METHOD FOR DETERMINING THE CONCENTRATION OF VIRUS PARTICLES/VIRUS ANTIGENS

1 - 24 . (canceled)

25 . A method for growing a virus propagation culture, the method comprising steps of:

a) removing a sample from a virus propagation culture comprising virus particles and/or virus antigens, wherein the sample volume is less than a complete culture volume of the virus propagation culture,

b) subjecting the sample to a cation-exchange matrix under a condition that allows binding of the virus particles and/or virus antigens to the cation-exchange matrix so as to separate the virus particles and/or virus antigens from the sample;

c) quantitating the virus particles and/or virus antigens with a detection signal, wherein the detection signal is indicative of the concentration of the virus particles and/or virus antigens in the sample; and,

d) further processing the virus propagation culture if the sample from step (c) has a yield of at least 5 μg per ml of virus particles and/or virus antigens.

26 . The method of claim 25 , wherein the steps (a) through (c) are performed within a period of several hours or less.

27 . The method of claim 25 , wherein the cation-exchange matrix comprises a cellulose matrix.

28 . The method of claim 27 , wherein the cellulose matrix has a gel exclusion limit of 2000 to 4000 Dalton.

29 . The method of claim 27 , wherein the cellulose matrix comprises sulfate ester.

30 . The method of claim 25 , wherein the virus propagation culture is an egg culture.

31 . The method of claim 25 , wherein the virus propagation culture is a mammalian cell culture.

32 . A method for determining the concentration of virus particles and/or virus antigens in a sample comprising the steps of

a) applying a sample containing virus particles and/or virus antigens to a cellulose matrix under a condition that allows binding of said virus particles and/or virus antigens to the cellulose matrix, thereby separating said virus particles and/or virus antigens from other sample components;

b) eluting said bound virus particles and/or virus antigens from the cellulose matrix; and

c) detecting the virus particles and/or virus antigens; wherein the detection signal is indicative for the concentration of said virus particles and/or virus antigens in the sample.

33 . The method according to claim 32 , wherein the method further comprises the step of comparing the detection signal to at least one reference value obtained from detecting a sample containing said virus particles and/or virus antigens in a known concentration in order to determine the concentration of virus particles and/or virus antigens in the sample.

34 . The method according to claim 33 , wherein the detection signal is compared to more than one reference value.

35 . The method of claim 32 , wherein the virus is an influenza virus.

36 . The method of claim 32 , wherein said sample is from an egg culture.

37 . The method of claim 32 , wherein said sample is from a cell culture.

38 . The method of claim 32 , wherein the condition that allows binding of the virus particles and/or virus antigens comprises a low salt condition.

39 . The method of claim 32 , wherein the step of eluting the virus particles and/or virus antigens comprises a high salt condition.

40 . The method of claim 32 , wherein the step of detection comprises measuring UV absorbance of elution fractions.