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.
A novel picornavirus genome was sequenced, showing 42.6%, 35.2%, and 44.6% of deduced amino acid identities corresponding to the P1, P2, and P3 regions, respectively, of the Aichi virus. Divergent strains of this new virus, which we named salivirus, were detected in 18 stool samples from Nigeria, Tunisia, Nepal, and the United States. A statistical association was seen between virus shedding and unexplained cases of gastroenteritis in Nepal (P ؍ 0.0056). Viruses with approximately 90% nucleotide similarity, named klassevirus, were also recently reported in three cases of unexplained diarrhea from the United States and Australia and in sewage from Spain, reflecting a global distribution and supporting a pathogenic role for this new group of picornaviruses.The falling cost of DNA sequencing has led to a recent surge in human and animal virus discoveries (1-3, 5-12, 14, 16-17, 19-24, 27, 30, 31, 33, 39, 43, 44). While the pathogenicity of some newly characterized human viruses has been demonstrated, it remains unknown or controversial for other viruses, which may be commensal or pathogenic in only a very small fraction of infections (25,32,40,42,45). Genetic characterization of previously unknown viruses allows the rapid design of nucleic acid tests needed to determine their association with different medical conditions, their presence in different populations, and the design of antibody tests for determining seroprevalence (25, 28, 34, 35, 47).Using sequence-independent PCR amplification, pyrosequencing, and sequence similarity searches (46) (see the text in the supplemental material), we analyzed the virus sequences present in 95 stool samples from Nigerian children suffering from nonpolio acute flaccid paralysis (AFP). Sequences derived from a 10-month-old female child exhibiting right-side asymmetric sudden flaccid paralysis (patient no. NG-J1) formed a 6,981-bp contig consisting of 2,903 individual sequence reads, which was distantly related to sequence of the Aichi virus species in the Kobuvirus genus of the Picornaviridae family (48, 49). Similar sequences were also observed in a second, 24-month-old patient with right-side asymmetric sudden flaccid paralysis (patient no. NG-F1). Gaps between sequenced viral fragments were connected by nested reverse transcription-PCR (RT-PCR), while the 5Ј and 3Ј extremity sequences were acquired using primers designed over conserved regions of bovine, porcine, and human kobuviruses. We temporarily named these viruses saliviruses (stool Aichi-like viruses).The resulting salivirus genome, NG-J1, was 7,124 bp in length with a GC content of 57%, excluding a poly(A) tail. NG-J1 contained a large open reading frame of 7,125 bp encoding a putative polyprotein precursor of 2,374 amino acids (aa), a 5Ј untranslated region (UTR) of 709 bp, and a 3ЈUTR of 148 bp (Fig. 1).NG-J1 and NG-F1 were highly similar, with nucleotide similarities of 94% and 95% in the P1 and P3 regions, respectively. Salivirus NG-J1 had approximately 90% nucleotide similarity to the recently described klasse...
Serum samples from 33,363 healthy people in Tunisia have been tested for serological markers of hepatitis B, C and delta viruses (HBV, HCV and HDV). Hepatitis B surface antigen (HBsAg) was detected in 6.5% of sera. The overall seroprevalence of HBV was 37.5%. Vertical and perinatal transmission of HBV in the first 3 months of life occurred in only 0.4% of 177 mother and child pairs. HBV seroprevalence was 10.7% in infants under 5 years old and increased with age rapidly till 25 years of age and then more slowly in adulthood, reaching 54% for people aged over 40 years. HBsAg seropositivity varied throughout the country, ranging from 3% to 13% with higher prevalences in the south and central-west regions. Overall seroprevalences for HDV and HCV were 17.7% and 0.4%, respectively. HDV superinfection occurred later than HBV and increased with age in parallel with HBV. Overall, HCV and HBV infections had different geographical distributions throughout the country. The study confirmed the high prevalence of HBV infection in Tunisia; it occurs mainly in children and teenagers, and vertical and perinatal transmission of HBV does not appear to be significant. HDV superinfection is quite common in Tunisia and occurs in almost 44% of individuals infected with HBV. In contrast, seroprevalence of HCV in the Tunisian general population was low (0.4%). These results indicate differences in the distribution of the viruses and/or different routes of transmission.
The suspected measles case definition captures rubella cases. Therefore, measles surveillance will be improved in the course of the control and eventual elimination of rubella transmission. One aspect of rubella control, virologic surveillance, is reviewed here. A systematic nomenclature for rubella viruses (RVs) based on 13 genotypes has been established and is updated when warranted by increases in information about RVs. From 2005 through 2010, the genotypes of RVs most frequently reported were 1E, 1G, and 2B, and genotypes 1a, 1B, 1C, 1h, 1j, and 2C were less frequently reported. Virologic surveillance can support rubella control and elimination. Synopses of rubella virologic surveillance in various countries, regions, and globally are given, including characterization of viruses from imported cases in a country that has eliminated rubella and studies of endemic viruses circulating in countries without rubella control objectives. Current challenges are discussed.
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