Two MP2CL5 Antigen Vaccines from Naegleria fowleri Stimulate the Immune Response against Meningitis in the BALB/c Model.

Naegleria fowleri is an etiological agent that generates primary amoebic meningoencephalitis; unfortunately, no effective treatment or vaccine is available. The objective of this work was to determine the immunoprotective response of two vaccine antigens, as follows: (i) the polypeptide band of 19 kDa or (ii) a predicted immunogenic peptide from the membrane protein MP2CL5 (Smp145). Both antigens were administered intranasally in mice using cholera toxin (CT) as an adjuvant. The survival rate and immune response of immunized mice with both antigens and challenged with N. fowleri trophozoites were measured in the nose-associated lymphoid tissue (NALT) and nasal passages (NPs) by flow cytometry and enzyme-linked immunosorbent assay (ELISA). We also determined the immunolocalization of both antigens in N. fowleri trophozoites by confocal microscopy. Immunization with the polypeptide band of 19 kDa alone or coadministered with CT was able to confer 80% and 100% of protection, respectively. The immunization with both antigens (alone or coadministered with CT) showed an increase in T and B lymphocytes. In addition, there was an increase in the expression of integrin α4ß1 and IgA in the nasal cavity of protected mice, and the IgA, IgG, and IgM levels were increased in serum and nasal washes. The immunolocalization of both antigens in N. fowleri trophozoites was observed in the plasma membrane, specifically in pseudopod-like structures. The MP2CL5 antigens evaluated in this work were capable of conferring protection which would lead us to consider them as potential candidates for vaccines against meningitis caused by N. fowleri.

The Protective Effects of the A/ZJU01/ PR8/2013 Split H7N9 Avian Influenza Vaccine Against Highly Pathogenic H7N9 in BALB/c Mice.

BACKGROUND/AIMS: Since the first case of novel H7N9 infection was reported, China has experienced five epidemics of H7N9. During the fifth wave, a highly pathogenic H7N9 strain emerged. In order to assess whether the H7N9 vaccine based on A/Zhejiang/DTID-ZJU01/2013(H7N9) was effective in protecting against highly pathogenic H7N9, we conducted this study. METHODS: Groups of mice were immunized twice by intraperitoneal injection with 500 µl of either split vaccine alone or MF59-adjuvanted vaccine. Serum was collected 2 weeks after the second vaccine booster. The hemagglutinin inhibition test was conducted on vaccine seed and highly pathogenic H7N9 to evaluate the neutralization of highly pathogenic H7N9. We also immunized mice and challenged them with highly pathogenic H7N9. Mice were observed for illness, weight loss, and death at 1 week and 2 weeks post-infection. Then, the mice were sacrificed and lungs were removed. Antibody responses were assessed and pathological changes in the lung tissue were evaluated. RESULTS: The ability of serum to neutralize highly pathogenic H7N9 was reduced. In mice, highly pathogenic H7N9 was more virulent than A/Zhejiang/DTID-ZJU01/2013(H7N9). After challenge with highly pathogenic H7N9, all mice died while mice challenged with A/Zhejiang/DTID-ZJU01/2013(H7N9) all recovered. The A/ZJU01/PR8/2013 split H7N9 avian influenza vaccine was able to protect against infection with highly pathogenic H7N9 in mice, with or without MF59. Moreover, H7N9 vaccine adjuvanted with MF59 produced high antibody levels, which lead to better protection. CONCLUSIONS: The A/ZJU01/PR8/2013 split H7N9 avian influenza vaccine based on A/Zhejiang/DTID-ZJU01/2013(H7N9) is effective in protecting against highly pathogenic H7N9. H7N9 vaccine adjuvanted with MF59 offers better protection against infection with highly pathogenic H7N9. In order to make the H7N9 vaccine applicable to humans, further clinical trials are required to evaluate MF59 adjuvanted vaccine. Meanwhile, the vaccine strain should be updated based on the highly pathogenic H7N9 gene sequence.

Extracellular vesicles elicit protective immune responses against Salmonella infection.

