In vitro evaluation of novel (nanoparticle) oral delivery systems allow selection of gut immunomodulatory formulations.

Oral delivery is the most convenient way to vaccinate cultured fish, however it is still problematic, primarily due to a lack of a commercially valid vaccine vehicle to protect the antigen against gastric degradation and ensure its uptake from the intestine. With the goal of advancing the potential to vaccinate orally, this study evaluates a novel silicon nanoparticle-based vehicle (VacSaf carrier). Aeromonas salmonicida antigens were formulated with the VacSaf carrier using different preparation methods to generate dry powder and liquid formulations. Twelve formulations were first subjected to an in vitro evaluation where the A. salmonicida bacterin conjugated to VacSaf carriers were found superior at inducing pro-inflammatory cytokine expression in primary leucocyte cultures and the macrophage/monocyte cell line RTS-11 compared with A. salmonicida bacterin alone. This was especially apparent after exposure to acid conditions to mimic stomach processing. One formulation (FD1) was taken forward to oral delivery using two doses and two administration schedules (5 days vs 10 days, the latter 5 days on, 5 days off, 5 days on), and the transcript changes of immune genes in the intestine (pyloric caeca, midgut and hindgut) and spleen were evaluated by qPCR and serum IgM was measured by ELISA. The VacSaf carrier alone was shown to be safe for use in vivo, in that no side-effects were seen, but it did induce expression of some cytokines, and may have value as an oral adjuvant candidate. The FD1 bacterin formulation was effective at inducing a range of cytokines associated with innate and adaptive immunity, mainly in the pyloric caeca, compared to A. salmonicida bacterin alone (which had almost no effect), and confirms the immune competence of this gut region following appropriate oral vaccination. These results reveal that in vitro screening of formulations for oral delivery has value and can be used to assess the most promising formulations to test further.

Diphtheria toxoid dissolving microneedle vaccination: Adjuvant screening and effect of repeated-fractional dose administration.

In this study the effect of repeated-fractional intradermal administration of diphtheria toxoid (DT) compared to a single administration in the presence or absence of adjuvants formulated in dissolving microneedles (dMNs) was investigated. Based on an adjuvant screening with a hollow microneedle (hMN) system, poly(I:C) and gibbsite, a nanoparticulate aluminum salt, were selected for further studies: they were co-encapsulated with DT in dMNs with either a full or fractional DT-adjuvant dose. Sharp dMNs were prepared regardless the composition and were capable to penetrate the skin, dissolve within 20 min and deposit the intended antigen-adjuvant dose, which remained in the skin for at least 5 h. Dermal immunization with hMN in repeated-fractional dosing (RFrD) resulted in a higher immune response than a single-full dose (SFD) administration. Vaccination by dMNs led overall to higher responses than hMN but did not show an enhanced response after RFrD compared to a SFD administration. Co-encapsulation of the adjuvant in dMNs did not increase the immune response further. Immunization by dMNs without adjuvant gave a comparable response to subcutaneously injected DT-AlPO4 in a 15 times higher dose of DT, as well as subcutaneous injected DT-poly(I:C) in a similar DT dose. Summarizing, adjuvant-free dMNs showed to be a promising delivery tool for vaccination performed in SFD administration.

A Novel Dendritic Cell-Based Vaccination Protocol to Stimulate Immunosurveillance of Aggressive Cancers.

A major challenge in the development of a successful tumor vaccination is to break immune tolerance and to sensitize efficiently the immune system toward relevant tumor antigens, thus enabling T-cell-mediated antitumor responses in vivo. Dendritic cell (DC)-based immunotherapy shows the advantage to induce an adaptive immune response against the tumor, with the potential to generate a long-lasting immunological memory able to prevent further relapses and hopefully metastasis. Recently different preclinical studies highlighted the golden opportunity to exploit the features of immunogenic cell death (ICD) to generate ex vivo a highly immunogenic tumor cell lysate as potent antigen formulation for improved DC-based vaccine against aggressive cancers. This chapter focuses on the methods to obtain tumor lysates from cells undergoing ICD to be used for DC pulsing and to test the functionality of the generated DCs for antitumor vaccine development.

Induction of broad immunity by thermostabilised vaccines incorporated in dissolvable microneedles using novel fabrication methods.

