The Penaeus stylirostris densovirus capsid protein interacts with the Litopenaeus vannamei BCCIP protein

Development of a real-time enzymatic recombinase amplification assay for rapid detection of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimp Penaeus vannamei

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is classified as a reportable crustacean disease by the World Organisation for Animal Health (WOAH), which causes poor growth in Penaeus vannamei. According to genome sequence alignment analysis, enzymatic recombinase amplification (ERA) primers and probe were designed based on the ORF1 region of IHHNV, and a real-time ERA assay for IHHNV detection (IHHNV-ERA) was established. The experimental results show that IHHNV-F2/IHHNV-R2 and IHHNV-Probe can effectively amplify the target gene, and the sensitivity is 1.4 × 101 copies/μL within 14.97 ± 0.19 min, while the qPCR using primers 309F/309R could reach the detection limit of 1.4 × 101 copies/μL within 21.76 ± 0.63 min, and the sensitivity results of one-step PCR could be as low as 1.4 copies/μL with expense of time and false positives. The IHHNV-ERA system can effectively amplify the target gene at 42 ℃ within 20 min, and has no cross-reaction with white spot syndrome virus (WSSV), Ecytonucleospora hepatopenaei (EHP), Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VpAHPND), and healthy shrimp genomic DNA. Test results of practical samples showed that the detection rate of IHHNV-ERA (18/20) was better than the industrial standard qPCR assay (17/20). Compared with the existing technology, the useful results of this detection assay are: (1) get rid of the dependence on the thermal cycle instrument in the PCR process; (2) the experimental procedure is simple, time-consuming and fast; (3) the detection sensitivity is high. This study provides an ERA based detection assay for IHHNV, which can be used not only for the rapid detection of IHHNV infection, but also for the field screening of pathogens. This assay can also be applied to clinical inspection, customs detection, enterprise quality inspection and other fields, and has obvious practical application value.

Research progress on hosts and carriers, prevalence, virulence of infectious hypodermal and hematopoietic necrosis virus (IHHNV)

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is one of the major viral pathogens of penaeid shrimp and it has spread worldwide. IHHNV causes substantial economic loss to the shrimp farming industry and has been listed as a notifiable crustacean disease pathogen by the World Organization for Animal Health (OIE). In this paper, we reviewed studies on the hosts and carriers, prevalence, genotypes and virulence of IHHNV. The pathogenesis mechanisms of IHHNV and the viral interference between IHHNV and white spot syndrome virus (WSSV) were also discussed. The mechanism of IHHNV infection and its virulence difference in different hosts and different developmental stages have not been fully studied yet. The mechanisms underlying viral interference between IHHNV and WSSV are not yet fully understood. Further studies are needed to elucidate the precise molecular mechanisms underlying IHHNV infection and to apply the insights gained from such studies for the effective control and prevention of IHHNV disease.

Penaeus stylirostris densovirus proteins CP and NS1 interact with peritrophin of Litopenaeus vannamei

The Penaeus stylirostris densovirus (PstDNV) is a major virus of shrimps that severely harms the shrimp farming industry. Peritrophin is a peritrophic membrane protein with chitin binding activity. To examine the roles of peritrophin in viral infection, we used yeast two-hybrid to analyze the interaction between the Pacific white shrimp (Litopenaeus vannamei) peritrophin and PstDNV proteins (CP, NS1 and NS2). The yeast two-hybrid results showed that NS1 and peritrophin had an interaction, CP and peritrophin had an interaction as well, and NS2 had no interaction with peritrophin. We validated the interactions with GST pull-down assays. We then conducted RNA interference and qRT-PCR. The results showed that when pre-injection of dsRNA-peritrophin, the quantity of PstDNV in the shrimps injected with viruses was significantly lower than in the control group (P < 0.01), indicating the viral infection was decreased when the peritrophin gene expression was inhibited. The results indicated that peritrophin of L. vannamei participated in the PstDNV infection.