The human cell's plasma membrane selectively allows molecules to pass through, based on size and polarity. Small non-polar molecules diffuse directly through the lipid bilayer, while small polar molecules move through specialized channels. Large polar molecules and ions require transport proteins, utilizing facilitated diffusion or active transport. Some large molecules are engulfed through phagocytosis, endocytosis, or pinocytosis.

The ISGF3 transcription factor complex upregulates various genes in response to type I interferon. Some key genes and their antiviral mechanisms include IFIT1 (inhibiting viral translation), OAS1 (activating RNase L for viral RNA degradation), and MX1 (interfering with viral replication). These genes collectively contribute to the host's innate antiviral defense by targeting different stages of viral replication.

The type I interferon receptor (IFNAR) activates downstream signaling pathways, including JAK-STAT, MAPK, PI3K-Akt, and Notch pathways. These pathways induce antiviral and immunomodulatory genes, regulate immune cell function, and play a crucial role in host defense against infections. The IFNAR signaling cascades orchestrate a complex cellular response essential for combating pathogens.