Dissolvable microneedle (DMN) patches for immunization have multiple benefits, including vaccine stability and ease-of-use. However, conventional DMN fabrication methods have several drawbacks. Here we describe a novel, microfluidic, drop dispensing-based dissolvable microneedle production method that overcomes these issues. Uniquely, heterogeneous arrays, consisting of microneedles of diverse composition, can be easily produced on the same patch. Robustness of the process was demonstrated by incorporating and stabilizing adenovirus and MVA vaccines. Clinically-available trivalent inactivated influenza vaccine (TIV) in DMN patches is fully stable for greater than 6months at 40°C. Immunization using low dose TIV-loaded DMN patches induced significantly higher antibody responses compared to intramuscular-based immunization in mice. TIV-loaded patches also induced a broader, heterosubtypic neutralizing antibody response. By addressing issues that will be faced in large-scale fill-finish DMN fabrication processes and demonstrating superior thermostable characteristics and immunogenicity, this study progresses the translation of this microneedle platform to eventual clinical deployment.

Improving the reach of vaccines to low-resource regions, with a needle-free vaccine delivery device and long-term thermostabilization.

Dry-coated microprojections can deliver vaccine to abundant antigen-presenting cells in the skin and induce efficient immune responses and the dry-coated vaccines are expected to be thermostable at elevated temperatures. In this paper, we show that we have dramatically improved our previously reported gas-jet drying coating method and greatly increased the delivery efficiency of coating from patch to skin to from 6.5% to 32.5%, by both varying the coating parameters and removing the patch edge. Combined with our previous dose sparing report of influenza vaccine delivery in a mouse model, the results show that we now achieve equivalent protective immune responses as intramuscular injection (with the needle and syringe), but with only 1/30th of the actual dose. We also show that influenza vaccine coated microprojection patches are stable for at least 6 months at 23°C, inducing comparable immunogenicity with freshly coated patches. The dry-coated microprojection patches thus have key and unique attributes in ultimately meeting the medical need in certain low-resource regions with low vaccine affordability and difficulty in maintaining "cold-chain" for vaccine storage and transport.

Preclinical evaluation of microneedle technology for intradermal delivery of influenza vaccines.

Recent clinical studies have suggested that, for certain strains of influenza virus, intradermal (i.d.) delivery may enable protective immune responses using a lower dose of vaccine than required by intramuscular (i.m.) injection. Here, we describe the first preclinical use of microneedle technology for i.d. administration of three different types of influenza vaccines: (i) a whole inactivated influenza virus, (ii) a trivalent split-virion human vaccine, and (iii) a plasmid DNA encoding the influenza virus hemagglutinin. In a rat model, i.d. delivery of the whole inactivated virus provided up to 100-fold dose sparing compared to i.m. injection. In addition, i.d. delivery of the trivalent human vaccine enabled at least 10-fold dose sparing for the H1N1 strain and elicited levels of response across the dose range similar to those of i.m. injection for the H3N2 and B strains. Furthermore, at least fivefold dose sparing from i.d. delivery was evident in animals treated with multiple doses of DNA plasmid vaccine, although such effects were not apparent after the first immunization. Altogether, the results demonstrate that microneedle-based i.d. delivery elicits antibody responses that are at least as strong as via i.m. injection and that, in many cases, dose sparing can be achieved by this new immunization method.

Gene gun bombardment with gold particles displays a particular Th2-promoting signal that over-rules the Th1-inducing effect of immunostimulatory CpG motifs in DNA vaccines.

The mode of administering a DNA vaccine can influence the type of immune response induced by the vaccine. For instance, application of a DNA vaccine by gene gun typically induces a Th2-type reaction, whereas needle inoculation triggers a Th1 response. It has been proposed that the approximately 100-fold difference in the amount of DNA administered by these two methods is the critical factor determining whether a Th1 or a Th2 response is made. To test this hypothesis, BALB/c mice were immunized with two plasmid DNA constructs encoding different proteins (OspC/ZS7 of Borrelia burgdorferi and Bet v 1a, the major birch pollen allergen). Both vaccines were applied by needle and/or by gene gun immunization at the same and at different sites of injection. An analysis of the IgG subclass distribution and measurement of IFN-gamma after antigen-specific lymphoproliferation does not support the widely accepted view that Th2-type immunity induced by gene gun application is solely due to the low amount of injected plasmid DNA thus falling below the critical concentration of CpG motifs necessary for Th1-induction. Furthermore, the data also indicate a strong and even systemic adjuvant effect of the gene gun shot itself.

Making vaccines more acceptable--methods to prevent and minimize pain and other common adverse events associated with vaccines.

