Nanocontainer designed from an infectious hypodermal and hematopoietic necrosis virus (IHHNV) has excellent physical stability and ability to deliver shrimp tissues

Confirmatory test of active IHHNV infection in shrimp by immunohistochemistry and IHHNV-LongAmp PCR

The presence of endogenous viral elements (EVE) in the penaeid shrimp genome has been recently reported and suggested to be involved in the host recognition of viral invaders. Our previous report of a search for EVE of infectious hypodermal and haematopoietic necrosis virus (IHHNV-EVE) in the Thai Penaeus monodon whole genome sequence project (GenBank accession no. JABERT000000000) confirmed the presence of three clusters of EVE derived from IHHNV in the shrimp genome. This study aimed to compare an immunohistochemistry method (IHC) and a PCR method to detect infectious IHHNV infection in shrimp. First, specimens collected from farms were checked for IHHNV using three PCR methods; two methods were recommended by WOAH (309 and 389 methods), and a newly established long-range PCR for IHHNV (IHHNV-LA PCR) targeting almost the whole genome (>90%) of IHHNV. Among 29 specimens tested, 24 specimens were positive for WOAH methods (at least one method). Among 24 WOAH-positive specimens (WOAH+), there were 18 specimens with positive IHHNV-LA PCR method (WOAH+/LA+), six specimens with negative IHHNV-LA PCR method (WOAH+/LA-). Six specimens were negative for all methods (WOAH-/LA-). The positive signals detected by IHC method were found only in the specimens with WOAH+/LA+. The results suggest that the WOAH+/LA- specimens were not infected with IHHNV, and the positive WOAH method might result from the EVE-IHHNV. The study recommends combining the IHHNV-LA PCR method and IHC with positive PCR results from WOAH's recommended methods to confirm IHHNV infection.

Precise Therapy Using the Selective Endogenous Encapsidation for Cellular Delivery Vector System

Interindividual variability in drug response is a major problem in the prescription of pharmacological treatments. The therapeutic effect of drugs can be influenced by human genes. Pharmacogenomic guidelines for individualization of treatment have been validated and used for conventional dosage forms. However, drugs can often target non-specific areas and produce both desired and undesired pharmacological effects. The use of nanoparticles, liposomes, or other available forms for drug formulation could help to overcome the latter problem. Virus-like particles based on retroviruses could be a potential envelope for safe and efficient drug formulations. Human endogenous retroviruses would make it possible to overcome the host immune response and deliver drugs to the desired target. PEG10 is a promising candidate that can bind to mRNA because it is secreted like an enveloped virus-like extracellular vesicle. PEG10 is a retrotransposon-derived gene that has been domesticated. Therefore, formulations with PEG10 may have a lower immunogenicity. The use of existing knowledge can lead to the development of suitable drug formulations for the precise treatment of individual diseases.

Viral Capsid Change upon Encapsulation of Double-Stranded DNA into an Infectious Hypodermal and Hematopoietic Necrosis Virus-like Particle

In this study, we aimed to encapsulate the sizable double-stranded DNA (dsDNA, 3.9 kbp) into a small-sized infectious hypodermal and hematopoietic necrosis virus-like particle (IHHNV-VLP; T = 1) and compared the changes in capsid structure between dsDNA-filled VLP and empty VLP. Based on our encapsulation protocol, IHHNV-VLP was able to load dsDNA at an efficiency of 30-40% (w/w) into its cavity. Structural analysis revealed two subclasses of IHHNV-VLP, so-called empty and dsDNA-filled VLPs. The three-dimensional (3D) structure of the empty VLP produced in E. coli was similar to that of the empty IHHNV-VLP produced in Sf9 insect cells. The size of the dsDNA-filled VLP was slightly bigger (50 Å) than its empty VLP counterpart; however, the capsid structure was drastically altered. The capsid was about 1.5-fold thicker due to the thickening of the capsid interior, presumably from DNA-capsid interaction evident from capsid protrusions or nodules on the interior surface. In addition, the morphological changes of the capsid exterior were particularly observed in the vicinity of the five-fold axes, where the counter-clockwise twisting of the "tripod" structure at the vertex of the five-fold channel was evident, resulting in a widening of the channel's opening. Whether these capsid changes are similar to virion capsid maturation in the host cells remains to be investigated. Nevertheless, the ability of IHHNV-VLP to encapsulate the sizable dsDNA has opened up the opportunity to package a dsDNA vector that can insert exogenous genes and target susceptible shrimp cells in order to halt viral infection.

