Molecular Epidemiologic Study On Hemorrhagic Fever With Renal Syndrome In Beijing

In Beijing, hemorrhagic fever with renal syndrome (HFRS) is a significant public health problem with an increasing incidence since 1996. To understand the characteristics prevalent in this area, systematic molecular epidemiologic study were carried out on rodents and patients.First of all, rodents were captured from Haidian district where the HFRS incidence was high and hantaviruses were detected. Rattus norvegicus were found to be the dominant rodent hosts in this area. Seoul virus (SEOV) was the only hantavirus circulating in this area, which was proved to be most related to strains in S3 subtype according to previous studies.Hantavirus strains, designated as BjHD01 and BjHD02 were successfully isolated from Rattus norvegicus using Vero E6 cell line. Then the complete S and M sequence of BjHD01 strain were amplified and sequenced. Phylogenetic, neighbor-net network, and Bootscanning analyses revealed that BjHD01 was most closely related to R. norvegicus-bome Seoul virus, and possibly extensively interacted with other Seoul viruses in the early stage of its evolutionary history.Sequence analysis based on partial S segment amplified from blood of patients and lung samples of rodents showed that virus strains infected human fell into three different lineages, two of which were circulating in Beijing. One lineage circulated in areas from northwest to southwest, most of them near the center of Beijing. The other lineage circulated in northeast and northwest areas comparatively far away from the center of Beijing. Virus strains circulating in different areas had the distinct genetic characteristics at amino acid level.It was speculated that infectivity of strains carried by Mus musculus was limited due to virus mutation carried by them and it was worth of further study on mechanism of mutation.Quasispecies and short deletion located in 3' termini of S segment were detected for both viruses infected humans and carried by rodent hosts. Further investigation is required to determine that if the number of deleted bases for viruses from different host origin was different.In conclusion, this study presents valuable information on HFRS infection source and the main reason of increasing incidence of HFRS in Beijing in recent years. The study might thus lead to the better understanding of HFRS epidemiology and would be helpful to control HFRS infection in Beijng.