This process is facilitated by a BBB disruption brought about by circulating microbial endotoxins - such as lipopolysaccharide found on Gram-negative bacteria - that enter the blood stream by translocation from the gastrointestinal tract during the acute phase of HIV infection [22-24] and by soluble HIV proteins such as Tat, Nef and gp120 [25]. The gene discussed is TAT; the disease is HIV infectious disease.