Xero6ac: E.E. Worrall a,*, J.K. Litamoi b, B.M. Seck b, G. Ayelet b
The accepted procedure for the long-term preservation of live viruses and bacteria in vaccines has been lyophilisation. We show that thermolabile viruses can be dehydrated in vitro, within 18 h, in an excipient containing trehalose. We further demonstrate that in the resulting dehydrated state, where the viruses are captive in a metastable glass composed of trehalose, they are capable of resisting 45°C for a period of 14 days with minimal loss of potency.
© 2000 Elsevier Science Ltd. All rights reserved.
The preservation of biodegradable materials by dehydration and osmoconcentration is a familiar and ancient technology. When the task of preserving sensitive biomolecules became necessary, simple drying by dehydration failed, as structural water was removed, causing subsequent denaturation and loss of vital activity. Cryopreservation in liquid nitrogen and lyophilisation have become the accepted methods for the long term preservation of sensitive biomolecules, the latter method being used extensively for the preservation of live attenuated vaccines.
The results obtained from paired samples of RP and PPR vaccine dried for 1 h, using the method described above, in comparison with a control sample of lyophilised vaccine, and also with the parent untreated virus pool containing 2.5% trehalose were as depicted in Tables 3 and 4. The excipient containing 2.5% trehalose gave good protection of RP virus following the 1-h rapid dehydration at 37°C under conditions of reduced pressure at 800 mbar with the loss following drying of 0.45 log10 TCID50:ml. The protection of the PPR virus in the same excipient was excellent with only the loss of 0.15 log10 TCID50:ml following drying. The inclusion of a lyophilised reference vaccine of known titre was merely included as a check on the virus titration procedure.