RT Journal Article SR Electronic T1 Mice infected with Mycobacterium tuberculosis are resistant to secondary infection with SARS-CoV-2 JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.11.09.467862 DO 10.1101/2021.11.09.467862 A1 Mejia, Oscar Rosas A1 Gloag, Erin S. A1 Li, Jianying A1 Ruane-Foster, Marisa A1 Claeys, Tiffany A. A1 Farkas, Daniela A1 Farkas, Laszlo A1 Xin, Gang A1 Robinson, Richard T. YR 2021 UL http://biorxiv.org/content/early/2021/11/10/2021.11.09.467862.abstract AB Mycobacterium tuberculosis (Mtb) and SARS-CoV-2 (CoV2) are the leading causes of death due to infectious disease. Although Mtb and CoV2 both cause serious and sometimes fatal respiratory infections, the effect of Mtb infection and its associated immune response on secondary infection with CoV2 is unknown. To address this question we applied two mouse models of COVID19, using mice which were chronically infected with Mtb. In both model systems, Mtb-infected mice were resistant to secondary CoV2 infection and its pathological consequences, and CoV2 infection did not affect Mtb burdens. Single cell RNA sequencing of coinfected and monoinfected lungs demonstrated the resistance of Mtb-infected mice is associated with expansion of T and B cell subsets upon viral challenge. Collectively, these data demonstrate that Mtb infection conditions the lung environment in a manner that is not conducive to CoV2 survival.AUTHOR SUMMARY Mycobacterium tuberculosis (Mtb) and SARS-CoV-2 (CoV2) are distinct organisms which both cause lung disease. We report the surprising observation that Mtb-infected mice are resistant to secondary infection with CoV2, with no impact on Mtb burden and resistance associating with lung T and B cell expansion.Competing Interest StatementThe authors have declared no competing interest.