Evaluation of parenteral vaccination methods with glycoproteins against Aujeszky's disease in pigs

Skin-Based Vaccination: A Systematic Mapping Review of the Types of Vaccines and Methods Used and Immunity and Protection Elicited in Pigs

The advantages of skin-based vaccination include induction of strong immunity, dose-sparing, and ease of administration. Several technologies for skin-based immunisation in humans are being developed to maximise these key advantages. This route is more conventionally used in veterinary medicine. Skin-based vaccination of pigs is of high relevance due to their anatomical, physiological, and immunological similarities to humans, as well as being a source of zoonotic diseases and their livestock value. We conducted a systematic mapping review, focusing on vaccine-induced immunity and safety after the skin immunisation of pigs. Veterinary vaccines, specifically anti-viral vaccines, predominated in the literature. The safe and potent skin administration to pigs of adjuvanted vaccines, particularly emulsions, are frequently documented. Multiple methods of skin immunisation exist; however, there is a lack of consistent terminology and accurate descriptions of the route and device. Antibody responses, compared to other immune correlates, are most frequently reported. There is a lack of research on the underlying mechanisms of action and breadth of responses. Nevertheless, encouraging results, both in safety and immunogenicity, were observed after skin vaccination that were often comparable to or superior the intramuscular route. Further research in this area will underlie the development of enhanced skin vaccine strategies for pigs, other animals and humans.

Efficacy of Needle-Less Intradermal Vaccination against Porcine Epidemic Diarrhea Virus

To prevent diarrhea in suckling piglets infected by porcine epidemic diarrhea virus (PEDV), porcine epidemic diarrhea (PED) vaccines are administered mainly through intramuscular (IM) or oral routes. We found that growing pigs vaccinated with an inactivated PEDV vaccine via the intradermal (ID) route had higher neutralizing antibody titers and cytokine (IFN-γ, IL-4, and IL-10) levels than non-vaccinated pigs. In addition, suckling piglets acquired lactogenic immunity from pregnant sows inoculated with an ID PED vaccine. We evaluated the efficacy of vaccination via this route, along with subsequent protection against virulent PEDV. At six days post-challenge, the survival rate of suckling piglets exposed to virulent PEDV was 70% for the ID group and 0% for the mock group (no vaccine). At necropsy, villi length in the duodenum and ileum of piglets with lactogenic immunity provided by ID-vaccinated sows proved to be significant (p < 0.05) when compared with those in piglets from mock group sows. Thus, vaccination using an inactivated PED vaccine via the ID route provides partial protection against infection by virulent PEDV.

Frequency and risk factors of antibody-induced secondary failure of botulinum neurotoxin therapy

Objective

To investigate the risk factors of neutralizing antibody (NAB)–induced complete secondary treatment failure (cSTF) during long-term botulinum neurotoxin (BoNT) treatment in various neurologic indications.

Methods

This monocenter retrospective cohort study analyzed the data of 471 patients started on BoNT therapy between 1995 and 2015. Blood samples of 173 patients were investigated for NABs using the mouse hemidiaphragm test (93 with suspected therapy failure, 80 prospective study participants). The frequency of NAB-cSTF was assessed for various indications: hemifacial spasm, blepharospasm, cervical dystonia, other dystonia, and spasticity. A priori defined potential risk factors for NAB-cSTF were evaluated, and a stepwise binary logistic regression analysis was performed to identify independent risk factors.

Results

Treatment duration was 9.8 ± 6.2 years (range, 0.5–30 years; adherence, 70.6%) and number of treatment cycles 31.2 ± 22.5 (3–112). Twenty-eight of 471 patients (5.9%) had NAB-cSTF at earliest after 3 and at latest after 103 treatment cycles. None of the 49 patients treated exclusively with incobotulinumtoxinA over 8.4 ± 4.2 (1–14) years developed NAB-cSTF. Independent risk factors for NAB-cSTF were high BoNT dose per treatment, switching between onabotulinumtoxinA and other BoNT formulations (except for switching to incobotulinumtoxinA), and treatment of neck muscles.

Conclusions

We present a follow-up study with the longest duration to date on the incidence of NAB-cSTF in patients treated with various BoNT formulations, including incobotulinumtoxinA. Whereas the overall risk of NAB-cSTF is low across indications and BoNT formulations, our findings underpin the recommendations to use the lowest possible dose particularly in cervical dystonia, and to avoid unnecessary switching between different formulations.

