Article

Widespread Endogenization of Densoviruses and Parvoviruses in Animal and Human Genomes

College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China.
Journal of Virology (Impact Factor: 4.44). 07/2011; 85(19):9863-76. DOI: 10.1128/JVI.00828-11
Source: PubMed

ABSTRACT

Parvoviruses infect humans and a broad range of animals, from mammals to crustaceans, and generally are associated with a
variety of acute and chronic diseases. However, many others cause persistent infections and are not known to be associated
with any disease. Viral persistence is likely related to the ability to integrate into the chromosomal DNA and to establish
a latent infection. However, there is little evidence for genome integration of parvoviral DNA except for Adeno-associated virus (AAV). Here we performed a systematic search for homologs of parvoviral proteins in publicly available eukaryotic genome
databases followed by experimental verification and phylogenetic analysis. We conclude that parvoviruses have frequently invaded
the germ lines of diverse animal species, including mammals, fishes, birds, tunicates, arthropods, and flatworms. The identification
of orthologous endogenous parvovirus sequences in the genomes of humans and other mammals suggests that parvoviruses have
coexisted with mammals for at least 98 million years. Furthermore, some of the endogenized parvoviral genes were expressed
in eukaryotic organisms, suggesting that these viral genes are also functional in the host genomes. Our findings may provide
novel insights into parvovirus biology, host interactions, and evolution.

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    • "adeno-associated virus; Casto et al., 1967), and infected hosts may show no disease symptoms (Berns & Parrish, 2007). Parvoviruses may form persistent infections in their hosts and are endogenous within widespread metazoan genomes (Liu et al., 2011). For example, in a study of Penaeus stylirostris densovirus (also reported as an infectious hypodermal and haematopoietic necrosis virus), the presence of the virus in aquacultured black tiger shrimp caused no deleterious impacts on their hosts, but rather delayed mortality by the white spot syndrome virus (family Baculoviridae) when compared with ponds lacking the densovirus (Molthathong et al., 2013). "
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    ABSTRACT: Echinoderms are important constituents of marine ecosystems, where they may influence the recruitment success of benthic flora and fauna, and are important consumers of detritus and plant materials. There are currently no described viruses of echinoderms. We used a viral metagenomic approach to examine viral consortia within three urchins - Colobocentrotus atratus, Tripneustes gratilla, and Echinometra mathaei - which are common constituents of reef communities in the Hawaiian archipelago. Metagenomic libraries revealed the presence of bacteriophage and densoviruses (Parvoviridae) in tissues of all three urchins. Densoviruses are typically known to infect terrestrial and aquatic arthropods. Urchin-associated densoviruses were detected by qPCR in all tissues tested, and were also detected in filtered suspended matter (> 0.2µm) from plankton and in sediments at several locations near to where urchins were collected for metagenomic analysis. This is the first report of echinoderm-associated viruses, which extends the known host range of parvoviruses.
    Preview · Article · Dec 2013 · Journal of General Virology
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    • "Given that other parvoviruses are able to integrate into the host genome [18], and the first known pathogenic human parvovirus, parvovirus B19, is associated with several cancers, including lymphomas [19], testicular tumors [20], papillary and anaplastic thyroid carcinomas [21,22], and chronic inflammatory diseases such as Hashimoto’s thyroiditis [23], cardiomyopathy and myocarditis [24], a similar mechanism for HBoV-associated pathogenesis appears possible. "
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    ABSTRACT: Human bocavirus is the second autonomous human parvovirus with assumed pathogenic potential. Other parvoviruses are known to persist and even integrate into the host genome, eventually contributing to the multi-step development of cancer. Human bocavirus also persists in an unknown percentage of clinically asymptomatic patients in addition to those with primary infection. The aim of the present study was to analyze the role of Human bocavirus in lung and colorectal cancers. Therefore, formalin-fixed, paraffin-embedded, archived tumor samples were screened for Human bocavirus DNA by PCR, Southern blotting, and sequencing. Positive tissues were further subjected to fluorescence in situ hybridization analysis to specifically detect human bocavirus DNA in the infected cells. In total, 11 of the 60 (18.3%) lung and 9 of the 44 (20.5%) colorectal tumors tested positive for human bocavirus DNA by PCR and were confirmed by sequencing and fluorescence in situ hybridization analysis. Thus, human bocavirus DNA is present in the nuclei of infected cells, in either single or multiple copies, and appears to form concatemers. The occurrence of these human bocavirus DNA structures supports the existence of the postulated σ- or rolling-hairpin replication mechanism. Moreover, the fluorescence in situ hybridization patterns inspired the hypothesis that human bocavirus DNA either persists as cccDNA or is integrated into the host genome. This finding suggests that this virus may indirectly contribute to the development of some colorectal and lung cancers, as do other DNA viruses, such as the human hepatitis B virus, or may play an active role in cancer by interacting with the host genome.
    Full-text · Article · Jun 2013 · PLoS ONE
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    ABSTRACT: Although single stranded (ss) DNA viruses that infect humans and their domesticated animals do not generally cause major diseases, the arthropod borne ssDNA viruses of plants do, and as a result seriously constrain food production in most temperate regions of the world. Besides the well known plant and animal-infecting ssDNA viruses, it has recently become apparent through metagenomic surveys of ssDNA molecules that there also exist large numbers of other diverse ssDNA viruses within almost all terrestrial and aquatic environments. The host ranges of these viruses probably span the tree of life and they are likely to be important components of global ecosystems. Various lines of evidence suggest that a pivotal evolutionary process during the generation of this global ssDNA virus diversity has probably been genetic recombination. High rates of homologous recombination, non-homologous recombination and genome component reassortment are known to occur within and between various different ssDNA virus species and we look here at the various roles that these different types of recombination may play, both in the day-to-day biology, and in the longer term evolution, of these viruses. We specifically focus on the ecological, biochemical and selective factors underlying patterns of genetic exchange detectable amongst the ssDNA viruses and discuss how these should all be considered when assessing the adaptive value of recombination during ssDNA virus evolution.
    Full-text · Article · Sep 2011 · Viruses
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