Prophylactic Human Vaccines Research Articles

The association between rLiHyp1 protein plus adjuvant and amphotericin B is an effective immunotherapy against visceral leishmaniasis in mice

Treatment of visceral leishmaniasis (VL) is compromised by drug toxicity, high cost and/or the emergence of resistant strains. Though canine vaccines are available, there are no licensed prophylactic human vaccines. One strategy to improve clinical outcome for infected patients is immunotherapy, which associates a chemotherapy that acts directly to reduce parasitism and the administration of an immunogen-adjuvant that activates the host protective Th1-type immune response. In this study, we evaluated an immunotherapy protocol in a murine model by combining recombinant (r)LiHyp1 (a hypothetical amastigote-specific Leishmania protein protective against Leishmania infantum infection), with monophosphoryl-lipid A (MPLA) as adjuvant and amphotericin B (AmpB) as reference antileishmanial drug. We used this protocol to treat L. infantum infected-BALB/c mice, and parasitological, immunological and toxicological evaluations were performed at 1 and 30 days after treatment. Results showed that mice treated with rLiHyp1/MPLA/AmpB presented the lowest parasite burden in all organs evaluated, when both a limiting dilution technique and qPCR were used. In addition, these animals produced higher levels of IFN-γ and IL-12 cytokines and IgG2a isotype antibody, which were associated with lower production of IL-4 and IL-10 and IgG1 isotype. Furthermore, low levels of renal and hepatic damage markers were found in animals treated with rLiHyp1/MPLA/AmpB possibly reflecting the lower parasite load, as compared to the other groups. We conclude that the rLiHyp1/MPLA/AmpB combination could be considered in future studies as an immunotherapy protocol to treat against VL.

In Silico Design of Recombinant Chimera T Cell Peptide Epitope Vaccines for Visceral Leishmaniasis.

Visceral leishmaniasis (VL) is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. Systemic VL is fatal if untreated and there are no prophylactic human vaccines available. Several studies suggest that Th1 cell-mediated immunity plays a major role in protecting against VL. In this chapter we describe a method for designing recombinant chimera vaccines in silico based on the prediction of T cell epitopes within protein antigens identified as potential protective immunogens. Development of a recombinant chimera protein (RCP) vaccine using T cell epitope peptides identified from four Leishmania proteins is used as an exemplar of this method.

Monophosphoryl Lipid A and Pam3Cys Prevent the Increase in Seizure Susceptibility and Epileptogenesis in Rats Undergoing Traumatic Brain Injury.

Five percent of all epilepsy cases are attributed to traumatic brain injury (TBI), which are known as post-traumatic epilepsy (PTE). Finding preventive strategies for PTE is valuable. Remarkable feature of TBI is activation of microglia and subsequent neuroinflammation, which provokes epileptogenesis. The toll-like receptor agonists monophosphoryl lipid A (MPL) and tri-palmitoyl-S-glyceryl-cysteine (Pam3Cys) are safe, well-tolerated and effective adjuvants existing in prophylactic human vaccines. We examined the impact of early injection of MPL and Pam3Cys to rats, on the rate of kindled seizures acquisition following TBI. Rats received a single dose (1µg/rat) of MPL or Pam3Cys through intracerebroventricular injection. 5days later, trauma was exerted to temporo-parietal cortex of rats by controlled cortical impact device. After 24h, traumatic rats underwent amygdala kindling. Brain level of the inflammatory cytokine tumor necrosis factor-alpha (TNF-α) was also measured in traumatic rats by immunoblotting. Compared to non-traumatic (sham-operated) rats, traumatic rats showed three times lower seizure threshold (133 ± 5µA vs. 416.3 ± 16µA, p < 0.001); about three times less number of stimuli to become kindled (5 ± 1 vs. 14 ± 2, p < 0.01); longer duration of kindled seizure parameters including entire seizure behavior, generalized seizures, and afterdischarges (p < 0.001); and a two times increase in the TNF-α level. MPL and Pam3Cys did not change kindling rate and the seizure parameters in sham-operated rats. The MPL- and Pam3Cys-pretreated traumatic rats displayed seizure threshold, speed of kindling, and duration of kindled seizure parameters, similar to the non-traumatic rats. Pretreatment by MPL and Pam3Cys prevented the increase in TNF-α level by trauma. Given that MPL and Pam3Cys currently have clinical use as well-tolerated vaccines with reliable safety, they have the potential to be used in prevention of PTE.

Translating Observations From Leishmanization Into Non-Living Vaccines: The Potential of Dendritic Cell-Based Vaccination Strategies Against Leishmania.

