Cell-derived viral vaccines with low levels of residual cell DNA
The present invention relates to vaccine products for the treatment or prevention of viral infections. Further provided are methods of reducing contaminants associated with the preparation of cell culture vaccines. Residual functional cell culture DNA is degraded by treatment with a DNA alkylating agent, such as β-propiolactone (BPL), thereby providing a vaccine comprising immunogenic proteins derived from a virus propagated on cell culture, substantially free of residual functional cell culture DNA.
1. A method of preparing an influenza vaccine with less than 10 ng per 0.5 ml residual DNA fragments of less than 300 base pairs, wherein the vaccine is formulated in a sub-virion form comprising immunogenic proteins derived from an influenza virus propagated on a cell culture, comprising:
(i) treating the influenza virus with an alkylating agent that inactivates the influenza virus and degrades residual functional cell culture DNA, wherein the degradation is performed at a temperature that degrades the residual functional cell culture DNA into fragments of less than 300 base pairs in length, and wherein the alkylating agent is β-propiolactone (BPL);
(ii) disrupting or fragmenting the influenza virus from step (i) with a disrupting concentration of a splitting agent, wherein the splitting agent comprises cetyltrimethylammonium bromide (CTAB); and
(iii) isolating the immunogenic proteins.
2. The method of claim 1 , wherein said cell culture DNA is degraded by treatment with less than 0.1% of BPL.
3. The method of claim 1 , wherein said vaccine exhibits a reduced level of aggregation.
4. The method of claim 1 , wherein step (iii) involves separating DNA from virions.
5. The method of claim 1 , wherein the cell culture is selected from the group consisting of Madin-Darby canine kidney (MDCK) cells, Vero cells, and human embryonic retinoblasts.
6. The method of claim 1 , wherein the sub-virion vaccine is a purified viral protein vaccine.
7. The method of claim 1 , wherein the immunogenic proteins are viral antigens selected from the group consisting of hemagglutinin (HA), neuraminidase (NA), nucleoprotein (NP), matrix protein (M1), membrane protein (M2), and one or more of the transcriptase components (PB1, PB2 and PA).
8. The method of claim 7 , wherein the immunogenic protein is HA.
9. The method of claim 7 , wherein the immunogenic protein is NA.
10. The method of claim 1 , further comprising: (iv) formulating the immunogenic proteins into a vaccine.
11. The method of claim 1 , wherein the method does not include a step of adding an exogenous DNase.
12. The method of claim 1 , wherein the temperature is from 25° C. to 50° C.
13. The method of claim 1 , wherein the temperature is from 37° C. to 50° C.
14. The method of claim 1 , wherein the temperature is at least 25° C.
15. The method of claim 1 , wherein the temperature is at least 37° C.
16. The method of claim 1 , wherein the temperature is 25° C.
17. The method of claim 1 , wherein the temperature is 37° C.
18. The method of claim 1 , wherein the temperature is 50° C.