The present invention refers to Tat as the active principle for a prophylactic andor therapeutic vaccine against HIV infection, the progression towards AIDS and the development of tumors and other syndromes and symptoms in subjects infected by HIV. The present invention also relates to a water purification apparatus which includes the hydrophilic membrane, comprising one or more layers of hydrophilic polymers, to purify water which may contain suspended or dissolved impurities and solids, including but not limited to seawater, brackish water and other kinds of polluted water. Overhead is reduced by generating a trace hook only in response to activity associated with lock misses.