For in vivo use (animal models), is the cesium chloride purification required?
A. Yes: CsCl purification is essential in order to 1) remove defective particles, 2) remove condition media with its contaminants from the viral preparation, 3) concentrate the virus to a level suitable for injection and 4) resuspend the virus in a buffer suitable for injection. For in vivo work, the virus must be purified since a cell lysate contains defective particles, a large quantity of fiber and penton proteins which are known to be cytotoxic, as well as media, serum and cellular debris. If the virus is to be injected into animals, the presence of these components will elicit a very strong immune response.
