Novel Oliveros-like Clade C Mammarenaviruses from Rodents in Argentina, 1990-2020.

Following an Argentine Hemorrhagic Fever (AHF) outbreak in the early 1990s, a rodent survey for Junín virus, a New World Clade B arenavirus, in endemic areas of Argentina was conducted. Since 1990, INEVH has been developing eco-epidemiological surveillance of rodents, inside and outside the Argentine Hemorrhagic Fever endemic area. Samples from rodents captured between 1993 and 2019 that were positive for Arenavirus infection underwent Sanger and unbiased, Illumina-based high-throughput sequencing, which yielded 5 complete and 88 partial Mammarenaviruses genomes. Previously, 11 genomes representing four species of New World arenavirus Clade C existed in public records. This work has generated 13 novel genomes, expanding the New World arenavirus Clade C to 24 total genomes. Additionally, two genomes exhibit sufficient genetic diversity to be considered a new species, as per ICTV guidelines (proposed name Mammarenavirus vellosense). The 13 novel genomes exhibited reassortment between the small and large segments in New World Mammarenaviruses. This work demonstrates that Clade C Mammarenavirus infections circulate broadly among Necromys species in the Argentine Hemorrhagic Fever endemic area; however, the risk for Clade C Mammarenavirus human infection is currently unknown.

Luminescent reporter cells enable the identification of broad-spectrum antivirals against emerging viruses.

The emerging viruses SARS-CoV-2 and arenaviruses cause severe respiratory and hemorrhagic diseases, respectively. The production of infectious particles of both viruses and virus spread in tissues requires cleavage of surface glycoproteins (GPs) by host proprotein convertases (PCs). SARS-CoV-2 and arenaviruses rely on GP cleavage by PCs furin and subtilisin kexin isozyme-1/site-1 protease (SKI-1/S1P), respectively. We report improved luciferase-based reporter cell lines, named luminescent inducible proprotein convertase reporter cells that we employ to monitor PC activity in its authentic subcellular compartment. Using these sensor lines we screened a small compound library in high-throughput manner. We identified 23 FDA-approved small molecules, among them monensin which displayed broad activity against furin and SKI-1/S1P. Monensin inhibited arenaviruses and SARS-CoV-2 in a dose-dependent manner. We observed a strong reduction in infectious particle release upon monensin treatment with little effect on released genome copies. This was reflected by inhibition of SARS-CoV-2 spike processing suggesting the release of immature particles. In a proof of concept experiment using human precision cut lung slices, monensin potently inhibited SARS-CoV-2 infection, evidenced by reduced infectious particle release. We propose that our PC sensor pipeline is a suitable tool to identify broad-spectrum antivirals with therapeutic potential to combat current and future emerging viruses.

Epidemiology and Genomic characteristics of arenavirus in rodents from the southeast coast of P.R. China.

BACKGROUND: Wenzhou virus (WENV), a member of the Mammarenavirus genus in the Arenaviridae family, has been detected in wild rodents from eight provinces in China, including Zhejiang, Shandong, Hainan, Xinjiang, Hunan, Guangdong, Yunnan, and Jiangxi provinces, and some countries from Southeast Asia. The IgG-antibodies of WENV have been detected in both healthy populations and patients with unknown fever and respiratory symptoms. However, the potential harmfulness of WENV to humans has been underestimated due to mild symptoms after infection, similar to respiratory diseases. Thus, it is imperative to enhance the surveillance of WENV in wild rodents, particularly Rattus norvegicus, and continuously monitor its prevalence. RESULTS: From 2017 to 2021, a total of 390 wild rodents were collected from six provinces in the eastern and southern coastal areas, containing nine species of rats. Samples of each tissue were collected, and PCR amplified for identification. Four R. norvegicus samples were detected to be WENV-positive. No genomic sequence of WENV was detected in Rattus flavipectus, Rattus losea, Suncus murinus, Apodemus agrarius, Mus musculus, Microtus fortis, Micromys minutus, and Niviventer niviventer from Jiangsu, Zhejiang, Fujian, Hainan, Guangdong and Guangxi provinces. Three genomic sequences were identified to be WENV by phylogenetic analysis. The full-length sequences of HAIKOU-40 were amplified in R. norvegicus from Hainan, which showed a close relationship to Wufeng/ WFS, sharing 84.5-89.4% homology at the nucleotide level and 91.6-98.9% homology at the amino acid level. Phylogenetic analysis revealed that HAIKOU-40 formed an Asia-specific cluster with all WENVs and Loie River mammarenavirus (LORV), provisionally named Asian ancestry. This cluster has diverged earlier from the remaining mammarenavirus. The sequences obtained in Xiamen, Fujian province showed more than 90% nucleotide identities with WENV, which may be a strain of WENV. Additionally, the sequence of Wuxi-87 which was a positive sequence detected in Wuxi, Jiangsu province exhibited 83% nucleotide identity with Lassa virus (LASV). Further efforts will be made to isolate and identify this virus strain, verify the relationship between Wuxi-87 and LASV, and confirm whether R. norvegicus is a new host of LASV. CONCLUSIONS: In this study, we conducted a systematic examination of the prevalence of WENV among rodents on the southeast coast of China. Additionally, we characterized the genome of a newly discovered WENV strain, that confirmed the role of R. norvegicus in the transmission of WENV. This highlights the importance of investigating the prevalence of WENV in both wild rodents and humans.

