Room temperature stabilization of oral, live attenuated Salmonella enterica serovar Typhi-vectored vaccines.

Foam drying, a modified freeze drying process, was utilized to produce a heat-stable, live attenuated Salmonella Typhi 'Ty21a' bacterial vaccine. Ty21a vaccine was formulated with pharmaceutically approved stabilizers, including sugars, plasticizers, amino acids, and proteins. Growth media and harvesting conditions of the bacteria were also studied to enhance resistance to desiccation stress encountered during processing as well as subsequent storage at elevated temperatures.

Towards development of stable formulations of a live attenuated bacterial vaccine: a preformulation study facilitated by a biophysical approach.

Development of optimal formulation conditions stabilizing live attenuated bacterial vaccines is impeded by traditional methods used for viability measurement. To facilitate preformulation studies of such vaccines, spectroscopic techniques capable of providing real-time and high throughput information have been employed to obtain a global stability profile for a live attenuated Ty21a bacterial typhoid vaccine over a wide range of pH (4 to 8) and temperature (10 to 85 degrees C). Using the data obtained from fluorescence and circular dichroism techniques, an empirical phase diagram (EPD) has been subsequently constructed, which suggests that Ty21a cells exist in at least four apparent physical phases related to different viability states, with the most stable phase at pH 6 and 7 at temperatures below 30 degrees C.