Genetic properties of medium (M) and small (S) genomic RNA segments of Seoul hantavirus isolated from Rattus norvegicus and antigenicity analysis of recombinant nucleocapsid protein.

A novel isolate of Seoul (SEO) hantaviruses was detected and identified in Rattus norvegicus in Shandong Province, China and designated as JUN5-14. The partial M segment and the coding region of nucleocapsid protein (NP) in the S segment of JUN5-14 were PCR-amplified and sequenced. Nucleotide sequence analysis of the partial M segment (300 bp) revealed that JUN5-14 isolate was closely related to former SEO isolates in Shandong (97.3-99.0% homology) and non-Shandong SEO viruses (84.1-97.7% homology) but distantly related to other hantaviruses (61.5-75.1% homology). Consistent with the M segment, the coding region of the NP showed 87.5-97.8% and 97.9-99.8% identity with SEO viruses and 55.2-75.8% and 47.2-84.4% homology with other hantaviruses, at nucleotide and amino acid level, respectively. The virus isolate was identified as a member of the subtype 3 (S3) of SEO viruses by phylogenetic trees generated from the nucleotide sequences of the S and M segments. In order to develop a diagnostic assay for hantavirus infection in human, the full-length NP gene of JUN5-14 was expressed in BHK21 cells using the T7 RNA polymerase expression system. The NP expression was confirmed by indirect immunofluorescence assay (IFA) and Western blotting. The expressed NP protein was used as antigen to detect antibody response against NP in patients with hemorrhagic fever with renal syndrome (HFRS) in an IgG-IFA. Sixteen out of seventeen serum samples showed positive for the presence of anti-NP antibodies, indicating that the recombinant NP (rNP) protein of JUN5-14 was a good antigen for detecting hantavirus infection in human.