Biology Reference
In-Depth Information
1)
5'
+
Internal initiation
3'
2)
5'
3)
+
+
Subgenomic RNA
3'
4)
Subgenomic
-ve RNA from
co-infecting
virus
Recombination
event
Template switch
5)
5'
Recombinant
+
Fig. 2.
A simple mechanism for recombination in NoV. 1) RNA tran-
scription by the RNA-dependent RNA polymerase (RdRp) (grey circle) gen-
erates a negative strand intermediate (dashed line). 2) Binding of the RdRp
to the almost identical RNA promoter sequences (filled boxes) generates
positive-stranded (straight line) genomes and subgenomic RNA. 3) These
templates direct RNA synthesis from the 3´ end that leads to the generation
of both a full-length negative genome and a negative subgenomic RNA
species. 4) Recombination occurs when the enzyme initiates positive strand
synthesis at the 3´ end of the full-length negative strand, stalls at the subge-
nomic promoter, and then template switches to an available negative subge-
nomic RNA species generated by a co-infecting virus. The net result is a
recombinant virus that has acquired new ORF2 and ORF3 sequences.
cells can result in the formation of virus-like particles (VLPs) that are
morphologically similar to native NoV
6,19-24
(Fig. 3A). These studies
have provided valuable information, including the high-resolution
atomic structure, antigenic analysis, and binding factors. However, it
remains unclear how similar these VLPs are to native virions.
Barcena
et al.
25
showed that RHDV N-terminal-deleted
rVP1 constructs could form small and native-size VLPs and that all
RHDV C-terminal-deleted rVP1 constructs failed to form VLPs.
In contrast, Bertolotti-Ciarlet
et al.
26
showed that both NoV N- and
