4. Discussion
Although various primers have been designed for the detection of iridoviruses by PCR
gene amplification, it has not been determined whether those primers are suitable for
detecting variants of RSIVs found in different species, countries, and years. We tested four
primer sets targeting RSIVand, not surprisingly, found an interesting type of RSIV that is
not detected by PCR with any of the widely used primer sets (Table 1, Fig. 1). In the
present study, we tried to differentiate this newly isolated RSIV from other known RSIVs
by PCR. This was done by taking advantage of previous findings of our laboratory, which
are (1) the 3Vend flanking region (4436 bp long and designated as K1) (Jeong et al., 2003)
of the DPOL gene possessed the Pst I restriction fragment of Kurita et al. (1998) spanned
between ORF-1 and ORF-2 of the unknown function, (2) RSIVs isolated in Korea might
be classified as two different types, RSIV Sachun as a major type and RSIV Namhae
showing the same nucleotide sequence with that of RSIV Ehime-1, (3) the lowest degree
of DNA sequence homology were in the PCR products derived from the Pst I restriction
fragment.