Journal Description
Viruses
Viruses
is a peer-reviewed, open access journal of virology, published monthly online by MDPI. The American Society for Virology (ASV), Spanish Society for Virology (SEV), Canadian Society for Virology (CSV), Italian Society for Virology (SIV-ISV), Australasian Virology Society (AVS) and others are affiliated with Viruses and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, MEDLINE, PMC, Embase, PubAg, AGRIS, and other databases.
- Journal Rank: JCR - Q2 (Virology) / CiteScore - Q1 (Infectious Diseases)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 13.8 days after submission; acceptance to publication is undertaken in 2.5 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journals for Viruses include: COVID and Zoonotic Diseases.
Impact Factor:
4.7 (2022);
5-Year Impact Factor:
4.8 (2022)
Latest Articles
Exploring Viral Genome Profile in Mpox Patients during the 2022 Outbreak, in a North-Eastern Centre of Italy
Viruses 2024, 16(5), 726; https://doi.org/10.3390/v16050726 - 03 May 2024
Abstract
In 2022, an unprecedented outbreak of mpox raged in several nations. Sequences from the 2022 outbreak reveal a higher nucleotide substitution if compared with the estimated rate for orthopoxviruses. Recently, intra-lesion SNVs (single nucleotide variants) have been described, and these have been suggested
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In 2022, an unprecedented outbreak of mpox raged in several nations. Sequences from the 2022 outbreak reveal a higher nucleotide substitution if compared with the estimated rate for orthopoxviruses. Recently, intra-lesion SNVs (single nucleotide variants) have been described, and these have been suggested as possible sources of genetic variation. Until now, it has not been clear if the presence of several SNVs could represents the result of local mutagenesis or a possible co-infection. We investigated the significance of SNVs through whole-genome sequencing analysis of four unrelated mpox cases. In addition to the known mutations harboured by the circulating strains of virus (MPXV), 7 novel mutations were identified, including SNVs located in genes that are involved in immune evasion mechanisms and/or viral fitness, six of these appeared to be APOBEC3-driven. Interestingly, three patients exhibited the coexistence of mutated and wild-type alleles for five non-synonymous variants. In addition, two patients, apparently unrelated, showed an analogous pattern for two novel mutations, albeit with divergent frequencies. The coexistence of mixed viral populations, harbouring non-synonymous mutations in patients, supports the hypothesis of possible co-infection. Additional investigations of larger clinical cohorts are essential to validating intra-patient viral genome heterogeneity and determining the possibility of co-presence events of slightly divergent MPXV strains.
Full article
(This article belongs to the Topic Human Monkeypox Research)
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Open AccessArticle
CRISPR Screen Reveals PACT as a Pro-Viral Factor for Dengue Viral Replication
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Shwetha Shivaprasad, Wenjie Qiao, Kuo-Feng Weng, Pavithra Umashankar, Jan E. Carette and Peter Sarnow
Viruses 2024, 16(5), 725; https://doi.org/10.3390/v16050725 - 03 May 2024
Abstract
The dengue virus is a single-stranded, positive-sense RNA virus that infects ~400 million people worldwide. Currently, there are no approved antivirals available. CRISPR-based screening methods have greatly accelerated the discovery of host factors that are essential for DENV infection and that can be
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The dengue virus is a single-stranded, positive-sense RNA virus that infects ~400 million people worldwide. Currently, there are no approved antivirals available. CRISPR-based screening methods have greatly accelerated the discovery of host factors that are essential for DENV infection and that can be targeted in host-directed antiviral interventions. In the present study, we performed a focused CRISPR (Clustered Regularly Interspaced Palindromic Repeats) library screen to discover the key host factors that are essential for DENV infection in human Huh7 cells and identified the Protein Activator of Interferon-Induced Protein Kinase (PACT) as a novel pro-viral factor for DENV. PACT is a double-stranded RNA-binding protein generally known to activate antiviral responses in virus-infected cells and block viral replication. However, in our studies, we observed that PACT plays a pro-viral role in DENV infection and specifically promotes viral RNA replication. Knockout of PACT resulted in a significant decrease in DENV RNA and protein abundances in infected cells, which was rescued upon ectopic expression of full-length PACT. An analysis of global gene expression changes indicated that several ER-associated pro-viral genes such as ERN1, DDIT3, HERPUD1, and EIF2AK3 are not upregulated in DENV-infected PACT knockout cells as compared to infected wildtype cells. Thus, our study demonstrates a novel role for PACT in promoting DENV replication, possibly through modulating the expression of ER-associated pro-viral genes.
