Glycosylation of gp116 and gp64 envelope proteins of yellow head virus of Penaeus monodon shrimp

Ubiquitination as an Important Host-Immune Response Strategy in Penaeid Shrimp: Inferences From Other Species

Shrimp aquaculture is an essential economic venture globally, but the industry faces numerous challenges, especially pathogenic infections. As invertebrates, shrimp rely mainly on their innate immune system for protection. An increasing number of studies have shown that ubiquitination plays a vital role in the innate immune response to microbial pathogens. As an important form of posttranslational modification (PTM), both hosts and pathogens have exploited ubiquitination and the ubiquitin system as an immune response strategy to outwit the other. This short review brings together recent findings on ubiquitination and how this PTM plays a critical role in immune modulation in penaeid shrimps. Key findings inferred from other species would help guide further studies on ubiquitination as an immune response strategy in shrimp-pathogen interactions.

RNAi-based antiviral immunity of shrimp

As a kind of important economic marine crustaceans in aquaculture, shrimp can be infected by more than 20 viruses. To fight against the virus invasion, shrimp have developed the innate immunity, including RNA interference (RNAi). RNAi, mediated by short interfering RNAs (siRNAs) or microRNAs (miRNAs), plays important roles in virus-host interactions. At present, RNAi is considered to be an efficient antiviral response of shrimp. The siRNA-based RNAi, first recognized as an antiviral response of animals to resist RNA viruses, has emerged in animals as an efficient antiviral strategy against the invasion of DNA viruses and RNA viruses. In shrimp, as well as in other animals, siRNA contains a seed region (2nd-7th nt) and a supplementary region (12th-17th nt). Based on the findings in shrimp and other animals, miRNAs are essential regulators of virus-host interactions, such as virus infection/latency, and host apoptosis, autophagy and phagocytosis. Except for the seed sequence (2nd-7th), the complementary bases (to the target mRNA sequence) of a miRNA 9th-18th non-seed sequence are essential for the miRNA targeting. So far, rapidly growing evidences have supported the existence of functional RNAi machinery in shrimp. In this review, we summarize the progress of RNAi in the antiviral immune response of shrimp. The potential applications of RNAi to control shrimp diseases were also summarized.

Potential of RNAi applications to control viral diseases of farmed shrimp

Viral pathogens pose a primary threat to global shrimp aquaculture. Despite the urgent industry need for them, practical anti-viral control methods are unavailable due, in part, to lack of an adaptive immune response in crustaceans that renders conventional vaccination methods ineffective. One currently studied method of high interest for protecting shrimp against viral infection relies on the post-transcriptional gene silencing mechanism called RNA interference (RNAi) that is induced by gene-specific constructs of double stranded RNA (dsRNA). Although this approach was first described for successful protection of shrimp against white spot disease (WSD) by injecting dsRNA specific to genes of white spot syndrome virus (WSSV) into shrimp in the laboratory in 2005 no practical method for use of dsRNA in shrimp farms has been developed to date. The apparent bottleneck for farm-scale applications of RNAi-mediated viral control in shrimp aquaculture is the lack of simple and cost-effective delivery methods. This review summarizes recent studies on use and delivery of dsRNA to shrimp via injection and oral routes in hatcheries and on farms and it discusses the research directions that might lead to development of practical methods for applications with farmed shrimp. Oral delivery methods tested so far include use of dsRNA-expressing bacteria as a component of dry feed pellets or use of living brine shrimp (Artemia) pre-fed with dsRNA before they are fed to shrimp. Also tested have been dsRNA enclosed in nanocontainers including chitosan, liposomes and viral-like particles (VLP) before direct injection or use as components of feed pellets for hatchery or pond-reared shrimp.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

N-Linked glycosylation is essential for the yellow head virus replication cycle

Yellow head virus (YHV) particles contain a nucleocapsid protein (p20) and two envelope glycoproteins (gp116 and gp64). The glycans attached to the two glycoproteins are N-linked and are complex and high mannose types, respectively. Here, we show that treatment with the N-linked glycosylation inhibitor tunicamycin in YHV-infected black tiger shrimp (Penaeus monodon) resulted in less severe yellow head disease and reduced mortality when compared with untreated control shrimp. Quantitative real-time reverse transcription PCR analysis also revealed lower YHV copy numbers in the haemolymph of treated than control shrimp. This was concurrent with less intense immuno-reactions in tissues of treated versus untreated shrimp using mAbs against all three YHV structural proteins. In addition, transmission electron microscopy of lymphoid organ tissue of the treated and untreated shrimp [eight collected at 36 h and eight at 48 h post-infection (p.i.)] revealed only unenveloped nucleocapsids in all but one of the treated shrimp (collected at 48 h p.i.). By contrast, all the untreated shrimp showed a mixture of many unenveloped and enveloped virions. These results were supported by purification of YHV from the cell-free haemolymph of treated and untreated shrimp followed by YHV structural protein analysis by SDS-PAGE. It revealed three expected structural protein bands (116, 64 and 20 kDa) from the untreated shrimp but no structural protein bands from the tunicamycin-treated shrimp (confirmed by Western blot analysis). Overall, the results indicated that blocking glycosylation with tunicamycin inhibited the formation of mature YHV virions and their subsequent release into shrimp haemolymph, reducing the severity of disease.

Reprint of: Virus-binding proteins and their roles in shrimp innate immunity

Disease outbreaks caused by viral pathogens constitute a major limitation to development of the shrimp aquaculture industry. Many research have been conducted to better understand how host shrimp respond to viral infections with the aim of using the gained knowledge to develop better strategies for disease management and control. One approach has been to study the interactions between host and viral proteins, and particularly host virus-binding proteins that might play an important role in the viral infection process. Within the past five years, increasing numbers of virus-binding proteins (VBPs) have been reported in shrimp. Characterization of these molecules has emphasized on their potential therapeutic applications by demonstrating their activities in inhibition of viral replication via in vivo neutralization assay. However, signaling to induce innate antiviral immune responses as a consequence of binding between viral proteins and VBPs remain to be fully elucidated.

Virus-binding proteins and their roles in shrimp innate immunity

Disease outbreaks caused by viral pathogens constitute a major limitation to development of the shrimp aquaculture industry. Many research have been conducted to better understand how host shrimp respond to viral infections with the aim of using the gained knowledge to develop better strategies for disease management and control. One approach has been to study the interactions between host and viral proteins, and particularly host virus-binding proteins that might play an important role in the viral infection process. Within the past five years, increasing numbers of virus-binding proteins (VBPs) have been reported in shrimp. Characterization of these molecules has emphasized on their potential therapeutic applications by demonstrating their activities in inhibition of viral replication via in vivo neutralization assay. However, signaling to induce innate antiviral immune responses as a consequence of binding between viral proteins and VBPs remain to be fully elucidated.