Species richness of bat flies and their associations with host bats in a subtropical East Asian region.

BACKGROUND: Understanding the interactions between bat flies and host bats offer us fundamental insights into the coevolutionary and ecological processes in host-parasite relationships. Here, we investigated the identities, host specificity, and patterns of host association of bat flies in a subtropical region in East Asia, which is an understudied region for bat fly research. METHODS: We used both morphological characteristics and DNA barcoding to identify the bat fly species found on 11 cavernicolous bat species from five bat families inhabiting Hong Kong. We first determined the phylogenetic relationships among bat fly species. Then, we elucidated the patterns of bat-bat fly associations and calculated the host specificity of each bat fly species. Furthermore, we assembled the mitogenomes of three bat fly species from two families (Nycteribiidae and Streblidae) to contribute to the limited bat fly genetic resources available. RESULTS: We examined 641 individuals of bat flies and found 20 species, of which many appeared to be new to science. Species of Nycteribiidae included five Nycteribia spp., three Penicillidia spp., two Phthiridium spp., one Basilia sp., and one species from a hitherto unknown genus, whereas Streblidae included Brachytarsina amboinensis, three Raymondia spp., and four additional Brachytarsina spp. Our bat-bat fly association network shows that certain closely related bat flies within Nycteribiidae and Streblidae only parasitized host bat species that are phylogenetically more closely related. For example, congenerics of Raymondia only parasitized hosts in Rhinolophus and Hipposideros, which are in two closely related families in Rhinolophoidea, but not other distantly related co-roosting species. A wide spectrum of host specificity of these bat fly species was also revealed, with some bat fly species being strictly monoxenous, e.g. nycteribiid Nycteribia sp. A, Phthiridium sp. A, and streblid Raymondia sp. A, while streblid B. amboinensis is polyxenous. CONCLUSIONS: The bat fly diversity and specificity uncovered in this study have shed light on the complex bat-bat fly ecology in the region, but more bat-parasite association studies are still needed in East Asian regions like China as a huge number of unknown species likely exists. We highly recommend the use of DNA barcoding to support morphological identification to reveal accurate host-ectoparasite relationships for future studies.

Recent transmission of a novel alphacoronavirus, bat coronavirus HKU10, from Leschenault's rousettes to pomona leaf-nosed bats: first evidence of interspecies transmission of coronavirus between bats of different suborders.

Although coronaviruses are known to infect various animals by adapting to new hosts, interspecies transmission events are still poorly understood. During a surveillance study from 2005 to 2010, a novel alphacoronavirus, BatCoV HKU10, was detected in two very different bat species, Ro-BatCoV HKU10 in Leschenault's rousettes (Rousettus leschenaulti) (fruit bats in the suborder Megachiroptera) in Guangdong and Hi-BatCoV HKU10 in Pomona leaf-nosed bats (Hipposideros pomona) (insectivorous bats in the suborder Microchiroptera) in Hong Kong. Although infected bats appeared to be healthy, Pomona leaf-nosed bats carrying Hi-BatCoV HKU10 had lower body weights than uninfected bats. To investigate possible interspecies transmission between the two bat species, the complete genomes of two Ro-BatCoV HKU10 and six Hi-BatCoV HKU10 strains were sequenced. Genome and phylogenetic analyses showed that Ro-BatCoV HKU10 and Hi-BatCoV HKU10 represented a novel alphacoronavirus species, sharing highly similar genomes except in the genes encoding spike proteins, which had only 60.5% amino acid identities. Evolution of the spike protein was also rapid in Hi-BatCoV HKU10 strains from 2005 to 2006 but stabilized thereafter. Molecular-clock analysis dated the most recent common ancestor of all BatCoV HKU10 strains to 1959 (highest posterior density regions at 95% [HPDs], 1886 to 2002) and that of Hi-BatCoV HKU10 to 1986 (HPDs, 1956 to 2004). The data suggested recent interspecies transmission from Leschenault's rousettes to Pomona leaf-nosed bats in southern China. Notably, the rapid adaptive genetic change in BatCoV HKU10 spike protein by ~40% amino acid divergence after recent interspecies transmission was even greater than the ~20% amino acid divergence between spike proteins of severe acute respiratory syndrome-related Rhinolophus bat coronavirus (SARSr-CoV) in bats and civets. This study provided the first evidence for interspecies transmission of coronavirus between bats of different suborders.

