Virus purification
Described herein are improved purification methods for virus vaccines and compositions. Also described are Zika, Chikungunya, dengue and yellow fever vaccines and methods of producing and administering said vaccines to subjects in need thereof.
1. A method for purification of infectious Chikungunya virus particles, comprising the steps of
i) providing a crude harvest (a) comprising virus particles and impurities, wherein the impurities are generated from growing said virus particles on a cell substrate;
ii) reducing impurities from said crude harvest (a) by precipitation with an agent comprising protamine to obtain a virus preparation (b);
iii) further purifying said virus preparation (b) by sucrose density gradient centrifugation to obtain a Chikungunya virus preparation (c),
wherein the sucrose gradient is provided such that the protamine can be completely or almost completely separated from the virus fraction; and wherein the protamine concentration in the Chikungunya virus preparation (c) is below 1 μg/ml, and wherein said sucrose gradient comprises a Chikungunya virus comprising fraction in a 10%+/−1% (w/w) sucrose solution and three further layers of sucrose solutions with different densities, wherein the three further layers of sucrose solutions comprise a first sucrose solution with 15%+/−1% (w/w) sucrose, a second sucrose solution with 35%+/−1% (w/w) sucrose, and a third sucrose solution with 50%+/−1% (w/w) sucrose.
2. The method according to claim 1 , additionally comprising a further step of
iv) further purifying said Chikungunya virus preparation (c) on a solid-phase matrix packed in a column comprising a ligand-activated core and an inactive shell comprising pores, wherein the molecular weight cut off of the pores excludes the virus particles from entering the ligand-activated core, and wherein a molecule smaller than the molecular weight cut-off of the pores can enter the ligand-activated core,
to obtain a Chikungunya virus preparation (d).
3. The method according to claim 1 , wherein said crude harvest (a) comprising Chikungunya virus particles and impurities is subjected to one or more pre-purification step(s) prior to step (ii), wherein said one or more pre-purification step(s) comprise
a) filtration using a filter having a pore size equal to or less than 0.2 μm; and/or
b) digestion of host cell genomic DNA by enzymatic treatment; and/or
c) ultra/diafiltration using a hollow fiber membrane having a pore size equal to or greater than 100 kDa.
4. The method according to claim 1 , wherein the residual host cell DNA content of said Chikungunya virus preparation (c) is less than 10 ng/mL and the residual host cell protein content of said Chikungunya virus preparation (c) is less than 100 ng/mL.
5. The method according to claim 1 , wherein the concentration of protamine is from 0.5 mg/ml to 3 mg/ml.
6. The method according to claim 1 , wherein said protamine is selected from the group consisting of a protamine salt, a protamine sulphate and a recombinant protamine sulphate.
7. The method according to claim 1 , wherein the enrichment of infectious Chikungunya virus particles in said Chikungunya virus preparation (c) or any final virus preparation relative to total virus products in the crude harvest (a) is in the range of at least 50% to 95%.
8. The method according to claim 1 , wherein said infectious Chikungunya virus particles are propagated in a cell line selected from the group consisting of an EB66 cell line, a Vero cell line, a Vero-αHis cell line, a HeLa cell line, a HeLa-S3 cell line, a 293 cell line, a PC12 cell line, a CHO cell line, a 3T3 cell line, a PerC6 cell line, an MDSK cell line, a chicken embryonic fibroblast cell line, a duck cell line and a diploid avian cell line.
9. The method according to claim 1 , wherein said infectious Chikungunya virus particles are selected from the group consisting of a live virus, a live attenuated virus, a chimeric virus, a modified live virus, and a recombinant live virus.
10. The method according to claim 9 , wherein said live attenuated virus has an RNA genome corresponding to the DNA sequence provided by SEQ ID NO: 77, or an immunogenic variant thereof, wherein said immunogenic variant has an RNA genome that is at least 88% identical to the corresponding DNA sequence of SEQ ID NO: 77 and is able to pack an infectious Chikungunya virus.
11. The method according to claim 1 , wherein said step resulting in the Chikungunya virus preparation (c) or (d) is followed by an inactivation step.
12. The method according to claim 11 , wherein said inactivation step is a formaldehyde inactivation step.