Hantaviruses Infect Cultured Cortical Astrocyte Of Newborn Rat

Hantaviruses (HTVs) constitute a genus in the family Bunyaviridae. Infections with certain Hantavirus species are known to cause two serious and often fatal human diseases, hemorrhagic fever with renal syndrome (HFRS) and Hantavirus pulmonary syndrome (HPS). HFRS is caused by Hantaan virus (HTNV), Seoul virus (SEOV), Dobrava-Belgrade virus (DOBV) and Puumala virus (PUUV) .HTVs infect abroad range of organs and cells in many animal experiments, Newborn-rat brain is highly sensitive to HTVs infection and induced fatal encephalitis which is one of the important fatal causes. HTVs invade bodies and first proliferate in endothelial cell, and then are released into blood. HTVs can invade brain through blood-brain barrier. Astrocyte is the most abundant cell type in the central nervous system (CNS). Their end feet surround the capillaries in the CNS. Astrocyte plays a critical role in many viral infections by supporting viral replication and sequestering viruses. So far, it has not been clearly established whether HTVs productively infect microglia and astrocyte, leaving the unanswered question of whether these cells are susceptible to infection or simply absorb or phagocytose virus or cellular debris from infected neurons.In the present study, we established the primary cortical glial cultures of newborn rats less than 24 hours of age,and examined the purity of astrocyte,the purified astrocyte was infected with HTNV strain 76-118 and SEOV strain L99. At 1 d , 2 d , 3 d , 4 d , 5 d , 6 d , 7 d after virus infection , the cultures were harvested for detection of virus nucleocapsid protein by indirect immunofluorescense and western blot and of virus S segment by RT-PCR . Furthermore, the harvested cultures were prepared for detection of the interaction of Hantaviruses and the infected astrocyte by RT-PCR, Hoechst 33342 and Annexin-V.We found that the virus NP and virus S segment could be detected as early as 1 d after infection in astrocyte culture of newborn rats, the positive rates were progressively and significantly increased from 1 d to 7 d after virus infection, and there was a significant increased tendency in a time-dependent manner (P﹤0.01). There was a increasing tendency in Hsp70 and GFAP expression at different time after HTVs infection. But compared to the astrocyte in normal condition, the cytopathogenic effect could not be found in virus infection condition.In conclusion, the primary cortical astrocyte of newborn rats in culture was successfully established and susceptiable to HTVs infection. We futher confirmed the change of Hsp70 and GFAP. And, HTVs infection induced an increase in the Hsp70 and GFAP expression. The GFAP and HTVs NP existed colocalization. But HTVs infection did not produce the cytopathogenic effect. Hsp70 and GFAP are probably related to the pathogenesis of HFRS. Our study provided an experimental mode for further study of the interaction between HTVs and host cells and pathogenesis of HFRS.