Penaeidins restrict white spot syndrome virus infection by antagonizing the envelope proteins to block viral entry

Abstract

Emerging studies have indicated that some penaeidins restrict virus infection; however, the mechanism(s) involved are poorly understood. In the present study, we uncovered that penaeidins are a novel family of antiviral effectors against white spot syndrome virus (WSSV), which antagonize the envelope proteins to block viral entry. We found that the expression levels of four identified penaeidins from Litopenaeus vannamei, including BigPEN, PEN2, PEN3, and PEN4, were significantly induced in hemocytes during the early stage of WSSV infection. Knockdown of each penaeidin in vivo via RNA interference resulted in elevated viral loads and rendered shrimp more susceptible to WSSV, while the survival rate was rescued via the injection of recombinant penaeidins. All penaeidins, except PEN4, were shown to interact with several envelope proteins of WSSV, and all four penaeidins were observed to be located on the outer surface of the WSSV virion. Co-incubation of each recombinant penaeidin with WSSV inhibited virion internalization into hemocytes. More importantly, we found that PEN2 competitively bound to the envelope protein VP24 to release it from polymeric immunoglobulin receptor (pIgR), the cellular receptor required for WSSV infection. Moreover, we also demonstrated that BigPEN was able to bind to VP28 of WSSV, which disrupted the interaction between VP28 and Rab7the Rab GTPase that contributes to viral entry by binding with VP28. Taken together, our results demonstrated that penaeidins interact with the envelope proteins of WSSV to block multiple viral infection processes, thereby protecting the host against WSSV.

Effect of a Black Soldier Fly Ingredient on the Growth Performance and Disease Resistance of Juvenile Pacific White Shrimp (Litopenaeus vannamei)

“…Anti-microbial peptides (AMPs) are a broad family of peptides found widely in nature [ 50 ] and are an essential part of the innate immune response. These molecules have been shown to boost the performance of livestock animals [ 24 , 51 ] and shrimp more specifically [ 52 ], and indeed recently evidence of AMPs restricting infection of WSSV was shown in L. vannamei [ 53 ].…”

Feasibility Study on the Use of Fly Maggots (Musca domestica) as Carriers to Inhibit Shrimp White Spot Syndrome

“…According to Xiao et al’s research, WSSV infection activates the Toll and IMD (NF-κB-related) signalling pathways that induce the production of penaeidins, including BigPEN, PEN2, PEN3, and PEN4. Specifically, PEN2 interferes with the ability of the receptor-binding protein VP24 to bind to the host receptor LvpIgR, thereby blocking viral entry into the target cells [ 35 ]. The real-time PCR data showed that the rVP24-fed maggot carried rVP24 to the digestive tract of the shrimp, where it successfully induced a specific immune gene response.…”

A Novel Forkhead Box Protein P (FoxP) From Litopenaeus vannamei Plays a Positive Role in Immune Response

“…Silencing of LvFoxP decreased expression of most immune effector proteins analyzed in this study, including CTLs, lysozyme, hemolin, PPOs, and AMPs from ALF, PEN, and Crustin families, which are all essential for humoral immune responses. Previous studies have described that PENs, ALFs and SWDs, and secreted immune functional proteins hemolin and CTLs possess both antibacterial and antiviral activities in shrimp ( 25 , 28 , 32 , 33 ). It can be inferred that through up-regulating expression of these proteins, LvFoxP may enhance immune responses in shrimp.…”