Fusogenic structural changes in arenavirus glycoproteins are associated with viroporin activity.

Many enveloped viruses enter host cells by fusing with acidic endosomes. The fusion activity of multiple viral envelope glycoproteins does not generally affect viral membrane permeability. However, fusion induced by the Lassa virus (LASV) glycoprotein complex (GPc) is always preceded by an increase in viral membrane permeability and the ensuing acidification of the virion interior. Here, systematic investigation of this LASV fusion phenotype using single pseudovirus tracking in live cells reveals that the change in membrane barrier function is associated with the fusogenic conformational reorganization of GPc. We show that a small-molecule fusion inhibitor or mutations that impair viral fusion by interfering with GPc refolding into the post-fusion structure prevent the increase in membrane permeability. We find that the increase in virion membrane permeability occurs early during endosomal maturation and is facilitated by virus-cell contact. This increase is observed using diverse arenavirus glycoproteins, whether presented on lentivirus-based pseudoviruses or arenavirus-like particles, and in multiple different cell types. Collectively, these results suggest that conformational changes in GPc triggered by low pH and cell factor binding are responsible for virion membrane permeabilization and acidification of the virion core prior to fusion. We propose that this viroporin-like activity may augment viral fusion and/or post-fusion steps of infection, including ribonucleoprotein release into the cytoplasm.

A dsRNA-binding mutant reveals only a minor role of exonuclease activity in interferon antagonism by the arenavirus nucleoprotein.

The arenavirus nucleoprotein (NP) plays an important role in the virus' ability to block interferon (IFN) production, and its exonuclease function appears to contribute to this activity. However, efforts to analyze this contribution are complicated by the functional overlap between the exonuclease active site and a neighboring region involved in IKKε-binding and subsequent inhibition of IRF3 activation, which also plays an important role in IFN production. To circumvent this issue, we mutated a residue located away from the active site that is involved in binding of the dsRNA substrate being targeted for exonuclease digestion, i.e. H426A. We found that expression of Tacaribe virus (TCRV) NP containing this RNA-binding H426A mutation was still able to efficiently block IFN-ß promoter activity in response to Sendai virus infection, despite being strongly impaired in its exonuclease activity. This was in contrast to a conventional exonuclease active site mutant (E388A), which was impaired with respect to both exonuclease activity and IFN antagonism. Importantly, growth of a recombinant virus encoding the RNA-binding mutation (rTCRV-H426A) was similar to wild-type in IFN-deficient cells, unlike the active site mutant (rTCRV-E388A), which was already markedly impaired in these cells. Further, in IFN-competent cells, the TCRV-H426A RNA-binding mutant showed more robust growth and delayed IFN-ß mRNA upregulation compared to the TCRV-E388A active site mutant. Taken together, this novel mutational approach, which allows us to now dissect the different contributions of the NP exonuclease activity and IKKε-binding/IRF3 inhibition to IFN antagonism, clearly suggests that conventional exonuclease mutants targeting the active site overestimate the contribution of the exonuclease function, and that rather other IFN antagonistic functions of NP play the dominant role in IFN-antagonism.

Highly Diverse Arenaviruses in Neotropical Bats, Brazil.

We detected arenavirus RNA in 1.6% of 1,047 bats in Brazil that were sampled during 2007-2011. We identified Tacaribe virus in 2 Artibeus sp. bats and a new arenavirus species in Carollia perspicillata bats that we named Tietê mammarenavirus. Our results suggest that bats are an underrecognized arenavirus reservoir.