Full article
(This article belongs to the Special Issue Host Cell-Virus Interaction, 3rd Edition)
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Open AccessReview
Hepatitis B Virus Infection: A Mini Review
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Diana Asema Asandem, Selorm Philip Segbefia, Kwadwo Asamoah Kusi and Joseph Humphrey Kofi Bonney
Viruses 2024, 16(5), 724; https://doi.org/10.3390/v16050724 - 03 May 2024
Abstract
Hepatitis B and C viruses (HBV and HCV) are the leading causes of end-stage liver disease worldwide. Although there is a potent vaccine against HBV, many new infections are recorded annually, especially in poorly resourced places which have lax vaccination policies. Again, as
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Hepatitis B and C viruses (HBV and HCV) are the leading causes of end-stage liver disease worldwide. Although there is a potent vaccine against HBV, many new infections are recorded annually, especially in poorly resourced places which have lax vaccination policies. Again, as HBV has no cure and chronic infection is lifelong, vaccines cannot help those already infected. Studies to thoroughly understand the HBV biology and pathogenesis are limited, leaving much yet to be understood about the genomic features and their role in establishing and maintaining infection. The current knowledge of the impact on disease progression and response to treatment, especially in hyperendemic regions, is inadequate. This calls for in-depth studies on viral biology, mainly for the purposes of coming up with better management strategies for infected people and more effective preventative measures for others. This information could also point us in the direction of a cure. Here, we discuss the progress made in understanding the genomic basis of viral activities leading to the complex interplay of the virus and the host, which determines the outcome of HBV infection as well as the impact of coinfections.
Full article
(This article belongs to the Special Issue Viral Hepatitis Coinfection)
Open AccessArticle
Long-Read Nanopore-Based Sequencing of Anelloviruses
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Raghavendran Anantharam, Dylan Duchen, Andrea L. Cox, Winston Timp, David L. Thomas, Steven J. Clipman and Abraham J. Kandathil
Viruses 2024, 16(5), 723; https://doi.org/10.3390/v16050723 - 02 May 2024
Abstract
Routinely used metagenomic next-generation sequencing (mNGS) techniques often fail to detect low-level viremia (<104 copies/mL) and appear biased towards viruses with linear genomes. These limitations hinder the capacity to comprehensively characterize viral infections, such as those attributed to the Anelloviridae family. These
[...] Read more.
Routinely used metagenomic next-generation sequencing (mNGS) techniques often fail to detect low-level viremia (<104 copies/mL) and appear biased towards viruses with linear genomes. These limitations hinder the capacity to comprehensively characterize viral infections, such as those attributed to the Anelloviridae family. These near ubiquitous non-pathogenic components of the human virome have circular single-stranded DNA genomes that vary in size from 2.0 to 3.9 kb and exhibit high genetic diversity. Hence, species identification using short reads can be challenging. Here, we introduce a rolling circle amplification (RCA)-based metagenomic sequencing protocol tailored for circular single-stranded DNA genomes, utilizing the long-read Oxford Nanopore platform. The approach was assessed by sequencing anelloviruses in plasma drawn from people who inject drugs (PWID) in two geographically distinct cohorts. We detail the methodological adjustments implemented to overcome difficulties inherent in sequencing circular genomes and describe a computational pipeline focused on anellovirus detection. We assessed our protocol across various sample dilutions and successfully differentiated anellovirus sequences in conditions simulating mixed infections. This method provides a robust framework for the comprehensive characterization of circular viruses within the human virome using the Oxford Nanopore.
Full article
(This article belongs to the Special Issue Advancing Research of Anelloviruses)
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Open AccessArticle
Gut Microbiome and Cytokine Profiles in Post-COVID Syndrome
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Karakoz Mussabay, Samat Kozhakhmetov, Marat Dusmagambetov, Aitolkyn Mynzhanova, Madiyar Nurgaziyev, Zharkyn Jarmukhanov, Elizaveta Vinogradova, Aigul Dusmagambetova, Aiganym Daulbaeva, Laura Chulenbayeva, Ainur Tauekelova, Makhabbat Bekbossynova and Almagul Kushugulova
Viruses 2024, 16(5), 722; https://doi.org/10.3390/v16050722 - 02 May 2024
Abstract
Recent studies highlight the crucial role of the gut microbiome in post-infectious complications, especially in patients recovering from severe COVID-19. Our research aimed to explore the connection between gut microbiome changes and the cytokine profile of patients with post-COVID syndrome. Using 16S rRNA
[...] Read more.
Recent studies highlight the crucial role of the gut microbiome in post-infectious complications, especially in patients recovering from severe COVID-19. Our research aimed to explore the connection between gut microbiome changes and the cytokine profile of patients with post-COVID syndrome. Using 16S rRNA amplicon sequencing, we analyzed the composition of the gut microbiome in 60 COVID-19 patients over the course of one year. We also measured the levels of serum cytokines and chemokines using the Milliplex system. Our results showed that severe SARS-CoV-2 infection cases, especially those complicated by pneumonia, induce a pro-inflammatory microbial milieu with heightened presence of Bacteroides, Faecalibacterium, and Prevotella_9. Furthermore, we found that post-COVID syndrome is characterized by a cross-correlation of various cytokines and chemokines MDC, IL-1b, Fractalkine, TNFa, FGF-2, EGF, IL-1RA, IFN-a2, IL-10, sCD40L, IL-8, Eotaxin, IL-12p40, and MIP-1b as well as a shift in the gut microbiome towards a pro-inflammatory profile. At the functional level, our analysis revealed associations with post-COVID-19 in homolactic fermentation, pentose phosphate, NAD salvage, and flavin biosynthesis. These findings highlight the intricate interplay between the gut microbiota, their metabolites, and systemic cytokines in shaping post-COVID symptoms. Unraveling the gut microbiome’s role in post-infectious complications opens avenues for new treatments for those patients with prolonged symptoms.
