Biology Reference
In-Depth Information
the interaction of NoV VPg with the translation initiation factor eIF3
has been reported,
63
and thus it is possible that the NoV VPg regulates
transcription and translation initiation events. For some animal cali-
civiruses, synthesis of the capsid protein is initiated from the subgenomic
RNA and involves sequences conserved at the 5
end of the genomic and
subgenomic RNA,
61,64
which may also be the case for NoV.
65
A number
of studies have expressed human NoV in cultured human embryonic
kidney 293T cells using a number of different constructs designed to
produce RNA identical to the genomic RNA.
66,67
In these studies the
negative-strand genomic-like RNA and the subgenomic-like RNA were
transcribed by the functional viral RdRp. This was evident from the
fact that a disrupted RdRp failed to produce genomic and subgenomic
RNA. However, VLPs were not formed when the full-length genomic-
like construct was transfected alone, but were formed when both the
full-length genomic-like and subgenomic-like construct were co-trans-
fected. NoV RNA was not packed into the VLPs when the subgenomic-
like construct was expressed alone, but NoV genomic RNA appeared to
be packed into the VLPs when the full-length genomic-like and
subgenomic-like constructs were co-transfected. This suggested that RNA
packaging signals resided in the ORF1 region and/or non-structural pro-
teins were required for the RNA packaging and viral replication.
7,66,68,69
Recently, a murine NoV cell culture system has been established
70
of
which two aspects were examined, the expression of a subgenomic RNA
and the rearrangement of intracellular membranes during replication.
Subgenomic RNA was detected from the murine NoV-infected cells and
reorganization of intracellular membranes and loss of an intact Golgi
apparatus was observed.
70
′
Comparisons between human NoV replica-
tion systems
66,67
and the murine NoV cell culture system
70
should pro-
vide some fundamental mechanisms.
References
1. Kapikian AZ, Wyatt RG, Dolin R,
et al
. (1972) Visualization by immune
electron microscopy of a 27-nm particle associated with acute infectious
nonbacterial gastroenteritis.
J Virol
10
: 1075-1081.
