Molecular biology of astroviruses: selected highlights.
Human astrovirus, the prototype of the Astroviridae family, is a non-enveloped positive-strand RNA virus with distinctive morphology. Initially named for a characteristic 5-6 point star evident on the surface of faecally shed viral particles by direct electron microscopy, a recent study using cryoelectron microscopy and image reconstruction indicates that viral particles consist of a smoothly rippled, solid capsid decorated with short spikes. Mechanisms underlying the assembly of these viral particles have not been fully elucidated. However, studies of two full-length cDNA clones of human astrovirus serotype 1 suggest that capsid residue Thr227 plays a critical role in the assembly of infectious viral progeny. The development of a full-length clone (pAVIC) from which infectious RNA can be transcribed has also facilitated studies of the viral 3C-like serine protease, encoded in ORF1a. These studies demonstrate that the full-length ORF1a product (101 kDa) is processed in vitro to an N-terminal 64 kDa fragment and a C-terminal 38 kDa fragment. Mutation of the predicted catalytic triad inhibits proteolysis. In other studies based on modifications of pAVIC, preliminary evidence supports the feasibility of developing a reporter cell line to facilitate astrovirus detection.
Matsui
S M
SM
Department of Medicine, Division of Gastroenterology, Stanford University School of Medicine, Stanford, CA 94305-5487, USA.
Kiang
D
D
Ginzton
N
N
Chew
T
T
Geigenmüller-Gnirke
U
U
D000595:Amino Acid Sequence; D016679:Genome, Viral; D006801:Humans; D001257:Mamastrovirus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D012367:RNA, Viral; D014764:Viral Proteins; D012697:Serine Endopeptidases