Full article
(This article belongs to the Special Issue COVID-19 and Gastrointestinal Symptoms)
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Open AccessArticle
Epigenetic Modifications of White Blood Cell DNA Caused by Transient Fetal Infection with Bovine Viral Diarrhea Virus
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Hana Van Campen, Jeanette V. Bishop, Zella Brink, Terry E. Engle, Carolina L. Gonzalez-Berrios, Hanah M. Georges, Jessica N. Kincade, Dilyara A. Murtazina and Thomas R. Hansen
Viruses 2024, 16(5), 721; https://doi.org/10.3390/v16050721 - 01 May 2024
Abstract
Bovine viral diarrhea virus (BVDV) infections cause USD 1.5–2 billion in losses annually. Maternal BVDV after 150 days of gestation causes transient fetal infection (TI) in which the fetal immune response clears the virus. The impact of fetal TI BVDV infections on postnatal
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Bovine viral diarrhea virus (BVDV) infections cause USD 1.5–2 billion in losses annually. Maternal BVDV after 150 days of gestation causes transient fetal infection (TI) in which the fetal immune response clears the virus. The impact of fetal TI BVDV infections on postnatal growth and white blood cell (WBC) methylome as an index of epigenetic modifications was examined by inoculating pregnant heifers with noncytopathic type 2 BVDV or media (sham-inoculated controls) on Day 175 of gestation to generate TI (n = 11) and control heifer calves (n = 12). Fetal infection in TI calves was confirmed by virus-neutralizing antibody titers at birth and control calves were seronegative. Both control and TI calves were negative for BVDV RNA in WBCs by RT-PCR. The mean weight of the TI calves was less than that of the controls (p < 0.05). DNA methyl seq analysis of WBC DNA demonstrated 2349 differentially methylated cytosines (p ≤ 0.05) including 1277 hypomethylated cytosines, 1072 hypermethylated cytosines, 84 differentially methylated regions based on CpGs in promoters, and 89 DMRs in islands of TI WBC DNA compared to controls. Fetal BVDV infection during late gestation resulted in epigenomic modifications predicted to affect fetal development and immune pathways, suggesting potential consequences for postnatal growth and health of TI cattle.
Full article
(This article belongs to the Special Issue Epigenetic Modifications in Viral Infections)
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Open AccessArticle
Low-Level Viremia among Adults Living with HIV on Dolutegravir-Based First-Line Antiretroviral Therapy Is a Predictor of Virological Failure in Botswana
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Ontlametse T. Bareng, Sikhulile Moyo, Mbatshi Mudanga, Kagiso Sebina, Catherine K. Koofhethile, Wonderful T. Choga, Natasha O. Moraka, Dorcas Maruapula, Irene Gobe, Modisa S. Motswaledi, Rosemary Musonda, Bornapate Nkomo, Dinah Ramaabya, Tony Chebani, Penny Makuruetsa, Joseph Makhema, Roger Shapiro, Shahin Lockman and Simani Gaseitsiwe
Viruses 2024, 16(5), 720; https://doi.org/10.3390/v16050720 - 01 May 2024
Abstract
We evaluated subsequent virologic outcomes in individuals experiencing low-level virem ia (LLV) on dolutegravir (DTG)-based first-line antiretroviral therapy (ART) in Botswana. We used a national dataset from 50,742 adults who initiated on DTG-based first-line ART from June 2016–December 2022. Individuals with at least
[...] Read more.
We evaluated subsequent virologic outcomes in individuals experiencing low-level virem ia (LLV) on dolutegravir (DTG)-based first-line antiretroviral therapy (ART) in Botswana. We used a national dataset from 50,742 adults who initiated on DTG-based first-line ART from June 2016–December 2022. Individuals with at least two viral load (VL) measurements post three months on DTG-based first-line ART were evaluated for first and subsequent episodes of LLV (VL:51–999 copies/mL). LLV was sub-categorized as low-LLV (51–200 copies/mL), medium-LLV (201–400 copies/mL) and high-LLV (401–999 copies/mL). The study outcome was virologic failure (VF) (VL ≥ 1000 copies/mL): virologic non-suppression defined as single-VF and confirmed-VF defined as two-consecutive VF measurements after an initial VL < 1000 copies/mL. Cox regression analysis identified predictive factors of subsequent VF. The prevalence of LLV was only statistically different at timepoints >6–12 (2.8%) and >12–24 (3.9%) (p-value < 0.01). LLV was strongly associated with both virologic non-suppression (adjusted hazards ratio [aHR] = 2.6; 95% CI: 2.2–3.3, p-value ≤ 0.001) and confirmed VF (aHR = 2.5; 95% CI: 2.4–2.7, p-value ≤ 0.001) compared to initially virally suppressed PLWH. High-LLV (HR = 3.3; 95% CI: 2.9–3.6) and persistent-LLV (HR = 6.6; 95% CI: 4.9–8.9) were associated with an increased hazard for virologic non-suppression than low-LLV and a single-LLV episode, respectively. In a national cohort of PLWH on DTG-based first-line ART, LLV > 400 copies/mL and persistent-LLV had a stronger association with VF. Frequent VL testing and adherence support are warranted for individuals with VL > 50 copies/mL.
