ICTV Virus Taxonomy Profile: Nairoviridae 2024.

Nairoviridae is a family for negative-sense RNA viruses with genomes of about 17.2-21.1 kb. These viruses are maintained in and/or transmitted by arthropods among birds, reptiles and mammals. Norwaviruses and orthonairoviruses can cause febrile illness in humans. Several orthonairoviruses can infect mammals, causing mild, severe and sometimes, fatal diseases. Nairovirids produce enveloped virions containing two or three single-stranded RNA segments with open reading frames that encode a nucleoprotein (N), sometimes a glycoprotein precursor (GPC), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) report on the family Nairoviridae, which is available at www.ictv.global/report/nairoviridae.

ICTV Virus Taxonomy Profile: Filoviridae 2024.

Filoviridae is a family of negative-sense RNA viruses with genomes of about 13.1-20.9 kb that infect fish, mammals and reptiles. The filovirid genome is a linear, non-segmented RNA with five canonical open reading frames (ORFs) that encode a nucleoprotein (NP), a polymerase cofactor (VP35), a glycoprotein (GP1,2), a transcriptional activator (VP30) and a large protein (L) containing an RNA-directed RNA polymerase (RdRP) domain. All filovirid genomes encode additional proteins that vary among genera. Several filovirids (e.g., Ebola virus, Marburg virus) are pathogenic for humans and highly virulent. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Filoviridae, which is available at www.ictv.global/report/filoviridae.

Re-emerging human monkeypox: A major public-health debacle.

A multicountry outbreak of the monkeypox virus has gained global attention. As of May 25, 250 confirmed human monkeypox cases have been reported globally. Monkeypox is caused by the Monkeypox virus, which belongs to the Orthopoxvirus genus and Poxviridae family. Monkeypox is often a self-limiting infection, with symptoms lasting 2-4 weeks with the case fatality ratio around 3%-6%. Monkeypox is transmitted to humans by direct contact with an infected person or animal or contact with virus-contaminated material. Human monkeypox infections may lead to various medical complications such as fever, rash, and lymphadenopathies. Pneumonitis, encephalitis, sight-threatening keratitis, and subsequent bacterial infections are all possible complications of monkeypox. An antiviral agent developed to treat smallpox has also been approved for use in the treatment of monkeypox in the United States. Vaccines used in the smallpox eradication program also provided immunity to monkeypox. Newer vaccines have been developed, one of which has been approved for monkeypox prevention. In this study, we provide information about the recent outbreaks of human monkeypox, epidemiology, transmission pattern, possible diagnosis techniques, therapeutics, and available preventive strategies.

Antiviral and anti-inflammatory activity of natural compounds against Japanese encephalitis virus via inhibition of NS5 protein and regulation of key immune and inflammatory signaling pathways.

Japanese encephalitis virus (JEV) is the foremost cause of viral encephalitis in Southeast Asia and Australia leading to approximately 68 000 clinical cases and about 13 600-20 400 deaths annually. Vaccination is not completely sure and safe. Despite this, no specific antiviral has been available or approved for JEV infection yet and treatment is generally symptomatic. Therefore, this study aims to examine the antiviral activity of natural compounds against JEV proteins. The antiviral activity of natural compounds was investigated via molecular docking, cytopathic effect (CPE) inhibition assay, western blotting, and indirect immunofluorescence assay. Physiochemical, pharmacokinetics, and toxicity analysis were evaluated for the safety and efficacy of natural compounds. Network pharmacology-based approaches have been used to study the molecular mechanisms of drug-target interactions. Molecular docking results suggested that the NS5 protein of JEV is the major target for natural compounds. Network pharmacology-based analysis revealed that these drugs majorly target IL6, AKT1, tumor necrosis factor (TNF), and PTGS2 to regulate key immune and inflammatory pathways such as nuclear factor kappa B, PI3K-Akt, and TNF signaling, during JEV infection. Our in vitro results show that among the natural compounds, curcumin provides the highest protection against JEV infection via reducing the JEV-induced CPE (IC50 = 5.90 ± 0.44 µM/mL), and reduces the expression of NS5 protein, IL6, AKT1, TNF-α, and PTGS2. However, other natural compounds also provide protection to some extent but their efficacy is lower compared to curcumin. Therefore, this study shows that natural compounds, mainly curcumin, may offer novel therapeutic avenues for the treatment of JEV via inhibiting key viral proteins and regulating crucial host pathways involved in JEV replication.

Renaming of genera Ebolavirus and Marburgvirus to Orthoebolavirus and Orthomarburgvirus, respectively, and introduction of binomial species names within family Filoviridae.

