Reovirus Infection Changes Transcript Levels of Eukaryotic Translation Initiation Factor 4E (eIF4E) Family Members and eIF4E-Binding Protein (4E-Bp) in the Blue Crab Callinectes sapidus

Abstract

The blue crab Callinectes sapidus reovirus 1 (CsRV1), a double-stranded RNA virus, belongs to the Class III virus family Reoviridae and infects marine invertebrates, including the blue crab C. sapidus. Callinectes sapidus reovirus 1 levels correlate with disease progression, and high levels of infection usually result in death. To understand CsRV1 disease progression, the impact of CsRV1 infection on the translation initiation machinery in adult female C. sapidus was determined. Using transcriptome analysis of C. sapidus, sequences representing each of the three classes of metazoan eukaryotic translation initiation factor 4E (eIF4E) family members, eIF4E1, eIF4E2, and eIF4E3, as well as the eIF4E-binding protein (4E-BP), were identified as the first description of a Class III eIF4E in decapod crustaceans. Transcripts encoding the three eIF4E family members and 4E-BP are found in all tissues examined by end-point RT-PCR analysis, except for the hypodermis. In the noninfected animals, EIF4E1 transcript levels are;11.5- to 150-fold higher than those of EIF4E2, EIF4E3, or 4EBP in both hemocytes and eyestalk ganglia. In CsRV1 infected animals, transcript levels of eIF4E family members and 4EBP initially increase in hemocytes and to a much lesser extent in eyestalk ganglia. In hemocytes, EIF4E2, EIF4E3, and 4EBP transcript levels are highest at low levels of infection. By contrast, EIF4E1 transcript levels peak at moderate levels of infection. In the eyestalk ganglia, an endocrine tissue, CsRV1 infection only slightly impacts EIF4E1 and EIF4E2 levels, although more substantial increases in EIF4E3 and 4EBP are seen. These results provide the first window into how CsRV1 infection and disease progression perturb the host C. sapidus eIF4E family members and 4E-BP in different tissues, suggesting nuanced responses of the host translationalmachinery during disease progression.