key: cord-0033689-g5fqxdqh authors: Chu, Daniel K. W.; Peiris, J. S. Malik; Poon, Leo L. M. title: Novel coronaviruses and astroviruses in bats date: 2009-04-14 journal: Virol Sin DOI: 10.1007/s12250-009-3031-6 sha: fd2c1ba07facb5e7defbb870ae98817cf65a8826 doc_id: 33689 cord_uid: g5fqxdqh Zoonotic transmissions of emerging pathogens from wildlife to human have shaped the history of mankind. These events have also highlighted our poor understanding of microorganisms circulated in wild animals. Coronaviruses and astroviruses, which can be found from a wide range of mammals, were recently detected in bats. Strikingly, these bat viruses are genetically highly diverse and these interesting findings might help to better understand the evolution and ecology of these viruses. The discoveries of these novel bats viruses not only suggested that bats are important hosts for these virus families, but also reiterated the role of bats as a reservoir of viruses that might pose a zoonotic threat to human health. The expanding human population has shaped the emergence of infectious diseases in human or poultry by sustaining disease transmission with extremely high population density that did not exist anywhere in the world before (6, 28) . Previous analysis has also shown that more than 70% of emerging or reemerging pathogens are known to be zoonotic (29) , and many of these emerging infections are associated with wildlife (4) . These observations suggested that human encroachment on wildlife habitats has caused the exposure of previously unknown pathogens in wild animals and An explanation for this is that RNA viruses might have much higher nucleotide mutation rates than those pathogens that have a DNA genome, thereby allowing the RNA viruses to better adapt to a new host (7) . Many emerging pathogens of human, domestic animals are assumed to be maintained in wildlife. However, many of these reservoirs for emerging viruses have never been identified. These perhaps (19) . In human, astroviruses are the second or third most common viral agent found in children with diarrhea (5, 14) , and these viruses can also cause significant diseases in elderly (17) and in immunocompromised patients (9) . The prevalence of astroviruses in different species of apparently healthy Miniopterus bats roosting at a single cave in Hong Kong ranges from 36% to 100% throughout a year. This suggested that these astroviruses might persistently infect the same bat population. Interestingly, the genetic diversity of these viruses at a single habitat 102 Virol. Sin. (2009) 24: 100-104 was found to be greater than the one for all the previously known mamastroviruses. More importantly, some bat astroviruses were found to be genetically closely related to human astroviruses, suggesting these bat and human viruses might share the same ancestor. A similar high prevalence of genetically diversified astroviruses has also been detected in bats captured from different part of China (unpublished data). Based on a phylogenetic analysis on viral RdRp gene, astroviruses detected from two different host species (Miniopterus magnater and Miniopterus pusillus) were found to be clustered together, suggesting some of these bat astroviruses are more ready to cause zoonotic transmission. This observation is notably different from that observed from bat coronaviruses (2, 3) . With these findings, it is tempting to speculate that some of these bat astroviruses might have a great zoonotic potential. Further investigations of bat astroviruses might provide new insights into the ecology and evolution of astroviruses. The majority of previous studies of coronaviruses and astroviruses were limited to the detection of viruses in clinical and veterinary samples. In particular for astrovirus, genetic information was based on short fragments of viral DNA amplified by reverse transcription-PCR (12, 21) . With the discovery of these novel coronaviruses and astroviruses in bats, unprecedented information about these two viral families can be generated. The availability of the genetic information enables us to elucidate the phylogenetic relationships and selection pressure and recombination events in these viruses. The information also helps the development of better detection methods for possible unknown coronaviruses and astroviruses which may cause diseases in livestock or in human. These results might also help to identify crucial viral features which might be useful for novel drug designs. More importantly, the discoveries of these novel bat viruses highlighted the role of bats as the major reservoirs of emerging viruses with zoonotic potential. As efficiency disease control must be directed at the reservoir (13), surveillance for unknown pathogens in wildlife is a step needed to be taken for our better preparedness for future zoonotic diseases. Bats: important reservoir hosts of emerging viruses Genomic characterizations of bat coronaviruses (1A, 1B and HKU8) and evidence for co-infections in Miniopterus bats Coronaviruses in bent-winged bats (Miniopterus spp.) Diseases of humans and their domestic mammals: pathogen characteristics, host range and the risk of emergence Astrovirus acute gastroenteritis among children in Madrid, Spain Emerging infectious diseases of wildlife--threats to biodiversity and human health Viruses at the edge of adaptation Detection of group 1 coronaviruses in bats in North America Use of a heminested reverse transcriptase PCR assay for detection of astrovirus in environmental swabs from an outbreak of gastroenteritis in a pediatric primary immunodeficiency unit Detection and prevalence patterns of group I 103 Isolation and characterization of viruses related to the SARS coronavirus from animals in southern China Human astrovirus diagnosis and typing: current and future prospects Identifying reservoirs of infection: a conceptual and practical challenge Astroviruses as a cause of gastroenteritis in children Evidence of the recombinant origin of a bat severe acute respiratory syndrome (SARS)-like coronavirus and its implications on the direct ancestor of SARS coronavirus Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats Outbreaks of astrovirus type 1 and rotavirus gastroenteritis in a geriatric in-patient population Bats are natural reservoirs of SARS-like coronaviruses Fields Virology Biological characters of bats in relation to natural reservoir of emerging viruses Molecular characterization and typing of chicken and turkey astroviruses circulating in the United States: implications for diagnostics Coronavirus as a possible cause of severe acute respiratory syndrome Identification of a novel coronavirus in bats Full-length genome sequences of two SARS-like coronaviruses in horseshoe bats and genetic variation analysis Cross-host evolution of severe acute respiratory syndrome coronavirus in palm civet and human Evolutionary insights into the ecology of coronaviruses Origins of major human infectious diseases Host range and emerging and reemerging pathogens Civets are equally susceptible to experimental infection by two different severe acute respiratory syndrome coronavirus isolates * Foundation items: This work was supported by the National Institute of Allergy and Infectious Diseases (NIAID contract HHSN266200700005C) and European