YHV was first mistakenly considered to be a
baculovirus but it was soon discovered during
purification and characterization that its morphology
differed from that of baculoviruses. By electron microscopy,
thin tissue sections revealed the presence of
unusual filamentous nucleocapsid precursors and much
shorter, mature, rod-shaped, enveloped virions (Fig. 12).
With negative staining, the virus particles were found to
be enveloped with a halo of appendages characteristic of
some RNA viruses (Fig. 13). Eventually, it was found
that the genome consisted of single-stranded RNA
(ssRNA) of positive sense (Wongteerasupaya et al.,
1995a). Diagnostic probes were prepared by cDNA
preparation and cloning. Diagnosis is currently best by
RT-PCR assays (Wongteerasupaya et al., 1997) rather
than in situ hybridization (Fig. 14), probably because of
the instability of the viral RNA. Even with the RT-PCR
assay, samples must be processed quickly, since storage
at −80 °C does not prevent deterioration of the RNA.
The original PCR amplicon sequence and the primers
described for YHV detection in infected shrimp by RTPCR
are as follows
YHV was first mistakenly considered to be a
baculovirus but it was soon discovered during
purification and characterization that its morphology
differed from that of baculoviruses. By electron microscopy,
thin tissue sections revealed the presence of
unusual filamentous nucleocapsid precursors and much
shorter, mature, rod-shaped, enveloped virions (Fig. 12).
With negative staining, the virus particles were found to
be enveloped with a halo of appendages characteristic of
some RNA viruses (Fig. 13). Eventually, it was found
that the genome consisted of single-stranded RNA
(ssRNA) of positive sense (Wongteerasupaya et al.,
1995a). Diagnostic probes were prepared by cDNA
preparation and cloning. Diagnosis is currently best by
RT-PCR assays (Wongteerasupaya et al., 1997) rather
than in situ hybridization (Fig. 14), probably because of
the instability of the viral RNA. Even with the RT-PCR
assay, samples must be processed quickly, since storage
at −80 °C does not prevent deterioration of the RNA.
The original PCR amplicon sequence and the primers
described for YHV detection in infected shrimp by RTPCR
are as follows
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