Small extracellular vesicles (sEVs) produced by antigen-presenting cells represent a novel mechanism of cell-to-cell communication. The sEVs have been shown to drive Th1-type adaptive immune responses against intracellular infections such as Salmonella. In this study, we have demonstrated that an administration of sEVs produced by Salmonella-infected macrophages to BALB/c mice that were then challenged with Salmonella infection decreased bacterial load in infected animals and led to protection against a lethal dose of Salmonella. Second, the same sEVs induced a robust production of IgA anti-Salmonella antibodies (Abs) in BALB/c mice, including IgA anti-OmpD Abs. These results show that the nanoscale sEVs stimulate adaptive immune responses against intracellular pathogens and that these sEVs can be used to provide animals with complete protection against lethal infection, such as the systemic bacterial infection in immunodeficient BALB/c mice.

Immunometabolism and Pulmonary Infections: Implications for Protective Immune Responses and Host-Directed Therapies.

The biology and clinical efficacy of immune cells from patients with infectious diseases or cancer are associated with metabolic programming. Host immune- and stromal-cell genetic and epigenetic signatures in response to the invading pathogen shape disease pathophysiology and disease outcomes. Directly linked to the immunometabolic axis is the role of the host microbiome, which is also discussed here in the context of productive immune responses to lung infections. We also present host-directed therapies (HDT) as a clinically viable strategy to refocus dysregulated immunometabolism in patients with infectious diseases, which requires validation in early phase clinical trials as adjuncts to conventional antimicrobial therapy. These efforts are expected to be continuously supported by newly generated basic and translational research data to gain a better understanding of disease pathology while devising new molecularly defined platforms and therapeutic options to improve the treatment of patients with pulmonary infections, particularly in relation to multidrug-resistant pathogens.

The double adjuvants LTB and CpG significantly enhanced the immuno-protective effects of recombinant GIT derived from Staphylococcus aureus and Streptococcus in mice.

PURPOSE: In this study, we prepared GapC1-150-IsdB126-361-TRAP (GIT) proteins plus heat-labile enterotoxin B (LTB) as an intra-molecular adjuvant, together with CpG to further enhance its immunogenicity. METHODOLOGY: Initially, the target genes were acquired and inserted into pET-32a (+) vectors to express LTB-GIT protein. LTB-GIT expression was confirmed by Western blotting and its immunocompetence was estimated through ELISA. Further, we immunized BALB/c mice with the LTB-GIT plus CpG adjuvant. After the second immunization, the antigen-specific CD4+ cell responses for IFN-γ, IL-2, IL-4 and IL-10 were monitored by intracellular cytokine staining (ICS) assay. After the third immunization, the level of IgG antibodies in the serum from immunized groups was assessed by ELISA, and the protective immune response was appraised by Staphylococcus aureus and Streptococcus dysgalactiae challenge. RESULTS: The ELISA results showed that the OD450nm value of the LTB-GIT group was significantly higher than that of the BSA group. The group immunized with LTB-GIT plus CpG exhibited significantly stronger CD4+ T cell responses for IFN-γ, IL-2, IL-4 and IL-10 compared to the group immunized with LTB-GIT, GIT alone orLTB-GIT plus CpG. In addition, the group immunized with LTB-GIT plus CpG generated the highest level of IgG antibodies against GIT among all of the groups, and our results also showed that LTB-GIT plus CpG markedly improved the survival percentage of mice compared to other groups. CONCLUSION: We confirmed that the novel double adjuvants, LTB and CpG, are able to significantly improve GIT-induced immune responses. This formula could be a promising strategy for enhancing the immune efficacy of multi-subunit vaccines against Staphylococcus aureus and streptococcal infection.

Longevity of protective immune responses induced by a split influenza A (H7N9) vaccine mixed with MF59 adjuvant in BALB/c mice.

