Early Detection of White Spot Syndrome Virus (WSSV) in Isolated Hemocytes of Litopenaeus vannamei

Abstract

To date, White Spot Syndrome (WSS) produced by the White Spot Syndrome Virus (WSSV) causes one of the most severe diseases infecting penaeid shrimps worldwide. Although a vast amount of studies has elucidated pathogenesis in live infection models, there is still little information about the interaction of WSSV infections using in vitro models in the whiteleg shrimp Litopenaeus vannamei (L. vannamei) hemocytes. In this study, a WSSV infection kinetics was performed using total hemocytes isolated from healthy L. vannamei organisms and maintained in in vitro conditions using isotonic solution for shrimp (ISS). The infected experimental cells received ≈ 30,000 viral copies of WSSV. The viability of the hemocytes (control and infected group) was measured during the kinetics with trypan blue exclusion method and cells were maintained up to 6 hpi (post-infection) with non-significant differences of viability between both groups. WSSV replication was assessed using RT- PCR at the RNA expression level of the early viral gene Ie1 and transcripts were detected as early as 30 min pi. Hemocytes from WSSV group showed disrupted integrity, degranulation and irregular shape. This study provides evidence of the capability of WSSV to infect and replicates in L. vannamei hemocytes using in vitro assays in short times as 30 min.