What are viruses that specifically infect bacteria called?

Viruses that specifically infect bacteria are known as bacteriophages, often abbreviated as phages. Bacteriophages are a unique category of viruses that target bacterial cells. They attach to the bacteria's surface, inject their genetic material into the bacterial cell, and then hijack the bacterial machinery to replicate themselves. This specificity is crucial because it allows bacteriophages to effectively target pathogenic bacteria without affecting human cells or other organisms.

The other terms, while related to viral biology, do not describe viruses that infect bacteria specifically. Virophages are viruses that infect other viruses, retroviruses are a group of viruses that use RNA as their genetic material and reverse transcriptase to integrate into the host genome, and the term "phage" is a shorthand for bacteriophage but is less specific in this context. Hence, bacteriophage is the correct and most precise term to describe viruses that specifically infect bacteria.