Non-Norovirus Viral Gastroenteritis Outbreaks Reported to the National Outbreak Reporting System, USA, 2009-2018.

During 2009-2018, four adenovirus, 10 astrovirus, 123 rotavirus, and 107 sapovirus gastroenteritis outbreaks were reported to the US National Outbreak Reporting System (annual median 30 outbreaks). Most were attributable to person-to-person transmission in long-term care facilities, daycares, and schools. Investigations of norovirus-negative gastroenteritis outbreaks should include testing for these viruses.

Experimental porcine astrovirus type 3-associated polioencephalomyelitis in swine.

Porcine astrovirus type 3 (PoAstV3) is an emerging virus in the family Astroviridae that has been recently associated with polioencephalomyelitis/encephalitis. Herein, we describe the experimental oral and intravenous inoculation of an infectious central nervous system (CNS) tissue homogenate containing PoAstV3 to cesarean-derived, colostrum-deprived pigs, and the subsequent development of clinical signs, histologic lesions, specific humoral immune response, and detection of viral particles by electron microscopy (EM) and viral RNA by RT-qPCR (reverse transcriptase quantitative polymerase chain reaction) and in situ hybridization (ISH). IgG against a portion of the PoAstV3 ORF2 capsid was first detected at 7 days post-inoculation (DPI) in 2 of 4 inoculated animals and in all inoculated animals by 14 DPI. At 21 and 28 DPI, 2 of 4 inoculated animals developed ataxia, tetraparesis, and/or lateral recumbency. All inoculated animals had histologic lesions in the CNS including perivascular lymphoplasmacytic cuffs, multifocal areas of gliosis with neuronal necrosis, satellitosis, and radiculoneuritis, and PoAstV3 RNA as detected by RT-qPCR within multiple anatomic regions of the CNS. Consistent viral structures were within the soma of a spinal cord neuron in the single pig examined by EM. Of note, PoAstV3 was not only detected by ISH in neurons of the cerebrum and spinal cord but also neurons of the dorsal root ganglion and nerve roots consistent with viral dissemination via axonal transport. This is the first study reproducing CNS disease with a porcine astrovirus strain consistent with natural infection, suggesting that pigs may serve as an animal model to study the pathogenesis of neurotropic astroviruses.

[Analysis of pathogenic composition and clinical characteristics of viral acute gastroenteritis in children under five years old in Beijing].

Objective: To understand the epidemiological characteristics and clinical features of rotavirus-, norovirus-, adenovirus-and astrovirus-associ ated acute gastroenteritis in children under 5 years old in Beijing from Octorber, 2015 to March, 2017. Methods: In the intestinal clinic of 6 hospitals in 6 districts of Beijing, information and stool samples of the first 30 patients with acute gastroenteritis who are under the age of 5 years are collected monthly.Rotavirus, norovirus, adenovirus and astrovirus are identified by PCR.Descriptive epidemiological method was used to describe the epidemiological characteristics of diarrhea caused by rotavirus, norovirus, adenovirus and astrovirus in Beijing. One-way analysis of variance was used to analyze the Vesikari clinical severity score of of acute gastroenteritis caused by each virus. Unconditional logistic regression analysis was used to analysis the associated factors of clinical features. Results: Of the 2 052 samples, 709 (34.6%) were non-mixed infections: the positive rate of rotavirus, norovirus, adenovirus and astrovirus were 20.0%, 7.5%, 4.2% and 2.9%, respectively. A total of 135 cases (6.6%) were mixed infection. The mean and standard deviation of Vesikari clinical severity score was 8.0±3.1 for rotavirus associated acute gastroenteritis, which was significantly higher than norovirus (6.4±2.4, P<0.001), adenovirus (6.2±2.1, P<0.001) and astrovirus (6.1±2.0, P<0.001). The comparison of clinical features showed that compared with astrovirus, the children under 5 years old infected with rotavirus were more likely to have a diarrhea ≥5 days (OR=3.334), have vomiting ≥3 times within one day (OR=8.788), have vomiting≥1 day (OR=3.963), have a Vesikari clinical severity score ≥11 severe cases (OR=13.194). Norovirus infected cases were prone to have vomiting≥3 times in 1 day (OR=5.710).Adenovirus infected cases were prone to have a diarrhea≥5 days (OR=2.616). When using rotavirus as a reference, children under 5 years of age were less likely to develop fever≥38.4 ℃ after infection with norovirus (OR=0.397) or adenovirus (OR=0.280). Conclusions: The results of this study showed that the characteristics of acute gastroenteritis caused by different viruses are different. The clinical symptoms caused by rotavirus are more serious. Children under 24 months of age are at high risk of rotavirus infection. Effective preventive measures such as vaccination should be taken as soon as possible.

