Final answer:
Viruses associated with cancers in animals are often retroviruses that utilize reverse transcriptase to integrate their RNA genome into the host's DNA, which can disrupt cell regulation and cause cancer.
Step-by-step explanation:
Many viruses that are associated with cancers in animals are retroviruses that use reverse transcriptase. These viruses have RNA genomes and when they infect a host cell, they use the enzyme reverse transcriptase to translate their RNA into DNA, which can then integrate with the host's genome. This integration has the potential to disrupt normal cellular regulation and potentially lead to cancer by either introducing oncogenes or interfering with tumor suppressor genes. Oncogenic viruses can be either DNA or RNA viruses, with examples including human papillomavirus (HPV) causing cervical cancer and hepatitis B virus leading to liver cancer. Retroviruses like HIV use reverse transcriptase, which is targeted by drugs such as reverse transcriptase inhibitors (e.g., AZT), to treat infections without affecting the host's cells.