Search

Climate change is likely to alterwildfire regimes, but the significance of climate-driven factors in regional fire regimes over extended temporal scales is poorly understood. Comparison of the reconstructed fire dynamics from charcoals in sediments with modern active fires may provide clues about the drivers of wildfire activities, and help us validate models of fire activity for both the past and the future. Microscopic charcoals fromMiocene sediments in Wenshan Basin (Yunnan, southwestern China), were used to reconstruct fire dynamics in deep time. Palaeoclimatic data were obtained from the previous quantitative reconstruction using pollen samples from a sedimentary sequence. The relationship between palaeoclimatic parameters and the ratio of charcoals during the Miocene was explored, and compared with maximumentropy (Maxent) model results throughout different time periods. Our results indicate that the temperature in the dry season was the main factor controlling the frequency of fire in Wenshan during theMiocene. Maxent modeling results based on the modern active fire dataset of Yunnan Province from NASA Earth observations are consistent with the results from fossil sediment analysis, that dry season temperature is the main driver of fire activity. Our findings suggest a significant fire-temperature relationship under the monsoonal climate since the Neogene. Furthermore, models suggest that the last-glacial maximum (LGM) had lower levels of fire activity than present, which increased during the Holocene prior to reaching present levels. Models also predict increases in fire activity across most of Yunnan in the future. [ABSTRACT FROM AUTHOR]

Significant efforts have been made to characterize viral diversity in bats from China. Many of these studies were prospective and focused mainly on Rhinolophus bats that could be related to zoonotic events. However, other species of bats that are part of ecosystems identified as virus diversity hotspots have not been studied in-depth. We analyzed the virome of a group of Myotis fimbriatus bats collected from the Yunnan Province during 2020. The virome of M. fimbriatus revealed the presence of families of pathogenic viruses such as Coronavirus, Astrovirus, Mastadenovirus, and Picornavirus, among others. The viral sequences identified in M. fimbriatus were characterized by significant divergence from other known viral sequences of bat origin. Complex phylogenetic landscapes implying a tendency of co-specificity and relationships with viruses from other mammals characterize these groups. The most prevalent and abundant virus in M. fimbriatus individuals was an alphacoronavirus. The genome of this virus shows evidence of recombination and is likely the product of ancestral host-switch. The close phylogenetic and ecological relationship of some species of the Myotis genus in China may have played an important role in the emergence of this alphacoronavirus. [ABSTRACT FROM AUTHOR]

Despite the discovery of animal coronaviruses related to SARS-CoV-2, the evolutionary origins of this virus are elusive. We describe a meta-transcriptomic study of 411 bat samples collected from a small geographical region in Yunnan province, China, between May 2019 and November 2020. We identified 24 full-length coronavirus genomes, including four novel SARS-CoV-2-related and three SARS-CoV-related viruses. Rhinolophus pusillus virus RpYN06 was the closest relative of SARS-CoV-2 in most of the genome, although it possessed a more divergent spike gene. The other three SARS-CoV-2-related coronaviruses carried a genetically distinct spike gene that could weakly bind to the hACE2 receptor in vitro. Ecological modeling predicted the co-existence of up to 23 Rhinolophus bat species, with the largest contiguous hotspots extending from South Laos and Vietnam to southern China. Our study highlights the remarkable diversity of bat coronaviruses at the local scale, including close relatives of both SARS-CoV-2 and SARS-CoV. [Display omitted] • Four novel SARS-CoV-2-related viruses were identified in rhinolophid bats • RpYN06 is the closest relative of SARS-CoV-2 in most of the virus genome • A high diversity of bat coronaviruses was present in a very small geographic area • Ecological modeling reveals a broad range of rhinolophid bats in parts of Asia A study of 411 bat samples collected in Yunnan province, China between 2019 and 2020 yields 24 full-length coronavirus genomes, including four viruses highly related to SARS-CoV-2 and three to SARS. The closest relative to SARS-CoV-2 infects a species of bats that is found in regions that extend from South Laos and Vietnam to southern China. [ABSTRACT FROM AUTHOR]

The unprecedented pandemic of pneumonia caused by a novel coronavirus, SARS-CoV-2, in China and beyond has had major public health impacts on a global scale 1 , 2. Although bats are regarded as the most likely natural hosts for SARS-CoV-2 3 , the origins of the virus remain unclear. Here, we report a novel bat-derived coronavirus, denoted RmYN02, identified from a metagenomic analysis of samples from 227 bats collected from Yunnan Province in China between May and October 2019. Notably, RmYN02 shares 93.3% nucleotide identity with SARS-CoV-2 at the scale of the complete virus genome and 97.2% identity in the 1ab gene, in which it is the closest relative of SARS-CoV-2 reported to date. In contrast, RmYN02 showed low sequence identity (61.3%) to SARS-CoV-2 in the receptor-binding domain (RBD) and might not bind to angiotensin-converting enzyme 2 (ACE2). Critically, and in a similar manner to SARS-CoV-2, RmYN02 was characterized by the insertion of multiple amino acids at the junction site of the S1 and S2 subunits of the spike (S) protein. This provides strong evidence that such insertion events can occur naturally in animal betacoronaviruses. • Metagenomic analysis identified a novel coronavirus, RmYN02, from R. malayanus • RmYN02 was the closest relative of SARS-CoV-2 in most of the virus genome • Two loop deletions in RBD may reduce the binding of RmYN02 with ACE2 • RmYN02 contains an insertion at the S1/S2 cleavage site in the spike protein Zhou et al. report a bat-derived coronavirus, RmYN02, which is the closest relative of SARS-CoV-2 in most of the virus genome reported to date. RmYN02 contains an insertion at the S1/S2 cleavage site in the spike protein in a similar manner to SARS-CoV-2. This suggests that such insertion events can occur naturally in animal betacoronaviruses. [ABSTRACT FROM AUTHOR]