Efficacy of intradermally administrated E2 subunit vaccines in reducing horizontal transmission of classical swine fever virus

To investigate if intradermal (ID) vaccination and intramuscular (IM) vaccination result in a comparable reduction of horizontal transmission of classical swine fever virus (CSFV), two registered E2 subunit marker vaccines were examined. Vaccine A was a water-in-oil emulsion containing the E2 glycoprotein originating from the Alfort/Tübingen strain and vaccine B was a water-oil-water emulsion containing the E2 glycoprotein originating from the Brescia strain. Eight groups, of ten pigs each, were vaccinated with either vaccine A or B, intramuscularly (IM) or intradermally (ID). Two different vaccination-challenge intervals were used for each vaccine. Furthermore, one group was vaccinated with a tenfold ID dose of vaccine A and one non-vaccinated group served as a control group. Five pigs from each group were challenged with the moderately virulent CSFV strain Paderborn, while the remaining five pigs served as contacts. Using vaccine A, full transmission to all contact pigs in both ID vaccinated groups occurred. No virus transmission was observed when IM vaccinated pigs were challenged 14 days post-vaccination (14dpv) whereas only one out of five contact pig became infected when they were challenged 10dpv. Using vaccine B no virus transmission was observed when pigs were ID or IM vaccinated and challenged 10dpv. When challenged 3dpv full transmission occurred in the ID vaccinated group, whereas four out of five contact pigs became infected in the IM vaccinated group. This result indicates that ID vaccination does not result in better protection against horizontal CSFV transmission compared to IM vaccination, for the vaccines studied.

Comparison of immune responses in parenteral FaeG DNA primed pigs boosted orally with F4 protein or reimmunized with the DNA vaccine

We previously showed that an intradermal (i.d.) FaeG DNA prime (2x)-oral F4 protein boost immunization induces a systemic response and weakly primes a mucosal IgG response in pigs, especially when plasmid vectors encoding the A and B subunit of the E. coli thermo-labile enterotoxin (LT) are added to the DNA vaccine. In the present study, we evaluated whether addition of 1alpha,25-dihydroxyvitamin D(3) (vitD(3)) to the DNA vaccine could further enhance this mucosal priming and/or modulate the antibody response towards IgA. To further clarify priming of systemic and mucosal responses by the i.d. DNA vaccination, we firstly compared the localization of the F4-specific antibody response in pigs that were orally boosted with F4 to that in pigs that received a third i.d. DNA immunization and secondly evaluated cytokine mRNA expression profiles after i.d. DNA vaccination. The i.d. DNA prime (2x)-oral F4 boost immunization as well as the 3 i.d. DNA vaccinations induced mainly a systemic response, with a higher response observed following the heterologous protocol. Co-administration of vitD(3), and especially of the LT vectors, enhanced this response. Furthermore, only the heterologous immunization resulted in a weak mucosal priming, which appeared to require the presence of the LT vectors or vitD(3) as adjuvants. In addition, the LT vectors strongly enhanced the FaeG-specific lymphocyte proliferation and this was accompanied by the absence of a clear IL-10 response. However, despite two DNA immunizations in the presence of these adjuvants and an oral F4 boost, we failed to demonstrate the secretory IgA response needed to be protective against enterotoxigenic E. coli.

1alpha,25-dihydroxyvitamin D3 increases IgA serum antibody responses and IgA antibody-secreting cell numbers in the Peyer's patches of pigs after intramuscular immunization

Pigs were injected intramuscularly (i.m.) twice with human serum albumin (HSA) with or without 1alpha,25-dihydroxyvitamin D3[1alpha,25(OH)2D3] with a 5-week interval. The supplementation of 1alpha,25(OH)2D3 enhanced the HSA-specific IgA serum antibody response but decreased the IgM, IgG, IgG1 and IgG2 responses. Furthermore, higher numbers of HSA-specific IgA antibody-secreting cells were obtained in systemic lymphoid tissues (local draining lymph node, spleen and bone marrow) as well as in Peyer's patches and lamina propria of the gut (GALT). In addition, the in vivo mRNA expression for Th1 [interferon (IFN)-gamma, interleukin (IL-2)], Th2 (IL-4, IL-6 and IL-10) and Th3 [transforming growth factor (TGF)-beta] cytokines as well as the percentage of different cell subsets (CD2+, CD4+, CD8+, IgM+, MHC II+, CD25+) of monomorphonuclear cells from the local draining lymph node were determined at different time-points after the i.m. immunizations. Cytokine profiles did not resemble a typical Th-cytokine profile using 1alpha,25(OH)2D3: higher levels of IL-10 and significantly lower levels of IL-2 were observed the first day after the primary immunization. However, significantly higher levels of IL-2 and significantly lower levels of IFN-gamma were observed the first day after the second immunization. Furthermore, after the second immunization TGF-beta mRNA expression decreased more quickly in the 1alpha,25(OH)2D3 group. This difference became significant 7 days after the second immunization. One week later a significantly higher percentage of CD25+ cells was observed in this group, indicating more activated T and B cells using the steroid hormone. These results suggest that in pigs the addition of 1alpha,25(OH)2D3 to an intramuscularly injected antigen can enhance the antigen-specific IgA-response and prime GALT tissues, but the relation with cytokines and cell phenotype in the local draining lymph node needs further clarification.