Simultaneous Production of a Virus-Like Particle Linked to dsRNA to Enhance dsRNA Delivery for Yellow Head Virus Inhibition

A co-expressed Penaeus stylirostris densovirus (PstDNV) capsid and dsRNA specific to the yellow head virus (YHV) protease (CoEx cpPstDNV/dspro) has been shown to suppress YHV replication in the Pacific white-legged shrimp (Litopenaeus vannamei). However, maintaining two plasmids in a single bacterial cell is not desirable; therefore, a single plasmid harboring both the PstDNV capsid and the dsRNA-YHV-pro gene was constructed under the regulation of a single T7 promoter, designated pET28a-Linked cpPstDNV-dspro. Following induction, this novel construct expressed an approximately 37-kDa recombinant protein associated with a roughly 400-bp dsRNA (Linked cpPstDNV-dspro). Under a transmission electron microscope, the virus-like particles (VLP; Linked PstDNV VLPs-dspro) obtained were seen to be monodispersed, similar to the native PstDNV virion. A nuclease digestion assay indicated dsRNA molecules were both encapsulated and present outside the Linked PstDNV VLPs-dspro. In addition, the amount of dsRNA produced from this strategy was higher than that obtained with a co-expression strategy. In a YHV infection challenge, the Linked PstDNV VLPs-dspro was more effective in delaying and reducing mortality than other constructs tested. Lastly, the linked construct provides protection for the dsRNA cargo from nucleolytic enzymes present in the shrimp hemolymph. This is the first report of a VLP carrying virus-inhibiting dsRNA that could be produced without disassembly and reassembly to control virus infection in shrimp.

Infectious hypodermal and hematopoietic necrosis virus-like particle (IHHNV-VLP) induces peroxiredoxin expression and activity in Fenneropenaeus merguiensis

Virus like particles (VLPs) are non-infectious nanoparticles containing repetitive, high density viral epitopes on the surface and can prevent viral infections in aquatic animals. Here, we evaluated the immuno-stimulation effect of infectious hypodermal and hematopoietic necrosis virus like particle (IHHNV-VLP) using a next generation sequencing in Fenneropenaeus merguiensis to identify the important immune-related genes that may prevent viral infection. The in situ target of IHHNV was predominantly found in gill tissue following IHHNV-VLP administration in juvenile shrimp. Comparative transcriptome analysis in the injected gills showed that there were 326 unigenes expressed differently than the mock-injected samples. One of the most differential genes between the two animal groups was the antioxidative gene, peroxiredoxin (FmPrx), that was up-regulated after 6 h post-VLP injection. Phylogenetic tree analysis showed that this gene could be found among many shrimp species and was closely clustered among Prx families. The expression of FmPrx was also detected in all tissues examined, thus suggesting the multi-functional roles of this gene in many tissues. Administration of IHHNV-VLP in vivo led to a significant increase in peroxidase activity in gill tissue-approximately two-fold versus control animals; the WSSV copy number was significantly reduced. These data suggest that IHHNV-VLP exerts an immune-stimulating effect by enhancing the level of immune-related genes including FmPrx and its corresponding peroxidase activity, which are a well-known part of the shrimp innate immune system.

Virus-Like Particles: Revolutionary Platforms for Developing Vaccines Against Emerging Infectious Diseases

Virus-like particles (VLPs) are nanostructures that possess diverse applications in therapeutics, immunization, and diagnostics. With the recent advancements in biomedical engineering technologies, commercially available VLP-based vaccines are being extensively used to combat infectious diseases, whereas many more are in different stages of development in clinical studies. Because of their desired characteristics in terms of efficacy, safety, and diversity, VLP-based approaches might become more recurrent in the years to come. However, some production and fabrication challenges must be addressed before VLP-based approaches can be widely used in therapeutics. This review offers insight into the recent VLP-based vaccines development, with an emphasis on their characteristics, expression systems, and potential applicability as ideal candidates to combat emerging virulent pathogens. Finally, the potential of VLP-based vaccine as viable and efficient immunizing agents to induce immunity against virulent infectious agents, including, SARS-CoV-2 and protein nanoparticle-based vaccines has been elaborated. Thus, VLP vaccines may serve as an effective alternative to conventional vaccine strategies in combating emerging infectious diseases.