Full article
(This article belongs to the Special Issue HIV Reservoirs, Latency, and the Factors Responsible)
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Open AccessBrief Report
Seroprevalence of West Nile Virus in Tampa Bay Florida Patients Admitted to Hospital during 2020–2021 for Respiratory Symptoms
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Emma C. Underwood, Iset M. Vera, Dylan Allen, Joshua Alvior, Marci O’Driscoll, Suzane Silbert, Kami Kim and Kelli L. Barr
Viruses 2024, 16(5), 719; https://doi.org/10.3390/v16050719 - 30 Apr 2024
Abstract
West Nile virus (WNV) is an arbovirus spread primarily by Culex mosquitoes, with humans being a dead-end host. WNV was introduced to Florida in 2001, with 467 confirmed cases since. It is estimated that 80 percent of cases are asymptomatic, with mild cases
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West Nile virus (WNV) is an arbovirus spread primarily by Culex mosquitoes, with humans being a dead-end host. WNV was introduced to Florida in 2001, with 467 confirmed cases since. It is estimated that 80 percent of cases are asymptomatic, with mild cases presenting as a non-specific flu-like illness. Currently, detection of WNV in humans occurs primarily in healthcare settings via RT-PCR or CSF IgM when patients present with severe manifestations of disease including fever, meningitis, encephalitis, or acute flaccid paralysis. Given the short window of detectable viremia and requirement for CSF sampling, most WNV infections never receive an official diagnosis. This study utilized enzyme-linked immunosorbent assay (ELISA) to detect WNV IgG antibodies in 250 patient serum and plasma samples collected at Tampa General Hospital during 2020 and 2021. Plaque reduction neutralization tests were used to confirm ELISA results. Out of the 250 patients included in this study, 18.8% of them were IgG positive, consistent with previous WNV exposure. There was no relationship between WNV exposure and age or sex.
Full article
(This article belongs to the Section Human Virology and Viral Diseases)
Open AccessBrief Report
Nirmatrelvir Resistance in an Immunocompromised Patient with Persistent Coronavirus Disease 2019
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Chie Yamamoto, Masashi Taniguchi, Keitaro Furukawa, Toru Inaba, Yui Niiyama, Daisuke Ide, Shinsuke Mizutani, Junya Kuroda, Yoko Tanino, Keisuke Nishioka, Yohei Watanabe, Koichi Takayama, Takaaki Nakaya and Yoko Nukui
Viruses 2024, 16(5), 718; https://doi.org/10.3390/v16050718 - 30 Apr 2024
Abstract
Although the coronavirus disease 2019 (COVID-19) pandemic is coming to an end, it still poses a threat to the immunocompromised and others with underlying diseases. Especially in cases of persistent COVID-19, new mutations conferring resistance to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
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Although the coronavirus disease 2019 (COVID-19) pandemic is coming to an end, it still poses a threat to the immunocompromised and others with underlying diseases. Especially in cases of persistent COVID-19, new mutations conferring resistance to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) therapies have considerable clinical implications. We present a patient who independently acquired a T21I mutation in the 3CL protease after nirmatrelvir exposure. The T21I mutation in the 3CL protease is one of the most frequent mutations responsible for nirmatrelvir resistance. However, limited reports exist on actual cases of SARS-CoV-2 with T21I and other mutations in the 3CL protease. The patient, a 55 year-old male, had COVID-19 during chemotherapy for multiple myeloma. He was treated with nirmatrelvir early in the course of the disease but relapsed, and SARS-CoV-2 with a T21I mutation in the 3CL protease was detected in nasopharyngeal swab fluid. The patient had temporary respiratory failure but later recovered well. During treatment with remdesivir and dexamethasone, viruses with the T21I mutation in the 3CL protease showed a decreasing trend during disease progression while increasing during improvement. The impact of drug-resistant SARS-CoV-2 on the clinical course, including its severity, remains unknown. Our study is important for examining the clinical impact of nirmatrelvir resistance in COVID-19.
