Viruses can significantly influence gene expression by altering the transcription and translation processes within host cells.

When a virus infects a host cell, it commandeers the cell’s machinery to replicate its own genetic material. This process often involves the virus integrating its DNA or RNA into the host cell’s genome, which can disrupt normal patterns of gene expression. Additionally, viruses may produce proteins that interfere with the host cell’s transcription factors—proteins that play a crucial role in regulating gene expression.

In certain instances, viruses can either activate or repress specific genes within the host cell. For example, the human papillomavirus (HPV) can activate genes that promote cell growth and division, potentially leading to cancer development. Likewise, the hepatitis B virus can repress genes that are vital for immune system function, enabling the virus to evade detection and continue replicating within the host.

In summary, viruses can profoundly affect gene expression in host cells. Understanding these mechanisms is essential for developing effective treatments and vaccines for viral infections.