Membrane-based virus filtration is used in biotechnological processes due to advantages such as easy scale-up but is currently lacking standardized validation protocols. Thus, ultrafiltration (UF) of a rod-shaped virus was assessed to contribute to the body of knowledge regarding the characterization of virus filtration. A recombinant baculovirus of Autographa californica M nucleopolyhedrovirus (AcMNPV), vHSGFP, expressing egfp was filtered using polyethersulfone membranes ranging from 30 to 1000 kDa molecular weight cut-off (MWCO) and filtration parameters were previously assessed for their potential to affect virus stability. AcMNPV was concentrated 20-fold in the retentate using 100-1000 kDa membranes. However, evidence for a superposition of cake formation and pore plugging through viruses and other solution components (likely proteins) causing partially irreversible fouling of membranes dependent on the MWCO was observed. Results support UF using a 300 kDa MWCO to concentrate AcMNPV with minimized membrane fouling.