• Deletion of Irf3 and Irf7 Genes in Mice Results in Altered Interferon Pathway Activation and Granulocyte-Dominated Inflammatory Responses to Influenza A Infection.

      Hatesuer, Bastian; Hoang, Hang Thi Thu; Riese, Peggy; Trittel, Stephanie; Gerhauser, Ingo; Elbahesh, Husni; Geffers, Robert; Wilk, Esther; Schughart, Klaus; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr.7, 38124 Braunschweig, Germany. (2017)
      The interferon (IFN) pathway plays an essential role in the innate immune response following viral infections and subsequent shaping of adaptive immunity. Infections with influenza A viruses (IAV) activate the IFN pathway after the recognition of pathogen-specific molecular patterns by respective pattern recognition receptors. The IFN regulatory factors IRF3 and IRF7 are key players in the regulation of type I and III IFN genes. In this study, we analyzed the role of IRF3 and IRF7 for the host response to IAV infections in Irf3-/-, Irf7-/-, and Irf3-/-Irf7-/- knockout mice. While the absence of IRF3 had only a moderate impact on IFN expression, deletion of IRF7 completely abolished IFNα production after infection. In contrast, lack of both IRF3 and IRF7 resulted in the absence of both IFNα and IFNβ after IAV infection. In addition, IAV infection of double knockout mice resulted in a strong increase of mortality associated with a massive influx of granulocytes in the lung and reduced activation of the adaptive immune response.
    • Distinct gene loci control the host response to influenza H1N1 virus infection in a time-dependent manner.

      Nedelko, Tatiana; Kollmus, Heike; Klawonn, Frank; Spijker, Sabine; Lu, Lu; Heßman, Manuela; Alberts, Rudi; Williams, Robert W; Schughart, Klaus; Department of Infection Genetics, Helmholtz Centre for Infection Research and University of Veterinary Medicine Hannover, 38124, Braunschweig, Germany. (2012)
      There is strong but mostly circumstantial evidence that genetic factors modulate the severity of influenza infection in humans. Using genetically diverse but fully inbred strains of mice it has been shown that host sequence variants have a strong influence on the severity of influenza A disease progression. In particular, C57BL/6J, the most widely used mouse strain in biomedical research, is comparatively resistant. In contrast, DBA/2J is highly susceptible.
    • Immunization with live virus vaccine protects highly susceptible DBA/2J mice from lethal influenza A H1N1 infection.

      Dengler, Leonie; May, Mathias; Wilk, Esther; Bahgat, Mahmoud M; Schughart, Klaus; Department of Infection Genetics, Helmholtz Centre for Infection Research and University of Veterinary Medicine Hannover, Inhoffenstr. 7, D-38124 Braunschweig, Germany. (2012)
      The mouse represents an important model system to study the host response to influenza A infections and to evaluate new prevention or treatment strategies. We and others reported that the susceptibility to influenza A virus infections strongly varies among different inbred mouse strains. In particular, DBA/2J mice are highly susceptible to several influenza A subtypes, including human isolates and exhibit severe symptoms after infection with clinical isolates.
    • Inhibition of lung serine proteases in mice: a potentially new approach to control influenza infection.

      Bahgat, Mahmoud M; Błazejewska, Paulina; Schughart, Klaus; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2011-01-20)
      Host serine proteases are essential for the influenza virus life cycle because the viral haemagglutinin is synthesized as a precursor which requires proteolytic maturation. Therefore, we studied the activity and expression of serine proteases in lungs from mice infected with influenza and evaluated the effect of serine protease inhibitors on virus replication both in cell culture and in infected mice.
    • Protection from Severe Influenza Virus Infections in Mice Carrying the Mx1 Influenza Virus Resistance Gene Strongly Depends on Genetic Background.

      Shin, Dai-Lun; Hatesuer, Bastian; Bergmann, Silke; Nedelko, Tatiana; Schughart, Klaus; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2015-10)
      Influenza virus infections represent a serious threat to human health. Both extrinsic and intrinsic factors determine the severity of influenza. The MX dynamin-like GTPase 1 (Mx1) gene has been shown to confer strong resistance to influenza A virus infections in mice. Most laboratory mouse strains, including C57BL/6J, carry nonsense or deletion mutations in Mx1 and thus a nonfunctional allele, whereas wild-derived mouse strains carry a wild-type Mx1 allele. Congenic C57BL/6J (B6-Mx1(r/r)) mice expressing a wild-type allele from the A2G mouse strain are highly resistant to influenza A virus infections, to both mono- and polybasic subtypes. Furthermore, in genetic mapping studies, Mx1 was identified as the major locus of resistance to influenza virus infections. Here, we investigated whether the Mx1 protective function is influenced by the genetic background. For this, we generated a congenic mouse strain carrying the A2G wild-type Mx1 resistance allele on a DBA/2J background (D2-Mx1(r/r)). Most remarkably, congenic D2-Mx1(r/r) mice expressing a functional Mx1 wild-type allele are still highly susceptible to H1N1 virus. However, pretreatment of D2-Mx1(r/r) mice with alpha interferon protected them from lethal infections. Our results showed, for the first time, that the presence of an Mx1 wild-type allele from A2G as such does not fully protect mice from lethal influenza A virus infections. These observations are also highly relevant for susceptibility to influenza virus infections in humans.