Identification of White Spot Syndrome Virus Latency-Related Genes in Specific-Pathogen-Free Shrimps by Use of a Microarray

To investigate whether specific-pathogen-free (SPF) shrimps are asymptomatic carriers of white spot syndrome virus (WSSV), we used a WSSV-specific DNA microarray to measure WSSV gene expression in SPF and WSSV-infected shrimps. Three WSSV genes were found to be relatively highly expressed in SPF shrimps. Reverse transcription-PCR using nested primers as well as real-time detection confirmed that these genes have no detectable counterparts in GenBank; structural analysis of the putative proteins revealed helix-loop-helix and leucine zipper motifs. Viral sequences could be PCR amplified from genomic DNA of SPF shrimp, further supporting the suggestion that these shrimps are asymptomatic carriers.