ABSTRACT
The family Nimaviridae includes the single species White spot syndrome virus, isolates of which infect a wide range of aquatic crustaceans and cause substantial economic losses. Virions are ellipsoid to bacilliform with a terminal thread-like extension. The circular dsDNA genome is 280-307 kbp with several homologous repeat regions. More than 80 structural and functional proteins have been characterized from 531 ORFs. White spot syndrome is a highly lethal, contagious disease associated with white spot syndrome virus infection of shrimps. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Nimaviridae, which is available at www.ictv.global/report/nimaviridae.
Subject(s)
Decapoda/virology , Nimaviridae/classification , Nimaviridae/isolation & purification , Animals , Genome, Viral , Host Specificity , Nimaviridae/genetics , Nimaviridae/ultrastructure , Open Reading Frames , Shellfish/virology , Virus ReplicationABSTRACT
Blood coagulation is a conserved defense mechanism among invertebrates and it has been well studied in horseshoe crab and freshwater crayfish but is ill defined in shrimp. Transglutaminase (TGase) and clotting protein (CP) are molecules involved in the blood clotting system of shrimp. Here, we demonstrate in vivo the functional involvement of TGase and CP in the shrimp blood coagulation system using RNA interference. Expression of TGase mRNA was inhibited in gills, heart, hemocyte, hepatopancreas, intestine and lymphoid organ while the CP gene was suppressed only in gills and heart tissues on day-1 post-injection with 1 microg and 10 microg of TGase- and CP-dsRNA, respectively. However, at day-7 post-injection, systemic gene silencing was observed for both genes and dosages as shown by mRNA expression. We also show the efficiency of dsRNA silencing the protein expression as well as inhibited blood coagulation. Such silencing at the transcription, translation and phenotypic level is the first to be documented in the shrimp system. Challenge test with white spot virus and Vibrio penaecida revealed that TGase and CP are critical molecules for the immune function of shrimp against bacterial and viral infection.
