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.

A vesicular stomatitis virus (VSV) pseudotype bearing hantavirus envelope glycoproteins was produced and used in a neutralization test as a substitute for native hantavirus. The recombinant VSV, in which the enveloped protein gene (G) was replaced by the green fluorescent protein gene and complemented with G protein expressed in trans (VSV⌬G*G), was kindly provided by M. A. Whitt. 293T cells were transfected with plasmids for the expression of envelope glycoproteins (G1 and G2) of HTNV or SEOV and were then infected with VSV⌬G*G. Pseudotype VSV with the Hantaan (VSV⌬G*-HTN) or Seoul (VSV⌬G*-SEO) envelope glycoproteins were harvested from the culture supernatant. The number of infectious units (IU) of the pseudotype VSVs ranged from 10 5 to 10 6 /ml. The infectivity of VSV⌬G*-HTN and VSV⌬G*-SEO was neutralized with monoclonal antibodies, immune rabbit sera, and sera from patients with hemorrhagic fever with renal syndrome, and the neutralizing titers were similar to those obtained with native hantaviruses. These results show that VSV⌬G*-HTN and -SEO can be used as a rapid, specific, and safe neutralization test for detecting hantavirus-neutralizing antibodies as an effective substitute for the use of native hantaviruses. Furthermore, the IU of VSV⌬G*-HTN and -SEO did not decrease by more than 10-fold when stored at 4°C for up to 30 days.

Truncated recombinant nucleocapsid proteins (rNPs) of Hantaan virus (HTNV), Seoul virus (SEOV), andDobrava virus (DOBV) were expressed by a baculovirus system. The truncated rNPs, which lacked 49 (rNP50) or 154 (rNP155) N-terminal amino acids of the NPs of HTNV, SEOV, and DOBV, were able to differentiate HTNV-, SEOV-, and DOBV-specific immune sera. Recombinant NP50s retained higher reactivities than rNP155s and were proven useful for enzyme-linked immunosorbent assay (ELISA). The ELISAs based on the rNP50s of HTNV, SEOV, and DOBV successfully differentiated three groups of patient sera, previously defined by neutralization tests: 17 with HTNV infection, 12 with SEOV infection, and 20 with DOBV infection. The entire rNP of Puumala virus (PUUV) distinguished PUUV infection from the other types of hantavirus infection. Serotyping with these rNP50s can be recommended as a rapid and efficient system for hantavirus diagnosis.Hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome are rodent-borne viral zoonoses caused by viruses in the genus Hantavirus, family Bunyaviridae (3). Four antigenically and genetically distinct hantaviruses are known to cause HFRS. They are defined as different serotypes: Hantaan virus (HTNV), Seoul virus (SEOV), Dobrava virus (DOBV), and Puumala virus (PUUV). Sin Nombre virus and related viruses cause hantavirus pulmonary syndrome. There is a close association between the viruses and their rodent hosts (10,14,21). At present, the only serological assay available to define the serotype of a causative hantavirus is the neutralization test (NT) (4,12,15). However, the NT needs specialized techniques and equipment, takes 1 to 2 weeks to perform, and requires a containment laboratory for virus manipulation.Hantavirus nucleocapsid protein (NP) possesses immunodominant, linear, cross-reactive epitopes within the first 100 amino acids (aa) of the N terminus (6,7,26). In addition, serotype-specific conformational epitopes have been detected in about half of the C termini of the NPs by serotype-specific monoclonal antibodies (MAbs) (20,28). Recombinant NPs (rNPs) of HTNV and SEOV that were truncated 154 aa from the N termini of the NPs (rNP155s) were previously evaluated as diagnostic antigens with expression by a baculovirus system (13). An indirect immunofluorescent-antibody (IFA) test, using the truncated rNPs HTNV rNP155 and SEOV rNP155 as antigens, was able to differentiate HTNV and SEOV infections serologically. However, at least two problems remained. (i) The IFA titers with the rNP155s were more than 10 times lower than those with authentic viruses or whole rNPs. Therefore, patient sera with low titers could not be differentiated; (ii) The antigenicity of HTNV rNP155 was too low to be applied in an enzyme-linked immunosorbent assay (ELISA). These problems were probably caused by an alteration of the antigenic structure after removing 154 aa. It was reported that the crossreactive, immunodominant epitopes of Sin Nombre virus NP were mapped to the segment between aa 17 an...

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It is well known that anti-prion protein (PrP) monoclonal antibodies (mAbs) inhibit abnormal isoform PrP (PrPSc) formation in cell culture. Additionally, passive immunization of anti-PrP mAbs protects the animals from prion infection via peripheral challenge when mAbs are administered simultaneously or soon after prion inoculation. Thus, anti-PrP mAbs are candidates for the treatment of prion diseases. However, the effects of mAbs on disease progression in the middle and late stages of the disease remain unclear. This study carried out intraventricular infusion of mAbs into prion-infected mice before and after clinical onset to assess their ability to delay disease progression. A 4-week infusion of anti-PrP mAbs initiated at 120 days post-inoculation (p.i.), which is just after clinical onset, reduced PrPSc levels to 70–80 % of those found in mice treated with a negative-control mAb. Spongiform changes, microglial activation and astrogliosis in the hippocampus and thalamus appeared milder in mice treated with anti-PrP mAbs than in those treated with a negative-control mAb. Treatment with anti-PrP mAb prolonged the survival of mice infected with Chandler or Obihiro strain when infusion was initiated at 60 days p.i., at which point PrPSc is detectable in the brain. In contrast, infusion initiated after clinical onset prolonged the survival time by about 8 % only in mice infected with the Chandler strain. Although the effects on survival varied for different prion strains, the anti-PrP mAb could partly prevent disease progression, even after clinical onset, suggesting immunotherapy as a candidate for treatment of prion diseases.