Diverse replication-associated protein encoding circular DNA viruses in guano samples of Central-Eastern European bats

Genomoviruses in Liver Samples of Molossus molossus Bats

CRESS-DNA encompasses a broad spectrum of viruses documented across diverse organisms such as animals, plants, diatoms, fungi, and marine invertebrates. Despite this prevalence, the full extent of these viruses' impact on the environment and their respective hosts remains incompletely understood. Furthermore, an increasing number of viruses within this category lack detailed characterization. This investigation focuses on unveiling and characterizing viruses affiliated with the Genomoviridae family identified in liver samples from the bat Molossus molossus. Leveraging viral metagenomics, we identified seven sequences (MmGmV-PA) featuring a circular DNA genome housing two ORFs encoding replication-associated protein (Rep) and capsid protein (Cap). Predictions based on conserved domains typical of the Genomoviridae family were established. Phylogenetic analysis revealed the segregation of these sequences into two clades aligning with the genera Gemycirculavirus (MmGmV-06-PA and MmGmV-07-PA) and Gemykibivirus (MmGmV-01-PA, MmGmV-02-PA, MmGmV-03-PA, MmGmV-05-PA, and MmGmV-09-PA). At the species level, pairwise comparisons based on complete nucleotide sequences indicated the potential existence of three novel species. In summary, our study significantly contributes to an enhanced understanding of the diversity of Genomoviridae within bat samples, shedding light on previously undiscovered viral entities and their potential ecological implications.

Detection and genetic characterization of circoviruses in more than 80 bat species from eight countries on four continents

Several bat-associated circoviruses and circular rep-encoding single-stranded DNA (CRESS DNA) viruses have been described, but the exact diversity and host species of these viruses are often unknown. Our goal was to describe the diversity of bat-associated circoviruses and cirliviruses, thus, 424 bat samples from more than 80 species were collected on four continents. The samples were screened for circoviruses using PCR and the resulting amino acid sequences were subjected to phylogenetic analysis. The majority of bat strains were classified in the genus Circovirus and some strains in the genus Cyclovirus and the clades CRESS1 and CRESS3. Some strains, however, could only be classified at the taxonomic level of the order and were not classified in any of the accepted or proposed clades. In the family Circoviridae, 71 new species have been predicted. This screening of bat samples revealed a great diversity of circoviruses and cirliviruses. These studies underline the importance of the discovery and description of new cirliviruses and the need to establish new species and families in the order Cirlivirales.

Viral Co-Infection in Bats: A Systematic Review

Co-infection is an underappreciated phenomenon in contemporary disease ecology despite its ubiquity and importance in nature. Viruses, and other co-infecting agents, can interact in ways that shape host and agent communities, influence infection dynamics, and drive evolutionary selective pressures. Bats are host to many viruses of zoonotic potential and have drawn increasing attention in their role as wildlife reservoirs for human spillover. However, the role of co-infection in driving viral transmission dynamics within bats is unknown. Here, we systematically review peer-reviewed literature reporting viral co-infections in bats. We show that viral co-infection is common in bats but is often only reported as an incidental finding. Biases identified in our study database related to virus and host species were pre-existing in virus studies of bats generally. Studies largely speculated on the role co-infection plays in viral recombination and few investigated potential drivers or impacts of co-infection. Our results demonstrate that current knowledge of co-infection in bats is an ad hoc by-product of viral discovery efforts, and that future targeted co-infection studies will improve our understanding of the role it plays. Adding to the broader context of co-infection studies in other wildlife species, we anticipate our review will inform future co-infection study design and reporting in bats. Consideration of detection strategy, including potential viral targets, and appropriate analysis methodology will provide more robust results and facilitate further investigation of the role of viral co-infection in bat reservoirs.

