Vector classification — AcMNPV as an expression platform Autographa californica nuclear polyhedrosis virus (AcMNPV), commonly used for recombinant protein expression in insect cells, is an example of which vector type?

Introduction / Context:
Baculovirus expression vectors are a mainstay for producing complex eukaryotic proteins with proper folding and post-translational modifications in insect cell lines (e.g., Sf9). Recognizing the viral origin of popular expression systems is essential for vector selection in biotechnology.

Given Data / Assumptions:

• AcMNPV is the standard laboratory baculovirus backbone.
• Expression often uses the strong polyhedrin or p10 promoters.
• Infection is performed in lepidopteran cell lines.

Concept / Approach:
AcMNPV belongs to the Baculoviridae family. It is not a poxvirus (vaccinia), papillomavirus, or retrovirus. Its large dsDNA genome, insect host range, and capacity for high-level expression under late promoters identify it as a baculovirus.

Step-by-Step Solution:

Verification / Alternative check:
Vendor manuals and protocols (BEVS systems) explicitly cite AcMNPV as the baculovirus used for recombinant protein expression.

Why Other Options Are Wrong:

• Vaccinia: poxvirus used for recombinant vaccines; mammalian host range.
• Papillomavirus: small circular DNA viruses (e.g., HPV), not used for insect expression vectors.
• Retrovirus/AAV: mammalian gene delivery vectors, different biology.

Common Pitfalls:
Confusing baculovirus with vaccinia because both can produce high protein levels; host range and genome organization differ.

Final Answer:
Baculovirus