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The porcine reproductive and respiratory syndrome virus (PRRSV) is a threat to the health of pigs worldwide, but commercially available vaccines offer limited protection against PRRSV infection. It is necessary to develop a more effective DNA vaccine. The immunological effects of DNA vaccines with three adjuvants were examined in pigs ( Susscrofa domestica ) challenged with PRRSV. These DNA vaccines, which encoded PRRSV GP3 and GP5, were formulated with A1, A2, and A3. Serum specific and neutralizing antibodies, IL-4, IFN-γ, IL-2, IL-10, CD4 + and CD8 + T-lymphocytes, health status, histopathology, and viral loads were determined. The results showed that the use of adjuvant A3 led to higher levels of neutralizing antibodies and a lower viral load in pigs compared to the other adjuvants. The neutralizing antibody titers of the pVAX-GP35+A1 and pVAX-GP35+A3 groups reached a peak of 1:19 at 35 dpi. The maximum concentration of IL-4 was 136.77 pg/mL in the pVAX-GP35+A3 group. At 35 dpi, the IFN-γ concentration in the pVAX-GP35+A1 group was 227.4 pg/mL. pVAX-GP35+A3 group shows the highest IL-2 and IL-10 expression to the peak of 597.6 pg/mL and 189.1 pg/mL, respectively. We found a formulation demonstrated beneficial immune outcomes. This study provides an alternative vaccine to protect pigs from PRRSV., Competing Interests: The authors state that there were no commercial or financial relationships that may be considered as a potential conflict of interest during the research., (Copyright © 2022 Zhao, Zhang, Sun, Xie, Zhang, Gao, Wen, Ha, Nan, Zhu, Feng, Cao, Zhang, Zhu, Jin and Lu.)

Chikungunya virus (CHIKV) is a mosquito-borne virus. The emergence of CHIKV infection has raised global concern, and there is a growing need to develop safe and effective vaccines. Here, adenovirus 5 was used as the vaccine vector to construct recombinant adenoviruses expressing CHIKV E2, E1, and E2-6K-E1, respectively. And then the immunogenicity and protective efficiency against CHIKV were evaluated in BALB/c mice. Compared to the ad-wt control group, all three vaccines elicited significant humoral and cellar immune responses. The levels of neutralizing antibodies in the rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 groups both reached 1:256, which were 3.2 times higher than those in the rAd-CHIKV-E1 group. Furthermore, the levels of lymphocyte proliferation in rAd-CHIKV-E2-6K-E1 group were the highest. Besides, the concentrations of IFN-γ and IL-4 in mice immunized with rAd-CHIKV-E2-6K-E1 were 1.37 and 1.20 times higher than those in ad-wt immunized mice, respectively. After the challenge, mice in the rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 groups lost 2% of their body weight compared with 5% in the ad-wt control group. And low viral loads were detected in the heart, kidney, and blood of mice immunized with rAd-CHIKV-E2-6K-E1 and rAd-CHIKV-E2 at 3-5 dpc, which decreased by 0.4-0.7 orders of magnitude compared with the ad-wt control. Overall, these data suggest that the recombinant adenovirus is a potential candidate vaccine against CHIKV.

Highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) poses a significant threat to the pig industry, for which vaccination is considered to be an effective means of prevention and control. Here, we developed two recombinant Newcastle disease virus (NDV) LaSota-vectored PRRS candidate vaccines, rLaSota-GP5 and rLaSota-GP3-GP5, using reverse genetic techniques. The two recombinant viruses exhibited a high degree of genetic stability after 10 successive generations in chicken embryos. There was no significant difference in pathogenicity compared with the rLaSota parent strain in poultry, mice and pigs. The recombinant viruses could not be detected in the feeding environment of immunized pigs, but could be detected in the organs and tissues of pigs for no more than 10 days after immunization. Importantly, in contrast to rLaSota-GP5, rLaSota-GP3-GP5 elicited both significant humoral and cellular immune responses in pigs. In particular, the neutralizing antibody titer in the rLaSota-GP3-GP5 group was 1.51 times significantly higher than that of the commercial vaccine group at 42 days post-immunization. At the same time, there was significant difference in the level of IFN-γ between the rLaSota-GP3-GP5 group and the commercial vaccine group. Furthermore, the viral load in the organs and tissues of rLaSota-GP3-GP5-immunized pigs was substantially lower than that of unimmunized pigs after being challenged with HP-PRRS virus GD strain. These results suggest that rLaSota-GP3-GP5 is a safe and promising candidate vaccine, and there is potential for further development of a recombinant virus vaccine for PRRS using NDV., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Porcine reproductive and respiratory syndrome (PRRS) is almost always caused by the North American strain of PRRS virus (PRRSV) in China; the European genotype of PRRSV has emerged in China. The mixed infection of PRRSV and Porcine circovirus type 2 virus (PCV2) are always found in pigs and PRRSV-augmented PCV2 replication and serious clinical symptoms. Current vaccines cannot protect mixed European PRRSV and PCV2 infections. Therefore, the development of a safe and effective new vaccine to prevent and control the mixed infection of European PRRSV and PCV2 is both urgent and necessary. In this study, we developed a recombinant vaccinia vaccine co-expressing the GP3 and GP5 proteins of European PRRSV and the ORF2 protein of PCV2 and evaluated the immunogenicity and its protective effects and its inactivated vaccine in pigs. The recombinant vaccinia vaccine and its inactivated vaccine both elicited significant humoral and cellular immune responses with a higher level of specific antibody responses and T-lymphocyte proliferation than the control group. Furthermore, the pigs inoculated with the recombinant vaccinia vaccine were completely protected against challenge with 10 5 TCID 50 of European PRRSV strain LV. These data suggest that the recombinant vaccinia vaccine is a potential candidate vaccine against European PRRSV and PCV2.

The European (EU) type of porcine reproductive and respiratory syndrome virus (PRRSV) has recently emerged in China. In this study, three recombinant DNA vaccines, pVAX1-EU-ORF3-ORF5 (coexpressing EU type PRRSV GP3 and GP5), pVAX1-EU-ORF3 and pVAX1-EU-ORF5, were constructed and evaluated for their abilities to induce humoral and cellular responses as well as to protect piglets against homologous virus challenge. All piglets were given booster vaccinations at 21 days after the initial inoculation and then challenged 14 days later. Pigs inoculated with pVAX1-EU-ORF3-ORF5 developed significantly higher (P<0.05) PRRSV-specific antibody responses, neutralizing antibodies and levels of IL-4 and IL-10 than those given pVAX1-EU-ORF3, pVAX1-EU-ORF5 or pVAX1. Moreover, pigs immunized with pVAX1-EU-ORF3-ORF5 had markedly increased levels of IFN-γ and IL-2 in serum and T-lymphocytes (CD3(+)CD4(+) and CD3(+)CD8(+) T cells) in peripheral blood. Thus, EU-type PRRSV GP3 and GP5 proteins demonstrated good immunogenicity and reactogenicity and could induce cellular immunity in pigs. Following challenge with the Lelystad virus (LV) strain, piglets inoculated with pVAX1-EU-ORF3-ORF5 showed viremia and virus load distributed in organ tissues that were significantly lower (P<0.05) than those in the pVAX1-EU-ORF3 group and control group, and slightly lower than those in the pVAX1-EU-ORF5 group (P>0.05). As GP3 could enhance humoral- and cell-mediated immune responses to GP5, the results of this study suggested that these two proteins delivered by a vaccine can synergistically induce immunity against PRRSV., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: ORFV attenuated live vaccines have been the main prophylactic measure against contagious ecthyma in sheep and goats in the last decades, which play an important role in preventing the outbreak of the disease. However, the available vaccines do not induce lasting immunity in sheep and goats. On the other hand, variation in the terminal genome of Orf virus vaccine strains during cell culture adaptation may affect the efficacy of a vaccine. Currently, there are no more effective antiviral treatments available for contagious ecthyma., Results: We constructed three eukaryotic expression vectors pcDNA3.1-ORFV011, pcDNA3.1-ORFV059 and pcDNA3.1-ORFV011/ORFV059 and tested their immunogenicity in mouse model. High level expression of the recombinant proteins ORFV011, ORFV059 and ORFV011/ORFV059 was confirmed by western blotting analysis and indirect fluorescence antibody (IFA) tests. The ORFV-specific antibody titers and serum IgG1/IgG2a titers, the proliferation of lymphocytes and ORFV-specific cytokines (IL-2, IL-4, IL-6, IFN-γ, and TNF-α) were examined to evaluate the immune responses of the vaccinated mice. We found that mice inoculated with pcDNA3.1-ORFV 011/ORFV059 had significantly stronger immunological responses than those inoculated with pcDNA3.1-ORFV011, pcDNA3.1-ORFV059, or pcDNA3.1-ORFV011 plus pcDNA3.1-ORFV059. Compared to other vaccine plasmids immunized groups, pcDNA3.1-ORFV011/ORFV059 immunized group enhances immunogenicity., Conclusions: We concluded that DNA vaccine pcDNA3.1-ORFV011/ORFV059 expressing ORFV011 and ORFV059 chemeric-proteins can significantly improve the potency of DNA vaccination and could be served as more effective and safe approach for new vaccines against ORFV.

