Easily concentrate any retrovirus with Retro-Concentin, a reagent which enables ultracentrifugation-free retrovirus concentration for higher infectivity. Quantitatively precipitate any retrovirus with Retro-Concentin™. Instead of using lengthy spins in an ultracentrifuge, Retro-Concentin enables concentration of retroviruses directly from culture medium with a simple one (or an optional two) low-speed centrifugation steps. In addition, Retro-Concentin stabilizes the retroviruses for frozen storage, providing an additional advantage over other concentration methods.