Indication of Cross-Species Transmission of Astrovirus Associated with Encephalitis in Sheep and Cattle.

We report the identification of a neurotropic astrovirus associated with encephalitis in a sheep. This virus is genetically almost identical to an astrovirus recently described in neurologically diseased cattle. The similarity indicates that astroviruses of the same genotype may cause encephalitis in different species.

Ancient recombination events and the origins of hepatitis E virus.

BACKGROUND: Hepatitis E virus (HEV) is an enteric, single-stranded, positive sense RNA virus and a significant etiological agent of hepatitis, causing sporadic infections and outbreaks globally. Tracing the evolutionary ancestry of HEV has proved difficult since its identification in 1992, it has been reclassified several times, and confusion remains surrounding its origins and ancestry. RESULTS: To reveal close protein relatives of the Hepeviridae family, similarity searching of the GenBank database was carried out using a complete Orthohepevirus A, HEV genotype I (GI) ORF1 protein sequence and individual proteins. The closest non-Hepeviridae homologues to the HEV ORF1 encoded polyprotein were found to be those from the lepidopteran-infecting Alphatetraviridae family members. A consistent relationship to this was found using a phylogenetic approach; the Hepeviridae RdRp clustered with those of the Alphatetraviridae and Benyviridae families. This puts the Hepeviridae ORF1 region within the "Alpha-like" super-group of viruses. In marked contrast, the HEV GI capsid was found to be most closely related to the chicken astrovirus capsid, with phylogenetic trees clustering the Hepeviridae capsid together with those from the Astroviridae family, and surprisingly within the "Picorna-like" supergroup. These results indicate an ancient recombination event has occurred at the junction of the non-structural and structure encoding regions, which led to the emergence of the entire Hepeviridae family. The Astroviridae capsid is also closely related to the Tymoviridae family of monopartite, T = 3 icosahedral plant viruses, whilst its non-structural region is related to viruses of the Potyviridae; a large family of plant-infecting viruses with a flexible filamentous rod-shaped virion. Thus, we identified a separate inter-viral family recombination event, again at the non-structural/structural junction, which likely led to the creation of the Astroviridae. CONCLUSIONS: In summary, we have shown that new viral families have been created though recombination at the junction of the genome that encodes non-structural and structural proteins, and such recombination events are implicated in the genesis of important human pathogens; HEV, astrovirus and rubella virus.

Isolation and detection of duck astrovirus CPH: implications for epidemiology and pathogenicity.

The transmission routes of duck astrovirus CPH (DAstV/CPH) and its pathogenicity in duck embryos were investigated. Using a reverse transcription-polymerase chain reaction (RT-PCR) developed in this study, DAstV/CPH was detected in 23/50 fresh droppings of breeder ducks, 39/65 breeding eggs, 26/31 dead embryos, and 6/10 newly hatched ducklings, which were taken from a Pekin duck farm where DAstV/CPH had previously been identified. This finding, and the detection of DAstV/CPH in 36/130 dead-in-shell duck embryo samples collected from different hatcheries located in six provinces, suggests that the virus may be horizontally and vertically transmitted and associated with hatchability problems. Inoculation and repeated passages in embryonating duck eggs resulted in isolation of DAstV/CPH. The virus caused severe chorioallantoic membrane lesions as well as growth retardation and embryo mortality, indicating that DAstV/CPH is pathogenic for duck embryos. The effect of DAstV/CPH on hatching was confirmed by an embryo infection experiment in which 8/10 9-day-old duck embryos inoculated with the third passage of DAstV/CPH were unable to hatch, with most embryos succumbing in the final stage of incubation. The use of RT-PCR on the hatched ducklings provided evidence that the embryos could develop into infected ducklings.