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

The white spot syndrome virus (WSSV), currently affecting cultured shrimp, causes substantial economic losses to the worldwide shrimp industry. An antiviral therapy using double-stranded RNA interference (dsRNAi) by intramuscular injection (IM) has proven the most effective shrimp protection against WSSV. However, IM treatment is still not viable for shrimp farms. The challenge is to develop an efficient oral delivery system that manages to avoid the degradation of antiviral RNA molecules. The present work demonstrates that VLPs (virus-like particles) allow efficient delivery of dsRNAi as antiviral therapy in shrimp. In particular, VLPs derived from a virus that infects plants, such as cowpea chlorotic mottle virus (CCMV), in which the capsid protein (CP) encapsidates the dsRNA of 563 bp, are shown to silence the WSSV glycoprotein VP28 (dsRNAvp28). In experimental challenges in vivo, the VLPs- dsRNAvp28 protect shrimp against WSSV up to 40% by oral administration and 100% by IM. The novel research demonstrates that plant VLPs, which avoid zoonosis, can be applied to pathogen control in shrimp and also other organisms, widening the application window in nanomedicine.

Dual VP28 and VP37 dsRNA encapsulation in IHHNV virus-like particles enhances shrimp protection against white spot syndrome virus

Accumulative evidence of using double stranded (ds) RNA encapsulated into virus like particle (VLP) nanocarrier has open feasibility to fight against shrimp viral infection in aquaculture field. In this study, we co-encapsulated VP37 and VP28 dsRNA into hypodermal and hematopoietic necrosis virus (IHHNV) like particle and investigated its protection against white spot syndrome virus (WSSV). Five micrograms of each dsRNA were used as starting materials to load into VLP, while the loading efficiency was slightly different, i.e, VP37 dsRNA had somewhat a better load into VLP's cavity. It was apparent that co-encapsulation of dual dsRNA showed a superior WSSV silencing ability than the single dsRNA counterpart as evidence by the lower WSSV gene expression and its copy number in the gill tissues. Besides, we also demonstrated that co-encapsulated dual dsRNA into IHHNV-VLP stimulated the increased number of hemocytes and the corresponding PO activity as well as up-regulated proPO gene expression in hemocytes to resist viral invasion after an acute stage of WSSV infection. This synergistic action of dual dsRNA encapsulated into IHHNV-VLPs could thus act to delay time of shrimp death and reduced shrimp cumulative mortality greater than the single, naked dsRNA treatment and positive control groups. The obtaining results would encourage the feasibility to use it as a new weapon to fight WSSV infection in shrimp aquaculture.

Diversity of single-stranded DNA containing viruses in shrimp

Over the past four decades, shrimp aquaculture has turned into a major industry providing jobs for millions of people worldwide especially in countries with large coastal boundaries. While the shrimp industry continues to expand, the sustainability of shrimp aquaculture has been threatened by the emergence of diseases. Diseases caused by single-stranded DNA containing viruses, such as infectious hypodermal and hematopoietic necrosis virus (IHHNV) and hepatopancreatic parvovirus (HPV), have caused immense losses in shrimp aquaculture since the early 1980s. In fact, the disease outbreak in the blue shrimp (Penaeus stylirostris) caused by IHHNV in early 1980s ultimately led to the captive breeding program in shrimp being shifted from P. stylirostris to the white shrimp (Penaeus vannamei), and today P. vannamei is the preferred cultured shrimp species globally. To date, four single-stranded DNA viruses are known to affect shrimp; these include IHHNV, HPV, spawner-isolated mortality virus (SMV) and lymphoidal parvo-like virus (LPV). Due to the economic losses caused by IHHNV and HPV, most studies have focused on these two viruses, and only IHHNV is included in the OIE list of Crustacean Diseases. Hence this review will focus on IHHNV and HPV. IHHNV and HPV virions are icosahedral in morphology measuring 20-22 nm in size and contain a single-stranded DNA (ssDNA) of 4-6 kb in size. Both IHHNV and HPV are classified into the sub-order Brevidensoviruses, family Densovirinae. The genome architecture of both viruses are quite similar as they contain two completely (as in IHHNV) or partially overlapping (as in HPV) non-structural and one structural gene. Histopathology and polymerase chain reaction (PCR)-based methods are available for both viruses. Currently, there is no anti-viral therapy for any viral diseases in shrimp. Therefore, biosecurity and the use of genetically resistant lines remains as the corner stone in the management of viral diseases. In recent years, gene silencing using the RNA interference (RNAi) approach has been reported for both IHHNV and HPV via injection. However, the delivery of RNAi molecules via oral route remains a challenge, and the utility of RNAi-based therapy has yet to be materialized in shrimp aquaculture.