How can we to improve the titer of the virus in the cell culture?A strain of porcine parvovirus was isolated from a diseased pig. and it was cultivted for 3month and 30 passages,The TCID50 of the virus is 8.1*108， How can i improve the titer of the virus?
Over-passaging reduces virulence of parasite. One of the best way of increasing virulence of parasite is to grow it in suitable permissible host animal.
what i hope is to reduce the virulence,but the immunogenicity can be higher.And you said cultivated in siutable host animal is a way ,Will the virulence be increased?I don't think so. As we know the virulence of the Classic swine fever virus of China strains(shimen strain) was reduced by passaged in rabbit.
The virus titre you achieved is quite high and it will be difficult to increase it. You may try modifications of cultivation conditions, such as lowering the temperature to 35 C or increasing or decrteasing the content of bicarbonate in the cultivation medium. Definitely, you will increase the virus titre in your prepartions by physical means (such as ultracentrifugation)
Thanks for your suggestion , Vladimir Vonka, I tried to cultivated it at 39℃ for about a month,and trhere were no change. The physical way maybe is a solution but titre is not really get improved.
The answers of Dr. Vladimire are good, your virus title is high. perhaps you can decrease the quantity af medium (1/2 ) to concentrate the harvest along the culture. you can study the MOI of your viruse, you can use limit dilution to select a good one virus to use as seed. you can use the comparative culture cells ( feline cells..)
From my distant experience the culture of parvovirus, I can say that an infectious titer of between 108 and 109 is a very good title. Parvovirus grows on dividing cells, which limits the productivity of the cell culture.
Empirical techniques to reduce the virulence, such as the change in culture temperature, or change in target cells (as was the case for the C30 strain of classical swine fever) is very generally result in a sharp decline in production viral particles.
for example: the virus of swine fever has declined from 107 to the wild strain, 105 for lapinised C30 strain and produced in sheep kidney.
The same for FIV which was 107 on cat PBMC, and 105 after adaptation to culture CRKF.
Many other vaccine viruses have given this type of results: Aujezsky, BVDV, panleukopenia cat ....
Finally I think you have a great viral titer it will be difficult to increase.
Thanks for your answer Jean-Jacques Pin,I agree with your opinnion.and we have changed many ways to cultivate the virus, what a pity is no changing was obvioused.
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