Induction of CD8 T Cell Heterologous Protection by a Single Dose of Single-Cycle Infectious Influenza Virus
ABSTRACT The effector functions of specific CD8 T cells are crucial in mediating influenza heterologous protection. However, new approaches for influenza vaccines that can trigger effective CD8 T cell responses have not been extensively explored. Here, we report the generation of single cycle infectious influenza virus that lacks a functional HA gene on an X31 genetic background and demonstrate its potential for triggering protective CD8 T cell immunity against heterologous influenza challenge. In vitro, X31-sciIV can infect MDCK cells, but infectious virions are not produced unless HA is trans-complimented. In vivo, intranasal immunization with X31-sciIV does not cause any clinical symptoms in mice but generate influenza specific CD8 T cells in lymphoid (MLN and spleen) and non-lymphoid tissues including lung and BAL as measured by H2-Db NP366 and PA224 tetramer staining. In addition, a significant proportion of X31-sciIV induce, antigen specific respiratory CD8 T cells expressed VLA-1, a marker that is associated with heterologous influenza protection. Further, these influenza specific CD8 T cells produce antiviral cytokines when stimulated with NP366 and PA224 peptides, indicating CD8 T cells triggered by X31-sciIV are functional. When challenged with a lethal dose of heterologous PR8 virus, X31-sciIV primed mice were fully protected from death. However, when CD8 T cells were depleted after priming or before priming, mice could not effectively control virus replication or survive the lethal challenge, indicating X31-sciIV induced memory CD8 T cells mediate the heterologous protection. Thus, our results demonstrate the potential for sciIV as a CD8 T cell inducing vaccine.
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ABSTRACT: Despite countermeasures against influenza virus that prevent (vaccines) and treat (antivirals) infection, this upper respiratory human pathogen remains a global health burden, causing both seasonal epidemics and occasional pandemics. More potent and safe new vaccine technologies would contribute significantly to the battle against influenza and other respiratory infections. Using plasmid-based reverse genetics techniques, we have developed a single-cycle infectious Influenza Virus (sciIV) with immunoprotective potential. In our sciIV approach, the fourth viral segment, which encodes for the receptor-binding and fusion protein hemagglutinin (HA), has been removed. Thus upon infection of normal cells, although no infectious progeny are produced, the expression of other viral proteins occurs and is immunogenic. Consequently, sciIV is protective against influenza homologous and heterologous viral challenges in a mouse model. Vaccination with sciIV protects in a dose- and replication-dependent manner, which is attributed to both humoral responses and T cells. Safety, immunogenicity and protection conferred by sciIV vaccination were also demonstrated in ferrets, where this immunization additionally blocked direct and aerosol transmission events. Altogether, our studies suggest that sciIV may have potential as a broadly protective vaccine against influenza virus.Journal of Virology 05/2013; 87(15). DOI:10.1128/JVI.01081-13 · 4.65 Impact Factor
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ABSTRACT: Respiratory challenge of H-2b mice with an H3N2 influenza A virus causes an acute, transient pneumonitis characterized by the massive infiltration of CD8+ T lymphocytes. The inflammatory process monitored by quantitative analysis of lymphocyte populations recovered by bronchoalveolar lavage is greatly enhanced by prior exposure to an H1N1 virus, with the recall of cross-reactive CD8+-T-cell memory leading to more rapid clearance of the infection from the lungs. The predominant epitope recognized by the influenza virus-specific CD8+ set has long been thought to be a nucleoprotein (NP366–374) presented by H-2Db (DbNP366). This continues to be true for the secondary H3N2→H1N1 challenge but can no longer be considered the case for the primary response to either virus. Quantitative analysis based on intracellular staining for gamma interferon has shown that the polymerase 2 protein (PA224–233) provides a previously undetected epitope (DbPA224) that is at least as prominent as DbNP366 during the first 10 days following primary exposure to either the H3N2 or H1N1 virus. The response to DbNP366 seems to continue for longer, even when infectious virus can no longer be detected, but there is no obvious difference in the prevalence of memory T cells specific for DbNP366 and DbPA224. The generalization that the magnitude of the functional memory T-cell pool is a direct consequence of the clonal burst size during the primary response may no longer be useful. Previous CD8+-T-cell immunodominance heirarchies defined largely by cytotoxic T-lymphocyte assays may need to be revised.Journal of Virology 05/2000; 74(8). DOI:10.1128/JVI.74.8.3486-3493.2000 · 4.65 Impact Factor
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ABSTRACT: Influenza virus infection of humans results in a respiratory disease that ranges in severity from sub-clinical infection to primary viral pneumonia that can result in death. The clinical effects of infection vary with the exposure history, age and immune status of the host, and also the virulence of the influenza strain. In humans, the virus is transmitted through either aerosol or contact-based transfer of infectious respiratory secretions. As is evidenced by most zoonotic influenza virus infections, not all strains that can infect humans are able to transmit from person-to-person. Animal models of influenza are essential to research efforts aimed at understanding the viral and host factors that contribute to the disease and transmission outcomes of influenza virus infection in humans. These models furthermore allow the pre-clinical testing of antiviral drugs and vaccines aimed at reducing morbidity and mortality in the population through amelioration of the virulence or transmissibility of influenza viruses. Mice, ferrets, guinea pigs, cotton rats, hamsters and macaques have all been used to study influenza viruses and therapeutics targeting them. Each model presents unique advantages and disadvantages, which will be discussed herein.Viruses 08/2010; 2(8):1530-1563. DOI:10.3390/v20801530 · 3.28 Impact Factor