Stress Factors Affecting the Cryopreservation of Biological Components of Seed Virus for Avian Influenza Vaccine Production

In the past, many studies have been done to cryopreserve biological materials for future vaccine production. Scientists have been using different chemicals as cryoprotectants to preserve their cell lines on which desired viruses can be cultivated. Researchers have always been in search for better molecules to avoid cryoinjury during process of cryopreservation. In the present study, different molecules were evaluated for cryo-potency in preserving master seeds of “Vero cell” line and “Avian Influenza viruses”. Cryoprotectants such as (Dimethyl sulfoxide) DMSO and Glycerol were used in different concentration and evaluated at -80oC and -196oC for different time interval. After 15 days and 30 days of cryopreservation the percentage viability of preserved cells were almost equal at both temperatures whereas, after 60 days, 90 days and 120 days the higher percentage of viability was recorded at -196oC for both Vero cells and Avian Influenza virus.  Different pH levels were set for both samples separately with same time interval and found slightly acidic pH (pH5.5) optimum for cryopreservation of Vero cell line and Neutral pH (pH7) for Avian Influenza virus. DMSO (20%) and Glycerol (40%) showed optimum percentage viability when cryopreserved for 120 days without any ill effect.