The antigenic and genetic properties of 46 hantaviruses from China, 13 from patients, 23 from rodents, and 10 from unknown hosts, were compared with those of other hantaviruses. The viruses were classified as either Hantaan (HTN) or Seoul (SEO) viruses. A phylogenetic analysis of the partial M (300 bp) and S (around 485 bp) genomes of HTN viruses identified nine distinct genetic subtypes, one consisting of isolates from Korea. The SEO viruses were divided into five genetic subtypes, although they had less variability than the HTN subtypes. There was a correlation between the subtype and province of origin for four subtypes of HTN viruses, confirming geographical clustering. Hantaan virus NC167 isolated from Niviventer confucianus and SEO virus Gou3 isolated from Rattus rattus were the basal clades in each virus. The phylogenetic trees constructed from the entire S and M segments suggested that NC167 was introduced to N. confucianus in a host-switching event. The reactivity of a panel of 35 monoclonal antibodies was almost exactly the same in NC167 and a representative HTN virus and in Gou3 and a representative SEO virus. However, there was a one-way cross-neutralization between them. These results confirm the varied nature of Murinae-associated hantaviruses in China.

We report the genetic characterization of the M RNA segment of Crimean Congo hemorrhagic fever virus (CCHFV). Two CCHFV strains isolated in Xinjiang Province, a region endemic for CCHF in northwestern China, were studied. These strains, designated BA66019 and BA8402, were isolated in 1965 and 1984 from a CCHF patient and Hyalomma ticks, respectively. Viral RNA was extracted from suckling mouse brains infected with these two strains, amplified, and sequenced. The full-length M RNA, consisting of 5.3 kb, was determined for both strains. The coding nucleotide sequences of the two strains differed from each other by 17.5% and from the reference CCHFV strain IbAr10200 by a mean of 22%, suggesting that the genus Nairovirus comprises a group of genetically highly diverse strains.

In 2004 and 2005, an epidemiological survey of Crimean-Congo hemorrhagic fever virus (CCHFV) was conducted in Xinjiang, China. A total of 5,629 serum samples of human and livestock were collected and tested for the CCHFV antibody, and 17,319 ticks were collected for viral identification. Reverse passive hemagglutination inhibition assays showed that the average prevalence of CCHFV antibody was 1.7% for the humans and 12.7% for the livestock. A relatively high antibody prevalence, ranging from 19.1% to 23.4%, was found in the livestock of the northwest, southwest, and northeast parts of the Tarim Basin. When the ticks were pooled to inoculate suckling mice, followed by reverse transcription-PCR (RT-PCR) to detect CCHFV RNA, the average RT-PCR-positive rates for Hyalomma asiaticum kozlovi and H. asiaticum asiaticum were 12.9% and 2.6%, respectively. A significant correlation was found between the antibody prevalence in the livestock and the CCHFV prevalence in H. asiaticum of the same geographic region. No CCHFV RNA was detected in Dermacentor nivenus, Rhipicephalus turanius, or Rhipicephalus sanguineus. A total of 27 partial S segments of CCHFVs were sequenced and used for phylogeny analysis. All but one Chinese isolate grouped into the Asia 1 clade, which contains the strains from Xinjiang and Uzbekistan, while the other strain, Fub90009, grouped with strains from the Middle East.Crimean-Congo hemorrhagic fever virus (CCHFV) is an RNA virus that belongs to the genus Nairovirus of the family Bunyaviridae. The virus has a tripartite genome composed of a small (S), a medium (M), and a large (L) RNA segment (39). Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease with a mortality rate of 10% to 50% (16, 35) and has been reported in more than 30 countries in Africa, Europe, and Asia (16,20,26,36,38,43). The potential use of CCHFV as a terrorist agent is a threat to public health (5, 10). Some genera of the family Ixodidae (hard ticks) transmit vectors and reservoirs of this virus (10). Humans can be infected by tick bites and interaction with infected people or animals, which may cause CCHF outbreaks in some regions (1,9,17,19,24,27,33). In China, the first case of CCHF was reported in Bachu county of Xinjiang in 1965 (30), and since then, there have been several outbreaks in that area (3,4,21,23,37). Several regions in the Tarim Basin, such as the Tarim River and the Yeerqiang River, and the Junggar Basin were identified as natural epidemic foci of CCHF (2, 14). So far, the phylogenetic data for CCHFV in China all relate to the western part of the Tarim Basin (Bachu county and surrounding areas) (22, 28, 37), but the geographic distribution of Hyalomma asiaticum (the local major vector) in Xinjiang appears to occupy a much larger area (40).In this study, the epidemiology of CCHFV in the Tarim Basin, the Junggar Basin, the Turpan-Hami Basin, and the Ili Valley, which are the habitats of ticks, was studied. A total of 5,629 serum samples from livestock and humans living in these areas were collected and t...

The antigenic relationship between viral isolates from Apodemus and Rattus that appear to cause the classical and mild types of epidemic hemorrhagic fever (EHF) in China was studied by cross-immunofluorescence, cross-neutralization, immunofluorescence blocking tests, and cross-enzyme-linked immunosorbent assay (ELISA). Obvious antigenic diversity between the isolates was demonstrated by cross-neutralization, immunofluorescence blocking tests, and cross-ELISA. Antisera from patients with classical EHF neutralized viruses of both types to a similar degree, but antisera from patients with mild EHF showed little neutralization of apodemus virus. Similarly, antisera from classical EHF blocked immunofluorescence by monoclonal antibody (25-1 McAb) derived from apodemus virus to both viral antigens, but antisera from mild EHF gave only low-grade blocking against apodemus viral antigen. Direct antigenic titrations of both viral strains by cross-ELISA yielded similar results. That distinct antigenic differences exist between viral strains causing these two types of EHF might be of great importance to the serological differentiation of the viruses and the study of EHF vaccine.

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