In the past funding period we have significantly advanced our understanding on the virus/host interaction and receptors for human noroviruses (NVs): we have 1) described eight receptor binding patterns of NVs with human histo-blood group antigen (HBGAs) receptors, 2) mapped the receptor binding domain on the viral capsids by genetic and mutagenesis approaches, 3) elucidated the receptor binding interfaces by cryo-EM and crystallography, 4) discovered a unique subviral particle, the P particle, of NVs, which have greatly facilitated our ability to characterize NV-host interaction, and 5) obtained evidence of HBGA as an important factor in NV evolution based on genetic analysis of the receptor binding interfaces of NVs. These advancements strongly suggest that the HBGAs play an important role in host interaction and tropism of NVs. In addition, our and others' studies suggested that, like many non-enveloped viral pathogens, NVs may need a two-step process to enter into host cells to initiate infection (viral replication). The binding to the HBGAs is the first step that allows virions to attach to the host cells. In the second step, another receptor or co-receptor facilitates the attached virions to penetrate or enter into host cells. This two-step process has been proven for the feline calicivirus (FCV) that uses the sialic acid for attachment and fJAM- 1 for penetration. In this application we will characterize the two-step process of NVs by performing three lines of studies: 1) to search and characterize a functional receptor(s) or co- receptor(s) that involve in the penetration or entry of NVs into host cells, 2) to define the roles of HBGAs in NV binding/attachment to cell surfaces and tropism to the host, and 3) to develop a platform for screening and rational design of antivirals against NVs by computer- aided drug design (CADD) methods. We will take advantage of the newly developed TV cell culture as a model, follow the footsteps of FCV and use our newly resolved crystal structures of NVs to fulfill the goals. The research team includes experts in molecular virology, bioinformatics, structural biology and drug development and medicinal chemistry and with an outstanding track record in the past. We are confident that we will make a rapid progress in this application.
In this application we will characterize the two-step process of noroviruses (NVs), attachment and penetration/entry, into host cells for initiation of replication. This is based on the large body of information generated in recent years on the NVs recognizing the human histo-blood group antigens (HBGAs) as a receptor. Our hypothesis is that the recognition of the carbohydrate antigens (HBGAs) on the cell surface is the first step to allow the viruses to bind/attach to the cell surfaces, which may be important for host or tissue tropism, but, like many other non-enveloped small RNA viruses, another receptor or co- receptor may also be required for subsequent penetration or entry of viruses into host cells to initiate replication. In this study we will follow the footsteps of the feline calicivirus (FCV) that relies on the sialic acid for attachment and the tight junctional adhesion molecule (JAM) for penetration to characterize the two-step process of NVs. Three specific aims will be fulfilled. Aim 1 will search and characterize a functional receptor(s) or co-receptor(s) that is involved in the penetration or entry of NVs into host cells by a number of molecular cloning and biochemistry approaches, including characterization of the 105 kDa protein that was found in our preliminary studies and the JAM which may be a candidate receptor for NVs. Aim 2 will further define the roles of carbohydrate moiety and the backbone of the HBGAs in NV binding/attachment to cell surfaces by binding/blocking experiments and our recently developed new calicivirus model, the Tulane virus, including studying adaptation/evolution and structure/functional analysis of NVs. Aim 3 will develop a platform for screening and rational design of antivirals against NVs by computer-aided drug design (CADD) methods based on our recently resolved atomic structures of NVs and promising pre-screening data. The research team of this application includes experts in molecular virology, structure biology, bioinformatics and drug development and medicinal chemistry and with an outstanding track-record. We are confident that we will make a rapid progress.
| Dai, Ying-Chun; Zhang, Xu-Fu; Tan, Ming et al. (2013) A dual chicken IgY against rotavirus and norovirus. Antiviral Res 97:293-300 |
| Zhang, Xu-Fu; Dai, Ying-Chun; Zhong, Weiming et al. (2012) Tannic acid inhibited norovirus binding to HBGA receptors, a study of 50 Chinese medicinal herbs. Bioorg Med Chem 20:1616-23 |
| Dai, Ying-Chun; Wang, Yun-Yun; Zhang, Xu-Fu et al. (2012) Evaluation of anti-norovirus IgY from egg yolk of chickens immunized with norovirus P particles. J Virol Methods 186:126-31 |