Genome Sequences and Characterization of Chicken Astrovirus and Avian Nephritis Virus from Tanzanian Live Bird Markets.

The enteric chicken astrovirus (CAstV) and avian nephritis virus (ANV) are the type species of the genus Avastrovirus (AAstV; Astroviridae family), capable of causing considerable production losses in poultry. Using next-generation sequencing of a cloacal swab from a backyard chicken in Tanzania, we assembled genome sequences of ANV and CAstV (6918 nt and 7318 nt in length, respectively, excluding poly(A) tails, which have a typical AAstV genome architecture (5'-UTR-ORF1a-ORF1b-ORF2-'3-UTR). They are most similar to strains ck/ANV/BR/RS/6R/15 (82.72%) and ck/CAstV/PL/G059/14 (82.23%), respectively. Phylogenetic and sequence analyses of the genomes and the three open reading frames (ORFs) grouped the Tanzanian ANV and CAstV strains with Eurasian ANV-5 and CAstV-Aii viruses, respectively. Compared to other AAstVs, the Tanzanian strains have numerous amino acid variations (substitutions, insertions and deletions) in the spike region of the capsid protein. Furthermore, CAstV-A has a 4018 nt recombinant fragment in the ORF1a/1b genomic region, predicted to be from Eurasian CAstV-Bi and Bvi parental strains. These data should inform future epidemiological studies and options for AAstV diagnostics and vaccines.

Leveraging machine learning for taxonomic classification of emerging astroviruses.

Astroviruses are a family of genetically diverse viruses associated with disease in humans and birds with significant health effects and economic burdens. Astrovirus taxonomic classification includes two genera, Avastrovirus and Mamastrovirus. However, with next-generation sequencing, broader interspecies transmission has been observed necessitating a reexamination of the current host-based taxonomic classification approach. In this study, a novel taxonomic classification method is presented for emergent and as yet unclassified astroviruses, based on whole genome sequence k-mer composition in addition to host information. An optional component responsible for identifying recombinant sequences was added to the method's pipeline, to counteract the impact of genetic recombination on viral classification. The proposed three-pronged classification method consists of a supervised machine learning method, an unsupervised machine learning method, and the consideration of host species. Using this three-pronged approach, we propose genus labels for 191 as yet unclassified astrovirus genomes. Genus labels are also suggested for an additional eight as yet unclassified astrovirus genomes for which incompatibility was observed with the host species, suggesting cross-species infection. Lastly, our machine learning-based approach augmented by a principal component analysis (PCA) analysis provides evidence supporting the hypothesis of the existence of human astrovirus (HAstV) subgenus of the genus Mamastrovirus, and a goose astrovirus (GoAstV) subgenus of the genus Avastrovirus. Overall, this multipronged machine learning approach provides a fast, reliable, and scalable prediction method of taxonomic labels, able to keep pace with emerging viruses and the exponential increase in the output of modern genome sequencing technologies.

An outbreak of neonatal enteritis in buffalo calves associated with astrovirus.

BACKGROUND: Enteritis of an infectious origin is a major cause of productivity and economic losses to cattle producers worldwide. Several pathogens are believed to cause or contribute to the development of calf diarrhea. Astroviruses (AstVs) are neglected enteric pathogens in ruminants, but they have recently gained attention because of their possible association with encephalitis in humans and various animal species, including cattle. OBJECTIVES: This paper describes a large outbreak of neonatal diarrhea in buffalo calves (Bubalus bubalis), characterized by high mortality, which was associated with an AstV infection. METHODS: Following an enteritis outbreak characterized by high morbidity (100%) and mortality (46.2%) in a herd of Mediterranean buffaloes (B. bubalis) in Italy, 16 samples from buffalo calves were tested with the molecular tools for common and uncommon enteric pathogens, including AstV, kobuvirus, and torovirus. RESULTS: The samples tested negative for common enteric viral agents, including Rotavirus A, coronavirus, calicivirus, pestivirus, kobuvirus, and torovirus, while they tested positive for AstV. Overall, 62.5% (10/16) of the samples were positive in a single round reverse transcription polymerase chain reaction (PCR) assay for AstV, and 100% (16/16) were positive when nested PCR was performed. The strains identified in the outbreak showed a clonal origin and shared the closest genetic relationship with bovine AstVs (up to 85% amino acid identity in the capsid). CONCLUSIONS: This report indicates that AstVs should be included in a differential diagnosis of infectious diarrhea in buffalo calves.

