Progress 10/15/05 to 09/30/07
Outputs Interferons and ribavirin are non-specific antiviral agents with FDA approval for various viral diseases such as chronic hepatitis C virus infection and respiratory syncytial virus infection. Both agents were very effective in inhibiting Norwalk virus replication and when they were combined, we observed an additive effect. Without any commercially available drugs against noroviral gastroenteritis, these could be developed as antiviral drugs. As a continual study of the effects of bile acids on the calicivirus replication, we have studied the role of the farnesoid X receptor (FXR), a bile acid receptor, in the replication of norovirus. We have found that the activation of FXR promoted the replication of noroviruses in cells, demonstrated the importance of bile acids in norovirus replication.
Impacts Our study could lead to the isolation of fastidious noroviruses in cell culture and vaccine development.
Publications
- Chang, K.O., George, D.W. 2007. Interferons and Ribavirin Effectively Inhibit Norwalk Virus Replication in the Replicon-Bearing cells. J Virol. Nov;81(22):12111-8.
- Chang, K.O., George, D.W. 2007. Bile acids promote the replication of hepatitis C virus in the replicon harboring cells. J Virol. 81(18):9633-40.
- Kim, D.Y., J.G. Calvert, K.O. Chang, R.R. Rowland. 2007. The cysteine protease, nsp2, of porcine reproductive and respiratory syndrome virus: a potential target for heterologous gene expression. Virus Res. 128(1-2):106-14.
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Progress 01/01/06 to 12/31/06
Outputs We have developed the RT-PCR/hybridization assay for detecting porcine noroviruses or sapoviruses. The primer pairs for specific to porcine noroviruses and sapoviruses were designed, and optimum conditions were established. To solve problems with RT-PCR inhibitors in fecal RNA which frequently cause false-negative results, we developed a competitive internal control (IC) RNA. Microwell hybridization assays were also developed to confirm the specific RT-PCR products. We also generated cells expressing self-replicating Norwalk virus RNA (Norwalk virus replicon) following transfection of Norwalk virus RNA bearing an engineered neomycin resistance gene into cell lines of human (Huh-7) or hamster (BHK21) origin. We found that expression of replicon RNA was significantly reduced in the presence of interferon- in a dose-dependent manner in the Norwalk virus replicon-bearing cells, suggesting a role for innate immunity in the control of norovirus replication. This
stable replicon system should lead to new insights into norovirus replication, virus-host interactions, and approaches for the treatment of norovirus disease.
Impacts The replicon system is a platform to screen potential antiviral drugs against noroviruses.
Publications
- Wang, QH, Chang, KO, Han, MG, Sreevatsan, S, Saif, LJ. 2006. Development of a new microwell hybridization assay and an internal control RNA for the detection of porcine noroviruses and sapoviruses by reverse transcription-PCR. Mar;132(1-2):135-45.
- Chang, KO, Sosnovtsev, SO, Belliot, G, Green, KY. 2006. Stable expression of a Norwalk virus RNA replicon in a human hepatoma cell line. Virology. Sep;353(2):463-73.
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