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- Falkeborn, Tina, 1981-
(författare)
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Nasal vaccination using novel mucosal adjuvants : with main focus on influenza A virus
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Influenza viruses have sporadically caused pandemics during the last century, with the most severe occurring in 1918 when the “Spanish flu”, an A/H1N1 influenza virus, passed around the globe killing about 20-100 million people. Today 250 000-500 000 deaths occur annually due to influenza virus or secondary infection after influenza, e.g. pneumonia. Influenza viruses cause severe infections in susceptible age groups like children and elderly and in individuals with impaired immune response due to other medical conditions. The best way to prevent an influenza epidemic is by vaccination. Since the 1950´s we have vaccines against seasonal flu, but vaccine efficacy is not 100 % and there is a need to develop better and more effective vaccines, especially for the risk groups. Since the virus enters the host through the nasal cavity, nasal vaccination is a good approach. By stimulating a mucosal immune response already in the nasal cavity, the goal with nasal vaccination is to stop the virus before it enters the host. Nasal vaccination also reduces the risk of transmission of blood-borne diseases, and is less painful and easier to administer, compared to injectable vaccines.In order to be able to use less immunogenic antigens, like split and subunit antigens, as nasal vaccine components, an adjuvant is needed to enhance the immune response. At the moment there is no licensed mucosal adjuvant for human use. Several studies are ongoing, but it is a complicated and long way to reach the market. In this thesis nasal vaccination with influenza antigen together with the mucosal adjuvant Endocine™ and other mucosal adjuvants has been evaluated. The Endocine™ adjuvant has been shown to be safe and well tolerated in clinical trials. Depending on the pathogen of interest, different approaches are necessary. For HIV, DNA-vaccination has been evaluated together with a plasmid encoding Salmonella typhimurium flagellin C and the mucosal adjuvant N3. The results found in paper I-IV show that by adding adjuvant to the antigen enhances the protective immune response towards the antigen. Enhanced systemic, mucosal and cell-mediated immunity were observed. Hopefully in the future these adjuvants evaluated in this thesis, will be used in vaccines for humans.
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| 2. |
- Ellegård, Rada, 1985-
(författare)
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Effects of Complement Opsonization of HIV on Dendritic Cells : and Implications for the Immune Response
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dendritic cells are key players during HIV pathogenesis, and shape both the immediate immune response at the site of infection as well as directing the adaptive immune response against the virus. HIV has developed a plethora of immune evasion mechanisms that hijack dendritic cell functions, suppressing their ability to mount an accurate immune response and exploiting them for efficient viral transfer to target T cells.To achieve successful replication within dendritic cells without triggering danger signaling, HIV accomplishes a delicate balance where only a low level of transcription can be sustained without triggering antiviral responses that would harm the virus. Here, we describe how the presence of HSV2 coinfection, which is very common in geographic areas with a high HIV prevalence and almost triples the risk of HIV acquisition, alters dendritic cell state to support much higher levels of HIV infection. We found this effect to be mediated by the STING pathway, which is involved in the sensing of DNA in the cell cytosol. STING activation led to an upregulation of factors such as IRF3 and NFkB that can be used for HIV transcription and a degradation of factors that restrict HIV replication.In addition, we describe how HIV exploits the human complement system, a group of proteins that usually help the human body to identify dangerous pathogens while avoiding reaction towards self. HIV can coat itself, i.e. become opsonized, in complement fragments that are typically only present on the body’s own cells, allowing it to activate signaling pathways that are associated with tolerance. Dendritic cells that come into contact with complement opsonized HIV do not mount danger responses, despite the fact that HIV-derived single stranded RNA triggers the pathogen recognition receptor TLR8. The suppression of danger responses is mediated by activation of complement receptor 3, and leads to an increased infection of the dendritic cell and affects its interactions with other immune cells. There is a lack of recruitment of NK cells to the site of infection, and an inhibition of NK cell killing, which plays an important role in the destruction of HIV-infected cells in vivo. T cells primed by dendritic cells exposed to complement opsonized HIV have a lower ability to develop towards effector phenotype, and have an increased expression of the markers PD1, TIM3 and LAG3 which are associated with T cell dysfunction and exhaustion. In addition, T cells primed by these dendritic cells in the presence of NK cells upregulate markers CD38, CXCR3 and CCR4, which have been linked to an increased susceptibility to HIV infection.In summary, we add to the current knowledge on HIV immune evasion mechanisms that allow the virus to establish infection, as well as describing mechanisms that govern whether dendritic cells mount danger signaling and an immune response or not.
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