Astrovirus in Reunion Free-Tailed Bat (Mormopterus francoismoutoui).

Astroviruses (AstVs) are RNA viruses infecting a large diversity of avian and mammalian species, including bats, livestock, and humans. We investigated AstV infection in a free-tailed bat species, Mormopterus francoismoutoui, endemic to Reunion Island. A total of 380 guano samples were collected in a maternity colony during 38 different sampling sessions, from 21 June 2016 to 4 September 2018. Each sample was tested for the presence of the AstV RNA-dependent RNA-polymerase (RdRp) gene using a pan-AstV semi-nested polymerase chain reaction assay. In total, 27 guano samples (7.1%) tested positive, with high genetic diversity of the partial RdRp gene sequences among positive samples. Phylogenetic analysis further revealed that the detected viruses were genetically related to AstVs reported in rats, reptiles, dogs, and pigs, but did not cluster with AstVs commonly found in bats. Although more investigations need to be conducted to assess the prevalence of infected bats in the studied population, our findings show that Reunion free-tailed bats are exposed to AstVs, and suggest that cross-species transmission may occur with other hosts sharing the same habitat.

New insights and antimicrobial stewardship opportunities in viral pneumonia: five lung ultrasound cases.

BACKGROUND: Antimicrobial stewardship is crucial to avoid antimicrobial resistance in microbes and adverse drug effects in patients. In respiratory infections, however, viral pneumonia is difficult to distinguish from bacterial pneumonia, which explains the overuse of antibiotic therapy in this indication. CASES: Five cases of lung consolidation are presented. Lung ultrasound, in conjunction with procalcitonin levels, were used to exclude or corroborate bacterial pneumonia. CONCLUSION: Lung ultrasound is easy to learn and perform and is helpful in guiding diagnosis in unclear cases of pneumonia and may also offer new insights into the spectrum of certain virus diseases. The use of lung ultrasound can raise awareness in clinicians of the need for antimicrobial stewardship and may help to avoid the unnecessary use of antibiotics.

Detection of multiple viruses potentially infecting humans in sewage water from Xinjiang Uygur Autonomous Region, China.

The progress of sequencing technologies has facilitated metagenomics projects on environmental samples like sewage water. The present study concerned the analysis of sewage samples collected from 3 locations in Xinjiang Uygur Autonomous Region in China. The analysis focused on RNA viruses known to infect humans and identified viruses from 10 families. The proportion of human virus species in the sewage samples was relatively stable with an average of 17%. Thirty virus species known to infect humans were identified and they belonged to 6 families: Picornaviridae (12), Astroviridae (11), Reoviridae (3), Caliciviridae (2), Papillomaviridae (1) and Picobirnaviridae (1). A total of 16 full-length genomes were generated from Astroviridae, Picornaviridae (Salivirus and Kobuvirus) and Picobirnaviridae. Astroviruses appeared to be the most present viruses and were detected in all sewage samples. Analyzing the virome of sewage samples should help to monitor any potential risks to public health.

Genome analysis of canine astroviruses reveals genetic heterogeneity and suggests possible inter-species transmission.