The growing abundance of highly immunogenic vaccines has arrived with a burden of pain, distress, and common adverse reactions that in turn may interfere with parental compliance and aggravate anti-vaccine sentiment. In a study of 150 children in each of 2 age-groups, we found that approximately 20% of the subjects suffered serious distress or worse. During the procedural phase, approximately 90% of the 15-to-18 month old children and 45% of the 4-to-6 year old children showed serious distress or worse. To address non-adherence with pediatric vaccine schedules, we must consider all of the possible issues that might prevent a parent from taking a child to a health care provider for vaccination. In that same study we identified useful predictors for both preparatory and procedural distress - predictors that might be used in identifying children who might benefit from preventive interventions. Vaccine providers might consider a variety of interventions. Attitude, empathy, instruction, and practice have all been shown to have a salutatory effect upon pain and anxiety with medical procedures in general and specifically with vaccinations. Distraction has also been found to be an effective method for distress and pain prevention in children. More formal methods of clinical hypnosis which combine a deep state of relaxation with focused imagery and suggestion have also been found to be effective in helping children and adolescents prepare for, cope with, and tolerate the pain and anxiety associated with medical procedures. So-called 'sugar nipples' delivering small amounts of sucrose orally at the time of a painful procedure in an infant has been not been shown to decrease vaccination pain and studies on refrigerant topical anesthetics are mixed. Studies have found a eutectic mixture of 2.5% lidocaine and 2.5% prilocaine (EMLA) effective in providing adequate local anesthesia in children, but it suffers from problems in practical application. Studies with various injection techniques have not identified ready solutions, and although jet injection appears to provoke less anxiety and cause less immediate pain, studies also indicate a somewhat greater incidence of delayed local reactogenicity including soreness and edema. Other measures to prevent or rapidly treat other common adverse events have been shown effective and should be considered as well.

Ensuring vaccine safety in immunization programmes--a WHO perspective.

Ever since vaccines were firstly used against smallpox, adverse events following immunization have been reported. As immunization programmes expand to reach even the most remote communities in the poorest countries, it is likely that many more events will be temporally linked with vaccine administration. Furthermore, the profound shift in the general public and media interest in adverse events may lead to undue concerns and allegations which may ultimately jeopardize immunization programmes world-wide. While the health professional has understood this issue for some time, the public and the media have now also become all too aware of the significance of vaccine-related adverse events. The familiar vaccines, well-tested over decades, have not changed--but the perception regarding their safety has shifted. Claims outrageous or reasonable are being made against both the old and the newly-introduced vaccines. At the same time, the immunological and genetic revolution of the last decade may well bring to our notice some hypothetical risks that need to be addressed at pre-clinical level. WHO has been at the leading edge to guarantee vaccine safety for the last 30 years and will continue to do so. The Organization's plans for the next decade and beyond include the Safe Injection Global Network (SIGN), the development and introduction of safer technologies, and the prevention, early detection and management of AEFIs. The new technologies include needle-containing injection devices such as the autodisable syringe, as well as mucosal and transcutaneous immunization. Training will continue to be at the centre of WHO's efforts, limiting human error to a minimum. Mechanisms have been set in place to detect and respond to new and unforeseen events occurring. Above all, there is a willingness to respond to new climates and new technologies so that the Organization is in the best position to ensure safe immunization for all the world's children.

Home delivery of heat-stable vaccines in Indonesia: outreach immunization with a prefilled, single-use injection device.

Extending immunization coverage to underserved populations will require innovative immunization strategies. This study evaluated one such strategy: the use of a prefilled, single-use injection device for outreach immunization by village midwives. The device, UniJect, is designed to prevent refilling or reuse. Stored at ambient temperatures for up to 1 month in midwives' homes, vaccine-filled UniJect devices were immediately available for outreach. Between July 1995 and April 1996, 110 midwives on the Indonesia islands of Lombok and Bali visited the homes of newborn infants to deliver hepatitis B vaccine to the infants and tetanus toxoid to their mothers. Observations and interviews showed that the midwives used the device properly and safely to administer approximately 10,000 sterile injections in home settings. There were no problems with excessive heat exposure during the storage or delivery of vaccine. Injection recipients and midwives expressed a strong preference for the UniJect device over a standard syringe. Use of the prefilled device outside the cold chain simplified the logistics and facilitated the speed and efficiency of home visits, while the single-dose format minimized vaccine wastage.

PIP: Recent studies have found that up to 30% of injections given for immunization are not sterile. Disposable syringes are reused and reusable syringes are often improperly sterilized. Findings are presented from an evaluation of the use of a prefilled, single-use injection device for outreach immunization by village midwives. Such devices can reduce the transmission of bloodborne pathogens and diseases, and reduce vaccine wastage associated with multi-dose vials. The device evaluated, UniJect, is designed to prevent refilling or reuse. Stored at ambient temperatures for up to 1 month in midwives' homes, vaccine-filled UniJect devices were immediately available for use. Between July 1995 and April 1996, 110 midwives on the Indonesian islands of Lombok and Bali visited the homes of newborn infants to deliver hepatitis B vaccine to infants and tetanus toxoid to their mothers. Observations and interviews found that the midwives safely and properly used the device to administer approximately 10,000 sterile injections in home settings. No problems were experienced with excessive heat exposure during the storage or delivery of vaccine. Injection recipients and midwives strongly preferred the UniJect device over a standard syringe. Furthermore, use of the prefilled device outside of the cold chain simplified the logistics and facilitated the speed and efficiency of home visits, while the single-dose format minimized vaccine wastage.