Bacillus subtilis has been engineered successfully to express heterologous antigens for use as a vaccine vehicle that can elicit mucosal and systemic immunity response. In this study, a recombinant B. subtilis expressing the B subunit of cholera toxin (CT-B) and an epitope box constituted with antigen sites from foot-and-mouth disease virus (FMDV) type Asia 1 was constructed and named 1A751/CTB-TEpiAs. Its capability to induce mucosal, humoral, and cellular responses in mice and guinea pigs was evaluated after oral administration with vegetative cells of 1A751/CTB-TEpiAs. In addition, its capability to protect guinea pigs against homologous virus challenge was examined. All animals were given booster vaccination at day 21 after initial inoculation and guinea pigs were challenged 3 weeks after booster vaccination. The control groups were inoculated with a commercial vaccine or administered orally with 1A751/pBC38C or an oral buffer. All animals vaccinated with 1A751/CTB-TEpiAs developed specific anti-FMDV IgA in lung and gut lavage fluid, serum ELISA antibody, neutralizing antibody as well as T lymphocyte proliferation, and IFN-γ secretory responses. Three of the five guinea pigs vaccinated with 1A751/CTB-TEpiAs were protected completely from the viral challenge. The results demonstrate the potential viability of a B. subtilis-based recombinant vaccine for the control and prevention of FMDV infections., (Copyright © 2010 Elsevier B.V. All rights reserved.)

We designed and constructed a fuse expression gene OAAT and staphylococcal enterotoxin A (SEA) on the basis of the OAAT designed and constructed which consists of the structural protein VP1 genes from serotypes A and O FMDV, 5 major VP1 immunodominant epitopes from two genotypes of Asia1 serotype, and 3 Th2 epitopes originating from the non-structural protein, 3ABC gene and structural protein VP4 gene. The recombinant plasmids pEA was constructed using SEA as a genetic adjuvant. Expressions of target gene from the pEA in Hela cell were verified by IFA and Western blotting. The experiment of BALB/c mice immunized with the DNA vaccines showed that pA and pEA could induce simultaneously specific antibodies against serotypes A, Asia1, and O FMDV, and the highest antibody titres were found in the pEA and inactivated vaccine groups compared to pA vaccinating mice. Compared with the control, the levels of IL-2, IFN-gamma, IL-4, and IL-10 expression by splenic lymphocytes from mice immunized with pA and pEA were significantly increased. In addition, we found that the levels of IL-2, IFN-gamma and IL-4 from the mice immunized with pEA was higher than mice immunized with pA did. The results of viral challenge in guinea pigs showed the pA, pEA and inactivated vaccine provided full protection in 2/4, 2/4, 3/4, 3/4 and 4/4, 4/4 guinea pigs from challenge with FMDV O/NY00 and Asial/YNBS/58, respectively. The results demonstrated fuse protein OAAT and SEA may be potential immunoge against FMDV, furthermore, SEA may be an effective genetic adjuvant for DNA vaccine.