The International Committee on Taxonomy of Viruses (ICTV) Filoviridae Study Group continues to prospectively refine the established nomenclature for taxa included in family Filoviridae in an effort to decrease confusion of genus, species, and virus names and to adhere to amended stipulations of the International Code of Virus Classification and Nomenclature (ICVCN). Recently, the genus names Ebolavirus and Marburgvirus were changed to Orthoebolavirus and Orthomarburgvirus, respectively. Additionally, all established species names in family Filoviridae now adhere to the ICTV-mandated binomial format. Virus names remain unchanged and valid. Here, we outline the revised taxonomy of family Filoviridae as approved by the ICTV in April 2023.

Transmission dynamics and mutational prevalence of the novel Severe acute respiratory syndrome coronavirus-2 Omicron Variant of Concern.

The novel Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variant, Omicron (PANGO lineage B.1.1.529) is being reported from all around the world. The WHO has categorized Omicron as a Variant of Concern (VOC) considering its higher transmissibility and infectivity, vaccine breakthrough cases. As of January 6, 2022, Omicron has been reported in at least 149 countries. Therefore, this study was planned to investigate the transmission dynamics and mutational prevalence of the novel SARS-CoV-2 Omicron variant. The transmission dynamics and Omicron SARS-CoV-2 divergence was studied using GISAID and Nextstrain which provides information about the genetic sequences, epidemiological, geographical, and species-specific data of human, avian, and animal viruses. Further, the mutation prevalence in spike glycoprotein of Omicron was studied, and the frequency of the crucial mutations was compared with the other prevalent VOCs. The transmission dynamics suggest that the Omicron was first identified in South Africa and then it was reported in the United Kingdom followed by the United States and Australia. Further, our phylogenetic analysis suggests that Omicron (BA.1) was clustered distinctly from the other VOCs. In the Spike glycoprotein, the Omicron (B.1.1.529) demonstrates critical 32 amino acid changes. This study may help us to understand mutational hotspots, transmission dynamics, phylogenetic divergence, effect on testing and immunity, which shall promote the progress of the clinical application and basic research.

Characterization of the novel SARS-CoV-2 Omicron (B.1.1.529) variant of concern and its global perspective.

As the latest identified novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern (VOC), the influence of Omicron on our globe grows promptly. Compared with the last VOC (Delta variant), more mutations were identified, which may address the characteristics of Omicron. Considering these crucial mutations and their implications including an increase in transmissibility, COVID-19 severity, and reduction of efficacy of currently available diagnostics, vaccines, and therapeutics, Omicron has been classified as one of the VOC. Notably, 15 of these mutations reside in the receptor-binding domain of spike glycoprotein, which may alter transmissibility, infectivity, neutralizing antibody escape, and vaccine breakthrough cases of COVID-19. Therefore, our present study characterizes the mutational hotspots of the Omicron variant in comparison with the Delta variant of SARS-CoV-2. Furthermore, detailed information was analyzed to characterize the global perspective of Omicron, including transmission dynamic, effect on testing, and immunity, which shall promote the progress of the clinical application and basic research. Collectively, our data suggest that due to continuous variation in the spike glycoprotein sequences, the use of coronavirus-specific attachment inhibitors may not be the current choice of therapy for emerging SARS-CoV-2 VOCs. Hence, we need to proceed with a sense of urgency in this matter.

Tracing the origin of Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2): A systematic review and narrative synthesis.

The aim of the study was to trace and understand the origin of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through various available literatures and accessible databases. Although the world enters the third year of the coronavirus disease 2019 pandemic, health and socioeconomic impacts continue to mount, the origin and mechanisms of spill-over of the SARS-CoV-2 into humans remain elusive. Therefore, a systematic review of the literature was performed that showcased the integrated information obtained through manual searches, digital databases (PubMed, CINAHL, and MEDLINE) searches, and searches from legitimate publications (1966-2022), followed by meta-analysis. Our systematic analysis data proposed three postulated hypotheses concerning the origin of the SARS-CoV-2, which include zoonotic origin (Z), laboratory origin (L), and obscure origin (O). Despite the fact that the zoonotic origin for SARS-CoV-2 has not been conclusively identified to date, our data suggest a zoonotic origin, in contrast to some alternative concepts, including the probability of a laboratory incident or leak. Our data exhibit that zoonotic origin (Z) has higher evidence-based support as compared to laboratory origin (L). Importantly, based on all the studies included, we generated the forest plot with 95% confidence intervals (CIs) of the risk ratio estimates. Our meta-analysis further supports the zoonotic origin of SARS/SARS-CoV-2 in the included studies.

Rift Valley Fever Virus Seroprevalence among Humans, Northern KwaZulu-Natal Province, South Africa, 2018-2019.

