Patent ID: 8016120

Claim:
A method for obtaining viruses from a liquid viral suspension, the method comprising subjecting the viral suspension to density gradient ultracentrifugation, wherein, the ultracentrifugation is carried out continuously, and the density gradient is a discontinuous gradient comprising at least 2 steps wherein (i) the centrifugal force to which the liquid viral suspension is subjected at the inlet of the ultracentrifuge has a value of between 36 000 and 60 000 g, (ii) the centrifugal force to which the viral suspension is subjected at the end of the density gradient has a value of between 90 000 and 120 000 g, (iii) the volume available for the circulation of the liquid and the density gradient inside the ultracentrifuge is approximately 8 1, and (iv) the liquid viral suspension comprises flu virus and ovalbumin in suspension in concentrated allantoic fluid from eggs; and the virus-containing portion of the gradient is collected.