Pigs lacking TMPRSS2 displayed fewer lung lesions and reduced inflammatory response when infected with influenza A virus

Authors: CIACCI ZANELLA, GIOVANA - Iowa State University; SNYDER, CELESTE - Iowa State University; Arruda, Bailey; WHITWORTH, KRISTIN - University Of Missouri; GREEN, ERIN - University Of Missouri; POONOORU, RAVIKANTH - University Of Missouri; TELUGU, BHANU - University Of Missouri; Baker, Amy

Submitted to: Frontiers in Genome Editing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2023
Publication Date: 5/31/2024
Citation: Ciacci Zanella, G., Snyder, C.A., Arruda, B.L., Whitworth, K., Green, E., Poonooru, R.R., Telugu, B.P., Baker, A.L. 2024. Pigs lacking TMPRSS2 displayed fewer lung lesions and reduced inflammatory response when infected with influenza A virus. Frontiers in Genome Editing. https://doi.org/10.3389/fgeed.2023.1320180.
DOI: https://doi.org/10.3389/fgeed.2023.1320180

Interpretive Summary: Influenza A virus (IAV) causes respiratory disease in pigs and is a problem for the pork industry worldwide. Common control measures like biosecurity and vaccines are often unsuccessful, so novel approaches like gene editing pigs to be less susceptible to disease are needed. IAV enters respiratory cells by its glycoprotein called hemagglutinin (HA), like a key that unlocks the cell’s door. This key needs to be cut in a certain way by enzymes produced by the pig to work properly. TMPRSS2 is a protease enzyme produced in cells that surround the respiratory airways of pigs and was shown to cut the HA for virus infection. In mice, knocking out the TMPRSS2 gene decreased IAV disease severity. We genetically modified pigs to no longer express TMPRSS2 in their airways and then infected them with a IAV known to cause moderate disease. Although the pigs that did not express the TMPRSS2 gene were still infected, they had fewer lung lesions and lower inflammatory response. Knocking out the TMPRSS2 gene in pigs reduced disease severity which can benefit pig production. Additional gene edits may be necessary to add to the TMPRRS2 knockout to further reduce infection.

Technical Abstract: Influenza A virus (IAV) infection is initiated by hemagglutinin (HA), a glycoprotein exposed on the virion’s lipid envelope that undergoes cleavage by host cell proteases to ensure membrane fusion, entry into the host cells and completion of the viral cycle. Transmembrane protease serine S1 member 2 (TMPRSS2), a host transmembrane protease, is expressed throughout the porcine airway epithelium and is purported to play a major role in the HA cleavage process, thereby influencing viral pathogenicity and tissue tropism. Pigs are natural hosts of IAV and while the clinical signs of swine influenza are often mild, it is responsible for substantial economic impact on the pork industry worldwide. Previous studies in mice demonstrated that the deletion of TMPRSS2 gene was safe and inhibited the spread of IAV after experimental challenge., we hypothesized that ablation of TMPRSS2 will similarly prevent IAV infectivity in the swine model. We investigated this hypothesis by comparing pathogenesis of an H1N1pdm09 virus challenge in wildtype (WT) control and in TMPRSS2 knockout (KO) pigs. No differences in nasal viral shedding and lung lavage viral titers were observed between the WT and KO animals. However, the KO animal group had significantly less lung lesions and significant reductions in antiviral and proinflammatory cytokines in the lung. By RNAscope we illustrated that TMPRSS2 expression is dynamic in WT pigs and modified by IAV infection. The virus titer results in our direct challenge model contradict prior studies performed on the murine animal model, but the reduced lung lesions and cytokine profile suggest a possible role for TMPRSS2 in the proinflammatory antiviral response. Further research is warranted to investigate the role of TMPRSS2 in swine IAV infection and disease.