Generation of Reporter-Expressing New World Arenaviruses: A Systematic Comparison.

Replication-competent reporter-expressing viruses are crucial tools in molecular virology with applications that range from antiviral screening to live-cell imaging of protein spatiotemporal dynamics. However, there is currently little information available regarding viable strategies to develop reporter-expressing arenaviruses. To address this, we used Tacaribe virus (TCRV), an apathogenic BSL2 arenavirus, to assess the feasibility of different reporter expression approaches. We first generated trisegmented TCRV viruses with either the glycoprotein (GP) or nucleoprotein (NP) replaced by a reporter (GFP, mCherry, or nanoluciferase). These viruses were all viable, but showed marked differences in brightness and attenuation. Next, we generated terminal fusions with each of the TCRV proteins (i.e., NP, GP, polymerase (L), matrix protein (Z)) either with or without a T2A self-cleavage site. We tested both the function of the reporter-fused proteins alone, and the viability of corresponding recombinant TCRVs. We successfully rescued viruses with both direct and cleavable reporter fusions at the C-terminus of Z, as well as cleavable N-terminal fusions with NP. These viruses all displayed detectable reporter activity, but were also moderately attenuated. Finally, reporter proteins were inserted into a flexible hinge region within L. These viruses were also viable and showed moderate attenuation; however, reporter expression was only detectable for the luminescent virus. These strategies provide an exciting range of new tools for research into the molecular biology of TCRV that can likely also be adapted to other arenaviruses.

Structural basis for recognition and regulation of arenavirus polymerase L by Z protein.

Junin virus (JUNV) causes Argentine hemorrhagic fever, a debilitating human disease of high mortality rates and a great risk to public health worldwide. Studying the L protein that replicates and transcribes the genome of JUNV, and its regulator Z protein should provide critical clues to identify therapeutic targets for disrupting the life cycle of JUNV. Here we report the 3.54 Å cryo-EM structure of the JUNV L protein complexed with regulator Z protein. JUNV L structure reveals a conserved architecture containing signature motifs found in other L proteins. Structural analysis shows that L protein is regulated by binding of Z protein at the RNA product exit site. Based on these findings, we propose a model for the role of Z protein as a switch to turn on/off the viral RNA synthesis via its interaction with L protein. Our work unveils the mechanism of JUNV transcription, replication and regulation, which provides a framework for the rational design of antivirals for combating viral infections.

Activation of the STAT3 Signaling Pathway by the RNA-Dependent RNA Polymerase Protein of Arenavirus.

Arenaviruses cause chronic and asymptomatic infections in their natural host, rodents, and several arenaviruses cause severe hemorrhagic fever that has a high mortality in infected humans, seriously threatening public health. There are currently no FDA-licensed drugs available against arenaviruses; therefore, it is important to develop novel antiviral strategies to combat them, which would be facilitated by a detailed understanding of the interactions between the viruses and their hosts. To this end, we performed a transcriptomic analysis on cells infected with arenavirus lymphocytic choriomeningitis virus (LCMV), a neglected human pathogen with clinical significance, and found that the signal transducer and activator of transcription 3 (STAT3) signaling pathway was activated. A further investigation indicated that STAT3 could be activated by the RNA-dependent RNA polymerase L protein (Lp) of LCMV. Our functional analysis found that STAT3 cannot affect LCMV multiplication in A549 cells. We also found that STAT3 was activated by the Lp of Mopeia virus and Junin virus, suggesting that this activation may be conserved across certain arenaviruses. Our study explored the interactions between arenaviruses and STAT3, which may help us to better understand the molecular and cell biology of arenaviruses.

Molecular characterization of a new highly divergent Mobala related arenavirus isolated from Praomys sp. rodents.

Arenaviruses represent a family of viruses that are naturally present in rodents belonging to subfamily Murinae, Neotominae or Sigmodontinae. Except for Lassa virus, little information is available on other Old-World arenaviruses. Here, we describe strain AnRB3214, a virus isolated from a presumed Praomys sp. rodent in the Central African Republic in 1981 and assigned to Ippy virus based on antigenic similarity. The strain was simultaneously sequenced on Illumina NovaSeq 6000 and MinION Mk1B devices and analysed with various bioinformatics tools. We show that the best genome coverage and depth were obtained with the Kaiju and Minimap2 classification and identification tools, on either the MinION or the Illumina reads. The genetic analysis of AnRB3214 fragments showed 68% to 79% similarity with the Mobala and Gairo mammarenaviruses at the nucleic acid level. Strain AnRB3214 had a truncated nucleoprotein smaller than that of other Old World arenaviruses. Molecular clock analysis suggests that this strain diverged from Mobala virus at least 400 years ago. Finally, this study illustrates the importance of genomics in the identification of archived viruses and expands on the diversity of African arenaviruses, because strain AnRB3214 is either a variant or a close relative of Mobala virus, and not Ippy virus.

