Bacterial-induced or passively administered interferon gamma conditions the lung for early control of SARS-CoV-2.

Type-1 and type-3 interferons (IFNs) are important for control of viral replication; however, less is known about the role of Type-2 IFN (IFNγ) in anti-viral immunity. We previously observed that lung infection with Mycobacterium bovis BCG achieved though intravenous (iv) administration provides strong protection against SARS-CoV-2 in mice yet drives low levels of type-1 IFNs but robust IFNγ. Here we examine the role of ongoing IFNγ responses to pre-established bacterial infection on SARS-CoV-2 disease outcomes in two murine models.

Exposure to lung-migrating helminth protects against murine SARS-CoV-2 infection through macrophage-dependent T cell activation.

Helminth endemic regions report lower COVID-19 morbidity and mortality. Here, we show that lung remodeling from a prior infection with a lung-migrating helminth, , enhances viral clearance and survival of human-ACE2 transgenic mice challenged with SARS-CoV-2 (SCV2). This protection is associated with a lymphocytic infiltrate, including increased accumulation of pulmonary SCV2-specific CD8 T cells, and anti-CD8 antibody depletion abrogated the mediated reduction in viral loads.

The Dysbiosis Triggered by First-Line Tuberculosis Antibiotics Fails to Reduce Their Bioavailability.

Antituberculosis therapy (ATT) causes a rapid and distinct alteration in the composition of the intestinal microbiota that is long lasting in both mice and humans. This observation raised the question of whether such antibiotic-induced changes in the microbiome might affect the absorption or gut metabolism of the tuberculosis (TB) drugs themselves. To address this issue, we utilized a murine model of antibiotic-induced dysbiosis to assay the bioavailability of rifampicin, moxifloxacin, pyrazinamide, and isoniazid in mouse plasma over a period of 12 h following individual oral administration.

Helminth exposure protects against murine SARS-CoV-2 infection through macrophage dependent T cell activation.

Helminth endemic regions report lower COVID-19 morbidity and mortality. Here, we show that lung remodeling from a prior infection with a lung migrating helminth, , enhances viral clearance and survival of human-ACE2 transgenic mice challenged with SARS-CoV-2 (SCV2). This protection is associated with a lymphocytic infiltrate including an increased accumulation of pulmonary SCV2-specific CD8+ T cells and anti-CD8 antibody depletion abrogated the -mediated reduction in viral loads.

Intravenous administration of BCG protects mice against lethal SARS-CoV-2 challenge.

In addition to providing partial protection against pediatric tuberculosis, vaccination with bacille Calmette-Guérin (BCG) has been reported to confer nonspecific resistance to unrelated pulmonary pathogens, a phenomenon attributed to the induction of long-lasting alterations within the myeloid cell compartment. Here, we demonstrate that intravenous, but not subcutaneous, inoculation of BCG protects human-ACE2 transgenic mice against lethal challenge with SARS-CoV-2 (SCV2) and results in reduced viral loads in non-transgenic animals infected with an α variant. The observed increase in host resistance was associated with reductions in SCV2-induced tissue pathology, inflammatory cell recruitment, and cytokine production that multivariate analysis revealed as only partially related to diminished viral load.

Intravenous administration of BCG protects mice against lethal SARS-CoV-2 challenge.

Early events in the host response to SARS-CoV-2 are thought to play a major role in determining disease severity. During pulmonary infection, the virus encounters both myeloid and epithelioid lineage cells that can either support or restrict pathogen replication as well as respond with host protective versus detrimental mediators. In addition to providing partial protection against pediatric tuberculosis, vaccination with bacille Calmette-Guérin (BCG) has been reported to confer non-specific resistance to unrelated pulmonary pathogens, a phenomenon attributed to the induction of long-lasting alterations within the myeloid cell compartment.

Water-in-Oil-Only Adjuvants Selectively Promote T Follicular Helper Cell Polarization through a Type I IFN and IL-6-Dependent Pathway.

T follicular helper (Tfh) cells are a subset of CD4 T lymphocytes that promote the development of humoral immunity. Although the triggers required for the differentiation of the other major Th subsets are well defined, those responsible for Tfh cell responses are still poorly understood. We determined that mice immunized with peptide or protein Ags emulsified in IFA or related water-in-oil adjuvants develop a highly polarized response in which the majority of the Ag-specific CD4 T cells are germinal center-homing CXCR5Bcl6 Tfh cells.

Host-directed therapy of tuberculosis based on interleukin-1 and type I interferon crosstalk.

Tuberculosis remains second only to HIV/AIDS as the leading cause of mortality worldwide due to a single infectious agent. Despite chemotherapy, the global tuberculosis epidemic has intensified because of HIV co-infection, the lack of an effective vaccine and the emergence of multi-drug-resistant bacteria. Alternative host-directed strategies could be exploited to improve treatment efficacy and outcome, contain drug-resistant strains and reduce disease severity and mortality.