Full article
(This article belongs to the Special Issue Basic Sciences for the Conquest of COVID-19)
Open AccessArticle
Immunological Response against Breast Lineage Cells Transfected with Human Papillomavirus (HPV)
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Daffany Luana Santos, Bianca de França São Marcos, Georon Ferreira de Sousa, Leonardo Carvalho de Oliveira Cruz, Bárbara Rafaela da Silva Barros, Mariane Cajuba de Britto Lira Nogueira, Talita Helena de Araújo Oliveira, Anna Jessica Duarte Silva, Vanessa Emanuelle Pereira Santos, Cristiane Moutinho Lagos de Melo and Antonio Carlos de Freitas
Viruses 2024, 16(5), 717; https://doi.org/10.3390/v16050717 - 30 Apr 2024
Abstract
Breast cancer is the most common neoplasm worldwide. Viral infections are involved with carcinogenesis, especially those caused by oncogenic Human Papillomavirus (HPV) genotypes. Despite the detection of HPV in breast carcinomas, the virus’s activity against this type of cancer remains controversial. HPV infection
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Breast cancer is the most common neoplasm worldwide. Viral infections are involved with carcinogenesis, especially those caused by oncogenic Human Papillomavirus (HPV) genotypes. Despite the detection of HPV in breast carcinomas, the virus’s activity against this type of cancer remains controversial. HPV infection promotes remodeling of the host’s immune response, resulting in an immunosuppressive profile. This study assessed the individual role of HPV oncogenes in the cell line MDA-MB-231 transfected with the E5, E6, and E7 oncogenes and co-cultured with peripheral blood mononuclear cells. Immunophenotyping was conducted to evaluate immune system modulation. There was an increase in CD4+ T cell numbers when compared with non-transfected and transfected MDA-MB-231, especially in the Treg profile. Pro-inflammatory intracellular cytokines, such as IFN-γ, TNF-α, and IL-17, were impaired by transfected cells, and a decrease in the cytolytic activity of the CD8+ and CD56+ lymphocytes was observed in the presence of HPV oncogenes, mainly with E6 and E7. The E6 and E7 oncogenes decrease monocyte expression, activating the expected M1 profile. In the monocytes found, a pro-inflammatory role was observed according to the cytokines released in the supernatant. In conclusion, the MDA-MB-231 cell lineage transfected with HPV oncogenes can downregulate the number and function of lymphocytes and monocytes.
Full article
(This article belongs to the Special Issue Immune Responses to Papillomavirus Infections)
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Open AccessReview
Cell Culture Models for Hepatitis B and D Viruses Infection: Old Challenges, New Developments and Future Strategies
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Arnaud Carpentier
Viruses 2024, 16(5), 716; https://doi.org/10.3390/v16050716 - 30 Apr 2024
Abstract
Chronic Hepatitis B and D Virus (HBV and HDV) co-infection is responsible for the most severe form of viral Hepatitis, the Hepatitis Delta. Despite an efficient vaccine against HBV, the HBV/HDV infection remains a global health burden. Notably, no efficient curative treatment exists
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Chronic Hepatitis B and D Virus (HBV and HDV) co-infection is responsible for the most severe form of viral Hepatitis, the Hepatitis Delta. Despite an efficient vaccine against HBV, the HBV/HDV infection remains a global health burden. Notably, no efficient curative treatment exists against any of these viruses. While physiologically distinct, HBV and HDV life cycles are closely linked. HDV is a deficient virus that relies on HBV to fulfil is viral cycle. As a result, the cellular response to HDV also influences HBV replication. In vitro studying of HBV and HDV infection and co-infection rely on various cell culture models that differ greatly in terms of biological relevance and amenability to classical virology experiments. Here, we review the various cell culture models available to scientists to decipher HBV and HDV virology and host–pathogen interactions. We discuss their relevance and how they may help address the remaining questions, with one objective in mind: the development of new therapeutic approaches allowing viral clearance in patients.
Full article
(This article belongs to the Special Issue Life Cycle of Hepatitis D Virus (HDV) and HDV-Like Agents)
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Open AccessArticle
Phylogenomic Characterization of Ranavirus Isolated from Wild Smallmouth Bass (Micropterus dolomieu)
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Hannah Quail, Pedro H. O. Viadanna, Jordan A. Vann, Hui-Min Hsu, Andrea Pohly, Willow Smith, Scott Hansen, Nicole Nietlisbach, Danielle Godard, Thomas B. Waltzek and Kuttichantran Subramaniam
Viruses 2024, 16(5), 715; https://doi.org/10.3390/v16050715 - 30 Apr 2024
Abstract
In September 2021, 14 smallmouth bass (SMB; Micropterus dolomieu) with skin lesions were collected from Green Bay waters of Lake Michigan and submitted for diagnostic evaluation. All the skin samples tested positive for largemouth bass virus (LMBV) by conventional PCR. The complete genome
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In September 2021, 14 smallmouth bass (SMB; Micropterus dolomieu) with skin lesions were collected from Green Bay waters of Lake Michigan and submitted for diagnostic evaluation. All the skin samples tested positive for largemouth bass virus (LMBV) by conventional PCR. The complete genome of the LMBV (99,328 bp) isolated from a homogenized skin sample was determined using an Illumina MiSeq sequencer. A maximum likelihood (ML) phylogenetic analysis based on the 21 core iridovirus genes supported the LMBV isolated from SMB (LMBV-WVL21117) as a member of the species Santee-Cooper ranavirus. Pairwise nucleotide comparison of the major capsid protein (MCP) gene showed that LMBV-WVL21117 is identical to other LMBV reported from the United States and nearly identical to doctor fish virus and guppy virus 6 (99.2%) from Southeast Asia, as well as LMBV isolates from China and Thailand (99.1%). In addition, ML phylogenetic analysis based on the MCP gene suggests three genotypes of LMBV separated by region: genotype one from the United States, genotype two from Southeast Asia, and genotype three from China and Thailand. Additional research is needed to understand the prevalence and genetic diversity of LMBV strains circulating in wild and managed fish populations from different regions.
