One-step chromatographic purification of human papillomavirus type 16 L1 protein from Saccharomyces cerevisiae.

The prophylactic human papillomavirus vaccine is based on recombinant L1 protein produced in yeast or insect cells. L1 is a major capsid protein that self-assembles into virus-like particles (VLP). Conventionally, several chromatography steps are required to purify it; the steps are time consuming, and they result in losses of the target protein. Ultracentrifugation using a sucrose cushions or cesium chloride density gradients, and size-exclusion chromatography, has also been routinely used for small scale purification of L1 protein. However, these methods require a great deal of time and labor, and are not suitable for industrial-scale purification. To resolve these problems, we have developed two simple one-step chromatography methods for purifying recombinant HPV16 L1 protein produced in Saccharomyces cerevisiae. Eighty percent of the contaminating protein was removed by ammonium sulfate precipitation and by precipitating contaminants prior to the chromatography step. One method uses heparin chromatography and the other, cation-exchange chromatography, and recoveries by the two methods were both about 60%, the highest recoveries of L1 protein achieved so far. We confirmed that HPV16 L1 protein purified by either method self-assembles into VLP. We anticipate that these one-step chromatography methods will reduce the time, cost and labor needed for purification of L1 protein, and facilitate the study of prophylactic HPV vaccines.