Background Bovine viral diarrhea virus (BVDV) is a cause of substantial economic loss to the cattle industry worldwide, and there are currently no effective treatment or preventive measures. Bovine enterovirus (BEV) has a broad host range with low virulence and is a good candidate as a viral vaccine vector. In this study, we explored new insertion sites for the expression of exogenous genes in BEV, and developed a recombinant infectious cDNA clone for BEV BJ101 strain expressing BVDV E0 protein. Methods A recognition site for the viral proteinase 3C(pro)was inserted in the GpBSK-BEV plasmid at the 2C/3A junction by overlapping PCR. Subsequently, the optimized full-length BVDV E0 gene was inserted to obtain the recombinant infectious plasmid GpBSK-BEV-E0. The rescued recombinant virus was obtained by transfection with linearized plasmid. Expression of BVDV E0 in the recombinant virus was confirmed by PCR, western blotting, and immunofluorescence analysis, and the genetic stability was tested in MDBK cells over 10 passages. We further tested the ability of the recombinant virus to induce an antibody response in mice infected with BVDV and immunized them with the recombinant virus and parental strain. Results The rescued recombinant virus rBEV-E0 was identified and confirmed by western blot and indirect immunofluorescence. The sequencing results showed that the recombinant virus remained stable for 10 passages without genetic changes. There was also no significant difference in growth dynamics and plaque morphology between the recombinant virus and parental virus. Mice infected with both recombinant and parental viruses produced antibodies against BEV VP1, while the recombinant virus also induced antibodies against BVDV E0. Conclusion A new insertion site in the BEV vector can be used for the prevention and control of both BEV and BVDV, providing a useful tool for future research on the development of viral vector vaccines.

Currently, the widely used vaccine against duck Tembusu virus (DTMUV) disease is inactivated vaccine which, however, facing the limits of large inoculation dose, short immunization period, and incomplete effectiveness. Access to efficient adjuvants aiding for DTMUV inactivated vaccine seems to be of critical importance. Interleukin-2 (IL-2) was reported to induce a persistent expansion of effector T cells and could be a promising molecular adjuvant for many kinds of vaccines. In this study, the efficacy of duck interleukin (dIL)-2 as an adjuvant for a DTMUV inactivated vaccine was evaluated. Fifty-five Pekin ducks were divided into 5 groups and intramuscularly administered with 5 batches of vaccines at 42 D (A: DTUMV + dIL-2; B: 1/2DTUMV + dIL-2; C: DTUMV; D: 1/2DTUMV and E: PBS), respectively, and received the second vaccination 2 wk later. Fifty-six days after immunization, 6 ducks from each group were randomly selected to conduct a challenge protection test. Antibody titers and cytokine responses were detected to assess humoral and cellular immune responses in serum of inoculated ducks by hemagglutination inhibition and ELISA, respectively; virus isolation and RT-PCR method were used in immunity protective test. Our results showed that dIL-2 exerted an enhanced effect on the vaccine while reducing the dose of inoculated antigen highlighting high adjuvanticity of IL-2. The vaccines supplemented with IL-2 induced a higher level of antibodies and higher percentage of inhibition values than inactivated vaccines without IL-2 to a significant extent. The production level of IFN-α, IFN-γ, and IL-6 genes were elevated, enhancing both humoral and cellular responses. Furthermore, it provided higher protection after virus challenge. Therefore, IL-2 can be considered as a potential adjuvant for inactivated vaccine against DTMUV disease.

Complete genome and molecular characterization of genotype VII velogenic Newcastle disease virus isolated in China

Duck Tembusu virus (DTMUV) is an emerging pathogenic flavivirus responsible for massive economic losses in the duck industry. However, commercially inactivated DTMUV vaccines have been ineffective at inducing protective immunity in ducks. The widely used adjuvant cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) reportedly improve humoral and cellular immunities in animal models. However, its effectiveness in DTMUV vaccines requires validation. Here, we assessed the protective efficacy of pUC18-CpG as an adjuvant in an inactivated live DTMUV vaccine in ducks. Our results revealed that the serum hemagglutination inhibition (HI) antibody titers, positive rates of anti-DTMUV antibodies, the concentration of serum cytokines, and protection efficacy were significantly increased in ducks immunized with pUC18-CpG compared to that in the control group. Moreover, ducks immunized with a full vaccine dose containing a half dose of antigen supplemented with 40 μg of pUC18-CpG exhibited the most potent responses. This study suggests that pUC18-CpG is a promising adjuvant against DTMUV, which might prove effective in treating other viral diseases in waterfowl.

Pseudorabies virus (PRV) is a zoonotic agent that causes significant economic losses in animal husbandry worldwide, and gE-deleted vaccines play an important role in its treatment in the swine industry. However, the potential risk of attenuated PRV strains in commercial vaccines for other hosts remains unclear. Especially, cats are important companion animals for human beings. In this study, we investigated the prevalence and pathogenicity of the PRV wild strain in the cat population. We found that the occurrence of PR diseases in cats is sporadic, that the attenuated PRV strain causes slight clinical signs in cats, and that the virus is excreted 3 days post-infection. Our findings will be beneficial in furthering our understanding of the epidemiology and pathogenicity of PRV in cats and implying the great risk of RPV transmission from pigs to cats.

Pigeon Paramyxovirus Type 1 (PPMV-1), an antigenic and host variant of the Newcastle Disease Virus (NDV), can infect pigeons of all ages and cause severe economic losses in the poultry industry. The existing commercial vaccines are not capable of providing complete protection against the prevalent PPMV-1 strains. To address this issue, reverse genetic technology was employed to create a recombinant 167DM strain by incorporating the chimeric genotype Ⅵ hemagglutinin-neuraminidase (HN) with La Sota as the backbone. The optimal anti-PPMV-1 vaccine candidate was identified through a systematical comparison of biological characteristics and immune efficacy of the predominant PPMV-1 epidemic strain, the 167DM strain, and the La Sota strain. Results indicated that the 167DM strain exhibited the highest culture titers in allantoic fluid and the strongest heat resistance. The antibody titers in the 167DM vaccine group consistently surpassed those in other groups tested. Cross-hemagglutination inhibition (HI) tests revealed no detectable antigenic differences between the 167DM and the prevalent PPMV-1 strain. Furthermore, the 167DM strain conferred 100% protection by preventing PPMV-1 infection and completely inhibiting virus shedding. These findings provide valuable insights for the development of a novel vaccine targeting ND in pigeons, thus laying a foundation for further advancements in vaccine development within this avian population.