Knockout of the Tnfa Gene Decreases Influenza Virus-Induced Histological Reactions in Laboratory Mice

Abstract

Tumor necrosis factor alpha (TNF-α) is a cytokine that is responsible for many processes associated with immune response and inflammation. It is involved in the development of an antiviral response to many virus infections. This factor was shown to be activated in influenza A virus infection, which enhances production of other cytokines. The overexpression of these cytokines can lead to a cytokine storm. To study the role of TNF-α in the development of pathologies associated with viral infection, we generated a Tnfa knockout mouse strain. We demonstrated that these mice were characterized by a significant increase in the number of viral genomes compared to that in the parental strain, but the amount of live virus did not differ. A histopathology of the lungs in the genetically modified animals was significantly lower in terms of interalveolar septal infiltration. The generated model may be used to further study pathological processes in viral infections.

Keywords: CRISPR/Cas9; H1N1; TNF-α; influenza A virus; knockout mice.

Figure 1

Infection of Tnfa knockout mice with H1N1 influenza A virus. (a) Scheme of deletion in Tnfa gene of C57BL6/J-Tnfa_KO mice. (b) Graphical representation of the experimental design. (c) Amount of viral genomic RNA in lungs of infected mice ¹. (d) Amount of infectious viral particles in lungs of infected mice ¹. (e) Amount of viral genomic RNA in brain of infected mice ¹. (f) Histological alterations in organs on the 5th day after infection. Infiltration of lymphocytes into interalveolar septa is obvious in C57BL6/J mice. (g) Graphical representation of severity of interalveolar septal infiltration in mice ¹. Note: * p < 0.05, ** p < 0.01, *** p < 0.001, # p < 0.1. ¹ Legend on block (g) is common for blocks (c–e,g).