Full article
(This article belongs to the Special Issue Identifying and Characterizing Viral Infections in Reptiles, Amphibians, Fish and Other Aquatic Species)
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Open AccessReview
piRNA-Guided Transposon Silencing and Response to Stress in Drosophila Germline
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Samantha Ho, William Theurkauf and Nicholas Rice
Viruses 2024, 16(5), 714; https://doi.org/10.3390/v16050714 - 30 Apr 2024
Abstract
Transposons are integral genome constituents that can be domesticated for host functions, but they also represent a significant threat to genome stability. Transposon silencing is especially critical in the germline, which is dedicated to transmitting inherited genetic material. The small Piwi-interacting RNAs (piRNAs)
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Transposons are integral genome constituents that can be domesticated for host functions, but they also represent a significant threat to genome stability. Transposon silencing is especially critical in the germline, which is dedicated to transmitting inherited genetic material. The small Piwi-interacting RNAs (piRNAs) have a deeply conserved function in transposon silencing in the germline. piRNA biogenesis and function are particularly well understood in Drosophila melanogaster, but some fundamental mechanisms remain elusive and there is growing evidence that the pathway is regulated in response to genotoxic and environmental stress. Here, we review transposon regulation by piRNAs and the piRNA pathway regulation in response to stress, focusing on the Drosophila female germline.
Full article
(This article belongs to the Special Issue The Diverse Regulation of Transcription in Endogenous Retroviruses)
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Open AccessCommunication
Immune-Escape Mutations Are Prevalent among Patients with a Coexistence of HBsAg and Anti-HBs in a Tertiary Liver Center in the United States
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Mukarram Jamat Ali, Pir Ahmed Shah, Khalil Ur Rehman, Satinder Kaur, Vera Holzmayer, Gavin A. Cloherty, Mary C. Kuhns and Daryl T. Y. Lau
Viruses 2024, 16(5), 713; https://doi.org/10.3390/v16050713 - 30 Apr 2024
Abstract
The concurrent seropositivity of HBsAg and anti-HBs has been described among patients with chronic hepatitis B (CHB), but its prevalence is variable. HBV S-gene mutations can affect the antigenicity of HBsAg. Patients with mutations in the ‘α’ determinant region of the S gene
[...] Read more.
The concurrent seropositivity of HBsAg and anti-HBs has been described among patients with chronic hepatitis B (CHB), but its prevalence is variable. HBV S-gene mutations can affect the antigenicity of HBsAg. Patients with mutations in the ‘α’ determinant region of the S gene can develop severe HBV reactivation under immunosuppression. In this study at a tertiary liver center in the United States, we evaluated the frequency and virological characteristics of the HBsAg mutations among CHB patients with the presence of both HBsAg and anti-HBs. In this cohort, 45 (2.1%) of 2178 patients were identified to have a coexistence of HBsAg and anti-HBs, and 24 had available sera for the genome analysis of the Pre-S1, Pre-S2, and S regions. The frequency of mutations in the S gene was significantly higher among those older than 50 years (mean 8.5 vs. 5.4 mutations per subject, p = 0.03). Twelve patients (50%) had mutations in the ‘α‘ determinant region of the S gene. Mutations at amino acid position 126 were most common in eight subjects. Three had a mutation at position 133. Only one patient had a mutation at position 145—the classic vaccine-escape mutation. Despite the universal HBV vaccination program, the vaccine-escape mutant is rare in our cohort of predominantly Asian patients.
