Detection and quantification of infectious hypodermal and hematopoietic necrosis virus and white spot virus in shrimp using real-time quantitative PCR and SYBR green chemistry
Ak. Dhar et al., Detection and quantification of infectious hypodermal and hematopoietic necrosis virus and white spot virus in shrimp using real-time quantitative PCR and SYBR green chemistry, J CLIN MICR, 39(8), 2001, pp. 2835-2845
A rapid and highly sensitive real-time PCR detection and quantification met
hod for infectious hypodermal and hematopoietic necrosis virus (IHHNV), a s
ingle-stranded DNA virus, and white spot virus (WSV), a double-stranded DNA
(dsDNA) virus infecting penaeid shrimp (Penaeus sp.), was developed using
the Gene-Amp 5700 sequence detection system coupled with SYBR Green chemist
ry. The PCR mixture contains a fluorescence dye, SYBR Green, which upon bin
ding to dsDNA exhibits fluorescence enhancement. The enhancement of fluores
cence was proportional to the initial concentration of the template DNA. A
linear relationship was observed between the amount of input plasmid DNA an
d cycle threshold (C-T) values over a range of 1 to 10(5) copies of the vir
al genome. To control the variation in sampling and processing among sample
s, the shrimp beta -actin gene was amplified in parallel with the viral DNA
. The C-T values of IHHNV- and WSV-infected samples were used to determine
absolute viral copy numbers from the standard C-T curves of these viruses.
For each virus and its beta -actin control, the specificity of amplificatio
n was monitored by using the dissociation curve of the amplified product. U
sing genomic DNA as a template, SYBR Green PCR was found to be 100- to 2000
-fold more sensitive than conventional PCR, depending on the virus, for the
samples tested. The results demonstrate that SYBR Green PCR can be used as
a rapid and highly sensitive detection and quantification method for shrim
p viruses and that it is amenable to high-throughout assay.