We detected Rift Valley fever virus (RVFV) IgM and IgG in human serum samples collected during 2018-2019 in northern KwaZulu-Natal Province, South Africa. Our results show recent RVFV circulation and likely RVFV endemicity in this tropical coastal plain region of South Africa in the absence of apparent clinical disease.

Mammarenaviruses of Rodents, South Africa and Zimbabwe.

We conducted a survey for group-specific indirect immunofluorescence antibody to mammarenaviruses by using Lassa fever and Mopeia virus antigens on serum specimens of 5,363 rodents of 33 species collected in South Africa and Zimbabwe during 1964-1994. Rodents were collected for unrelated purposes or for this study and stored at -70°C. We found antibody to be widely distributed in the 2 countries; antibody was detected in serum specimens of 1.2%-31.8% of 14 species of myomorph rodents, whereas 19 mammarenavirus isolates were obtained from serum specimens and viscera of 4 seropositive species. Phylogenetic analysis on the basis of partial nucleoprotein sequences indicates that 14 isolates from Mastomys natalensis, the Natal multimammate mouse, were Mopeia virus, whereas Merino Walk virus was characterized as a novel virus in a separate study. The remaining 4 isolates from 3 rodent species potentially constitute novel viruses pending full characterization.

Lithium inhibits NF-κB nuclear translocation and modulate inflammation profiles in Rift valley fever virus-infected Raw 264.7 macrophages.

INTRODUCTION: Rift Valley fever virus (RVFV) is a zoonotic life-threatening viral infection endemic across sub-Saharan African countries and the Arabian Peninsula; however, there is a growing panic of its spread to non-endemic regions. This viral infection triggers a wide spectrum of symptoms that span from fibril illnesses to more severe symptoms such as haemorrhagic fever and encephalitis. These severe symptoms have been associated with dysregulated immune response propagated by the virulence factor, non-structural protein (NSs). Thus, this study investigates the effects of lithium on NF-κB translocation and RFVF-induced inflammation in Raw 264.7 macrophages. METHODS: The supernatant from RVFV-infected Raw 264.7 cells, treated with lithium, was examined using an ELISA assay kit to measure levels of cytokines and chemokines. The H2DCF-DA and DAF-2 DA florigenic assays were used to determine the levels of ROS and RNS by measuring the cellular fluorescence intensity post RVFV-infection and lithium treatment. Western blot and immunocytochemistry assays were used to measure expression levels of the inflammatory proteins and cellular location of the NF-κB, respectively. RESULTS: Lithium was shown to stimulate interferon-gamma (IFN-γ) production as early as 3 h pi. Production of the secondary pro-inflammatory cytokine and chemokine, interleukin-6 (IL-6) and regulated on activation, normal T cell expressed and secreted (RANTES), were elevated as early as 12 h pi. Treatment with lithium stimulated increase of production of tumor necrosis factor-alpha (TNF-α) and Interleukin-10 (IL-10) in RVFV-infected and uninfected macrophages as early as 3 h pi. The RVFV-infected cells treated with lithium displayed lower ROS and RNS production as opposed to lithium-free RVFV-infected control cells. Western blot analyses demonstrated that lithium inhibited iNOS expression while stimulating expression of heme oxygenase (HO) and IκB in RVFV-infected Raw 264.7 macrophages. Results from immunocytochemistry and Western blot assays revealed that lithium inhibits NF-κB nuclear translocation in RVFV-infected cells compared to lithium-free RVFV-infected cells and 5 mg/mL LPS controls. CONCLUSION: This study demonstrates that lithium inhibits NF-kB nuclear translocation and modulate inflammation profiles in RVFV-infected Raw 264.7 macrophage cells.

Silent Circulation of Rift Valley Fever in Humans, Botswana, 2013-2014.

We evaluated the prevalence of Rift Valley fever virus IgG and IgM in human serum samples (n = 1,276) collected in 2013-2014 in northern Botswana. Our findings provide evidence of active circulation of this virus in humans in the absence of clinical disease in this region.

Lyssaviruses in Insectivorous Bats, South Africa, 2003-2018.

We detected 3 lyssaviruses in insectivorous bats sampled in South Africa during 2003-2018. We used phylogenetic analysis to identify Duvenhage lyssavirus and a potentially new lyssavirus, provisionally named Matlo bat lyssavirus, that is related to West Caucasian bat virus. These new detections highlight that much about lyssaviruses remains unknown.

Shedding of Marburg Virus in Naturally Infected Egyptian Rousette Bats, South Africa, 2017.

We detected Marburg virus RNA in rectal swab samples from Egyptian rousette bats in South Africa in 2017. This finding signifies that fecal contamination of natural bat habitats is a potential source of infection for humans. Identified genetic sequences are closely related to Ravn virus, implying wider distribution of Marburg virus in Africa.

Rift Valley Fever Reemergence after 7 Years of Quiescence, South Africa, May 2018.

