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Micropterus salmoides rhabdovirus (MSRV) is one of the common pathogens in the largemouth bass industry, which can cause lethal diseases in juvenile fish and enormous economic losses. To establish effective means to prevent MSRV infection, the pcDNA3.1‐G plasmid containing the MSRV glycoprotein gene was successfully constructed and intramuscularly injected into the largemouth bass to evaluate the immune responses and protective effects in our study. As the results showed, the serum antibody levels of the fish vaccinated with different doses of pcDNA3.1‐G were significantly higher compared with the control groups (PBS and pcDNA3.1). Meanwhile, the immune parameters (acid phosphatase and alkaline phosphatase) were also significantly up‐regulated. Several immune‐related genes (IgM, IL‐8, IL‐12p40 and CD40) were expressed in the pcDNA3.1‐G groups at higher levels than in the control groups, which indicated that strong immune responses were induced. Besides, the survival percentages of fish in the control groups (PBS and pcDNA3.1) and pcDNA3.1‐G groups (2.5, 5, 10 and 20 μg/fish) at 14 days after challenge experiment with MSRV were 0%, 0%, 6.1%, 15.2%, 29.0% and 48.5% respectively. This study indicated that pcDNA3.1‐G was a prospective DNA vaccine candidate against MSRV‐induced mortality. [ABSTRACT FROM AUTHOR]

The interactive applications of immunization route, vaccine type and delivery vectors are emerging as a key area of research within the field of mass immunization in fishery production. In an effort to improve DNA vaccine's immune efficiency in large‐scale immunization, a promising bacterial ghost‐loaded DNA vaccine was constructed based on Escherichia coli DH5α. In common carp was investigated the immune response to immersion immunization via related indicator analysis, and the challenge test of spring viraemia of carp virus (SVCV) was carried out. The result indicated that BG‐loaded DNA vaccine induced higher serum antibody level than naked pEG‐G. Simultaneously, the immunophysiological indicators and genes change at the more advanced levels in the BG/pEG‐G immune group. At the treatment concentration of 20 mg/L of the BG/pEG‐G group, IgM and IgZ expressions in vivo were markedly increased by 21.62 times and 6.91 times, respectively, and the relative percentage survival reached the peak of 59.57%. This study paves the way for future aquatic animal vaccine research, which aimed to develop the highly effective immersion vaccine system by delivery vectors, with the ultimate aim to prevent and restrict SVCV in actual production. [ABSTRACT FROM AUTHOR]

To reduce the largemouth bass ulcer syndrome (LBUSV) aquatic economic losses, it must take effective preventive measures and coping strategies should be urgently investigated. In this research, the effects of a functionalized single-walled carbon nanotubes (SWCNTs) applied as a delivery vehicle for DNA vaccine administration in largemouth bass (Micropterus Salmoides) against LBUSV were studied. Our results showed that SWCNTs loaded with DNA vaccine induced a better protection to largemouth bass against LBUSV. We found more than 10 times increase in serum antibody levels, enzyme activities and immune-related genes (IL-6, IL-8, IFN-γ, IgM and TNF-α) expression, in the SWCNTs-pcDNA- MCP immunized groups compared with PBS group and the pure SWCNTs group. The survival rates for control group (PBS), pure SWCNTs groups (40 mg L−1), four pcDNA- MCP groups (5 mg L−1, 10 mg L−1, 20 mg L−1 and 40 mg L−1) and four SWCNTs-pcDNA- MCP groups (5 mg L−1, 10 mg L−1, 20 mg L−1 and 40 mg L−1) were 0%, 0%, 0%, 2.77%, 11.11%, 19.44%, 27.78%, 38.89%, 52.78% and 61.11%, respectively. Our results demonstrate that the SWCNTs-DNA vaccine can be used as a new method against LBUSV showing protection following challenge with LBUSV. • SWCNTs was used as an efficient DNA vaccine vector against LBUSV infection. • Immersed DNA vaccine confers strong immunity against LBUSV. • SWCNTs enhance the immunological effect of DNA vaccines. [ABSTRACT FROM AUTHOR]

