Distribution, diversity and evolution of endogenous retroviruses in perissodactyl genomes

The evolution of mammalian genomes has been shaped by interactions with endogenous retroviruses (ERVs). In this study, we investigated the distribution and diversity of ERVs in the mammalian order Perissodactyla, with a view to understanding their impact on the evolution of modern equids (family Equidae). We characterize the major ERV lineages in the horse genome in terms of their genomic distribution, ancestral genome organization and time of activity. Our results show that subsequent to their ancestral divergence from rhinos and tapirs, equids acquired four novel ERV lineages. We show that two of these proliferated extensively in the lineage leading to modern horses, and one contains loci that are actively transcribed in specific tissues. In addition, we show that the white rhinoceros has resisted germline colonisation by retroviruses for over 54 million years - longer than any other extant mammalian species. The map of equine ERVs that we provide here will be of great utility to future studies aiming to investigate the potential functional roles of equine ERVs, and their impact on equine evolution

Late restriction induced by an endogenous retrovirus

Exogenous retroviruses (i.e. horizontally transmitted) must integrate their proviral DNA into the host's genome as part of the retroviral cycle. Therefore, infections of the germ line can give rise to vertically transmitted endogenous retroviruses (ERVs). ERVs are present in all vertebrates. During evolution, most ERVs have accumulated mutations and/or deletions that hampered their ability to replicate and hence to harm the host. However, some ERVs have retained at least some of their open reading frames intact even after several million years. One possible reason for the selection of ERVs is that they protected the host against incoming pathogenic exogenous retroviruses. The fact that the vast majority of ERVs do not possess circulating exogenous counterparts supports this view. Ovine pulmonary adenocarcinoma (OPA) is a transmissible lung cancer of sheep caused by a Betaretrovirus known as Jaagsiekte sheep retrovirus (JSRV). Notably, the sheep genome possesses approximately 30 ERVs highly related to JSRV (and hence referred to as enJSRVs). A specific enJSRV provirus, termed enJS56Al, acts as a transdominant restriction factor that blocks the exogenous JSRV at late stages of the replication cycle. The main determinant of this block (termed JLR for JSRV late restriction) has been mapped to the N-terminal region of the Gag polyprotein, more precisely to residue 21 of the matrix protein, hi this study, the molecular basis of JLR was investigated by functionally characterizing the JSRV and enJS56Al Gag polyproteins. Putative Gag trafficking signals, such as membrane binding (M) and late domains (L) were identified, although it was determined that these domains lack any involvement in JLR. enJS56Al- expression constructs bearing truncated Gags were unable to block JSRV, indicating that an intact Gag polyprotein is required for JLR. Moreover, intracellular colocalization and protein-protein interaction between JSRV and enJS56Al Gag molecules was determined by confocal microscopy and co-immunoprecipitation, respectively. Complementation assays suggest that JSRV and enJS56Al Gag likely co-assemble. These data are supported by the fact that deletion of the major homology region of enJS56Al Gag allows JSRV to escape JLR. Confocal microscopy experiments indicate that JSRV must reach the pericentriolar region as part of its normal cell cycle and that JLR takes place before this stage. This work unveils basic aspects of JSRV biology that were previously unknown. It also provides insight on the molecular basis of JLR, highlighting the dynamic evolutionary interplay between viruses and host

Chapparvoviruses occur in at least three vertebrate classes and have a broad biogeographic distribution

Chapparvoviruses are a highly divergent group of parvoviruses (family Parvoviridae) that have recently been identified via metagenomic sampling of animal faeces. Here we report the sequences of six novel chapparvoviruses identified through both metagenomic sampling of bat tissues and in silico screening of published vertebrate genome assemblies. The novel chapparvoviruses share several distinctive genomic features, and group together as a robustly supported monophyletic clade in phylogenetic trees. Our data indicate that chapparvoviruses have a broad host range in vertebrates, and a global distribution

A novel Hepacivirus in wild rodents from South America

The Hepacivirus genus comprises single-stranded positive-sense RNA viruses within the family Flaviviridae. Several hepaciviruses have been identified in different mammals, including multiple rodent species in Africa, Asia, Europe, and North America. To date, no rodent hepacivirus has been identified in the South American continent. Here, we describe an unknown hepacivirus discovered during a metagenomic screen in Akodon montensis, Calomys tener, Oligoryzomys nigripes, Necromys lasiurus, and Mus musculus from São Paulo State, Brazil. Molecular detection of this novel hepacivirus by RT-PCR showed a frequency of 11.11% (2/18) in Oligoryzomys nigripes. This is the first identification of hepavivirus in sigmondonine rodents and in rodents from South America. In sum, our results expand the host range, viral diversity, and geographical distribution of the Hepacivirus genus

Discovery of novel astrovirus and calicivirus identified in ruddy turnstones in Brazil

