Can i dilute concentrated lentivirus directly without filtering it first?

Yes, you can dilute concentrated lentivirus directly without filtering it first, provided that you maintain good lab practices to keep the virus stock sterile. Filtering is generally not necessary unless there are concerns about contamination during virus production or if you're working with high titer virus where large debris might be present. Just ensure to use an appropriate medium for dilution and handle everything in a sterile environment to minimize any risk of contamination.