Rotaviruses, members of the family Reoviridae, are the major cause of acute gastroenteritis in young children. Despite the pathogenic importance of these viruses, the basic molecular biology of the rotaviruses is not well understood. The genome of these viruses consists of eleven segments of double-stranded RNA (dsRNA). The segmented nature of the genome allows different strains of the rotaviruses to undergo reassortment in nature producing new unique variants. The replication of each segment of the genome proceeds in an asymmetrical manner with viral messenger RNA (mRNA; plus- strand RNA) serving as the template for minus-strand RNA to produce dsRNA. To understand the mechanism of rotavirus RNA replication, we developed a cell-free system that supports the synthesis of simian rotavirus SAll dsRNA, mRNA and protein. Subsequently, this system allowed us to identify, isolate and provide a basic descrip- tion of rotavirus subviral particles (SVPs) that synthesize the viral genome. These data indicate that replicase particles contain cores that may be only partially surrounded by VP6, contain two nonstructural proteins (NS34 and NS35), and draw the template for replication into the core during dsRNA synthesis. The focus of this proposal is to characterize more completely the structure of the replicase particle, the function of proteins associated with these particles, and the recognition signals of viral mRNAs that allow their replication by replicase particles. Specifically, protein-proteins crosslinking, immunoelectron microscopy, and limited proteolytic digestion will be used to study the overall protein structure of the replicase particle. Site-specific cleavage, nuclease digestion and other methods will be used to examine the orientation of the mRNA template with replicase particles and how the template moves during replication. To establish possible function of viral proteins in replication, viral proteins that bind RNA and nucleotides will be identified. The role of VP6, NS34, NS35, and other viral proteins in rotavirus RNA replication, the assembly of single-shelled particles from replicase particles, and in mRNA translation will be studies using the cell-free system. Core particles will be disrupted and reassembled from subunits so as to understand better the morphogenesis of rotavirus SVPs. Initiation of minus-strand RNA synthesis on exogenous viral mRNAs in the cell-free system will be optimized and quantitated. Modified viral mRNAs will be synthesized in vitro by transcription vectors containing cDNAs and added to the system to identify recognition signals on viral mRNAs required for the initiation of minus-strand synthesis. These results should provide valuable information on events in the replication of the rotaviruses that may be useful for developing strategies of controlling diseases caused by these viruses.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Unknown (R22)
Project #
5R22AI021478-05
Application #
3566230
Study Section
Virology Study Section (VR)
Project Start
1987-09-01
Project End
1994-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
5
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Miami School of Medicine
Department
Type
DUNS #
City
Miami
State
FL
Country
United States
Zip Code
33146
Patton, J T (1996) Rotavirus VP1 alone specifically binds to the 3' end of viral mRNA, but the interaction is not sufficient to initiate minus-strand synthesis. J Virol 70:7940-7
Wentz, M J; Patton, J T; Ramig, R F (1996) The 3'-terminal consensus sequence of rotavirus mRNA is the minimal promoter of negative-strand RNA synthesis. J Virol 70:7833-41
Patton, J T; Wentz, M; Xiaobo, J et al. (1996) cis-Acting signals that promote genome replication in rotavirus mRNA. J Virol 70:3961-71
Kattoura, M D; Chen, X; Patton, J T (1994) The rotavirus RNA-binding protein NS35 (NSP2) forms 10S multimers and interacts with the viral RNA polymerase. Virology 202:803-13
Hua, J; Patton, J T (1994) The carboxyl-half of the rotavirus nonstructural protein NS53 (NSP1) is not required for virus replication. Virology 198:567-76
Patton, J T; Salter-Cid, L; Kalbach, A et al. (1993) Nucleotide and amino acid sequence analysis of the rotavirus nonstructural RNA-binding protein NS35. Virology 192:438-46
Patton, J T; Hua, J; Mansell, E A (1993) Location of intrachain disulfide bonds in the VP5* and VP8* trypsin cleavage fragments of the rhesus rotavirus spike protein VP4. J Virol 67:4848-55
Hua, J; Mansell, E A; Patton, J T (1993) Comparative analysis of the rotavirus NS53 gene: conservation of basic and cysteine-rich regions in the protein and possible stem-loop structures in the RNA. Virology 196:372-8
Kattoura, M D; Clapp, L L; Patton, J T (1992) The rotavirus nonstructural protein, NS35, possesses RNA-binding activity in vitro and in vivo. Virology 191:698-708
Valenzuela, S; Pizarro, J; Sandino, A M et al. (1991) Photoaffinity labeling of rotavirus VP1 with 8-azido-ATP: identification of the viral RNA polymerase. J Virol 65:3964-7

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