Suppression of influenza A virus replication in human lung epithelial cells by noncytotoxic concentrations bafilomycin A1

Abstract

Subcellular trafficking within host cells plays a critical role in viral life cycles, including influenza A virus (IAV). Thus targeting relevant subcellular compartments holds promise for effective intervention to control the impact of influenza infection. Bafilomycin A1 (Baf-A1), when used at relative high concentrations (≥10 nM), inhibits vacuolar ATPase (V-ATPase) and reduces endosome acidification and lysosome number, thus inhibiting IAV replication but promoting host cell cytotoxicity. We tested the hypothesis that much lower doses of Baf-A1 also have anti-IAV activity, but without toxic effects. Thus we assessed the antiviral activity of Baf-A1 at different concentrations (0.1-100 nM) in human alveolar epithelial cells (A549) infected with IAV strain A/PR/8/34 virus (H1N1). Infected and mock-infected cells pre- and cotreated with Baf-A1 were harvested 0-24 h postinfection and analyzed by immunoblotting, immunofluorescence, and confocal and electron microscopy. We found that Baf-A1 had disparate concentration-dependent effects on subcellular organelles and suppressed affected IAV replication. At concentrations ≥10 nM Baf-A1 inhibited acid lysosome formation, which resulted in greatly reduced IAV replication and release. Notably, at a very low concentration of 0.1 nM that is insufficient to reduce lysosome number, Baf-A1 retained the capacity to significantly impair IAV nuclear accumulation as well as IAV replication and release. In contrast to the effects of high concentrations of Baf-A1, very low concentrations did not exhibit cytotoxic effects or induce apoptotic cell death, based on morphological and FACS analyses. In conclusion, our results reveal that low-concentration Baf-A1 is an effective inhibitor of IAV replication, without impacting host cell viability.

The combination of oseltamivir with azithromycin does not show additional benefits over oseltamivir monotherapy in mice infected with influenza A(H1N1)pdm2009 virus

“…As expected, azithromycin monotherapy did not confer protection in terms of SR and weight loss; nevertheless, we interestingly observed that this macrolide could reduce viral replication in vivo and in vitro. These results are in agreement with previous studies where macrolides were associated with reduced viral titers in infected cells . Such direct antiviral effect was suggested to occur during the middle‐to‐late stage of the replication cycle .…”

Changes in circulating microRNA levels can be identified as early as day 8 of pregnancy in cattle

“…Four of the seven miRNAs, miR-143, miR-101, miR-30c and miR-26a, have been shown in previous studies to regulate insulin signalling and lipid metabolism and to be involved in diabetes [43–46], and thus they may play important roles regulating changes in maternal metabolism occurring early during pregnancy. In addition, miR-26a and let-7f have been shown to regulate macrophage- and T-cell-mediated immunity [47–50] which would be consistent with a role in establishing maternal immuno-tolerance, a key function during early pregnancy. Finally, miR-101, miR-205 and miR-26a are known regulators of angiogenesis [51–54], a key process during development of foeto-placental and maternal tissues during pregnancy.…”

New frontiers in the treatment of colorectal cancer: Autophagy and the unfolded protein response as promising targets

“…In both normal and malignant cells, autophagy may be induced in response to cellular stress, 62 including nutrient deprivation, hypoxia, and toxin accumulation 62 . The outcome of autophagy induction however, affects the cell in various ways, being protective, and promoting survival, or causing growth arrest and triggering programmed cell death 67 . The molecular components of this pathway were first discovered in yeasts and include more than 40 autophagy-related (ATG) proteins.…”