Antigen dose modulates the immunoglobulin isotype responses of pigs against intramuscularly administered F4-fimbriae

Parenteral immunisation normally induces a systemic antibody response characterised by high IgG and low IgA responses. In the present study, the effect of different doses of F4-fimbriae on the isotype-specific antibody response after intramuscular immunisation was studied in pigs. Pigs were injected twice with a 9 weeks interval with either 1, 0.1 or 0.01 mg of F4-ETEC fimbriae. The dose of 1mg F4 induced significantly lower primary F4-specific IgG and IgM responses than the doses of 0.1 and 0.01 mg F4, but primed for an enhanced F4-specific IgM serum antibody response after the booster immunisation. Furthermore, the dose of 0.1mg induced the highest F4-specific IgA serum response which was significantly higher than after injection with 0.01 and 1mg F4. Moreover, both lower doses (0.1 and 0.01 mg) showed a higher number of F4-specific IgA and IgG antibody secreting cells (ASC) in the local draining lymph nodes of the pigs. This study demonstrated that low doses of purified F4-ETEC fimbriae, especially the 0.1mg dose, are optimal for inducing F4-specific IgA responses after IM immunisation.

Efficacy of intradermal vaccination

Intradermal (ID) inoculation has been investigated as a means of vaccinating laboratory animals, domestic farm animals, and humans. Various forms of viral, bacterial, parasitic, and fungal antigens have been administered ID, with varying results. This review emphasizes results from studies reporting clinically relevant outcomes such as clinical protection and body weight change following experimental challenge. Antibody titers, cytokines, cellular responses are included as supportive data. Based on the reports reviewed, ID vaccination is a promising alternative to more traditional routes of vaccination. ID vaccination has particular appeal to the beef cattle industry based on recently emphasized quality assurance issues. It is evident that the ultimate test of vaccine efficacy is the ability to protect against clinical disease under natural challenge conditions. We propose that the immune response of ID vaccinated cattle, using clinically relevant outcomes such as morbidity, mortality, average daily gain and feed efficiency, needs to be further investigated to define the value of this potentially effective and practical means of antigen delivery, particularly for domesticated farm animals.

Recombinant porcine IFN-gamma potentiates the secondary IgG and IgA responses to an inactivated suid herpesvirus-1 vaccine and reduces postchallenge weight loss and fever in pigs

The effect of recombinant porcine interferon-gamma (IFN-gamma) on the immunogenicity in vivo of inactivated suid herpesvirus-1 (SHV-1, Phylaxia strain) was studied applying two successive i.m. immunizations. The animals were injected with inactivated virus alone or inactivated virus supplemented with 10(4) or 10(6) U IFN-gamma. After the first immunization, none of the animals responded with measurable virus-neutralizing antibody (VNAb), virus-specific IgG or IgA. Following a second immunization 4 weeks later, a significantly increased VNAb response was noted in animals that had received vaccine doses containing 10(4) U IFN-gamma (p < 0.05). These animals also had significantly augmented serum levels of IgG (p < 0.01) and IgA (p < 0.05). Inclusion of 10(6) U IFN-gamma in the vaccine preparation did not affect the antibody response. In one experiment, the pigs were challenged oronasally with 10(5) TCID50 of the 75V19 strain of SHV-1, 7 weeks after administration of the second vaccine dose. Those that had received 10(4) U IFN-gamma in the vaccination developed less fever during the postchallenge period (p < 0.004). In all challenged pigs, growth performance was compromised during the first week after challenge. However, the only animals retaining an average net increase in body mass were those covaccinated with 10(4) U IFN-gamma (p < 0.05). Nasal excretion of virus was not significantly different between groups that had been vaccinated with or without IFN-gamma. Multiple linear regression analysis of variables from individual vaccinated animals revealed the VNAb response to be correlated with serum IgG levels (p < 0.025) and with postchallenge growth performance (p < 0.0001) but not with serum IgA levels (p > 0.5). On the other hand, serum IgA appeared to be inversely correlated with early nasal virus excretion after challenge (p < 0.006). Taken together, our data suggest that addition of IFN-gamma to inactivated SHV-1 vaccine may be a useful tool for enhancement of both mucosal and systemic immune responses in pigs.