As a high mortality disease, Infectious spleen and kidney necrosis virus (ISKNV) can cause massive economic damage on mandarin fish farming industry in China, which seriously hindered the development of mandarin fish farming industry. In this research, SWCNTs (single-walled carbon nanotubes) as a candidate for DNA vaccine carrier was vaccinated by immersion (1, 2, 5, 10, 20 mg/L) in juvenile mandarin fish. In muscle, spleen and kidney tissues, the results showed that transcription and expression of MCP gene can be detected in pcDNA-MCP and SWCNTs-pcDNA-MCP groups after bath immunization. The immune response (immune-related genes expression, serum antibody production, enzyme activities and C3 content) was significantly enhanced in fish which vaccinated with SWCNTs-pcDNA-MCP in comparison with those vaccinated with pcDNA-MCP alone. After 14 d challenge, the RPS (relative percentage survival) can be enhanced which using SWCNTs as a carrier in SWCNTs-pcDNA-MCP (82.4%) group at 20 mg/L (the highest vaccine dose) than the naked pcDNA-MCP (54.2%) group. This study reveals that functionalized SWCNTs could be a promising immersion DNA vaccine carrier in aquaculture. • SWCNTs as a promising vehicle can enhance immune effect of DNA vaccine. • Mandarin fish immersed with SWCNTs-pcDNA-MCP confers strong immunity against ISKNV. • SWCNTs based immersion DNA vaccine have prospects for application to aquatic vaccine. [ABSTRACT FROM AUTHOR]

To elicit the immune protective of vaccine against the highly contagious and pathogenic disease caused by spring viremia of carp virus (SVCV), a novel functionalized single-walled carbon nanotubes (SWCNTs) were applied as a delivery vehicle for DNA vaccine. In this study, we report a SWCNTs-DNA vaccine encoding matrix protein of SVCV which, when injected in the muscle at a dose of 10 μg SWCNTs-pcDNA- M vaccine, confers up to 51.3% protection against intraperitoneal challenge with SVCV. In addition, SWCNTs as a promising vehicle can enhance about 17.5% of the immune protective effect in SWCNTs-pcDNA- M vaccinated common carp compared with fish injected with naked pcDNA- M DNA vaccine. In addition, serum antibody production, none specific immunity parameters (complement activity, superoxide dismutase activity (SOD), acid phosphatase activity (ACP) and alkaline phosphatase activity (AKP)) and immune-related genes were used to verify the enhancement immune response induced in SWCNTs-pcDNA- M vaccinated fish, herein all these mentioned immune activities were significantly enhanced after immunization. Thereby, it is revealed that the M gene of SVCV could be used as an antigen for DNA vaccine constructs, and SWCNTs could be a candidate DNA vaccine carrier to enhance the immunological response against fish disease. [ABSTRACT FROM AUTHOR]

To reduce the economic losses caused by diseases in aquaculture industry, more efficient and economic prophylactic measures should be urgently investigated. In this research, the effects of a novel functionalized single-walled carbon nanotubes (SWCNTs) applied as a delivery vehicle for DNA vaccine administration in juvenile grass carp against Aeromonas hydrophila were studied. Our results showed that SWCNTs loaded with DNA vaccine induced a better protection to juvenile grass carp against A. hydrophila . Moreover, SWCNTs conjugated with DNA vaccine provided significantly protective immunity compared with free DNA vaccine. Thereby, SWCNTs may be considered as a potential efficient DNA vaccine carrier to enhance the immunological activity. [ABSTRACT FROM AUTHOR]

To reduce the lethal hemorrhagic disease caused by grass carp reovirus (GCRV) and improve the production of grass carp, efficient and economic prophylactic measure against GCRV is the most pressing desired for the grass carp farming industry. In this work, a novel SWCNTs-pEGFP- vp5 DNA vaccine linked vp5 recombinant in the form of plasmid pEGFP- vp5 and ammonium-functionalized SWCNTs by a chemical modification method was prepared to enhance the efficacy of a vp5 DNA vaccine against GCRV in juvenile grass carp. After intramuscular injection (1, 2.5 and 5 μg) and bath administration (1, 10, and 20 mg/L), the ability of the different immune treatments to induce transgene expression was analyzed. The results showed that higher levels of transcription and expression of vp5 gene could be detected in muscle tissues of grass carp in SWCNTs-pEGFP- vp5 treatment groups compare with naked pEGFP- vp5 treatment groups. Moreover, antibody levels, immune-related genes, and relative percentage survival were significantly enhanced in fish immunized with SWCNTs-pEGFP- vp5 vaccine. In addition, we found that a good immune protective effect was observed in bath immunization group; which at a concentration of 20 mg/L could reach the similar relative percentage survival (approximately 100%) in injection group at a dose of 5 μg. All these results indicated that ammonium-functionalized SWCNTs could provide extensive application prospect to aquatic vaccine and might be used to vaccinate fish by intramuscular injection or bath administration method. [ABSTRACT FROM AUTHOR]