Full article
(This article belongs to the Special Issue Viral Genetic Variation)
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Open AccessReview
Research Progress on Spike-Dependent SARS-CoV-2 Fusion Inhibitors and Small Molecules Targeting the S2 Subunit of Spike
by
Matthew R. Freidel and Roger S. Armen
Viruses 2024, 16(5), 712; https://doi.org/10.3390/v16050712 - 30 Apr 2024
Abstract
Since the beginning of the COVID-19 pandemic, extensive drug repurposing efforts have sought to identify small-molecule antivirals with various mechanisms of action. Here, we aim to review research progress on small-molecule viral entry and fusion inhibitors that directly bind to the SARS-CoV-2 Spike
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Since the beginning of the COVID-19 pandemic, extensive drug repurposing efforts have sought to identify small-molecule antivirals with various mechanisms of action. Here, we aim to review research progress on small-molecule viral entry and fusion inhibitors that directly bind to the SARS-CoV-2 Spike protein. Early in the pandemic, numerous small molecules were identified in drug repurposing screens and reported to be effective in in vitro SARS-CoV-2 viral entry or fusion inhibitors. However, given minimal experimental information regarding the exact location of small-molecule binding sites on Spike, it was unclear what the specific mechanism of action was or where the exact binding sites were on Spike for some inhibitor candidates. The work of countless researchers has yielded great progress, with the identification of many viral entry inhibitors that target elements on the S1 receptor-binding domain (RBD) or N-terminal domain (NTD) and disrupt the S1 receptor-binding function. In this review, we will also focus on highlighting fusion inhibitors that target inhibition of the S2 fusion function, either by disrupting the formation of the postfusion S2 conformation or alternatively by stabilizing structural elements of the prefusion S2 conformation to prevent conformational changes associated with S2 function. We highlight experimentally validated binding sites on the S1/S2 interface and on the S2 subunit. While most substitutions to the Spike protein to date in variants of concern (VOCs) have been localized to the S1 subunit, the S2 subunit sequence is more conserved, with only a few observed substitutions in proximity to S2 binding sites. Several recent small molecules targeting S2 have been shown to have robust activity over recent VOC mutant strains and/or greater broad-spectrum antiviral activity for other more distantly related coronaviruses.
Full article
(This article belongs to the Special Issue Innovative Drug Discovery for Emerging Viral Diseases)
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The Significance of the 98th Amino Acid in GP2a for Porcine Reproductive and Respiratory Syndrome Virus Adaptation in Marc-145 Cells
by
Yao Chen, Zhantang Huo, Qi Jiang, Zhiheng Qiu, Zheng Shao, Chunquan Ma, Guihong Zhang and Qi Li
Viruses 2024, 16(5), 711; https://doi.org/10.3390/v16050711 - 30 Apr 2024
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogens in the pig industry. Marc-145 cells are widely used for PRRSV isolation, vaccine production, and investigations into virus biological characteristics. Despite their significance in PRRSV research, Marc-145 cells struggle
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Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important pathogens in the pig industry. Marc-145 cells are widely used for PRRSV isolation, vaccine production, and investigations into virus biological characteristics. Despite their significance in PRRSV research, Marc-145 cells struggle to isolate specific strains of the North American virus genotype (PRRSV-2). The involvement of viral GP2a, GP2b, and GP3 in this phenomenon has been noted. However, the vital amino acids have not yet been identified. In this study, we increased the number of blind passages and successfully isolated two strains that were previously difficult to isolate with Marc-145 cells. Both strains carried an amino acid substitution in GP2a, specifically phenylalanine to leucine at the 98th amino acid position. Through a phylogenetic and epidemiologic analysis of 32 strains, those that were not amenable to isolation widely exhibited this mutation. Then, by using the PRRSV reverse genetics system, IFA, and Western blotting, we identified the mutation that could affect the tropism of PRRSV-2 for Marc-145 cells. Furthermore, an animal experiment was conducted. Through comparisons of clinical signs, mortality rates, and viral load in the organs and sera, we found that mutation did not affect the pathogenicity of PRRSV-2. In conclusion, our study firmly establishes the 98th amino acid in GP2a as a key determinant of PRRSV-2 tropism for Marc-145 cells.
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(This article belongs to the Section Animal Viruses)
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Virus Quasispecies Rarefaction: Subsampling with or without Replacement?
by
Josep Gregori, Marta Ibañez-Lligoña, Sergi Colomer-Castell, Carolina Campos and Josep Quer
Viruses 2024, 16(5), 710; https://doi.org/10.3390/v16050710 - 29 Apr 2024
Abstract
In quasispecies diversity studies, the comparison of two samples of varying sizes is a common necessity. However, the sensitivity of certain diversity indices to sample size variations poses a challenge. To address this issue, rarefaction emerges as a crucial tool, serving to normalize
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In quasispecies diversity studies, the comparison of two samples of varying sizes is a common necessity. However, the sensitivity of certain diversity indices to sample size variations poses a challenge. To address this issue, rarefaction emerges as a crucial tool, serving to normalize and create fairly comparable samples. This study emphasizes the imperative nature of sample size normalization in quasispecies diversity studies using next-generation sequencing (NGS) data. We present a thorough examination of resampling schemes using various simple hypothetical cases of quasispecies showing different quasispecies structures in the sense of haplotype genomic composition, offering a comprehensive understanding of their implications in general cases. Despite the big numbers implied in this sort of study, often involving coverages exceeding 100,000 reads per sample and amplicon, the rarefaction process for normalization should be performed with repeated resampling without replacement, especially when rare haplotypes constitute a significant fraction of interest. However, it is noteworthy that different diversity indices exhibit distinct sensitivities to sample size. Consequently, some diversity indicators may be compared directly without normalization, or instead may be resampled safely with replacement.