Diverse DNA virus genomes identified in fecal samples of Mexican free-tailed bats (Tadarida brasiliensis) captured in Chiricahua Mountains of southeast Arizona (USA)

Bats (order Chiroptera) are some of the most abundant mammals on earth and their species ecology strongly influences zoonotic potential. While substantial research has been conducted on bat-associated viruses, particularly on those that can cause disease in humans and/or livestock, globally, limited research has focused on endemic bats in the USA. The southwest region of the US is of particular interest because of its high diversity of bat species. We identified 39 single-stranded DNA virus genomes in the feces of Mexican free-tailed bats (Tadarida brasiliensis) sampled in the Rucker Canyon (Chiricahua Mountains) of southeast Arizona (USA). Twenty-eight of these belong to the virus families Circoviridae (n = 6), Genomoviridae (n = 17), and Microviridae (n = 5). Eleven viruses cluster with other unclassified cressdnaviruses. Most of the viruses identified represent new species. Further research on identification of novel bat-associated cressdnaviruses and microviruses is needed to provide greater insights regarding their co-evolution and ecology relative to bats.

Molecular identification of the emerging Human Gemykibivirus-2 (HuGkV-2) among Brazilian blood donors

Human gemykibivirus-2 (HuGkV-2) belonging to the Gemykibivirus genus (Genomoviridae family) is an emerging DNA virus which has been described as a component of the virome of a wide variety of samples including clinical ones. So far, the HuGkV-2 DNA prevalence in the human population as well as its clinical impact are completely unknown. The objective of this study was to investigate the HuGkV-2 DNA prevalence among Brazilian healthy blood donors from three different geographic regions. A total of 450 blood samples were screened for HuGkV-2 DNA (150 samples were from the Brazilian Amazon, 150 from Midwest Brazil and 150 from South Brazil). The overall HuGkV-2 DNA prevalence was 7.8 %. Considering the examined regions, the highest prevalence was observed in the Brazilian Amazon (city of Macapa, state of Amapa), 15.3 %, followed by the Midwest Brazil (city of Brasilia, Federal District) (6.0 %) and South Brazil (city of Santa Maria, Rio Grande do Sul State) (2.0 %). This study gives preliminary insights on the molecular prevalence of HuGkV-2 DNA among Brazilian blood donors, highlighting that the highest HuGkV-2 prevalence was recorded in the Brazilian Amazon. However, more studies regarding the prevalence, transmission routes and any possible clinical effects appear to be crucial in order to understand the impact of this emerging viral agent.

The virome of the white-winged vampire bat Diaemus youngi is rich in circular DNA viruses

In the Neotropical region, the white-winged vampire bat (Diaemus youngi) is the rarest of the three species of vampire bats. This bat species feeds preferentially on bird blood, and there is limited information on the viruses infecting D. youngi. Hence, this study aimed to expand the knowledge about the viral diversity associated with D. youngi by sampling and pooling the lungs, liver, kidneys, heart, and intestines of all animals using high-throughput sequencing (HTS) on the Illumina MiSeq platform. A total of three complete and 10 nearly complete circular virus genomes were closely related to gemykrogvirus (Genomoviridae family), smacovirus (Smacoviridae family), and torque teno viruses (TTVs) (Anelloviridae family). In addition, three sequences of bat paramyxovirus were detected and found to be closely related to viruses reported in Pomona roundleaf bats and rodents. The present study provides a snapshot of the viral diversity associated with white-winged vampire bats and provides a baseline for comparison to viruses detected in future outbreaks.

Discovery of three cycloviruses in fecal samples from silver-haired bats (Lasionycteris noctivagans) in Arizona (USA)

Bats harbour a diverse array of viruses, some of which are zoonotic, and are one of the most speciose groups of mammals on earth. As part of an ongoing bat-associated viral diversity research project, we identified three cycloviruses (family Circoviridae) in fecal samples of silver-haired bats (Lasionycteris noctivagans) caught in Cave Creek Canyon of Arizona (USA). Two of the three identified genomes represent two new species in the genus Cyclovirus. Cycloviruses have been found in a wide range of environments and hosts; however, little is known about their biology. These new genomes of cycloviruses are the first from silver-haired bats, adding to the broader knowledge of cyclovirus diversity. With continuing studies, it is likely that additional viruses of the family Circoviridae will be identified in Arizona bat populations.

