Animal cell gene delivery — Which viruses are commonly used as vectors for transferring genes into animal cells?

Introduction / Context:
Viral vectors exploit natural infection and replication pathways to deliver genetic cargo into animal cells. Different vectors provide distinct advantages in host range, genome integration, packaging capacity, and expression persistence.

Given Data / Assumptions:

• SV40 is a well-studied small DNA tumor virus used historically for transient expression.
• BPV-based vectors can replicate episomally in certain mammalian cells.
• Retroviruses (including lentiviruses) integrate into host genomes, enabling stable expression in dividing (and, for lentivirus, non-dividing) cells.

Concept / Approach:
Select the option that correctly lists legitimate animal cell vectors. Each listed virus has documented use as a vector system. Therefore the inclusive answer is correct.

Step-by-Step Solution:

Verification / Alternative check:
Textbooks and vector supplier catalogs enumerate SV40-, BPV-, and retroviral-based vectors for animal transduction.

Why Other Options Are Wrong:

• a/b/c individually are incomplete; the question asks which viruses are used, and all listed are valid.
• e is false because several are indeed used.

Common Pitfalls:
Assuming only integrating vectors count; episomal and transient systems are widely used in protein production and functional assays.

Final Answer:
All of these