case Report

Darier's disease is a rare autosomal dominant disorder, characterized clinically by the appearance of multiple, pruritic, discrete, and scaly papules affecting seborrheic areas coupled with palmar pits, nail changes, and mucosal involvement. Histologically, the lesions show supra-basal clefts with acantholytic and dyskeratotic cells. Kaposi's varicelliform eruption (KVE) is the dissemination of the herpes simplex virus in the setting of preexisting skin disease, presenting with disseminated vesico-pustules. Darier's disease presenting as KVE is a rare occurrence. If misdiagnosed or left untreated can increase the rate of mortality. Here, we report the case of a 25-year-old male patient who presented with multiple vesicles and crusted lesions over the face, neck, chest, and upper back. After thorough cutaneous examination, he was found to have multiple hyperkeratotic, dirty-warty papules over seborrheic areas, present since childhood. With detailed clinical and laboratory evaluation, we arrived at the diagnosis of KVE with underlying Darier disease.

Evaluation of 5 Polymerase Chain Reaction Assays for the Detection of Mpox Virus.

In 2022, the global dissemination of mpox virus (MPXV) outside endemic regions prompted the expansion of diagnostic testing worldwide. This study assesses the performance characteristics of 5 real-time polymerase chain reaction (PCR) assays in detecting MPXV during the 2022 outbreak. Clinical specimens collected from patients across Ontario, Canada, were tested on the following assays: RealStar Orthopoxyvirus PCR and FlexStar Monkeypox virus PCR (Altona Diagnostics), Novaplex MPXV (Seegene), VIASURE Monkeypox virus Real Time PCR Reagents (CerTest Biotec), and a laboratory-developed test. Positive percent agreement (PPA), negative percent agreement (NPA), relative limit of detection (LOD), and precision were evaluated and MPXV lineages were determined using an amplicon-based whole-genome sequencing (WGS) assay. Swabs were collected from various anatomic sites (65 positive and 30 negative). All assays demonstrated 100% NPA (95% confidence interval, 88.4%/88.1%-100.0%), with PPA ranging from 92.2% (82.7%-97.4%) to 96.9% (89.3%-99.6%). LOD and precision were comparable across assays, with coefficient of variations <3%. WGS analysis identified 6 lineages, all belonging to subclade IIb. The assays exhibited excellent PPA, NPA, LOD, and precision. Ongoing performance monitoring is essential to detect assay escape mutants and ensure universal detection of evolving MPXV strains.