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The ongoing pandemic spread of a novel human coronavirus, SARS-COV-2, associated with severe pneumonia disease (COVID-19), has resulted in the generation of thousands of virus genome sequences. The rate of genome generation is unprecedented, yet there is currently no coherent nor accepted scheme for naming the expanding phylogenetic diversity of SARS-CoV-2. We present a rational and dynamic virus nomenclature that uses a phylogenetic framework to identify those lineages that contribute most to active spread. Our system is made tractable by constraining the number and depth of hierarchical lineage labels and by flagging and declassifying virus lineages that become unobserved and hence are likely inactive. By focusing on active virus lineages and those spreading to new locations this nomenclature will assist in tracking and understanding the patterns and determinants of the global spread of SARS-CoV-2.

Bats harbor a large diversity of coronaviruses (CoVs), several of which are related to zoonotic pathogens that cause severe disease in humans. Our screening of bat samples collected in Kenya from 2007 to 2010 not only detected RNA from several novel CoVs but, more significantly, identified sequences that were closely related to human CoVs NL63 and 229E, suggesting that these two human viruses originate from bats. We also demonstrated that human CoV NL63 is a recombinant between NL63-like viruses circulating in Triaenops bats and 229E-like viruses circulating in Hipposideros bats, with the breakpoint located near 5= and 3= ends of the spike (S) protein gene. In addition, two further interspecies recombination events involving the S gene were identified, suggesting that this region may represent a recombination "hot spot" in CoV genomes. Finally, using a combination of phylogenetic and distance-based approaches, we showed that the genetic diversity of bat CoVs is primarily structured by host species and subsequently by geographic distances.IMPORTANCE Understanding the driving forces of cross-species virus transmission is central to understanding the nature of disease emergence. Previous studies have demonstrated that bats are the ultimate reservoir hosts for a number of coronaviruses (CoVs), including ancestors of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and human CoV 229E (HCoV-229E). However, the evolutionary pathways of bat CoVs remain elusive. We provide evidence for natural recombination between distantly related African bat coronaviruses associated with Triaenops afer and Hipposideros sp. bats that resulted in a NL63-like virus, an ancestor of the human pathogen HCoV-NL63. These results suggest that interspecies recombination may play an important role in CoV evolution and the emergence of novel CoVs with zoonotic potential.KEYWORDS Africa, bats, coronavirus, HCoV-229E, HCoV-NL63, recombination, zoonoses C oronaviruses (CoVs) (subfamily Coronavirinae, family Coronaviridae, order Nidovirales) are common infectious agents that infect a wide range of hosts, including humans, causing respiratory, gastrointestinal, liver, and neurologic diseases, and that possess the largest genomes of any RNA viruses described to date (1). The subfamily Coronavirinae is currently classified into four genera: Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus (2). The alphacoronaviruses (alpha-CoVs) and

27The ongoing outbreak of viral pneumonia in China and beyond is associated with a novel 28 coronavirus, provisionally termed 2019-nCoV. This outbreak has been tentatively associated 29 with a seafood market in Wuhan, China, where the sale of wild animals may be the source of 30 zoonotic infection. Although bats are likely reservoir hosts for 2019-nCoV, the identity of 31 any intermediate host facilitating transfer to humans is unknown. Here, we report the 32 identification of 2019-nCoV related coronaviruses in pangolins (Manis javanica) seized in 33 anti-smuggling operations in southern China. Metagenomic sequencing identified pangolin 34 associated CoVs that belong to two sub-lineages of 2019-nCoV related coronaviruses, 35 including one very closely related to 2019-nCoV in the receptor-binding domain. The 36 discovery of multiple lineages of pangolin coronavirus and their similarity to 2019-nCoV 37 suggests that pangolins should be considered as possible intermediate hosts for this novel 38 human virus and should be removed from wet markets to prevent zoonotic transmission.

In the Acknowledgements section of this Article, the grant number 'SQ2019FY010009' should have been '2019FY101500'; this has been corrected online.