A prefilled injection device for outreach tetanus immunization by Bolivian traditional birth attendants.

This study evaluated the performance, acceptability, and appropriateness of a new, single-use, prefilled injection device called UniJect for an outreach immunization application. Between April and June 1995, UniJect devices were used by 36 traditional birth attendants to administer tetanus toxoid injections to 2,240 pregnant women during routine, antenatal home visits in the Northern, Ichilos, and Warnes Districts of Santa Cruz, Bolivia. Because tetanus toxoid is relatively heat stable, the traditional birth attendants were able to keep the tetanus toxoid-filled UniJect devices in their homes for up to one month without refrigeration. The devices were stored, transported, and disposed of in an outreach carrier designed to reduce the risks of improper handling and disposal. Data were collected from injection recipients, traditional birth attendants, and supervisors via observation, questionnaires, and post-study interviews. The performance of the UniJect device and its acceptability among all groups was very high. The traditional birth attendants used UniJect properly and safely; there were no reports or observations of device misuse, reuse, or needle-stick. Advantages cited included the fact that the device required no assembly, offered assured sterility, and reduced vaccine wastage sometimes associated with multi-dose vials. The ability to store and transport the vaccine-filled devices without ice also greatly simplified logistics.

A prefilled injection device for outreach tetanus immunization by Bolivian traditional birth attendants / Vacunación antitetánica extrainstitucional por parteras empíricas bolivianas mediante dispositivos desechables de una sola dosis

This study evaluated the performance, acceptability, and appropriateness of a new, single-use, prefilled injection device called UniJect™ for an outreach immunization application.6 Between April and June 1995, UniJect devices were used by 36 traditional birth attendants to administer tetanus toxoid injections to 2 240 pregnant women during routine, antenatal home visits in the Northern, Ichilos, and Warnes Districts of Santa Cruz, Bolivia. Because tetanus toxoid is relatively heat stable, the traditional birth attendants were able to keep the tetanus toxoid-filled UniJect devices in their homes for up to one month without refrigeration. The devices were stored, transported, and disposed of in an outreach carrier designed to reduce the risks of improper handling and disposal. Data were collected from injection recipients, traditional birth attendants, and supervisors via observation, questionnaires, and post-study interviews. The performance of the UniJect device and its acceptability among all groups was very high. The traditional birth attendants used UniJect properly and safely; there were no reports or observations of device misuse, reuse, or needle-stick. Advantages cited included the fact that the device required no assembly, offered assured sterility, and reduced vaccine wastage sometimes associated with multi-dose vials. The ability to store and transport the vaccine-filled devices without ice also greatly simplified logistics.

En este estudio se evaluaron el rendimiento, la aceptabilidad y la conveniencia de la inmunización antitetánica extrainstitucional con un nuevo dispositivo hipodérmico de una sola dosis, el UniJect®. De abril a junio de 1995, el dispositivo UniJect aprestado de fábrica con una sola dosis de toxoide tetánico fue utilizado por 36 parteras tradicionales para vacunar a 2 240 mujeres embarazadas durante las visitas domiciliarias prenatales de rutina en los distritos Norte, Ichilos y Warnes de Santa Cruz, Bolivia. Ya que el toxoide tetánico es termoestable, las parteras pudieron mantener los dispositivos UniJect sin refrigeración en sus hogares por un período de hasta un mes. Los UniJect se guardaron, transportaron y desecharon en portadores extrainstitucionales diseñados para reducir los riesgos de manipularlos y desecharlos de forma inadecuada. Se recolectaron datos de las mujeres vacunadas, las parteras tradicionales y sus supervisores, mediante observación, cuestionarios y entrevistas realizadas después del estudio. Todos los grupos consideraron muy satisfactorios el rendimiento y la aceptabilidad del dispositivo UniJect. Las parteras tradicionales lo usaron de forma apropiada y cuidadosa; no hubo informes ni observaciones de mala utilización, reúso o puntazos accidentales. Se mencionaron, como ventajas del dispositivo, que no requiere montaje, asegura la esterilidad y reduce el desperdicio de vacuna que a veces ocurre con las ampollas de dosis múltiples. Además, todo el procedimiento se simplifica porque los dispositivos pueden almacenarse y transportarse sin necesidad de hielo.