Which body fluid is NOT known to transmit HIV?

Saliva is not considered a significant vector for the transmission of HIV. While HIV can be detected in saliva, the concentration of the virus is much lower than in other bodily fluids such as blood, semen, or breast milk. The presence of enzymes and other components in saliva also inhibits the virus's ability to infect cells, making transmission through saliva exceedingly rare. The primary modes of HIV transmission involve direct exposure to blood, semen, vaginal fluids, and breast milk, where the virus is present in much higher concentrations and capable of establishing infection.