DNA-based vaccination is an attractive alternative for overcoming the disadvantages of inactivated virus vaccines; however, DNA vaccines alone often generate only weak immune responses. In this study, the efficacy of LMS as a chemical adjuvant on a DNA vaccine (pVIR-P12A-IL18-3C) encoding the P1-2A and 3C genes of the FMDV and swine IL-18, which provides protection against FMDV challenge, was tested. All test pigs were administered booster vaccinations 28 days after the initial inoculation, and were challenged with 1000 ID50 FMDV O/NY00 20 days after the booster vaccination. Positive and negative control groups were inoculated with inactivated virus vaccine and PBS respectively. The DNA vaccine plus LMS induced greater humoral and cell-mediated responses than the DNA vaccine alone, as evidenced by higher concentrations of neutralizing and specific anti-FMDV antibodies, and by higher concentrations of T-lymphocyte proliferation and IFN-y production, respectively. FMDV challenge revealed that the DNA vaccine plus LMS provided higher protection than the DNA vaccine alone. This study demonstrates that LMS may be useful as an adjuvant for improving the protective efficiency of DNA vaccination against FMDV in pigs.

Two recombinant fowlpox viruses (rFPV-P1 and rFPV-IL18-2AP12A) containing foot-and-mouth disease virus (FMDV) capsid polypeptide, 3C coding regions of O/NY00 were evaluated to determine their abilities to induce humoral and cellular responses in the presence or absence of swine IL-18 as genetic adjuvant. The ability to protect swine against homologous virus challenge was examined. All swine were given booster vaccinations at 21 days after the initial inoculation and were challenged 10 days after the booster vaccination. Control groups were inoculated with wild-type fowlpox virus (wtFPV). All animals vaccinated with rFPV-P12A and rFPV-IL18-P12A developed specific anti-FMDV ELISA antibody and neutralizing antibody and T-lymphocyte proliferation was observed. Cellular immune function was evaluated via examination of IFN-gamma production in swine peripheral blood serum. The results demonstrate the potential viability of a fowlpox virus-based recombinant vaccine in the control and prevention of FMDV infections.

Two recombinant fowlpox viruses (rFPV-ORF5-ORF3 and rFPV-IL-18-ORF5-ORF3) containing the ORF5/ORF3 cDNAs of PRRSV (strain Chang Chun) and IL-18 of swine were constructed and evaluated for theirs abilities to induce humoral and cellular responses in piglets. In addition, their abilities to protect piglets against homologous virus challenge were examined. All piglets were given booster vaccinations at 21 days after the initial inoculation, and all piglets were challenged at 60 after the initial inoculation. Control groups were inoculated with wild-type fowlpox virus (wtFPV). All animals vaccinated with rFPV-ORF5-ORF3 and rFPV-IL-18-ORF5-ORF3 developed specific anti-PRRSV ELISA antibody and neutralizing antibody, as well as T-lymphocyte proliferation response. To evaluate the cellular immune function, IFN-gamma production in pigs serum and T-lymphocytes (CD4 and CD8 T cells) in peripheral blood were examined. Following challenge with a pathogenic strain of PRRSV (strain Chang Chun), piglets inoculated with recombinant fowlpox virus (rFPV) showed lower (P<0.05) temperature, viremia and virus load in bronchial lymph nodes than control animals, suggesting the establishment of partial protection against PRRSV infection. The results demonstrated the potential use of a fowlpox virus-based recombinant vaccine in the control and prevention of PRRSV infections.

Foot-and-mouth disease virus (FMDV) is an important pathogen with worldwide economic consequences. Consequently, an important goal is the development of a vaccine that can provide rapid protection while overcoming the potential risk associated with the production of conventional inactivated vaccines. An important secondary feature of the vaccine would be the ability to distinguish vaccinated from infected animals. A recombinant fowlpox virus (vUTAL3CP1) containing FMDV capsid polypeptide and 3C coding regions of O/NY00 was constructed and evaluated for its ability to induce humoral and cellular responses in mice and guinea pigs. In addition, the ability to protect guinea pigs against homologous virus challenge was examined. Mice and guinea pigs were given booster vaccinations twice and once, respectively, and guinea pigs were challenged 20 days after the booster vaccination. Control groups included animals inoculated with commercial vaccine, fowlpox virus or phosphate-buffered saline (PBS). All animals vaccinated with vUTAL3CP1 developed specific anti-FMDV antibody and neutralizing antibody, as well as T lymphocyte proliferation response and CTL cytotoxic activity. Three of four guinea pigs vaccinated with vUTAL3CP1 were completely protected from viral challenge. The results demonstrated the potential of a fowlpox virus-based recombinant FMD vaccine.