Phylogenetic analysis of Rift Valley fever virus partial genomic sequences from a patient infected in South Africa in May 2018 suggests reemergence of an endemic lineage different from that of the epidemic in South Africa during 2010-2011. Surveillance during interepidemic periods should be intensified to better predict future epidemics.

ICTV Virus Taxonomy Profile: Filoviridae.

Members of the family Filoviridae produce variously shaped, often filamentous, enveloped virions containing linear non-segmented, negative-sense RNA genomes of 15-19 kb. Several filoviruses (e.g., Ebola virus) are pathogenic for humans and are highly virulent. Several filoviruses infect bats (e.g., Marburg virus), whereas the hosts of most other filoviruses are unknown. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on Filoviridae, which is available at www.ictv.global/report/filoviridae.

Taxonomy of the order Mononegavirales: second update 2018.

In October 2018, the order Mononegavirales was amended by the establishment of three new families and three new genera, abolishment of two genera, and creation of 28 novel species. This article presents the updated taxonomy of the order Mononegavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).

Marburg Virus Infection in Egyptian Rousette Bats, South Africa, 2013-20141.

We detected a high seroprevalence of Marburg virus (MARV) antibodies in fruit bats in South Africa; 19.1% of recaptured bats seroconverted. The MARV RNA isolated closely resembled the 1975 Ozolin strain. These findings indicate endemic MARV circulation in bats in South Africa and should inform policies on MARV disease risk reduction.

Immunization with DNA Plasmids Coding for Crimean-Congo Hemorrhagic Fever Virus Capsid and Envelope Proteins and/or Virus-Like Particles Induces Protection and Survival in Challenged Mice.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a bunyavirus causing severe hemorrhagic fever disease in humans, with high mortality rates. The requirement of a high-containment laboratory and the lack of an animal model hampered the study of the immune response and protection of vaccine candidates. Using the recently developed interferon alpha receptor knockout (IFNAR-/-) mouse model, which replicates human disease, we investigated the immunogenicity and protection of two novel CCHFV vaccine candidates: a DNA vaccine encoding a ubiquitin-linked version of CCHFV Gc, Gn, and N and one using transcriptionally competent virus-like particles (tc-VLPs). In contrast to most studies that focus on neutralizing antibodies, we measured both humoral and cellular immune responses. We demonstrated a clear and 100% efficient preventive immunity against lethal CCHFV challenge with the DNA vaccine. Interestingly, there was no correlation with the neutralizing antibody titers alone, which were higher in the tc-VLP-vaccinated mice. However, the animals with a lower neutralizing titer, but a dominant cell-mediated Th1 response and a balanced Th2 response, resisted the CCHFV challenge. Moreover, we found that in challenged mice with a Th1 response (immunized by DNA/DNA and boosted by tc-VLPs), the immune response changed to Th2 at day 9 postchallenge. In addition, we were able to identify new linear B-cell epitope regions that are highly conserved between CCHFV strains. Altogether, our results suggest that a predominantly Th1-type immune response provides the most efficient protective immunity against CCHFV challenge. However, we cannot exclude the importance of the neutralizing antibodies as the surviving immunized mice exhibited substantial amounts of them.IMPORTANCE Crimean-Congo hemorrhagic fever virus (CCHFV) is responsible for hemorrhagic diseases in humans, with a high mortality rate. There is no FDA-approved vaccine, and there are still gaps in our knowledge of the immune responses to infection. The recently developed mouse models mimic human CCHF disease and are useful to study the immunogenicity and the protection by vaccine candidates. Our study shows that mice vaccinated with a specific DNA vaccine were fully protected. Importantly, we show that neutralizing antibodies are not sufficient for protection against CCHFV challenge but that an extra Th1-specific cellular response is required. Moreover, we describe the identification of five conserved B-cell epitopes, of which only one was previously known, that could be of great importance for the development of diagnostics tools and the improvement of vaccine candidates.

Possibility and Challenges of Conversion of Current Virus Species Names to Linnaean Binomials.

Botanical, mycological, zoological, and prokaryotic species names follow the Linnaean format, consisting of an italicized Latinized binomen with a capitalized genus name and a lower case species epithet (e.g., Homo sapiens). Virus species names, however, do not follow a uniform format, and, even when binomial, are not Linnaean in style. In this thought exercise, we attempted to convert all currently official names of species included in the virus family Arenaviridae and the virus order Mononegavirales to Linnaean binomials, and to identify and address associated challenges and concerns. Surprisingly, this endeavor was not as complicated or time-consuming as even the authors of this article expected when conceiving the experiment. [Arenaviridae; binomials; ICTV; International Committee on Taxonomy of Viruses; Mononegavirales; virus nomenclature; virus taxonomy.].