What is the name of a virus that infects bacteria?

A virus that specifically infects bacteria is called a bacteriophage. Bacteriophages, or phages for short, are a significant group of viruses and can be highly specific to the bacterial species they infect, often targeting specific strains within those species. They play a crucial role in regulating bacterial populations and influencing microbial communities in various environments, including human microbiomes and ecosystems.

These viruses attach to bacterial cells, inject their genetic material, and initiate a process where they can either replicate within the host leading to cell lysis or integrate into the bacterial genome in a lysogenic cycle.

The other types of viruses listed do not infect bacteria. Retroviruses, for example, primarily infect animal cells and are well-known for their role in diseases such as HIV. Mycophages are viruses that infect fungi, and archaeoviruses infect archaeal cells, which are distinct from both bacteria and eukaryotes. Therefore, the correct answer highlights the unique relationship between bacteriophages and their bacterial hosts.