Which of the following phage types cause productive infections that do not kill the host cell?

• A. Retroviruses
• B. Lytic phages
• C. Filamentous phages
• D. Temperate phages

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the types of phage infections. Productive infections are those where new phage particles are produced inside the host cell.
2. Step 2: Recall that lytic phages cause productive infections that result in host cell lysis (death), so they do not fit the criteria of productive infection without killing the host.
3. Step 3: Temperate phages can integrate into the host genome and enter a lysogenic cycle, where they do not produce new phages immediately and do not kill the host cell during lysogeny; however, when they enter the lytic cycle, they do cause host cell death.
4. Step 4: Retroviruses are not phages; they infect eukaryotic cells and integrate into the host genome, but this is outside the scope of phage biology.
5. Step 5: Filamentous phages cause productive infections by continuously releasing new phage particles without lysing (killing) the host cell, allowing the host to survive and continue producing phages.