Leishmaniasis is a health-threatening vector-borne disease in almost 90 different countries. While a prophylactic human vaccine is not yet available, the fact that recovery from leishmaniasis establishes lifelong immunity against secondary infection suggests that a vaccine is attainable. In the past, deliberate infection with virulent parasites, termed Leishmanization, was used as a live-vaccine against cutaneous leishmaniasis and effectively protected against vector-transmitted disease in endemic areas. However, the practice was discontinued due to major complications including non-healing skin lesions, exacerbation of skin diseases, and the potential impact of immunosuppression. Instead, tremendous effort has been made to develop killed, live attenuated, and non-living subunit formulations. Many of these formulations produce promising experimental results but have failed in field trials or against experimental challenge with infected sand flies. Recently, experimental models of leishmanization have unraveled the critical role of parasite persistence in maintaining the circulating CD4+ effector T cells responsible for mitigating the inflammatory response early after sand fly challenge and mediating protective immunity. Here, we put forward the notion that for effective vaccine design (especially non-living vaccines), the role of antigen persistence and pre-existing effector CD4+ T cells should be taken into consideration. We propose that dendritic cell-based vaccination strategies warrant greater attention because of their potential to act as long-term antigen depots, thereby emulating this critical requirement of naturally acquired protective immunity against infected sand fly challenge.

Vaccine-induced antibodies to herpes simplex virus glycoprotein D epitopes involved in virus entry and cell-to-cell spread correlate with protection against genital disease in guinea pigs.

Herpes simplex virus type 2 (HSV-2) glycoprotein D (gD2) subunit antigen is included in many preclinical candidate vaccines. The rationale for including gD2 is to produce antibodies that block crucial gD2 epitopes involved in virus entry and cell-to-cell spread. HSV-2 gD2 was the only antigen in the Herpevac Trial for Women that protected against HSV-1 genital infection but not HSV-2. In that trial, a correlation was detected between gD2 ELISA titers and protection against HSV-1, supporting the importance of antibodies. A possible explanation for the lack of protection against HSV-2 was that HSV-2 neutralization titers were low, four-fold lower than to HSV-1. Here, we evaluated neutralization titers and epitope-specific antibody responses to crucial gD2 epitopes involved in virus entry and cell-to-cell spread as correlates of immune protection against genital lesions in immunized guinea pigs. We detected a strong correlation between neutralizing antibodies and protection against genital disease. We used a high throughput biosensor competition assay to measure epitope-specific responses to seven crucial gD2 linear and conformational epitopes involved in virus entry and spread. Some animals produced antibodies to most crucial epitopes while others produced antibodies to few. The number of epitopes recognized by guinea pig immune serum correlated with protection against genital lesions. We confirmed the importance of antibodies to each crucial epitope using monoclonal antibody passive transfer that improved survival and reduced genital disease in mice after HSV-2 genital challenge. We re-evaluated our prior study of epitope-specific antibody responses in women in the Herpevac Trial. Humans produced antibodies that blocked significantly fewer crucial gD2 epitopes than guinea pigs, and antibody responses in humans to some linear epitopes were virtually absent. Neutralizing antibody titers and epitope-specific antibody responses are important immune parameters to evaluate in future Phase I/II prophylactic human vaccine trials that contain gD2 antigen.

Pathophysiology and epidemiology of virus-induced asthma.

Many respiratory viruses are mainly responsible for common cold, bronchitis, bronchiolitis, and pneumonia. Furthermore, asthma and chronic obstructive pulmonary disease (COPD) are major cause of mortality. The prevalence of asthma in developed countries is approximately 10% in adults and even higher in children (Barnes, 2008). Thus, the medical costs for these diseases are a major burden in many countries. Respiratory virus infections also cause the most of acute exacerbation of asthma (virus-induced asthma) or COPD. Among them, human rhinoviruses (HRV) are detected in the two thirds of the cases with asthma exacerbations in children (Johnston et al., 1995). However, epidemiology and pathophysiology of asthma and COPD is not known. Furthermore, a few effective vaccines have been applied. Therefore, it may be important to better understand pathophysiology of virus-induced asthma or virus-induced COPD exacerbation. Both aspects of the virus agents and host defense systems including acute/chronic inflammation and airway tissue remodeling should be clarified. This e-book aims to review and discuss pathophysiology and epidemiology of virus-induced asthma and COPD focusing on new findings of the host immunity and virology. This Research Topic contains 7 review articles and 3 original articles regarding pathophysiology of virus-induced asthma. As the first article, Kudo et al. (2013) reviewed pathology of asthma. This article globally covers from molecular histopathology involved in cytokine networks of asthma. The readers may easily understand molecular immunopathology of virus-induced asthma. In the second issue, Okayama (2013) presents cellular and humoral immunity of asthma. Accumulating evidence implicates that the genetic and environmental factors may be associated with virus-induced asthma. This work focuses on the immunological mechanisms that may explain why asthma is associated with RSV-and HRV-infection. As the third review article, Kimura et al. (2013) present the molecular mechanisms between various cytokines and innate immunity of viral respiratory infections including virus-induced asthma. The authors also show the signaling pathways with regard to them. In the 4th review article, Tsukagoshi et al. (2013) discuss the genetic characteristics and molecular evolution of respiratory viruses, and epidemiology of asthma. They also show phylogenetic analysis of the detected viruses in the children with respiratory syncytial virus- (RSV) and/or HRV-associated wheezing and asthma. As the 5th review article, Inoue and Shimojo (2013) present epidemiology and pathophysiology of virus-induced asthma in children. They summarize the previous findings and discuss how clinicians can effectively intervene in these viral infections to prevent the development of asthma. Next, Kurai et al. (2013) and Saraya et al. (2014) present pathophysiology of virus-induced COPD and asthma in adults. They summarize current knowledge concerning exacerbation of both COPD and asthma by focusing on the clinical significance of associated respiratory virus infections. Furthermore, influenza A(H1N1)pdm09 virus have suddenly emerged in Mexico in the spring, 2009. The virus can cause influenza pandemy accompanying with pneumonia/wheezing. Obuchi et al. (2013) review essential reports with regard to asthma in patients infected with the virus, and they discuss the utility of influenza vaccines and antivirals. Although HPIV3 is an etiological agent for respiratory disorders such as pneumonia and asthma, there is no prophylactic human vaccine against the virus infection. In the 9th issue as original article, Senchi et al. (2013) present the development of an oligomannose-coated liposome (OML) nasal vaccine against HPIV3 in combination with an effective adjuvant Poly(I:C). They report that their newly-developed vaccine can successfully induce antigen-specific immunity with a small amount of antigen via the nasal route. These results highlight the utility of combining sophisticated systems in the development of a novel vaccine against HPIV3. In the final article, Matsunaga et al. (2014) present the development of monoclonal antibodies (MAbs) against hemagglutinin-neuraminidase (HN) of HPIV3. For synthesizing the antigen protein, they utilized the wheat germ cell-free system. This new cell-free system-based protocol for antigen production enabled to create the MAbs that can be applicable in various immune assays such as flowcytometry and immunoprecipitation analyses. The newly-developed MAbs could thus be a valuable tool for the study of HPIV3 infection as well as the several diagnostic tests of this virus. In conclusion, we believe that these works are well summarized and informative to glimpse the field of virus-associated asthma/COPD, and may help understanding the basic and clinical aspects of the disease. We would be happy if this collection of papers will offer new stimuli and perspectives for not only researchers but also clinicians working around the exciting and emerging the e-book.

