The Millex® filters are designed to remove microorganisms, particles, precipitates, and undissolved powders larger than the membrane’s rated pore size, which for this product is 0.45 μm. A lentiviral particle is typically 80-100 nm (0.080 - 0.100μm) in diameter, so these should pass through the pores easily.
For compatibility information, operating steps, and other product specifications, please view this user guide: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/327/360/millex-sterile-syringe-filter-pw05510w-ms.pdf