Complete genome analysis of three novel picornaviruses from diverse bat species.

Although bats are important reservoirs of diverse viruses that can cause human epidemics, little is known about the presence of picornaviruses in these flying mammals. Among 1,108 bats of 18 species studied, three novel picornaviruses (groups 1, 2, and 3) were identified from alimentary specimens of 12 bats from five species and four genera. Two complete genomes, each from the three picornaviruses, were sequenced. Phylogenetic analysis showed that they fell into three distinct clusters in the Picornaviridae family, with low homologies to known picornaviruses, especially in leader and 2A proteins. Moreover, group 1 and 2 viruses are more closely related to each other than to group 3 viruses, which exhibit genome features distinct from those of the former two virus groups. In particular, the group 3 virus genome contains the shortest leader protein within Picornaviridae, a putative type I internal ribosome entry site (IRES) in the 5'-untranslated region instead of the type IV IRES found in group 1 and 2 viruses, one instead of two GXCG motifs in 2A, an L→V substitution in the DDLXQ motif in 2C helicase, and a conserved GXH motif in 3C protease. Group 1 and 2 viruses are unique among picornaviruses in having AMH instead of the GXH motif in 3C(pro). These findings suggest that the three picornaviruses belong to two novel genera in the Picornaviridae family. This report describes the discovery and complete genome analysis of three picornaviruses in bats, and their presence in diverse bat genera/species suggests the ability to cross the species barrier.

Ecoepidemiology and complete genome comparison of different strains of severe acute respiratory syndrome-related Rhinolophus bat coronavirus in China reveal bats as a reservoir for acute, self-limiting infection that allows recombination events.

Despite the identification of severe acute respiratory syndrome-related coronavirus (SARSr-CoV) in Rhinolophus Chinese horseshoe bats (SARSr-Rh-BatCoV) in China, the evolutionary and possible recombination origin of SARSr-CoV remains undetermined. We carried out the first study to investigate the migration pattern and SARSr-Rh-BatCoV genome epidemiology in Chinese horseshoe bats during a 4-year period. Of 1,401 Chinese horseshoe bats from Hong Kong and Guangdong, China, that were sampled, SARSr-Rh-BatCoV was detected in alimentary specimens from 130 (9.3%) bats, with peak activity during spring. A tagging exercise of 511 bats showed migration distances from 1.86 to 17 km. Bats carrying SARSr-Rh-BatCoV appeared healthy, with viral clearance occurring between 2 weeks and 4 months. However, lower body weights were observed in bats positive for SARSr-Rh-BatCoV, but not Rh-BatCoV HKU2. Complete genome sequencing of 10 SARSr-Rh-BatCoV strains showed frequent recombination between different strains. Moreover, recombination was detected between SARSr-Rh-BatCoV Rp3 from Guangxi, China, and Rf1 from Hubei, China, in the possible generation of civet SARSr-CoV SZ3, with a breakpoint at the nsp16/spike region. Molecular clock analysis showed that SARSr-CoVs were newly emerged viruses with the time of the most recent common ancestor (tMRCA) at 1972, which diverged between civet and bat strains in 1995. The present data suggest that SARSr-Rh-BatCoV causes acute, self-limiting infection in horseshoe bats, which serve as a reservoir for recombination between strains from different geographical locations within reachable foraging range. Civet SARSr-CoV is likely a recombinant virus arising from SARSr-CoV strains closely related to SARSr-Rh-BatCoV Rp3 and Rf1. Such frequent recombination, coupled with rapid evolution especially in ORF7b/ORF8 region, in these animals may have accounted for the cross-species transmission and emergence of SARS.