Immunogenicity and safety of Advax™, a novel polysaccharide adjuvant based on delta inulin, when formulated with hepatitis B surface antigen: A randomized controlled Phase 1 study

There is a need for additional safe and effective human vaccine adjuvants. Advax™ is a novel adjuvant produced from semi-crystalline particles of delta inulin. In animal studies Advax enhanced humoral and cellular immunity to hepatitis B surface antigen (HBsAg) without inducing local or systemic reactogenicity. This first-in-man Phase 1 clinical trial tested the safety and tolerability of three intramuscular doses of HBsAg formulated with Advax in a group of healthy adult subjects. Advax was well tolerated with injection site pain scores not significantly different to subjects receiving HBsAg alone and no adverse events were reported in subjects that received Advax. Seroprotection and HBsAb geometric mean titers (GMT) after three immunizations were higher in the Advax 5mg (seroprotection 5/6, 83.3%, GMT 40.7, 95% CI 11.9–139.1) and 10mg (seroprotection 4/5, 80%, GMT 51.6, 95% CI 10.0–266.2) groups versus HBsAg alone (seroprotection 1/5, 20%, GMT 4.1, 95% CI 1.3–12.8). Similarly the proportion of subjects with positive CD4 T-cell responses to HBsAg was higher in the Advax 5mg (4/6, 67%) and Advax 10mg (4/5, 80%) groups versus HBsAg alone (1/5, 20%). These results confirm the safety, tolerability and immunogenicity of Advax adjuvant observed in preclinical studies. Advax may represent a suitable replacement for alum adjuvants in prophylactic human vaccines subject to confirmation of current results in larger studies. Australia and New Zealand Clinical Trial Registry: ACTRN12607000598482.

Efficacy of ABX196, a new NKT agonist, in prophylactic human vaccination

We have assessed the immune-regulatory and adjuvant activities of a synthetic glycolipid, ABX196, a novel analog of the parental compound α-GalCer. As expected, ABX196 demonstrated a measurable and significant adjuvant effect in mice and monkeys with no appreciable toxicity at the doses used to promote immune responses. We performed a phase I/II dose escalation study of ABX196 in healthy volunteers, with the objectives to evaluate its safety profile, as well as its ability to be utilized as an adjuvant in the context of a prophylactic vaccine against hepatitis B. ABX196 was administered at three doses: 0.2, 0.4, and 2.0μg, in 44 subjects. In all the individuals injected with ABX196, peripheral blood NKT cells displayed hallmarks of activation, and 45% of them had measurable circulating IFN-γ 24h after the first administration. More importantly, the addition of ABX196 to the very poorly immunogenic HBs antigen resulted in protective anti-HBs antibody responses in majority of patients, demonstrating the adjuvant properties of ABX196 in human. Further analysis of the cohort of subjects receiving ABX196 with HBs antigen also indicates that a single injection appears sufficient to provide protection. A limited set of adverse events linked to the systemic delivery of ABX196 and access to the liver, is discussed in the context of formulation and the need to limit transport of ABX196 to secondary lymphoid tissues for maximal efficacy (Eudra-CT 2012-001566-15).