Novel Bat-borne Hantavirus, Vietnam

To the Editor: Compelling evidence of genetically distinct hantavi-ruses (family Bunyaviridae) in multiple species of shrews and moles (order Soricomorpha, families Soricidae and Talpidae) across 4 continents (1–7) suggests that soricomorphs, rather than rodents (order Rodentia, families Muridae and Cricetidae), might be the primordial hosts (6,7). Recently, the host range of hantaviruses has been further expanded by the discovery that insectivorous bats (order Chiroptera) also serve as reservoirs (8,9). Conjecturing that Mouyassué virus in the banana pipistrelle (Neoromicia nanus) in Côte d'Ivoire (8) and Magboi virus (MGBV) in the hairy split-faced bat (Nycteris hispida) in Sierra Leone (9) represent a much broader geographic distribution of bat-borne hantaviruses, we analyzed tissues from bats captured in Mongolia and Vietnam. Total RNA was extracted from 51 lung tissues, collected in RNA-from insectivo-rous bats, representing 7 genera and 12 species, captured in Mongolia and Vietnam. cDNA was then prepared by using PrimeScript II 1st strand cDNA Synthesis Kit (Takara Bio, Otsu, Shi-ga, Japan) for reverse transcription PCR (RT-PCR), and using oligonucle-otide primers previously designed for amplification of soricid-and talpid-borne hantaviruses (1–7). A novel hantavirus, designated Xuan Son virus (XSV), was detected in 1 of 5 Pomona roundleaf bats (Hip-posideros pomona) by using a hemin-ested large (L)–segment primer set For confirmation, RNA extraction and RT-PCR were performed independently in a laboratory in which hantaviruses had never been handled. Pairwise alignment and comparison (with ClustalW, www. clustal.org) of a 4,582-nt (1,527 aa) region of the RNA-dependent RNA polymerase–encoding L segment indicated sequence similarities of 71.4%–71.5% and 75.9%–78.7% at the nucleotide and amino acid levels , respectively, between XSV and Mouyassué virus and MGBV. Sequence analysis of a 499-nt (166 aa) region of the nucleocapsid-encoding S segment showed that XSV differed by 42.8%–58.3% from representative hantaviruses harbored by rodents and most soricomorphs. XSV sequences were identical in lung, liver, kidney, and spleen; and the highest number of virus copies (7.6 × 10 1) was in lung tissue, determined by real-time RT-PCR. No additional hantavirus-infected Pomona roundleaf bats were found by RT-PCR that used XSV-specific primers. Phylogenetic analyses was performed with maximum-likelihood and Bayesian methods, and we used the GTR+I+Γ model of evolution, as selected by the hierarchical likelihood ratio test in MrModel-test version 2.3 and jModelTest version 0.1 (10), partitioned by codon position. Results indicated 4 distinct phylogroups, with XSV sharing a common ancestry with MGBV (Figure). Similar topologies, supported by high bootstrap (>70%) and posterior node …