Grass carp hemorrhagic disease has widely received great attention for Chinese freshwater aquaculture due to its strong infectiousness and high fatality rate. The pathogen is grass carp reovirus (GCRV). DNA vaccination is a high efficient approach for disease control. Although some encouraging progress have been made, developing a highly-efficient DNA vaccine with genetic type II GCRV predominant antigen epitope is less successful and still require further research. However, the DNA vaccine has made it challenging to avoid the problem of easily metabolized and degraded in vivo. In an effort to overcome this challenge, we constructed the DNA vaccine using single-walled carbon nanotubes (SWCNTs) as delivery vector (SWCNTs-pcDNA- vp4-3) and immunized grass carp (1.2 ± 0.2 g) by intramuscular injection. Experiments are grouped as follows: control group, pcDNA- vp4-3 immune group (10 μg per fish) and SWCNTs-pcDNA- vp4-3 immune groups (2.5, 5 and 10 μg per fish, respectively). The immune effect of DNA vaccine is evaluated comprehensively by testing immune-related parameters (the persistence and expression of DNA vaccine, serum antibody level, immune-related physiological indexes, immune-related genes expression and relative percentage survival). The results showed that serum antibody levels of grass carp were elevated significantly after immunization with DNA vaccines. And the serum antibody levels in SWCNTs-pcDNA- vp4-3 immune groups were higher than pcDNA- vp4-3 immune group. Likewise, the immune-related physiological indexes and immune-related genes expression were elevated significantly after immunization. The IgM gene expression in the SWCNTs-pcDNA- vp4-3 immune group (5 μg per fish) was 3.14 times as much as control group. The relative percentage survival in SWCNTs-pcDNA- vp4-3 immune group (5 μg per fish) reached the peak, protected 74% of grass carp from type II GCRV. Conclusively, the vp4-3 -centric DNA vaccine can induce efficient immune response by injection. Single-walled carbon nanotubes extend the retention time of DNA vaccine in the body and improve its expression intensity. SWCNTs-loaded DNA vaccine induce stronger immune response and enhance the resistance to grass carp haemorrhagic disease. • We introduced a DNA vaccine (pcDNA-vp4-3) based on the GCRV II predominant antigen epitope VP4-3. • SWCNT-loaded DNA vaccine based on predominant antigen epitope widely applied to prevent and control grass carp hemorrhagic diseases in the future. • SWCNTs is promising suitable candidate for improving the delivery efficiency of DNA vaccine in fish. [ABSTRACT FROM AUTHOR]

Grass carp reovirus (GCRV), causative agent of grass carp hemorrhagic disease, causes high mortality of grass carp and results in huge economic losses in grass carp farming. Vaccination is considered the most effective way of preventing GCRV infection and losses of grass carp. In the study, recombination pcDNA3.1-vp4 and pcDNA3.1-vp4-3 plasmids were constructed and respectively transformed into E. coli DH5α. The pcDNA3.1-vp4 and pcDNA3.1-vp4-3 plasmids were used to vaccinate grass carp via intramuscular injection and we evaluated the immune responses induced by different forms of the DNA vaccine and investigated the efficacy in vaccinated fish. The results indicate that better immune responses of grass carp immunized with the pcDNA3.1-vp4 (10 μg/fish) compared with the pcDNA3.1-vp4-3 (10 μg/fish) DNA vaccine. Immune genes were expressed at higher levels in pcDNA3.1-vp4-3 treatment group compared to pcDNA3.1-vp4. The survival post vaccination and challenge of pcDNA3.1-vp4-3 vaccinated fish was 57.89% compared to 36.84% for pcDNA3.1-vp4 group and at 100% mortality in control groups. These results indicated that the segment of vp4-3 could be a plausible candidate for preventing GCRV-JX02 infection among grass carp. • Grass carp injected with pcDNA3.1-vp4 and pcDNA3.1-vp4-3 confers strong immunity against GCRV-JX02. • The DNA vaccine was manufactured by the core of dominant antigen epitope of GCRV-JX02, and its protective effects on grass carp against GCRV-JX02 infection by injection were assessment. • pcDNA3.1-vp4-3 could be a potential therapeutic vaccine against GCRV-JX02. [ABSTRACT FROM AUTHOR]