Vector taxonomy — Moloney murine leukemia virus (MoMLV / Moloney–Mu–leukemia virus) is best classified as which type of virus?

Introduction / Context:
MoMLV is a prototypical gamma-retrovirus widely used in early gene therapy vectors. Understanding its classification informs properties such as integration into host DNA and the requirement for cell division during transduction.

Given Data / Assumptions:

• MoMLV is an RNA virus that uses reverse transcriptase.
• Its life cycle includes conversion of RNA to DNA and integration into the host genome (provirus).
• Classically transduces dividing cells efficiently.

Concept / Approach:
Retroviruses are defined by their reverse transcription step and proviral integration. Baculoviruses infect insects; vaccinia is a large DNA poxvirus; adenoviruses are non-enveloped DNA viruses; herpesviruses are enveloped dsDNA viruses with latent replication—none match MoMLV’s key traits.

Step-by-Step Solution:

Verification / Alternative check:
Retroviral packaging systems (gag/pol/env) are derived from MoMLV, confirming its class.

Why Other Options Are Wrong:

• a/b/d/e: These are different DNA virus families without obligatory reverse transcription integration cycles.

Common Pitfalls:
Confusing lentiviruses (a retrovirus subgroup that infects non-dividing cells) with oncoretroviruses like MoMLV that require cell division for nuclear entry.

Final Answer:
Retrovirus