The evolution of rabies viruses of predominantly European origin was studied by comparing nucleotide sequences of the nucleoprotein and glycoprotein genes, and by typing isolates using RFLP. Phylogenetic analysis of the gene sequence data revealed a number of distinct groups, each associated with a particular geographical area. Such a pattern suggests that rabies virus has spread westwards and southwards across Europe during this century, but that physical barriers such as the Vistula river in Poland have enabled localized evolution. During this dispersal process, two species jumps took place -one into red foxes and another into raccoon dogs, although it is unclear whether virus strains are preferentially adapted to particular animal species or whether ecological forces explain the occurrence of the phylogenetic groups.

The extent to which recombination disrupts the bifurcating treelike phylogeny and clonal structure imposed by binary fission on bacterial populations remains contentious. Here, we address this question with a study of nucleotide sequence data from 107 isolates of the human pathogen Neisseria meningitidis. Gene fragments from 12 house-keeping loci distributed around the meningococcal chromosome were analyzed, showing that (1) identical alleles are disseminated among genetically diverse isolates, with no evidence for linkage disequilibrium; (2) different loci give distinct and incongruent phylogenetic trees; and (3) allele sequences are incompatible with a bifurcating treelike phylogeny at all loci. These observations are consistent with the hypothesis that meningococcal populations comprise organisms assembled from a common gene pool, with alleles and allele fragments spreading independently, together with the occasional importation of genetic material from other species. Further, they support the view that recombination is an important genetic mechanism in the generation new meningococcal clones and alleles. Consequently, for anything other than the short-term evolution of this species, a bifurcating treelike phylogeny is not an appropriate model.

bioRxiv preprint 2 Emerging and re-emerging infectious diseases, such as SARS, MERS, Zika and highly 25 pathogenic influenza present a major threat to public health 1-3 . Despite intense research 26 effort, how, when and where novel diseases appear are still the source of considerable 27 uncertainly. A severe respiratory disease was recently reported in the city of Wuhan, 28 Hubei province, China. At the time of writing, at least 62 suspected cases have been 29 reported since the first patient was hospitalized on December 12 nd 2019. Epidemiological 30 investigation by the local Center for Disease Control and Prevention (CDC) suggested 31 that the outbreak was associated with a sea food market in Wuhan. We studied seven 32 patients who were workers at the market, and collected bronchoalveolar lavage fluid 33 (BALF) from one patient who exhibited a severe respiratory syndrome including fever, 34 dizziness and cough, and who was admitted to Wuhan Central Hospital on December 35 26 th 2019. Next generation metagenomic RNA sequencing 4 identified a novel RNA virus 36 from the family Coronaviridae designed WH-Human-1 coronavirus (WHCV). 37 Phylogenetic analysis of the complete viral genome (29,903 nucleotides) revealed that 38 WHCV was most closely related (89.1% nucleotide similarity similarity) to a group of 39 Severe Acute Respiratory Syndrome (SARS)-like coronaviruses (genus Betacoronavirus, 40 subgenus Sarbecovirus) previously sampled from bats in China and that have a history 41 of genomic recombination. This outbreak highlights the ongoing capacity of viral spill-42 over from animals to cause severe disease in humans. 43 44 Seven patients, comprising five men and two women, were hospitalized at the Central 45 : bioRxiv preprint 3 patients was 43, ranging from 31 to 70 years old. The clinical characteristics of the patients 47 are shown in Table 1. Fever and cough were the most common symptoms. All patients had 48 fever with body temperatures ranging from 37.2 o C to 40 o C. Patients 1, 2, 5, 6 and 7 had 49 cough, while patients 1, 2 and 7 presented with severe cough with phlegm at onset of illness. 50 Patients 4 and 5 also complained of chest tightness and dyspnea. Patients 1, 3, 4 and 6 51 experienced dizziness and patient 3 felt weakness. No neurological symptoms were observed 52 in any of the patients. Bacterial culture revealed the presence of Streptococcus bacteria in 53 throat swabs from patients 3, 4 and 7. Combination antibiotic, antiviral and glucocorticoid 54 therapy were administered. Unfortunately, patient 1 and 4 showed respiratory failure: patient 55 1 was given high flow noninvasive ventilation, while patient 4 was provided with nasal/face 56 mask ventilation (Table 1). 57Epidemiological investigation by the Wuhan CDC revealed that all the suspected cases 58 were linked to individuals working in a local indoor seafood market. Notably, in addition to 59 fish and shell fish, a variety of live wild animals including hedgehogs, badgers, snakes, and 60 birds (turtledoves) were available for sale in th...