Circoviruses are known to infect birds and pigs and can cause a wide range of severe symptoms with significant economic impact. Using viral metagenomics, we identified circovirus-like DNA sequences and characterized 15 circular viral DNA genomes in stool samples from humans in Pakistan, Nigeria, Tunisia, and the United States and from wild chimpanzees. Distinct genomic features and phylogenetic analysis indicate that some viral genomes were part of a previously unrecognized genus in the Circoviridae family we tentatively named "Cyclovirus" whose genetic diversity is comparable to that of all the known species in the Circovirus genus. Circoviridae detection in the stools of U.S. adults was limited to porcine circoviruses which were also found in most U.S. pork products. To determine whether the divergent cycloviruses found in non-U.S. human stools were of dietary origin, we genetically compared them to the cycloviruses in muscle tissue samples of commonly eaten farm animals in Pakistan and Nigeria. Limited genetic overlap between cycloviruses in human stool samples and local cow, goat, sheep, camel, and chicken meat samples indicated that the majority of the 25 Cyclovirus species identified might be human viruses. We show that the genetic diversity of small circular DNA viral genomes in various mammals, including humans, is significantly larger than previously recognized, and frequent exposure through meat consumption and contact with animal or human feces provides ample opportunities for cyclovirus transmission. Determining the role of cycloviruses, found in 7 to 17% of non-U.S. human stools and 3 to 55% of non-U.S. meat samples tested, in both human and animal diseases is now facilitated by knowledge of their genomes.

We analyzed viral nucleic acids in stool samples collected from 35 South Asian children with nonpolio acute flaccid paralysis (AFP). Sequence-independent reverse transcription and PCR amplification of capsid-protected, nuclease-resistant viral nucleic acids were followed by DNA sequencing and sequence similarity searches. Limited Sanger sequencing (35 to 240 subclones per sample) identified an average of 1.4 distinct eukaryotic viruses per sample, while pyrosequencing yielded 2.6 viruses per sample. In addition to bacteriophage and plant viruses, we detected known enteric viruses, including rotavirus, adenovirus, picobirnavirus, and human enterovirus species A (HEV-A) to HEV-C, as well as numerous other members of the Picornaviridae family, including parechovirus, Aichi virus, rhinovirus, and human cardiovirus. The viruses with the most divergent sequences relative to those of previously reported viruses included members of a novel Picornaviridae genus and four new viral species (members of the Dicistroviridae, Nodaviridae, and Circoviridae families and the Bocavirus genus). Samples from six healthy contacts of AFP patients were similarly analyzed and also contained numerous viruses, particularly HEV-C, including a potentially novel Enterovirus genotype. Determining the prevalences and pathogenicities of the novel genotypes, species, genera, and potential new viral families identified in this study in different demographic groups will require further studies with different demographic and patient groups, now facilitated by knowledge of these viral genomes.

Using viral metagenomics we identified a novel parvovirus species in human stool whose closest phylogenetic relative is the human bocavirus (HBoV). HBoV2 has an identical genomic organization to HBoV but share only 78%, 67%, and 80% identity to its NS1, NP1 and VP1/VP2 proteins. Using PCR we detected HBoV2 sequences in 5/98 Pakistani children stool samples and 3/699 stool samples from the UK. Near full genome sequencing showed the presence of three divergent genotypes and evidence of recombination. Further studies are required to determine sites of replication of HBoV2 and potential associations with clinical symptoms or disease.

This article summarizes the status of environmental surveillance (ES) used by the Global Polio Eradication Initiative, provides the rationale for ES, gives examples of ES methods and findings, and summarizes how these data are used to achieve poliovirus eradication. ES complements clinical acute flaccid paralysis (AFP) surveillance for possible polio cases. ES detects poliovirus circulation in environmental sewage and is used to monitor transmission in communities. If detected, the genetic sequences of polioviruses isolated from ES are compared with those of isolates from clinical cases to evaluate the relationships among viruses. To evaluate poliovirus transmission, ES programs must be developed in a manner that is sensitive, with sufficiently frequent sampling, appropriate isolation methods, and specifically targeted sampling sites in locations at highest risk for poliovirus transmission. After poliovirus ceased to be detected in human cases, ES documented the absence of endemic WPV transmission and detected imported WPV. ES provides valuable information, particularly in high-density populations where AFP surveillance is of poor quality, persistent virus circulation is suspected, or frequent virus reintroduction is perceived. Given the benefits of ES, GPEI plans to continue and expand ES as part of its strategic plan and as a supplement to AFP surveillance.

