Innate immune responses help control SARS-CoV-2 replication, and a specific lactic acid bacteria strain, Lactococcus lactis strain Plasma (LC-Plasma), can activate immune cells called plasmacytoid dendritic cells (pDCs).
Research showed that when pDCs are stimulated with LC-Plasma, their secretions can reduce SARS-CoV-2 replication in cell cultures.
The study also found that the secretion of interferon-α (IFN-α) from pDCs is crucial to this suppression; blocking IFN-α decreased the effectiveness of LC-Plasma in reducing the virus's replication.