Special Issue "Arenaviruses 2020".

Rodent-borne arenaviruses have been traditionally predominantly associated with certain muroid species from Mastomys/Praomys genera (African arenaviruses) or with species that belong to murid subfamily Cricetidae (New World arenaviruses) [...].

Structural analysis of viral ExoN domains reveals polyphyletic hijacking events.

Nidoviruses and arenaviruses are the only known RNA viruses encoding a 3'-5' exonuclease domain (ExoN). The proofreading activity of the ExoN domain has played a key role in the growth of nidoviral genomes, while in arenaviruses this domain partakes in the suppression of the host innate immune signaling. Sequence and structural homology analyses suggest that these proteins have been hijacked from cellular hosts many times. Analysis of the available nidoviral ExoN sequences reveals a high conservation level comparable to that of the viral RNA-dependent RNA polymerases (RdRp), which are the most conserved viral proteins. Two highly preserved zinc fingers are present in all nidoviral exonucleases, while in the arenaviral protein only one zinc finger can be identified. This is in sharp contrast with the reported lack of zinc fingers in cellular ExoNs, and opens the possibility of therapeutic strategies in the struggle against COVID-19.

Lassa Virus, but Not Highly Pathogenic New World Arenaviruses, Restricts Immunostimulatory Double-Stranded RNA Accumulation during Infection.

The arenaviruses Lassa virus (LASV), Junín virus (JUNV), and Machupo virus (MACV) can cause severe and fatal diseases in humans. Although these pathogens are closely related, the host immune responses to these virus infections differ remarkably, with direct implications for viral pathogenesis. LASV infection is immunosuppressive, with a very low-level interferon response. In contrast, JUNV and MACV infections stimulate a robust interferon (IFN) response in a retinoic acid-inducible gene I (RIG-I)-dependent manner and readily activate protein kinase R (PKR), a known host double-stranded RNA (dsRNA) sensor. In response to infection with RNA viruses, host nonself RNA sensors recognize virus-derived dsRNA as danger signals and initiate innate immune responses. Arenavirus nucleoproteins (NPs) contain a highly conserved exoribonuclease (ExoN) motif, through which LASV NP has been shown to degrade virus-derived immunostimulatory dsRNA in biochemical assays. In this study, we for the first time present evidence that LASV restricts dsRNA accumulation during infection. Although JUNV and MACV NPs also have the ExoN motif, dsRNA readily accumulated in infected cells and often colocalized with dsRNA sensors. Moreover, LASV coinfection diminished the accumulation of dsRNA and the IFN response in JUNV-infected cells. The disruption of LASV NP ExoN with a mutation led to dsRNA accumulation and impaired LASV replication in minigenome systems. Importantly, both LASV NP and RNA polymerase L protein were required to diminish the accumulation of dsRNA and the IFN response in JUNV infection. For the first time, we discovered a collaboration between LASV NP ExoN and L protein in limiting dsRNA accumulation. Our new findings provide mechanistic insights into the differential host innate immune responses to highly pathogenic arenavirus infections.IMPORTANCE Arenavirus NPs contain a highly conserved DEDDh ExoN motif, through which LASV NP degrades virus-derived, immunostimulatory dsRNA in biochemical assays to eliminate the danger signal and inhibit the innate immune response. Nevertheless, the function of NP ExoN in arenavirus infection remains to be defined. In this study, we discovered that LASV potently restricts dsRNA accumulation during infection and minigenome replication. In contrast, although the NPs of JUNV and MACV also harbor the ExoN motif, dsRNA readily formed during JUNV and MACV infections, accompanied by IFN and PKR responses. Interestingly, LASV NP alone was not sufficient to limit dsRNA accumulation. Instead, both LASV NP and L protein were required to restrict immunostimulatory dsRNA accumulation. Our findings provide novel and important insights into the mechanism for the distinct innate immune response to these highly pathogenic arenaviruses and open new directions for future studies.