Diarrhoea remains a significant cause of morbidity and mortality in developing countries where numerous cases remain without identified aetiology. Astroviruses are a recently identified cause of animal gastroenteritis which currently includes two species suspected of causing human diarrhoea. Using pan-astrovirus RT-PCR, we analysed human stool samples from different continents for astrovirus-related RNA sequences. We identified variants of the two known human astrovirus species plus, based on genetic distance criteria, three novel astrovirus species all distantly related to mink and ovine astroviruses, which we provisionally named HMOAstV species A-C. The complete genome of species A displayed all the conserved characteristics of mammalian astroviruses. Each of the now three groups of astroviruses found in human stool (HAstV, AstV-MLB and HMOAstV) were more closely related to animal astroviruses than to each other, indicating that human astroviruses may periodically emerge from zoonotic transmissions. Based on the pathogenic impact of their closest phylogenetic relatives in animals, further investigations of the role of HMOAstV, so far detected in Nigeria, Nepal and Pakistan, in human gastroenteritis are warranted. INTRODUCTIONThe family Astroviridae consists of small (28-30 nm in diameter), non-lipid enveloped, single-stranded positivesense RNA viruses whose genomes range in size from 6.4 to 7.3 kb. The genome includes three open reading frames (ORFs) designated ORF1a, ORF1b and ORF2. ORF1a encodes the non-structural polyprotein 1a while the longer ORF1b encodes polyprotein 1ab including the RNA dependent RNA polymerase (RdRp) expressed through a ribosomal frameshift at the ORF1a/1b junction mediated by a slippery polyA sequence. ORF2 encodes the viral capsid structural polyprotein (Mendéz & Arias, 2007; Monroe et al., 2005).The family Astroviridae consists, so far, of two genera, Avastrovirus and Mamastrovirus, that infect avian and mammalian hosts, respectively. Astroviruses, transmitted through the faecal-oral route can cause gastroenteritis in mammalian and avian species, including humans, calves, piglets, sheep, minks, dogs, cats, mice, chickens and turkeys (Jonassen et al., 2001(Jonassen et al., , 2003. All eight known human astrovirus serotypes belonging to the first identified human astrovirus species (HAstV) have been associated with gastroenteritis (Clark & McKendrick, 2004;Fodha et al., 2006; Gabbay et al., 2007;Jin et al., 2009; Tayeb et al., 2008). Clinical symptoms of HAstV infection in humans usually last between 2 and 4 days and consist of watery diarrhoea and, less commonly, vomiting, headache, fever, abdominal pains and anorexia (Mendéz & Arias, 2007; Monroe et al., 2005). HAstV can also cause significant disease in the elderly and in immunocompromised patients (Liste et al., 2000). Recently, a second species of astrovirus was found in a child with diarrhoea and named AstV-MLB (Finkbeiner et al., 2008).Group-reactive or pan-PCR approaches have been used successfully to identify new viruses ...

Viral metagenomics focused on particle-protected nucleic acids was used on the stools of South Asian children with nonpolio acute flaccid paralysis (AFP). We identified sequences distantly related to Seneca Valley virus and cardioviruses that were then used as genetic footholds to characterize multiple viral species within a previously unreported genus of the Picornaviridae family. The picornaviruses were detected in the stools of >40% of AFP and healthy Pakistani children. A genetically diverse and highly prevalent enteric viral infection, characteristics similar to the Enterovirus genus, was therefore identified substantially expanding the genetic diversity of the RNA viral flora commonly found in children.Cardiovirus ͉ Cosavirus ͉ metagenomics ͉ Picornavirus ͉ polio M etagenomics analyses have revealed a high degree of microbial genetic diversity in environmental and human samples. Human stool, containing numerous bacteriophages and plant viruses (1, 2), also appears to be a readily accessible source of novel eukaryotic viruses (3). Stools from children with acute flaccid paralysis (AFP) are being systematically analyzed by using cell cultures to identify and control remaining foci of poliovirus in 4 endemic countries (www.who.int/ immunizationmonitoring/laboratorypolio/en/index.html and www.polioeradication.org/content/general/infectedistricts.pdf). Inoculated cell cultures from nonpolio AFP cases show the presence of other, nonpoliovirus, human enteroviruses (HEVs) (4, 5), some serotypes of which have been associated with neurological symptoms. Because HEVs are detected in less than half of the nonpolio AFP cases a majority of these cases remain without a potential etiological agent. To characterize the viruses circulating in this population we used viral particle nucleic acid purification and limited shotgun sequencing, a method initially reported for animal viruses by Allander et al. (6) and extensively used for environmental viral metagenomics (7-9). We genetically characterized multiple picornavirus species (themselves diversified into serotypes) belonging to a previously unreported genus of the Picornaviridae family. Members of this genus were detected in the stools of nearly half of the AFP and healthy children. This high level of viral genetic diversity and prevalence, reminiscent of that observed for HEV infections, indicate that this genus of picornaviruses has the potential to be involved in a variety of diseases. Results Metagenomic Identification and Sequencing of a Highly DivergentPicornavirus. Stool samples from cases of nonpolio AFP were analyzed by using a simple viral particle nucleic acid purification method involving filtration at 450 nm and DNA and RNA nuclease treatment to reduce contamination from bacteria, eukaryotic cells, and nonviral capsid protected nucleic acids. Extracted viral nucleic acids where then amplified in a sequenceindependent manner by using 3Ј randomized oligonucleotides for reverse transcription, Klenow fragment DNA polymerase extension, and PCR. Amplified DNA libr...

Both AFP patients and healthy children in Pakistan were found to be excreting SAFV at high frequencies of 9 and 12%, respectively. Further studies are needed to examine the roles of these highly common and diverse SAFV genotypes in nonpolio AFP and other human diseases.

Circoviruses consist of highly prevalent and genetically diverse porcine and avian pathogens. The genomes of cycloviruses, a proposed new genus in the family Circoviridae, were recently identified in human and chimpanzee faeces. Here, six cyclovirus and four circovirus genomes from the tissues of chickens, goats, cows, and a bat were amplified and sequenced using rolling-circle amplification and inverse PCR. A goat cyclovirus was nearly identical to a cyclovirus from a cow. USA beef contained circoviruses with .99 % similarity to porcine circovirus 2b. Circoviruses in chicken were related to those of pigeons. The close genetic similarity of a subset of cycloviruses and circoviruses replicating in distinct animal species may reflect recent cross-species transmissions. Further studies will be required to determine the impact of these highly prevalent infections on the health of farm animals.