Birds are the natural reservoir of viruses with zoonotic potential, as well as contributing to the evolution, emergence, and dissemination of novel viruses. In this study, we applied a high-throughput screening approach to identify the diversity of viruses in 118 samples of birds captured between October 2006 to October 2010 in the North and Northeast regions of Brazil. We found nearly complete genomes of novel species of astrovirus and calicivirus in cloacal swabs of ruddy turnstones (Arenaria interpres) collected in Coroa do Avião islet, Pernambuco State. These viruses are positive-sense single-stranded RNA with a genome of ~7 to 8 kb, and were designated as Ruddy turnstone astrovirus (RtAstV) and Ruddy turnstone calicivirus (RTCV), respectively. Phylogenetic analysis showed that RtAstV and RTCV grouped in a monophyletic clade with viruses identified from poultry samples (i.e., chicken, goose, and turkey), including viruses associated with acute nephritis in chickens. Attempts of viral propagation in monkey and chicken cell lines for both viruses were unsuccessful. Also, we found genomes related with viral families that infect invertebrates and plants, suggesting that they might be ingested in the birds' diet. In sum, these findings shed new light on the diversity of viruses in migratory birds with the notable characterization of a novel astrovirus and calicivirus

Novel orthohepeviruses in wild rodents from São Paulo State, Brazil

The Hepeviridae comprise single-stranded positive-sense RNA viruses classified into two genera, Orthohepevirus and Piscihepevirus. Orthohepeviruses have a wide host range that includes rodents, but previous studies had been restricted to rodents of the Muridae family. In this study, we applied a high-throughput sequencing approach to examine the presence of orthohepeviruses in rodents from São Paulo State, Brazil. We also used RT-PCR to determine the frequency of orthohepeviruses in our sampled population. We identified novel orthohepeviruses in blood samples derived from Necromys lasiurus (1.19%) and Calomys tener (3.66%). Therefore, our results expand the host range and viral diversity of the Hepeviridae family

Pingu virus : a new picornavirus in penguins from Antarctica

Picornaviridae family comprises single-stranded, positive-sense RNA viruses distributed into forty-seven genera. Picornaviruses have a broad host range and geographic distribution in all continents. In this study, we applied a high-throughput sequencing approach to examine the presence of picornaviruses in penguins from King George Island, Antarctica. We discovered and characterized a novel picornavirus from cloacal swab samples of gentoo penguins (Pygoscelis papua), which we tentatively named Pingu virus. Also, using RT-PCR we detected this virus in 12.9 per cent of cloacal swabs derived from P. papua, but not in samples from adelie penguins (Pygoscelis adeliae) or chinstrap penguins (Pygoscelis antarcticus). Attempts to isolate the virus in a chicken cell line and in embryonated chicken eggs were unsuccessful. Our results expand the viral diversity, host range, and geographical distribution of the Picornaviridae52FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP13/14929-1; 17/13981-0; 12/24150-9; 15/05778-5; 14/20851-8, 16/01414-1; 06/00572-0This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo, Brazil (Grant no. 13/14929-1, and Scholarships nos. 17/13981-0; 12/24150-9; 15/05778-5; 14/20851-8; 16/01414-1; 06/00572-0). P.R.M. was supported by the Medical Research Council of the UK (Grant no. MC_UU_120/14/9

Krykféie dicistrovirus: a novel dicistrovirus in velvety free-tailed bats from Brazil

The Dicistroviridae family comprises positive single-stranded RNA viruses that are classified into Picornavirales order. These viruses are identified in arthropod hosts, including some having devastating economic consequences. Here, we described and characterized a novel nearly complete dicistrovirus genome identified in liver samples of velvety free-tailed bats (Molossus molossus) collected in June 2010 in Araçatuba city, São Paulo State, Brazil. This novel virus presents a genome of 9262 nucleotides in length and a typical dicistrovirus genome organization. Based on our phylogenetic analysis and ICTV criteria, we propose this virus as a novel species into the Triatovirus genus. Attempts of viral propagation in Vero E6 and C6/36 cell lines were unsuccessful. The novel dicistrovirus was detected only in one out of nine liver bat samples, representing for the first time an internal organ detection from a representative of this virus family

Viral diversity of Rhipicephalus microplus parasitizing cattle in southern Brazil

Ticks are ectoparasites spread worldwide and are well known as vectors of many viruses of great importance to human and animal health. However, the viral diversity in ticks is still poorly understood, particularly in South America. Here we characterized the viral diversity present in Rhipicephalus microplus parasitizing cattle in the southern region of Brazil using metagenomics. Our study revealed the presence of viruses that had not been previously described in the region, including lihan tick virus (Phenuiviridae family) and wuhan tick virus 2 (Chuviridae family), as well as expands the biogeography of jingmen tick virus (Flaviviridae family) in Brazil. Also, we described three novel tymoviruses (Tymovirales order), named guarapuava tymovirus-like 1 to 3. We described the genomic and phylogenetic characterization of these viruses. Our study sheds light on the viral diversity of Rhipicephalus microplus in South America, and also expands the biogeography of tick viruses that were previously described only in Asia

Discovery of novel anelloviruses in small mammals expands the host range and diversity of the Anelloviridae

The Anelloviridae comprises single-stranded DNA viruses currently grouped in sixty-eight species classified in twelve genera. They have been found in many vertebrate hosts including primates. In this study, we describe the application of the high-throughput sequencing to examine the frequency and diversity of anelloviruses in rodents, bats and opossums captured in São Paulo State, Brazil. We report a total of twenty-six anelloviruses with sixteen nearly complete genomes and ten partial genomes, which include eleven potential novel species identified in rodents (Cricetidae), bats (Molossidae and Phyllostomidae), and opossums (Didelphidae). We also propose the inclusion of two potential new genera within the Anelloviridae family, provisionally named Omegatorquevirus and Sigmatorquevirus, including six and three novel species of anelloviruses, respectively. In summary, this study expands the diversity and the host range of the known anelloviruses