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Liao ning virus (LNV) is related to Banna virus, a known human-pathogen present in south-east Asia. Both viruses belong to the genus Seadornavirus, family Reoviridae. LNV causes lethal haemorrhage in experimentally infected mice. Twenty seven isolates of LNV were made from mosquitoes collected in different locations within the Xinjiang province of north-western China during 2005. These mosquitoes were caught in the accommodation of human patients with febrile manifestations, or in animal barns where sheep represent the main livestock species. The regions where LNV was isolated are affected by seasonal encephalitis, but are free of Japanese encephalitis (JE). Genome segment 10 (Seg-10) (encoding cell-attachment and serotype-determining protein VP10) and Seg-12 (encoding non-structural protein VP12) were sequenced for multiple LNV isolates. Phylogenetic analyses showed a less homogenous Seg-10 gene pool, as compared to segment 12. However, all of these isolates appear to belong to LNV type-1. These data suggest a relatively recent introduction of LNV into Xinjiang province, with substitution rates for LNV Seg-10 and Seg-12, respectively, of 2.29×10-4 and 1.5 ×10-4 substitutions/nt/ year. These substitution rates are similar to those estimated for other dsRNA viruses. Our data indicate that the history of LNV is characterized by a lack of demographic fluctuations. However, a decline in the LNV population in the late 1980s - early 1990s, was indicated by data for both Seg-10 and Seg-12. Data also suggest a beginning of an expansion in the late 1990s as inferred from Seg-12 skyline plot. [ABSTRACT FROM AUTHOR]

During an investigation of arboviruses in China, a novel dsRNA virus was isolated from adult female Armigeres subalbatus. Full genome sequence analysis showed the virus to be related to members of the family Totiviridae, and was therefore named 'Armigeres subalbatus totivirus' (AsTV). Transmission electron microscopy identified icosahedral, non-enveloped virus particles with a mean diameter of 40 nm. The AsTV genome is 7510 bp in length, with two ORFs. ORF1 (4443 nt) encodes the coat-protein and a dsRNA-binding domain (which may be involved in the evasion of 'gene silencing'), while ORF2 (2286 nt) encodes the viral RNA-dependent RNA polymerase (RdRp). The AsTV coat protein shows a higher level of amino acid identity with Drosophila totivirus (DTV, 52 %) than with infectious myonecrosis virus (IMNV, 29 %). Similarly, the RdRp shows higher identity levels with DTV (51 %) than with IMNV (44 %). Identity levels to other members of the family Totiviridae, in either the coat protein or the RdRp, ranged from 6 to 11 %. Based on a recent reassessment of the coding strategy used by IMNV, we suggest that an AsTV coat-RdRp fusion protein could be synthesized via a -1 frameshift. Elements favouring -1 frameshift such as 'slippery heptamers' and pseudonkots, were identified in the AsTV, DTV and IMNV genomes. AsTV was shown to grow in both mosquito and mammalian cells, suggesting that it is an arbovirus that can infect mammals.

Ten virus isolates belonging to species Getah virus (GETV) have been obtained during surveys for arboviruses in China since 1964. Seven of these isolates (YN0540, YN0542, SH05-6, SH05-15, SH05-16, SH05-17 and GS10-2) were obtained during the current study. The full-length sequences of three Chinese isolates (M1, isolated in 1964; HB0234, isolated in 2002; YN0540, isolated in 2005) were determined. The full-length sequences of these isolates were respectively 11 696, 11 686 and 11 690 nt, and showed more than 97 % intraspecies identity. Deletions were found in the capsid protein of strain M1 and non-structural protein nsP3 of strain HB0234. The E2 gene and 3' UTR of all ten isolates were also characterized. The E2 gene of the Chinese GETV isolates showed nucleotide sequence identities of 98-100 % when compared with other GETV isolates. In the 3' UTR of the Chinese isolates, an insertion of 10 consecutive adenine residues (nt 189-198) appeared in strain M1, and 9 or 3 consecutive adenines were found towards the 3' end of the third RES in strains SH05-6 and SH05-15, respectively. The 3' UTRs of the Chinese isolates showed a deletion between positions 45 and 54 and nucleotide transitions at positions 43, 64 and 148. Sequence and phylogenetic analyses showed that there was a relatively high degree of conservation among GETV isolates. The isolation of GETV from various provinces in China and also in Russia and Mongolia (including regions of the northern tundra) are an indication of changes in the world distribution of this re-emerging virus.

During an investigation of arboviruses in China, a novel densovirus (DNV) was isolated from the adult female Culex pipiens pallens. The virus, designated Culex pipiens pallens densovirus (CppDNV), caused cytopathic effect in C6/36 cells. The virus particles were icosahedral, non-enveloped and had a mean diameter of 24 nm. The complete coding region of CppDNV was found to be 3335 nt and it contained three open reading frames (ORFs). CppDNV shares 82-93 % identical nucleotides with isolates of the Aedes albopictus densovirus [isolates AalDNV-1, AalDNV-2 (C6/36 DNV) and AalDNV-3], Aedes aegypti densovirus (AaeDNV) and Haemagogus equines densovirus (HeDNV). The nucleotide sequence identity among CppDNV isolates exceeds 98 %. Phylogenetic trees based on non-structural (NS1 and NS2) and capsid (VP) genes show that CppDNV clustered with the species AaeDNV and represents a novel variant of this species within the genus Brevidensovirus.

An orbivirus designated Yunnan orbivirus (YUOV) was isolated from Culex tritaeniorhynchus mosquitoes collected in the Yunnan province of China. Electron microscopy showed particles with typical orbivirus morphology. The YUOV genome was sequenced completely and compared with previously characterized orbivirus genomes. Significant identity scores were detected between proteins encoded by the segments (Seg-1 to Seg-10) of YUOV and those encoded by their homologues in insect-borne and tick-borne orbiviruses. Analysis of VP1 (Pol) and VP2 (T2, which correlates with the virus serogroup) indicated that YUOV is a new species of the genus Orbivirus that is unrelated to the other insect-borne orbiviruses. The replication of YUOV in mosquito cell lines was restricted to Aedes albopictus cells and the virus failed to replicate in mammalian cell lines. However, intraperitoneal injection of virus into naïve mice resulted in productive, non-lethal virus replication and viraemia. Infected mice developed serum neutralizing antibodies and were protected against a new infection challenge. Sequence analysis of clones from the segments encoding outer coat proteins (Seg-3 and Seg-6) of YUOV recovered from mouse blood did not show significant changes in the sequences. The availability of the complete genome sequence will facilitate the development of sequence-specific PCR assays for the study of YUOV epidemiology in the field.