Rational design of universal immunotherapy for TfR1-tropic arenaviruses.

Certain arenaviruses that circulate in rodent populations can cause life-threatening hemorrhagic fevers when they infect humans. Due to their efficient transmission, arenaviruses pose a severe risk for outbreaks and might be exploited as biological weapons. Effective countermeasures against these viruses are highly desired. Ideally, a single remedy would be effective against many or even all the pathogenic viruses in this family. However, despite the fact that all pathogenic arenaviruses from South America utilize transferrin receptor 1 (TfR1) as a cellular receptor, their viral glycoproteins are highly diversified, impeding efforts to isolate cross-neutralizing antibodies. Here we address this problem using a rational design approach to target TfR1-tropic arenaviruses with high potency and breadth. The pan-reactive molecule is highly effective against all arenaviruses that were tested, offering a universal therapeutic approach. Our design scheme avoids the shortcomings of previous immunoadhesins and can be used to combat other zoonotic pathogens.

Endangered wild salmon infected by newly discovered viruses.

The collapse of iconic, keystone populations of sockeye (Oncorhynchus nerka) and Chinook (Oncorhynchus tshawytscha) salmon in the Northeast Pacific is of great concern. It is thought that infectious disease may contribute to declines, but little is known about viruses endemic to Pacific salmon. Metatranscriptomic sequencing and surveillance of dead and moribund cultured Chinook salmon revealed a novel arenavirus, reovirus and nidovirus. Sequencing revealed two different arenavirus variants which each infect wild Chinook and sockeye salmon. In situ hybridisation localised arenavirus mostly to blood cells. Population surveys of >6000 wild juvenile Chinook and sockeye salmon showed divergent distributions of viruses, implying different epidemiological processes. The discovery in dead and dying farmed salmon of previously unrecognised viruses that are also widely distributed in wild salmon, emphasizes the potential role that viral disease may play in the population dynamics of wild fish stocks, and the threat that these viruses may pose to aquaculture.

Biological Characterization of Conserved Residues within the Cytoplasmic Tail of the Pichinde Arenaviral Glycoprotein Subunit 2 (GP2).

Several mammarenaviruses can cause deadly hemorrhagic fever infections in humans, with limited preventative and therapeutic measures available. Arenavirus cell entry is mediated by the viral glycoprotein (GP) complex, which consists of the stable signal peptide (SSP), the receptor-binding subunit GP1, and the transmembrane subunit GP2. The GP2 cytoplasmic tail (CT) is relatively conserved among arenaviruses and is known to interact with the SSP to regulate GP processing and membrane fusion, but its biological role in the context of an infectious virus has not been fully characterized. Using a Pichinde virus (PICV) GP expression vector and a PICV reverse genetics system, we systematically characterized the functional roles of 12 conserved residues within the GP2 CT in GP processing, trafficking, assembly, and fusion, as well as in viral replication. Except for P478A and K505A R508A, alanine substitutions at conserved residues abolished GP processing and membrane fusion in plasmid-transfected cells. Six invariant H and C residues and W503 are essential for viral replication, as evidenced by the fact that their mutant viruses could not be rescued. Both P480A and R482A mutant viruses were rescued, grew similarly to wild-type (WT) virus, and produced evidently processed GP1 and GP2 subunits in virus-infected cells, despite the fact that the same mutations abolished GP processing and membrane fusion in a plasmid-based protein expression system, illustrating the importance of using an infectious-virus system for analyzing viral glycoprotein function. In summary, our results demonstrate an essential biological role of the GP2 CT in arenavirus replication and suggest it as a potential novel target for developing antivirals and/or attenuated viral vaccine candidates.IMPORTANCE Several arenaviruses, such as Lassa virus (LASV), can cause severe and lethal hemorrhagic fever diseases with high mortality and morbidity, for which no FDA-approved vaccines or therapeutics are available. Viral entry is mediated by the arenavirus GP complex, which consists of the stable signal peptide (SSP), the receptor-binding subunit GP1, and the transmembrane subunit GP2. The cytoplasmic tail (CT) of GP2 is highly conserved among arenaviruses, but its functional role in viral replication is not completely understood. Using a reverse genetics system of a prototypic arenavirus, Pichinde virus (PICV), we show that the GP2 CT contains certain conserved residues that are essential for virus replication, implicating it as a potentially good target for developing antivirals and live-attenuated viral vaccines against deadly arenavirus pathogens.

A short history of Lassa fever: the first 10-15 years after discovery.