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(This article belongs to the Section General Virology)
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COVID-19 in Lung Transplant Recipients: A Report on 10 Recent Cases
by
Lea Reemann, Nikolaus Kneidinger, Bernd Sczepanski and Andreas Rembert Koczulla
Viruses 2024, 16(5), 709; https://doi.org/10.3390/v16050709 - 29 Apr 2024
Abstract
Due to immunosuppression, transplant recipients are at higher risk of infections with SARS-CoV-2 and worse clinical outcomes than immunocompetent hosts. Furthermore, lung transplant patients represent a special group among solid organ recipients, since pneumonia is the main manifestation of COVID-19. However, data on
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Due to immunosuppression, transplant recipients are at higher risk of infections with SARS-CoV-2 and worse clinical outcomes than immunocompetent hosts. Furthermore, lung transplant patients represent a special group among solid organ recipients, since pneumonia is the main manifestation of COVID-19. However, data on the course of disease and the changes in morbidity and mortality during the course of the pandemic are limited. In our pulmonary rehabilitation clinic, we treat patients shortly after lung transplant as well as long-term transplant patients. Over the last almost 4 years of pandemic, we witnessed several COVID-19 infections in lung transplant patients in our clinic as well as patients who acquired an infection beforehand. In this paper, we aim at retrospectively describing a series of recent COVID-19 cases in our clinic, looking at the clinical course of disease and outcomes in lung transplant patients.
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(This article belongs to the Section Coronaviruses)
Open AccessArticle
Development of a Cell Culture Model for Inducible SARS-CoV-2 Replication
by
Xiaoyan Wang, Yuanfei Zhu, Qiong Wu, Nan Jiang, Youhua Xie and Qiang Deng
Viruses 2024, 16(5), 708; https://doi.org/10.3390/v16050708 - 29 Apr 2024
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces direct cytopathic effects, complicating the establishment of low-cytotoxicity cell culture models for studying its replication. We initially developed a DNA vector-based replicon system utilizing the CMV promoter to generate a recombinant viral genome bearing reporter
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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces direct cytopathic effects, complicating the establishment of low-cytotoxicity cell culture models for studying its replication. We initially developed a DNA vector-based replicon system utilizing the CMV promoter to generate a recombinant viral genome bearing reporter genes. However, this system frequently resulted in drug resistance and cytotoxicity, impeding model establishment. Herein, we present a novel cell culture model with SARS-CoV-2 replication induced by Cre/LoxP-mediated DNA recombination. An engineered SARS-CoV-2 transcription unit was subcloned into a bacterial artificial chromosome (BAC) vector. To enhance biosafety, the viral spike protein gene was deleted, and the nucleocapsid gene was replaced with a reporter gene. An exogenous sequence was inserted within NSP1 as a modulatory cassette that is removable after Cre/LoxP-mediated DNA recombination and subsequent RNA splicing. Using the PiggyBac transposon strategy, the transcription unit was integrated into host cell chromatin, yielding a stable cell line capable of inducing recombinant SARS-CoV-2 RNA replication. The model exhibited sensitivity to the potential antivirals forsythoside A and verteporfin. An innovative inducible SARS-CoV-2 replicon cell model was introduced to further explore the replication and pathogenesis of the virus and facilitate screening and assessment of anti-SARS-CoV-2 therapeutics.
Full article
(This article belongs to the Special Issue Novel Antiviral Agents: Synthesis, Molecular Modelling Studies and Biological Investigation, 2nd Edition)
Open AccessReview
The Adaptive Immune Response in Hepatitis B Virus-Associated Hepatocellular Carcinoma Is Characterized by Dysfunctional and Exhausted HBV-Specific T Cells
by
Malene Broholm, Anne-Sofie Mathiasen, Ása Didriksen Apol and Nina Weis
Viruses 2024, 16(5), 707; https://doi.org/10.3390/v16050707 - 29 Apr 2024
Abstract
This systematic review investigates the immunosuppressive environment in HBV-associated hepatocellular carcinoma (HCC), characterized by dysfunctional and exhausted HBV-specific T cells alongside an increased infiltration of HBV-specific CD4+ T cells, particularly regulatory T cells (Tregs). Heightened expression of checkpoint inhibitors, notably PD-1, is linked
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This systematic review investigates the immunosuppressive environment in HBV-associated hepatocellular carcinoma (HCC), characterized by dysfunctional and exhausted HBV-specific T cells alongside an increased infiltration of HBV-specific CD4+ T cells, particularly regulatory T cells (Tregs). Heightened expression of checkpoint inhibitors, notably PD-1, is linked with disease progression and recurrence, indicating its potential as both a prognostic indicator and a target for immunotherapy. Nevertheless, using PD-1 inhibitors has shown limited effectiveness. In a future perspective, understanding the intricate interplay between innate and adaptive immune responses holds promise for pinpointing predictive biomarkers and crafting novel treatment approaches for HBV-associated HCC.
Full article
(This article belongs to the Section Human Virology and Viral Diseases)
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