Title

Stable Yellowhead Virus (YHV) RNA Detection by qRT-PCR During Six-Day Storage

Document Type

Article

Publication Date

6-10-2008

Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Storage conditions of haemolymph samples which contain yellowhead virus (YHV) may result in a decline of YHV RNA concentration or false-negative results in the detection of YHV. We evaluated the stability of YHV RNA in haemolymph stored at different temperatures for 6 d with conventional RT-PCR and TaqMan qRT-PCR. Specific pathogen free individuals of Litopenaeus vannamei were challenged with YHV92TH isolate, and haemolymph samples of 3 groups of 10 pooled moribund shrimp were aliquoted and stored at 4 and 25 degrees C for 0, 2,6,12,24,48,72,96,120, and 144 h. All samples were evaluated by conventional RT-PCR and qRT-PCR. After the optimization of experimental conditions, TaqMan qRT-PCR showed a very strong linear relationship between the log scale of the standard DNA copy number and the C-T values (R-2 = 0.999) over a 7-log range from 10(2) to 10(8) copy number per reaction. Even though the haemolymph was stored at either 4 or 25 degrees C for a 6-day period, the viral load number at 4 degrees C was not significantly different from that stored at 25 degrees C. The only difference was between the samples stored for 144 h at either 4 or 25 degrees C and those stored at -80 degrees C. We conclude that shrimp haemolymph can be drawn from shrimp at farms or in the wild and stored at either 4 or 25 degrees C for 3-5 d without a significant reduction in measured YHV RNA levels and without having to immediately freeze the samples. (C) 2008 Elsevier B.V. All rights reserved.

Publication Title

Aquaculture

Volume

278

Issue

1-4

First Page

10

Last Page

13