This brief review is focused on the events surrounding the initial discovery of a new viral hemorrhagic fever in 1969 and the subsequent 10-15 years during which a substantial understanding of the disease was gained. In 1969, a series of sequential life-threating or fatal infections occurred among health care workers in Nigeria and the laboratory scientist who isolated and characterized the causative agent. The agent, Lassa virus was named after the geographical location of the first recognized human case. The new virus was shown to be related to lymphocytic choriomeningitis and to previously unclassified neotropical viruses, including Argentine and Bolivian hemorrhagic fevers, and a new taxonomic grouping, the Arenaviruses, was proposed. In 1970-72, three further epidemics occurred in Nigeria, Liberia and Sierra Leone, the first two involved nosocomial transmission, and the third was a community-based outbreak, during which the rodent reservoir host was identified. In 1976, a long-term research project commenced in Sierra Leone, which produced a rich body of data from prospectively designed studies on the clinical features, transmission, and treatment of the disease.

Arenavirus genomics: novel insights into viral diversity, origin, and evolution.

Next-generation sequencing technologies have revolutionized our knowledge of virus diversity and evolution. In the case of arenaviruses, which are the focus of this review, metagenomic/metatranscriptomic approaches identified reptile-infecting and fish-infecting viruses, also showing that bi-segmented genomes are not a universal feature of the Arenaviridae family. Novel mammarenaviruses were described, allowing inference of their geographic origin and evolutionary dynamics. Extensive sequencing of Lassa virus (LASV) genomes revealed the zoonotic nature of most human infections and a Nigerian origin of LASV, which subsequently spread westward. Future efforts will likely identify many more arenaviruses and hopefully provide insight into the ultimate origin of the family, the pathogenic potential of its members, as well as the determinants of their geographic distribution.

Characterization of Haartman Institute snake virus-1 (HISV-1) and HISV-like viruses-The representatives of genus Hartmanivirus, family Arenaviridae.

The family Arenaviridae comprises three genera, Mammarenavirus, Reptarenavirus and the most recently added Hartmanivirus. Arenaviruses have a bisegmented genome with ambisense coding strategy. For mammarenaviruses and reptarenaviruses the L segment encodes the Z protein (ZP) and the RNA-dependent RNA polymerase, and the S segment encodes the glycoprotein precursor and the nucleoprotein. Herein we report the full length genome and characterization of Haartman Institute snake virus-1 (HISV-1), the putative type species of hartmaniviruses. The L segment of HISV-1 lacks an open-reading frame for ZP, and our analysis of purified HISV-1 particles by SDS-PAGE and electron microscopy further support the lack of ZP. Since we originally identified HISV-1 in co-infection with a reptarenavirus, one could hypothesize that co-infecting reptarenavirus provides the ZP to complement HISV-1. However, we observed that co-infection does not markedly affect the amount of hartmanivirus or reptarenavirus RNA released from infected cells in vitro, indicating that HISV-1 does not benefit from reptarenavirus ZP. Furthermore, we succeeded in generating a pure HISV-1 isolate showing the virus to replicate without ZP. Immunofluorescence and ultrastructural studies demonstrate that, unlike reptarenaviruses, HISV-1 does not produce the intracellular inclusion bodies typical for the reptarenavirus-induced boid inclusion body disease (BIBD). While we observed HISV-1 to be slightly cytopathic for cultured boid cells, the histological and immunohistological investigation of HISV-positive snakes showed no evidence of a pathological effect. The histological analyses also revealed that hartmaniviruses, unlike reptarenaviruses, have a limited tissue tropism. By nucleic acid sequencing, de novo genome assembly, and phylogenetic analyses we identified additional four hartmanivirus species. Finally, we screened 71 individuals from a collection of snakes with BIBD by RT-PCR and found 44 to carry hartmaniviruses. These findings suggest that harmaniviruses are common in captive snake populations, but their relevance and pathogenic potential needs yet to be revealed.

Xapuri virus, a novel mammarenavirus: natural reassortment and increased diversity between New World viruses.

Mammarenavirus RNA was detected in Musser's bristly mouse (Neacomys musseri) from the Amazon region, and this detection indicated that rodents were infected with a novel mammarenavirus, with the proposed name Xapuri virus (XAPV), which is phylogenetically related to New World Clade B and Clade C viruses. XAPV may represent the first natural reassortment of the Arenaviridae family and a new unrecognized clade within the Tacaribe serocomplex group.