The influenza virus is a serious threat to public health worldwide. A novel avian influenza A (H7N9) virus with a mortality rate of approximately 30% has been identified as an unusually dangerous virus for humans by the World Health Organization. Pathogenic H7N9 continue to represent a public health concern, and several candidate vaccines are currently in development. We generated candidate H7N9 vaccine strains using reverse genetics, consisting of hemagglutinin and neuraminidase genes derived from a human H7N9 virus and the remaining genes from the PR8 (A/PuertoRico/8/34 (H1N1)) virus. This H7N9 vaccine exhibited superior efficacy when combined with MF59 compared to other adjuvants. Immunized BALB/c mice were followed to determine the duration of the protective immune response. Antibody levels decreased to between one-half and one-eighth of the peak values four months after the final dose of the vaccine. Previously vaccinated mice received an A/Zhejiang/DTID-ZJU01/2013 H7N9 challenge six months post-vaccination, and all remained protected. We also verified that MF59 enhanced the HI, MN, and IgG antibody titers to influenza antigens. The humoral immune response and Th2 cytokine production following influenza challenge was potently induced in the animals that received the split vaccine. Therefore, the split H7N9 influenza vaccine with the MF59 adjuvant could effectively induce antibody production and protect mice from H7N9 virus challenge even after six months.

Novel Adjuvants and Immunomodulators for Veterinary Vaccines.

Adjuvants are crucial for efficacy of vaccines, especially subunit and recombinant vaccines. Rational vaccine design, including knowledge-based and molecularly defined adjuvants tailored for directing and potentiating specific types of host immune responses towards the antigens included in the vaccine is becoming a reality with our increased understanding of innate and adaptive immune activation. This will allow future vaccines to induce immune reactivity having adequate specificity as well as protective and recallable immune effector mechanisms in appropriate body compartments, including mucosal surfaces. Here we describe these new developments and, when possible, relate new immunological knowledge to the many years of experience with traditional, empirical adjuvants. Finally, some protocols are given for production of emulsion (oil-based) and liposome-based adjuvant/antigen formulations.

Delivery systems for Leishmania vaccine development.

Leishmaniasis is a neglected disease and is endemic in tropical and sub-tropical areas worldwide. Lifelong immunity after recovery indicates that vaccination could be a promising approach to overcome the disease. Although different antigens have been successfully tested against all clinical forms, none of them have been shown to fulfill the safety and efficiency requirements for human applications. Hence, strong vehicles are needed to carry antigens of interest and potentiate its presence in the body. So far, various live or chemical carriers have been applied to reinforce the immunological effects of ideal antigens. In the current review, the recent attempts in this field have been summarized.

Technologies for the development of West Nile virus vaccines.

West Nile virus (WNV), an emerging mosquito-borne and zoonotic flavivirus, continues to spread worldwide and represents a major problem for human and veterinary medicine. In recent years, severe outbreaks were observed in the USA and Europe with neighboring countries, and the virus is considered to be endemic in an increasing number of areas. Although most infections remain asymptomatic, WNV can cause severe, even fatal, neurological disease, which affects mostly the elderly and immunocompromised individuals. Several vaccines have been licensed in the veterinary sector, but no human vaccine is available today. This review summarizes recent strategies that are being followed to develop WNV vaccines with emphasis on technologies suitable for the use in humans.

Immune reconstitution and vaccination outcome in HIV-1 infected children: present knowledge and future directions.

Current evidence on routine immunization of HIV-1 infected children point out the need for a special vaccine schedule in this population. However, optimal strategies for identifying individuals susceptible to infections, and then offering them sustained protection through appropriate immunization schedule, both in terms of timing and number of vaccine doses, still remain to be elucidated. Understanding the degree of immune recovery after HAART initiation is important in guiding administration of routine vaccination in HIV-1 infected children. Although quantitative measures (e.g., CD4+ T-cell counts and immunoglobulin levels) are frequently performed to evaluate immune parameters, these measures do not fully mirror functional immune recovery. Here, we will review the status of single mandatory and recommended vaccines for HIV-1 infected children in relation to immune recovery after HAART initiation with the aim of identifying new means to help design personalized vaccine schedules for this population.