Canine astrovirus RNA was detected in the stools of 17/63 (26.9%) samples, using either a broadly reactive consensus RT-PCR for astroviruses or random RT-PCR coupled with massive deep sequencing. The complete or nearly complete genome sequence of five canine astroviruses was reconstructed that allowed mapping the genome organization and to investigate the genetic diversity of these viruses. The genome was about 6.6kb in length and contained three open reading frames (ORFs) flanked by a 5' UTR, and a 3' UTR plus a poly-A tail. ORF1a and ORF1b overlapped by 43 nucleotides while the ORF2 overlapped by 8 nucleotides with the 3' end of ORF1b. Upon genome comparison, four strains (HUN/2012/2, HUN/2012/6, HUN/2012/115, and HUN/2012/135) were more related genetically to each other and to UK canine astroviruses (88-96% nt identity), whilst strain HUN/2012/126 was more divergent (75-76% nt identity). In the ORF1b and ORF2, strains HUN/2012/2, HUN/2012/6, and HUN/2012/135 were related genetically to other canine astroviruses identified formerly in Europe and China, whereas strain HUN/2012/126 was related genetically to a divergent canine astrovirus strain, ITA/2010/Zoid. For one canine astrovirus, HUN/2012/8, only a 3.2kb portion of the genome, at the 3' end, could be determined. Interestingly, this strain possessed unique genetic signatures (including a longer ORF1b/ORF2 overlap and a longer 3'UTR) and it was divergent in both ORF1b and ORF2 from all other canine astroviruses, with the highest nucleotide sequence identity (68% and 63%, respectively) to a mink astrovirus, thus suggesting a possible event of interspecies transmission. The genetic heterogeneity of canine astroviruses may pose a challenge for the diagnostics and for future prophylaxis strategies.

The epidemiology of adults acute viral gastroenteritis in Shanghai Changning district from 2010 ;to 2013 / 中国医师进修杂志

Objective To investigate the epidemiology of adults acute viral gastroenteritis in Shanghai Changning district. Methods All of 1 554 stool specimens of adults acute gastroenteritis in Shanghai Changning district from June 2010 to December 2013, and the enzyme-linked immunosorbent assay and multiple polymerase chain reaction was used to detecte different viruses. Results In all of 1 554 cases, the average age was (46.19 ± 15.59) years. Among them, 691 persons were male, 863 persons were female. Virus infection was detected in 407 cases, and the detection rate was 26.19%. Among them, 395 cases (97.05%) were single virus infection, and 12 cases (2.95%) were mixed infection. The peak of epidemic was from every November to next February. The incidence of watery diarrhea, vomiting and fever in virus positive group was significantly higher than that in virus negative group:95.09%(387/407) vs. 88.14%(1 011/1 147), 31.20%(127/407) vs. 18.83%(216/1 147), and 11.06%(45/407) vs. 7.59%(87/1147), P<0.01 or<0.05. Conclusions Rotavirus infection is common in adults with acute viral gastroenteritis. Patients with positive virus infection had a higher incidence of watery diarrhea, vomiting and fever. The peak of epidemic is winter.

Characteristics of astrovirus infection and typing characteristics analysis among children hospitalized with diarrhea in Tianjin / 中华检验医学杂志

Objective To study the pathogenic prevalence and genotypes of astrovirus among children under 5 years old hospitalized with diarrhea in Tianjin. Methods A total 837 stool specimens were collected from children with diarrhea hospitalized in Tianjin children's hospital from May 2008 to April 2009. Astrovirus antigens were detected using ELISA and the postive specimens were inoculated in CaCo-2cells. After the CPE caused by virus were observed, the total RNA of virus was extracted, then the genomc fragments of the strains were amplified by using RT-PCR and confirmed by sequencing of the RT-PCR products. Detection of rotavirus was employed by Colloidal Gold Device. Results Astrovirus antigen was found positive in 3.0% of the patients. The coinfection rate of astrovirus and rotavirus was 0. 7% (6/837).Ninety-six persent of children with astrovirus diarrhea were younger than 2 years of age, Forty-eight persent of children with astrovirus diarrhea were younger than 6 months. The astrovirus infections occurred mainly between August 2008 and April 2009. Of the 21 astrovirus positive specimens, 11 cases were successfully identified by RT-PCR and they were all serotype 1. Conclusion Astrovirus is a major cause of nonbacterical diarrhea between 2008 and 2009 in Tianjin, and the predominant serotype is type 1.