Family Genomoviridae: 2021 taxonomy update

The family Genomoviridae (phylum Cressdnaviricota, class Repensiviricetes, order Geplafuvirales) includes viruses with circular single-stranded DNA genomes encoding two proteins, the capsid protein and the rolling-circle replication initiation protein. The genomes of the vast majority of members in this family have been sequenced directly from diverse environmental or animal- and plant-associated samples, but two genomoviruses have been identified infecting fungi. Since the last taxonomic update of the Genomoviridae, a number of new members of this family have been sequenced. Here, we report on the most recent taxonomic update, including the creation of one new genus, Gemytripvirus, and classification of ~420 new genomoviruses into 164 new species. We also announce the adoption of the "Genus + freeform epithet" binomial system for the naming of all 236 officially recognized species in the family Genomoviridae. The updated taxonomy presented in this article has been accepted by the International Committee on Taxonomy of Viruses (ICTV).

Update on Potentially Zoonotic Viruses of European Bats

Bats have been increasingly gaining attention as potential reservoir hosts of some of the most virulent viruses known. Numerous review articles summarize bats as potential reservoir hosts of human-pathogenic zoonotic viruses. For European bats, just one review article is available that we published in 2014. The present review provides an update on the earlier article and summarizes the most important viruses found in European bats and their possible implications for Public Health. We identify the research gaps and recommend monitoring of these viruses.

A Preliminary Study of the Virome of the South American Free-Tailed Bats (Tadarida brasiliensis) and Identification of Two Novel Mammalian Viruses

Bats provide important ecosystem services as pollinators, seed dispersers, and/or insect controllers, but they have also been found harboring different viruses with zoonotic potential. Virome studies in bats distributed in Asia, Africa, Europe, and North America have increased dramatically over the past decade, whereas information on viruses infecting South American species is scarce. We explored the virome of Tadarida brasiliensis, an insectivorous New World bat species inhabiting a maternity colony in Rosario (Argentina), by a metagenomic approach. The analysis of five pooled oral/anal swab samples indicated the presence of 43 different taxonomic viral families infecting a wide range of hosts. By conventional nucleic acid detection techniques and/or bioinformatics approaches, the genomes of two novel viruses were completely covered clustering into the Papillomaviridae (Tadarida brasiliensis papillomavirus type 1, TbraPV1) and Genomoviridae (Tadarida brasiliensis gemykibivirus 1, TbGkyV1) families. TbraPV1 is the first papillomavirus type identified in this host and the prototype of a novel genus. TbGkyV1 is the first genomovirus reported in New World bats and constitutes a new species within the genus Gemykibivirus. Our findings extend the knowledge about oral/anal viromes of a South American bat species and contribute to understand the evolution and genetic diversity of the novel characterized viruses.

Eukaryotic Circular Rep-Encoding Single-Stranded DNA (CRESS DNA) Viruses: Ubiquitous Viruses With Small Genomes and a Diverse Host Range

While single-stranded DNA (ssDNA) was once thought to be a relatively rare genomic architecture for viruses, modern metagenomics sequencing has revealed circular ssDNA viruses in most environments and in association with diverse hosts. In particular, circular ssDNA viruses encoding a homologous replication-associated protein (Rep) have been identified in the majority of eukaryotic supergroups, generating interest in the ecological effects and evolutionary history of circular Rep-encoding ssDNA viruses (CRESS DNA) viruses. This review surveys the explosion of sequence diversity and expansion of eukaryotic CRESS DNA taxonomic groups over the last decade, highlights similarities between the well-studied geminiviruses and circoviruses with newly identified groups known only through their genome sequences, discusses the ecology and evolution of eukaryotic CRESS DNA viruses, and speculates on future research horizons.